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Background: Xylopic acid (XA), a kaurene diterpene from the dried fruits of Xylopia aethiopica, has anxiolytic- and antidepressant-like activity in mice and zebrafish. We aimed to assess the potential synergistic antidepressant-like effects of XA when combined with selected antidepressants in the mouse forced-swim test. Materials and methods: The antidepressant-like effect of xylopic acid (XA) (10, 30, 100 mgkg−1), fluoxetine (Flx) (3, 10, 30 mgkg−1), sertraline (Sert) (3, 10, 30 mgkg−1), imipramine (Imi) (10, 30, 100 mgkg-1) and ketamine (Ket) (0.1, 0.3, 1.0 mgkg−1), was evaluated in forced swim test. The dose (ED50) that achieved a 50% reduction in immobility time was determined from the respective log-dose response curves. XA and the selected antidepressants were co-administered in fixed-dose ratio combinations (1/2:1/2, 1/4:1/4, 1/8:1/8) of the ED50 to identify the experimental ED50 (ED50mix). The theoretical ED50(ED50add), of all combinations was determined using isobolograms and compared with the ED50mix to identify the nature of the interaction. The effect of dose combinations on general locomotor activity was assessed in the open-field test. Results: The interaction index (γ) for the following XA combinations, XA/Flx, XA/Sert, XA/Imi and XA/Ket were 0.42, 0.41, 0.31 and 0.34. An independent sample t-test revealed that the experimental ED50 (ED50mix) was significantly lower than the theoretical ED50 (ED50add) in all combinations of XA, indicative of a synergistic antidepressant-like effect. However, combinations of XA with ketamine significantly reduced general locomotor activity at all dose combinations. Conclusion: The co-administration of xylopic acid and fluoxetine, imipramine, sertraline and ketamine produces a synergistic antidepressant-like effect in mice.

Background: Plant-derived antimicrobials (PDAs) are considered a viable alternative to synthetic antimicrobial agents. Diverse antimicrobial mechanisms of PDAs significantly reduce the risk of developing antimicrobial resistance. Utilization of PDAs also offers economic and environmental advantages, as they can be derived from agricultural byproducts, such as olive pomace. Results: In this study, a green, water-based, ultrasound-assisted extraction (UAE) was deployed to obtain aqueous olive pomace extract (OPE) from dry olive pomace. Total phenolic content, extraction yield, chemical compositions, and antimicrobial activities of OPE were evaluated. In addition, the potential synergistic interaction between the phenolic components in OPE and the antimicrobial mechanisms underlying the synergistic interaction were characterized. The results show that ca. 25 mg GAE/g of extraction yields were achieved by the UAE of dry olive pomace. Based on the high-performance liquid chromatography (HPLC) analysis, diverse phenolic compounds such as gallic acid (GA), hydroxytyrosol (HT), and 4-hydroxyphenylacetic acid (4-HPA) were identified in OPE. OPE exhibited strong antimicrobial activities, and 0.2 mg GAE/mL of OPE achieved > 5 log reductions of Escherichia coli O157:H7 and Listeria innocua cells within 30 min of treatment. A 3D isobologram analysis demonstrated that OPE exhibited strong synergistic antimicrobial activities, compared to those of individual phenolic components (GA, HT, or 4-HPA), showing interaction index (γ) of 0.092 and 0.014 against E. coli O157:H7 and L. innocua, respectively (γ < 1: synergistic activity). Antimicrobial mechanism analyses revealed that phenolic components in OPE exerted strong synergistic activities through diverse modes of action, and increased levels of oxidative stress, membrane damage, and decreased levels of metabolic activities were observed in the OPE-treated bacterial cells. Conclusions: These findings demonstrate an approach for valorizing agricultural byproducts to develop plant byproduct-based antimicrobials with strong synergistic activities. Multiple modes of action of this byproduct extract may enable the control of diverse microbes in food and agriculture systems. [ABSTRACT FROM AUTHOR]

This study examined the cutaneous analgesic effects of lidocaine co-injected with guanfacine and its comparison with dexmedetomidine. Cutaneous analgesic effects are quantified through the blocking effects of the cutaneous trunci muscle reflex against skin pinpricks in rats. The dose-response curves of guanfacine, dexmedetomidine, and lidocaine were constructed and drug-drug interactions were analyzed by the ED50 isobologram. Subcutaneous injections of guanfacine, dexmedetomidine, and lidocaine produced dose-dependently nociceptive/sensory blockade. On the ED50 (50% effective dose) basis, the potency rankings of the drug are dexmedetomidine (0.09 [0.08–0.11] μmol/kg) > guanfacine (3.98 [2.96–5.34] μmol/kg) > lidocaine (25.40 [23.51–27.44] μmol/kg) (p < 0.01). On their equipotent doses (ED25, ED50, and ED75), the duration of sensory blockade induced by guanfacine or dexmedetomidine was longer than lidocaine's (p < 0.01). Both guanfacine and dexmedetomidine showed synergistic effects with lidocaine. We showed that guanfacine elicits dose-dependent cutaneous analgesia when administered subcutaneously. Lidocaine is less potent than guanfacine or dexmedetomidine. Both guanfacine and dexmedetomidine enhance the potency and duration of lidocaine. Better synergistic responses we are getting with guanfacine plus lidocaine. [ABSTRACT FROM AUTHOR]

Introduction: The recreational use of fentanyl in combination with xylazine (i.e., "tranq-dope") represents a rapidly emerging public health threat characterized by significant toxicity and mortality. This study quantified the interactions between these drugs on lethality and examined the effectiveness of potential rescue medications to prevent a lethal overdose. Methods: Male and femalemice were administered acute doses of fentanyl, xylazine, or their combination via intraperitoneal injection, and lethalitywas determined 0.5, 1.0, 1.5, 2.0, and 24 h after administration. Both fentanyl and xylazine produced dosedependent increases in lethality when administered alone. Results: A nonlethal dose of fentanyl (56 mg/kg) produced an approximately 5-fold decrease in the estimated LD50 for xylazine (i.e., the dose estimated to produce lethality in 50% of the population). Notably, a nonlethal dose of xylazine (100 mg/kg) produced an approximately 100-fold decrease in the estimated LD50 for fentanyl. Both drug combinations produced a synergistic interaction as determined via isobolographic analysis. The opioid receptor antagonist, naloxone (3 mg/kg), but not the alpha-2 adrenergic receptor antagonist, yohimbine (3 mg/kg), significantly decreased the lethality of a fentanyl-xylazine combination. Lethality was rapid, with death occurring within 10 min after a high dose combination and generally within 30 min at lower dose combinations. Males were more sensitive to the lethal effects of fentanyl-xylazine combinations under some conditions suggesting biologically relevant sex differences in sensitivity to fentanyl-xylazine lethality. Discussion: These data provide the first quantification of the lethal effects of "tranq-dope" and suggest that rapid administration of naloxone may be effective at preventing death following overdose. [ABSTRACT FROM AUTHOR]

[Display omitted] The potentiation of pharmacological effects can be achieved through several strategies, such as the association of substances and delivery in nanostructured systems. In practice, potentiation can be measured by the law of mass action and joint evaluation of the combination index (CI) and dose–response curves. In this context, this study aimed to evaluate the anti-inflammatory effect of the association of β-caryophyllene and indomethacin in the free form and delivered in nanoemulsions using the in vitro model of LPS-stimulated murine macrophage. The results indicated potentiation of the anti-inflammatory effect of nanoemulsified substances compared to free substances, as well as synergistic action between the sesquiterpene and the selected NSAID. In comparison, the association of β-caryophyllene and indomethacin in the free form inhibited the production of nitric oxide by 50% at 48.60 µg/mL (CI = 0.21), while the nanoemulsified association of these substances resulted in an IC 50 of 1.45 µg/mL (CI = 0.14). In parallel, cytotoxicity assays on HaCaT and MRC-5 cell lines demonstrated the safety of IC 50 -equivalent concentrations of the anti-inflammatory action, and no irritating effects on the chorioallantoic membrane of embryonated eggs were observed (HET-CAM assay). The results suggest that β-caryophyllene may be an alternative to replace an inert oily core in nanoemulsion systems when anti-inflammatory effects are desirable. [ABSTRACT FROM AUTHOR]

Objective: The antinociceptive pharmacological interaction between N-palmitoylethanolamide (PEA) and morphine (MOR), as well as gabapentin (GBP), was investigated to obtain synergistic antinociception at doses where side effects were minimal. In addition, the possible antinociceptive mechanism of PEA + MOR or PEA + GBP combinations was explored. Methods: Individual dose-response curves (DRCs) of PEA, MOR and GBP were evaluated in female mice in which intraplantar nociception was induced with 2% formalin. Isobolographic method was used to detect the pharmacological interaction in the combination of PEA + MOR or PEA + GBP. Key findings: The ED50 was calculated from the DRC; the order of potency was MOR > PEA > GBP. The isobolographic analysis was obtained at a 1:1 ratio to determine the pharmacological interaction. The experimental values of flinching (PEA + MOR, Zexp = 2.72 ± 0.2 μg/paw and PEA + GBP Zexp = 2.77 ± 0.19 μg/paw) were significantly lower than those calculated theoretically (PEA + MOR Zadd = 7.78 ± 1.07 and PEA + GBP Zadd = 24.05 ± 1.91 μg/paw), resulting in synergistic antinociception. Pretreatment with GW6471 and naloxone demonstrated that peroxisome proliferator-activated receptor alpha (PPARα) and opioid receptors are involved in both interactions. Conclusions: These results suggest that MOR and GBP synergistically enhance PEA-induced antinociception through PPARα and opioid receptor mechanisms. Furthermore, the results suggest that combinations containing PEA with MOR or GBP could be of interest in aiding the treatment of inflammatory pain. [ABSTRACT FROM AUTHOR]

The prevalence of clinical resistance of P. falciparum towards artemisinin and its partner drugs has significantly hampered malarial chemotherapy. To circumvent this situation, identifying a new class of partner drugs with significant anti-malarial efficacy and multi-stage activity can slow the development of resistance. This study demonstrates the potential interactions of carboxylic ionophores such as monensin (MON), maduramicin (MAD) or salinomycin (SAL) with standard antimalarial drugs artemisinin (ART) or chloroquine (CQ). The in vitro drug interactions were studied in P. falciparum 3D7 strain by a growth inhibition SYBR green 1 assay. The asynchronized parasites were exposed for 48 h in the presence of varying proportions of two drug concentrations using the modified fixed-ratio isobologram method. We determined the growth inhibition response and the sums of the fractional inhibitory concentrations (ΣFICs) of the following drug combinations (4:1, 3:2, 2:3, 1:4) and (1:1, 1:3, 3:1) were calculated for 50% inhibitory concentrations (IC50s). Combining artemisinin with monensin, maduramicin, or salinomycin showed significant additive interaction. A combination of chloroquine with monensin, maduramicin, or salinomycin showed slight synergism to additive interaction. None of the drug combinations displayed an antagonistic effect indicating ionophores usage in combination therapy to treat drug-resistant malarial infections.

Introduction: The recreational use of fentanyl in combination with xylazine (i.e., “tranq-dope”) represents a rapidly emerging public health threat characterized by significant toxicity and mortality. This study quantified the interactions between these drugs on lethality and examined the effectiveness of potential rescue medications to prevent a lethal overdose.Methods: Male and female mice were administered acute doses of fentanyl, xylazine, or their combination via intraperitoneal injection, and lethality was determined 0.5, 1.0, 1.5, 2.0, and 24 h after administration. Both fentanyl and xylazine produced dose-dependent increases in lethality when administered alone.Results: A nonlethal dose of fentanyl (56 mg/kg) produced an approximately 5-fold decrease in the estimated LD50 for xylazine (i.e., the dose estimated to produce lethality in 50% of the population). Notably, a nonlethal dose of xylazine (100 mg/kg) produced an approximately 100-fold decrease in the estimated LD50 for fentanyl. Both drug combinations produced a synergistic interaction as determined via isobolographic analysis. The opioid receptor antagonist, naloxone (3 mg/kg), but not the alpha-2 adrenergic receptor antagonist, yohimbine (3 mg/kg), significantly decreased the lethality of a fentanyl-xylazine combination. Lethality was rapid, with death occurring within 10 min after a high dose combination and generally within 30 min at lower dose combinations. Males were more sensitive to the lethal effects of fentanyl-xylazine combinations under some conditions suggesting biologically relevant sex differences in sensitivity to fentanyl-xylazine lethality.Discussion: These data provide the first quantification of the lethal effects of “tranq-dope” and suggest that rapid administration of naloxone may be effective at preventing death following overdose.

Pain represents one of the leading causes of suffering and disability worldwide. Currently available drugs cannot treat all types of pain and may have adverse effects. Hence, the use of pharmacological combinations is an alternative treatment strategy. Therefore, this study aimed to evaluate the combination of resveratrol and ketorolac through isobolographic analysis. CD1 mice were used to study the antinociceptive effect of this combination using the formalin test and the study was divided into two phases. In the first phase, four individual doses of each drug were evaluated, totaling eight testing groups. From these data, the median effective doses (ED50) of each drug were calculated. In the second phase, four testing groups were used to evaluate the combination of sub-doses of both drugs and obtain the experimental ED50. To evaluate gastric damage, five groups were employed, including indomethacin, vehicle, resveratrol, ketorolac, and combined resveratrol and ketorolac groups. Stomach samples from the mice were taken after 5 h of treatment, and the area of the ulcers was determined. Resveratrol plus ketorolac elicited a reduction in nociceptive behavior during both phases of the formalin test, and isobologram analysis revealed that the theoretical and experimental ED50 values of resveratrol and ketorolac did not differ significantly, implying an additive interaction between the drugs. Additionally, the drug combination did not generate gastric ulcers, thus enhancing the desired effects without increasing the adverse effects. Consequently, these findings substantiate the efficacy of the resveratrol and ketorolac combination in the formalin test, thereby highlighting its potential as a viable alternative for alleviating pain. [ABSTRACT FROM AUTHOR]

Kazutaka Nozawa,1 Yusuke Karasawa,1 Yuka Shidahara,2 Takahiro Ushida3 1Medical Affairs, Viatris Pharmaceuticals Japan Inc., Minato-ku, Tokyo, Japan; 2Bioscience Business Division, KAC Co., Ltd, Ritto, Shiga, Japan; 3Multidisciplinary Pain Center, Aichi Medical University, Nagakute, Aichi, JapanCorrespondence: Kazutaka Nozawa, Medical Affairs, Viatris Pharmaceuticals Japan Inc, Minato-ku, Tokyo, Japan, Tel +81 80-5001-3029, Email Kazutaka.Nozawa@viatris.comPurpose: Neuropathic pain is sometimes difficult to manage because of limited efficacy of analgesic monotherapy even at high doses. Combination therapy may help address this issue, but there is little evidence for its effectiveness. Therefore, we evaluated the efficacy of combination therapy with pregabalin, an anchor drug for treating neuropathic pain, using the rat L5 spinal nerve ligation model.Methods: Experiments were performed on four-week-old L5 spinal nerve ligated male Sprague-Dawley rats. Mechanical allodynia was assessed using the von Frey test, where the 50% withdrawal threshold was evaluated for five drugs: pregabalin, duloxetine, venlafaxine, tramadol, and celecoxib. The single-drug experiment included 112 rats, where each drug was tested independently. Median effective doses (ED50s) were determined. Combinations of pregabalin with each of the other four drugs were tested (n=84). The 50% withdrawal threshold in the von Frey test was evaluated. The ED50 of each combination was determined experimentally. Isobolographic analyses were conducted to assess the synergistic potential of the drug combinations, excluding pregabalin-celecoxib, since the ED50 of celecoxib could not be determined.Results: In the single-drug experiment, all drugs except celecoxib resulted in a dose-dependent increase in the 50% withdrawal threshold 2 h after administration, with a maximum possible effect ranging from 4.4% to 79.6%. Similarly, all pregabalin combinations demonstrated a dose-dependent increase in the 50% withdrawal threshold, with pregabalin-tramadol showing the greatest increment. Isobolographic analysis of this combination revealed synergistic effects. Specifically, the combination index was γ=0.4 (< 1). Combinations of pregabalin with duloxetine and venlafaxine demonstrated additive (γ=0.9) and antagonistic effects (γ=2.0), respectively.Conclusion: This study demonstrated that combination of pregabalin with tramadol has synergistic antiallodynic effects, while that with duloxetine has additive effects. Moreover, pregabalin combined with venlafaxine was potentially antagonistic. Pregabalin combined with tramadol may serve as a promising drug combination for the effective management of neuropathic pain.Keywords: analgesic, animal model, isobologram, synergistic effects

Humans are exposed to complex mixtures of mycotoxins through diet. Despite the serious threat they pose, mycotoxin risk assessment often overlooks co-exposure. With the aim of filling this gap, the present study investigates the combined cytotoxicity of sterigmatocystin (STE), ochratoxin A (OTA) and patulin (PAT) in human tumour Neuroblastoma and healthy Mesenchymal Stem Cells three-dimensional (3D) spheroids. The range of concentrations tested (1.56–50 μM for STE, 0.78–25 μM for OTA and 0.15–5 μM for PAT) was selected considering the IC 50 values obtained in previous studies and the estimated dietary exposure of consumers. To ensure appropriate experimental conditions, assessments for single mycotoxins and their combinations were conducted simultaneously. The nature of the toxicological interactions among the mycotoxins was then defined using the isobologram analysis. Our results demonstrated increased cytotoxicity in mycotoxin mixtures compared to individual exposure, with abundance of synergistic interactions. These findings highlight that the co-occurrence of STE, OTA and PAT in food may increase their individual toxic effects and should not be underestimated. Moreover, the use of advanced culture models increased the reliability and physiological relevance of our results which can serve as a groundwork for formulating standardized regulatory approaches towards mycotoxin mixtures in food and feed. • To assess the cytotoxicity associated with the co-exposure to STE, OTA and PAT. • To facilitate a deeper understanding, advanced culture models (spheroids) were used. • The nature of toxicological interactions was defined by isobologram analysis. • In BM-MSCs spheroids, single mycotoxin effects were enhanced by combined exposure. • In SH-SY5Y spheroids, mainly additive/synergistic interactions were revealed. [ABSTRACT FROM AUTHOR]

Xanthine oxidase (XO) has been well-recognized as a key enzyme in the pathogenesis of hyperuricemia. In this study, Chuanxiong Rhizome, a tonic food widely consumed in China, was found to inhibit XO activity. The potential XO inhibitory ingredients were screened by UPLC-ZenoTOF system and bioactivity assays. Coniferyl ferulate (CF), a main constitute of Chuanxiong Rhizome, was identified as a potent XO inhibitor with an IC50 value (1.97 ± 0.11 μM) lower than that of allopurinol (2.49 ± 0.07 μM). Enzyme-kinetic assays showed that CF reversibly inhibited XO in an uncompetitive manner. And hydrogen bonds played crucial roles on the binding interaction according to the fluorescence titration and molecular docking. Moreover, the combination of CF with allopurinol exhibited a synergistic inhibitory effect on XO. Our results revealed for the first time the XO inhibitory effect of CF from Chuanxiong Rhizome, which shed light on its potential application for developing anti-hyperuricemia agents.

Emerging artemisinin resistance in Plasmodium falciparum malaria has the potential to become a global public health crisis. In Southeast Asia, this phenomenon clinically manifests in the form of delayed parasite clearance following artemisinin treatment. Reduced artemisinin susceptibility is limited to the early ring stage window, which is sufficient to allow parasites to survive the short half-life of artemisinin exposure. A screen of known clinically-implemented antimalarial drugs was performed to identify a drug capable of enhancing the killing activity of artemisinins during this critical resistance window. As a result, lumefantrine was found to increase the killing activity of artemisinin against an artemisinin-resistant clinical isolate harboring the C580Y kelch13 mutation. Isobologram analysis revealed synergism during the early ring stage resistance window, when lumefantrine was combined with artemether, an artemisinin derivative clinically partnered with lumefantrine. These findings suggest that lumefantrine should be clinically explored as a partner drug in artemisinin-based combination therapies to control emerging artemisinin resistance.

The bioactive compounds present in the edible products of the olive tree have been extensively studied and their favorable effects on various disease risk factors have been demonstrated. The aim of this study was to perform a comparative analysis of the anti-leishmanial effects of total phenolic fractions (TPFs) derived from extra virgin olive oil with different phenolic contents and diverse quantitative patterns. Moreover, the present study investigated their association with miltefosine, a standard anti-leishmanial drug, against both extracellular promastigotes and intracellular amastigotes of a viscerotropic and a dermotropic Leishmania strain. The chemical compositions of TPFs were determined by high performance liquid chromatography with diode array detection (HPLC-DAD). Analysis of parasite growth kinetics, reactive oxygen species production and apoptotic events were determined by microscopy and flow cytometry. Our results revealed that the presence of oleacein (OLEA) and oleocanthal (OLEO) secoiridoids enhances the anti-leishmanial effect of TPF. The association between TPFs and miltefosine was suggested as being additive in Leishmania infantum and Leishmania major promastigotes, and as antagonistic in intracellular amastigotes, as was evaluated with the modified isobologram method. The obtained data verified that TPFs are bioactive dietary extracts with a strong anti-leishmanial activity and highlighted that fractions that are richer in OLEA and OLEO phenolic compounds possess stronger inhibitory effects against parasites. This study may contribute to improving the therapeutic approaches against leishmaniasis. [ABSTRACT FROM AUTHOR]

Pain represents one of the leading causes of suffering and disability worldwide. Currently available drugs cannot treat all types of pain and may have adverse effects. Hence, the use of pharmacological combinations is an alternative treatment strategy. Therefore, this study aimed to evaluate the combination of resveratrol and ketorolac through isobolographic analysis. CD1 mice were used to study the antinociceptive effect of this combination using the formalin test and the study was divided into two phases. In the first phase, four individual doses of each drug were evaluated, totaling eight testing groups. From these data, the median effective doses (ED50) of each drug were calculated. In the second phase, four testing groups were used to evaluate the combination of sub-doses of both drugs and obtain the experimental ED50. To evaluate gastric damage, five groups were employed, including indomethacin, vehicle, resveratrol, ketorolac, and combined resveratrol and ketorolac groups. Stomach samples from the mice were taken after 5 h of treatment, and the area of the ulcers was determined. Resveratrol plus ketorolac elicited a reduction in nociceptive behavior during both phases of the formalin test, and isobologram analysis revealed that the theoretical and experimental ED50 values of resveratrol and ketorolac did not differ significantly, implying an additive interaction between the drugs. Additionally, the drug combination did not generate gastric ulcers, thus enhancing the desired effects without increasing the adverse effects. Consequently, these findings substantiate the efficacy of the resveratrol and ketorolac combination in the formalin test, thereby highlighting its potential as a viable alternative for alleviating pain.

The administration of combinations of drugs is a method widely used in the treatment of different pathologies as it can lead to an increase in the therapeutic effect and a reduction in the dose compared to the administration of single drugs. For these reasons, it is of interest to study combinations of drugs and to determine whether a specific combination has a synergistic, antagonistic or additive effect. Various mathematical models have been developed, which use different methods to evaluate the synergy of a combination of drugs. We have developed an open access and easy to use app that allows different models to be explored and the most fitting to be chosen for the specific experimental data: SiCoDEA (Single and Combined Drug Effect Analysis). Despite the existence of other tools for drug combination analysis, SiCoDEA remains the most complete and flexible since it offers options such as outlier removal or the ability to choose between different models for analysis. SiCoDEA is an easy to use tool for analyzing drug combination data and to have a view of the various steps and offer different results based on the model chosen. [ABSTRACT FROM AUTHOR]

ObjectiveN-butane and n-pentane can both produce general anesthesia. Both compounds potentiate γ-aminobutyric acid type A (GABAA) receptor function, but only butane inhibits N-methyl-d-aspartate (NMDA) receptors. It was hypothesized that butane and pentane would exhibit anesthetic synergy due to their different actions on ligand-gated ion channels.Study designProspective experimental study.AnimalsA total of four Xenopus laevis frogs and 43 Sprague-Dawley rats.MethodsAlkane concentrations for all studies were determined via gas chromatography. Using a Xenopus oocyte expression model, standard two-electrode voltage clamp techniques were used to measure NMDA and GABAA receptor responses in vitro as a function of butane and pentane concentrations relevant to anesthesia. The minimum alveolar concentrations (MAC) of butane and pentane were measured separately in rats, and then pentane MAC was measured during coadministration of 0.25, 0.50 or 0.75 times MAC of butane. An isobole with 95% confidence intervals was constructed using regression analysis. A sum of butane and pentane that was statistically less than the lower-end confidence bound isobole indicated a synergistic interaction.ResultsBoth butane and pentane dose-dependently potentiated GABAA receptor currents over the study concentration range. Butane dose-dependently inhibited NMDA receptor currents, but pentane did not modulate NMDA receptors. Butane and pentane MAC in rats was 39.4±0.7 and 13.7±0.4 %, respectively. A small but significant (p

AbstractBackground Ursolic acid (UA) is a potent plant-based hepatoprotective agent having poor bioavailability, which hampers its therapeutic efficacy. The present study tries to overcome this limitation by combining it with piperine (PIP), a proven bioenhancer and hepatoprotective agent.Methods The type of interaction (synergism, addition, or antagonism) resulting between UA and PIP was analyzed and quantified by isobologram and combination index analysis. The hepatoprotective activity of UA and PIP was evaluated by measuring the level of hepatic marker enzymes. Pharmacokinetic analysis was carried out to ascertain the improvement of bioavailability.Results The combinations significantly decrease the enzyme levels, which indicate better hepatoprotective activity compared to single drugs. The relative oral bioavailability of UA was increased about tenfold (from AUC0–t =12.78 ± 2.59 µg/h/ml to 125.15 ± 1.84 µg/h/ml) along with the improvement of plasma concentration and elimination half-life.Conclusions The findings indicated that the combination of PIP and UA is an effective strategy in enhancing the bioavailability and hepatoprotective potential of UA.KEY MESSAGESUrsolic acid in a combination with piperine provides a synergistic hepatoprotective effect in carbon tetrachloride induced liver damage in rats.Piperine improves the pharmacokinetic properties of ursolic acid when given in combination.Piperine improves the relative oral bioavailability of ursolic acid by tenfold when combined together.

Glioblastoma, a type of brain cancer, is one of the most aggressive and lethal types of malignancy. The present study shows that JCI-20679, an originally synthesized mitochondrial complex I inhibitor, enhances the anti-proliferative effects of suboptimal concentrations of the clinically used chemotherapeutic drug temozolomide in glioblastoma cells. Analysis of the effects of temozolomide combined with JCI-20679 using isobologram and combination index methods demonstrated that the combination had synergistic effects in murine and human glioblastoma cells. We found that JCI-20679 inhibited the temozolomide-mediated induction of autophagy that facilitates cellular survival. The autophagy induced by temozolomide increased ATP production, which confers temozolomide resistance in glioblastoma cells. JCI-20679 blocked temozolomide-mediated increases in ATP levels and increased the AMP/ATP ratio. Furthermore, JCI-20679 enhanced the therapeutic effects of temozolomide in an orthotopic transplantation model of glioblastoma. These results indicate that JCI-20679 may be promising as a novel agent for enhancing the efficacy of temozolomide against glioblastoma. • JCI-20679 synergistically enhances the effects of temozolomide on glioblastoma cells. • JCI-20679 blocks temozolomide-induced autophagy and increases in ATP levels. • JCI-20679 sensitizes an orthotropic glioblastoma mouse model to the effects of temozolomide. [ABSTRACT FROM AUTHOR]

Emerging artemisinin resistance in Plasmodium falciparum malaria has the potential to become a global public health crisis. In Southeast Asia, this phenomenon clinically manifests in the form of delayed parasite clearance following artemisinin treatment. Reduced artemisinin susceptibility is limited to the early ring stage window, which is sufficient to allow parasites to survive the short half-life of artemisinin exposure. A screen of known clinically-implemented antimalarial drugs was performed to identify a drug capable of enhancing the killing activity of artemisinins during this critical resistance window. As a result, lumefantrine was found to increase the killing activity of artemisinin against an artemisinin-resistant clinical isolate harboring the C580Y kelch13 mutation. Isobologram analysis revealed synergism during the early ring stage resistance window, when lumefantrine was combined with artemether, an artemisinin derivative clinically partnered with lumefantrine. These findings suggest that lumefantrine should be clinically explored as a partner drug in artemisinin-based combination therapies to control emerging artemisinin resistance. [Display omitted] • Artemisinin booster compound screening targeting the early ring resistance window in Plasmodium falciparum was performed. • Lumefantrine improves the activity of artesunate against the parasite during the resistance window. • Artemether and lumefantrine are synergistic during the early ring stage resistance window. [ABSTRACT FROM AUTHOR]

Ursolic acid (UA) is a potent plant-based hepatoprotective agent having poor bioavailability, which hampers its therapeutic efficacy. The present study tries to overcome this limitation by combining it with piperine (PIP), a proven bioenhancer and hepatoprotective agent. The type of interaction (synergism, addition, or antagonism) resulting between UA and PIP was analyzed and quantified by isobologram and combination index analysis. The hepatoprotective activity of UA and PIP was evaluated by measuring the level of hepatic marker enzymes. Pharmacokinetic analysis was carried out to ascertain the improvement of bioavailability. The combinations significantly decrease the enzyme levels, which indicate better hepatoprotective activity compared to single drugs. The relative oral bioavailability of UA was increased about tenfold (from AUC0–t =12.78 ± 2.59 µg/h/ml to 125.15 ± 1.84 µg/h/ml) along with the improvement of plasma concentration and elimination half-life. The findings indicated that the combination of PIP and UA is an effective strategy in enhancing the bioavailability and hepatoprotective potential of UA. Ursolic acid in a combination with piperine provides a synergistic hepatoprotective effect in carbon tetrachloride induced liver damage in rats. Piperine improves the pharmacokinetic properties of ursolic acid when given in combination. Piperine improves the relative oral bioavailability of ursolic acid by tenfold when combined together. [ABSTRACT FROM AUTHOR]

Clinacanthus nutans (Acanthaceae), locally known as Sabah snake grass, is popularly taken as prevention as well as treatment for cancer in Malaysia, despite lack of concrete clinical evidence. However, it is crucial to evaluate potential antagonistic, additive, or synergistic interactions that may result from the co-treatment of this plant in chemotherapy. In this study, we demonstrate the drug-herb interaction using combination treatment of C. nutans extracts and cyclophosphamide on the WRL 68 cell line. Materials and Methods: Aqueous and 70% ethanol extract of C. nutans leaves were prepared using decoction and maceration methods. MTT assay was used to test single treatment as well as the combination of C. nutans extract and cyclophosphamide. Phytochemical profiling and flavonoid were identified using HPLC. Results: C. nutans ethanolic extract exhibits low antiproliferative activity. A combination of ethanolic extract of C. nutans and cyclophosphamide at various concentrations resulted in antagonism with combination index values of 1.413, 1.482, and 1.525. Flavonoids identified in the phytochemical profile of both extracts were schaftoside, isoorientin, orientin, and vitexin. High flavonoids level in C. nutans ethanolic extract could potentially interact with metabolic enzymes of the cell line, which might have affected metabolism and activated the cyclophosphamide. The in vitro data suggested that there was a potential for drug-herb interactions, which could negatively affect the chemotherapeutic outcomes. Further investigation should be done in vivo and clinical research model.

Introduction: Diabetic neuropathies are the most prevalent chronic complications of diabetes, characterized by pain and substantial morbidity. Although many drugs have been approved for the treatment of this type of pain, including gabapentin, tramadol (TMD), and classical opioids, it is common to report short-term results or potentially severe side effects. TMD, recommended as a second-line treatment can lead to unwanted side effects. Cannabidiol (CBD) has been gaining attention recently due to its therapeutic properties, including pain management. This study aimed to characterize the pharmacological interaction between CBD and TMD over the mechanical allodynia associated with experimental diabetes using isobolographic analysis. Materials and Methods: After diabetes induction by streptozotocin (STZ), diabetic rats were systemically treated with CBD or TMD alone or in combination (doses calculated based on linear regression of effective dose 40% [ED 40 ]) and had the mechanical threshold evaluated using the electronic Von Frey apparatus. Both experimental and theoretical additive ED 40 values ( Z mix and Z add , respectively) were determined for the combination of CBD plus TMD in this model. Results: Acute treatment with CBD (3 or 10 mg/kg) or TMD (2.5, 5, 10, or 20 mg/kg) alone or in combination (0.38+1.65 or 1.14+4.95 mg/kg) significantly improved the mechanical allodynia in STZ-diabetic rats. Isobolographic analysis revealed that experimental ED 40 of the combination ( Z mix ) was 1.9 mg/kg (95% confidence interval [CI]=1.2-2.9) and did not differ from the theoretical additive ED 40 2.0 mg/kg (95% CI=1.5-2.8; Z add ), suggesting an additive antinociceptive effect in this model. Conclusions: Using an isobolographic analysis, these results provide evidence of additive pharmacological interaction between CBD and TMD over the neuropathic pain associated with experimental diabetes induced by STZ.

Noscapine, an opium alkaloid, was discovered to bind tubulin, arrest dividing cells at mitosis, and selectively induce apoptosis to cancer cells. N‐3‐Br‐Benzyl‐Noscapine (Br‐Bn‐Nos), one of the derivatives of noscapine, was demonstrated to have improved anticancer potential compared with noscapine. We approached to evaluate the single and combined effect of Br‐Bn‐Nos and docetaxel (DOX) based on molecular modeling and cellular study. The individual predicted free energy of binding (∆Gbind,pred) for Br‐Bn‐Nos and DOX with tubulin was found to be −28.89 and −36.07 kcal/mol based on molecular mechanics generalized Born solvation area (MM‐GBSA) as well as −26.21 and −34.65 kcal/mol based on molecular mechanics Poisson Boltzmann solvation area (MM‐PBSA), respectively. However, the ∆Gbind,pred of Br‐Bn‐Nos was significantly reduced (−33.02 and −30.24 kcal/mol using MM‐GBSA and MM‐PBSA) in the presence of DOX on its binding pocket. Parenthetically, the ∆Gbind,pred of DOX was significantly reduced (−37.17 and −32.80 kcal/mol using MM‐GBSA and MM‐PBSA) in the presence of Br‐Bn‐Nos on its binding pocket. The reduced ∆Gbind,pred in the presence of Br‐Bn‐Nos and DOX together indicated a combination effect of both the ligands. The combined interaction of both the agents onto tubulin dimmer was also determined experimentally using purified tubulin, in which a combination regimen of Br‐Bn‐Nos and DOX reduced the fluorescence intensity of tubulin to a higher value (68%) compared with the single regimen. Further, isobologram analysis revealed the synergistic effect of Br‐Bn‐Nos and DOX in antiproliferative activity using MCF‐7 cell line at 48 hr (sum FIC = 0.49) and at 72 hr (sum FIC = 0.62). The combination dose regimen of Br‐Bn‐Nos and DOX blocks the cell cycle progression at the G2/M phase and induces apoptosis to cancer cells more effectively compared with the single regimen. Taken together, our study provides compelling evidence that the anticancer potential of noscapine derivatives may be substantially improved when it is used in a combined application with DOX for breast cancer. [ABSTRACT FROM AUTHOR]

The bioactive compounds present in the edible products of the olive tree have been extensively studied and their favorable effects on various disease risk factors have been demonstrated. The aim of this study was to perform a comparative analysis of the anti-leishmanial effects of total phenolic fractions (TPFs) derived from extra virgin olive oil with different phenolic contents and diverse quantitative patterns. Moreover, the present study investigated their association with miltefosine, a standard anti-leishmanial drug, against both extracellular promastigotes and intracellular amastigotes of a viscerotropic and a dermotropic Leishmania strain. The chemical compositions of TPFs were determined by high performance liquid chromatography with diode array detection (HPLC-DAD). Analysis of parasite growth kinetics, reactive oxygen species production and apoptotic events were determined by microscopy and flow cytometry. Our results revealed that the presence of oleacein (OLEA) and oleocanthal (OLEO) secoiridoids enhances the anti-leishmanial effect of TPF. The association between TPFs and miltefosine was suggested as being additive in Leishmania infantum and Leishmania major promastigotes, and as antagonistic in intracellular amastigotes, as was evaluated with the modified isobologram method. The obtained data verified that TPFs are bioactive dietary extracts with a strong anti-leishmanial activity and highlighted that fractions that are richer in OLEA and OLEO phenolic compounds possess stronger inhibitory effects against parasites. This study may contribute to improving the therapeutic approaches against leishmaniasis.

The combination of drugs with different mechanisms of action could be more effective due to an enhanced synergistic activity. The pharmacological interactions between rutin and paracetamol, and rutin and non-steroidal anti-inflammatory drugs (NSAIDs), such as naproxen, ketorolac, and diclofenac were investigated using in vitro and in vivo assays. Individual and drug combination response curves of rutin-NSAIDs, and rutin-paracetamol (each at 0.001–0.1 mmol for in vitro studies and ranging from 1.25–100 mg/kg p.o. for in vivo studies) were evaluated in RAW 264.7 macrophages [inhibition of nitric oxide (NO) using the Griess reagent] and Balb/c mice (acetic acid-induced writhing test). An isobolographic analysis was used to assess the type of interaction between rutin and NSAIDs and rutin-paracetamol in a proportion of 1:1. Rutin alone and in combination with paracetamol and NSAIDs decreased NO production and the number of writhings in a concentration/dose-dependent manner. The isobolograms showed that all in vitro combinations of rutin-NSAIDs and rutin-paracetamol exerted synergistic effects. The combination rutin-diclofenac showed an interaction index of 0.17. In the in vivo assay, the combinations of rutin-diclofenac (interaction index = 0.195) and rutin-ketorolac (interaction index = 0.408) displayed synergistic effects, and the combination rutin-paracetamol exhibited additive effects. Rutin produces synergistic effects with paracetamol and NSAIDs in in vitro and in vivo assays. [Display omitted] [ABSTRACT FROM AUTHOR]

In the environment, organisms are exposed to mixtures of different toxicants, which may interact in ways that are difficult to predict when only considering each component individually. Adapting and expanding tools from pharmacology, the toxicology field uses analytical, graphical, and computational methods to identify and quantify interactions in multi-component mixtures. The two general frameworks are concentration addition, where components have similar modes of action and their effects sum together, or independent action, where components have dissimilar modes of action and do not interact. Other interaction behaviors include synergism and antagonism, where the combined effects are more or less than the additive sum of individual effects. This review covers foundational theory, methods, an in-depth survey of original research from the past 20 years, current trends, and future directions. As humans and ecosystems are exposed to increasingly complex mixtures of environmental contaminants, analyzing mixtures interactions will continue to become a more critical aspect of toxicological research. [ABSTRACT FROM AUTHOR]

The administration of combinations of drugs is a method widely used in the treatment of different pathologies as it can lead to an increase in the therapeutic effect and a reduction in the dose compared to the administration of single drugs. For these reasons, it is of interest to study combinations of drugs and to determine whether a specific combination has a synergistic, antagonistic or additive effect. Various mathematical models have been developed, which use different methods to evaluate the synergy of a combination of drugs. We have developed an open access and easy to use app that allows different models to be explored and the most fitting to be chosen for the specific experimental data: SiCoDEA (Single and Combined Drug Effect Analysis). Despite the existence of other tools for drug combination analysis, SiCoDEA remains the most complete and flexible since it offers options such as outlier removal or the ability to choose between different models for analysis. SiCoDEA is an easy to use tool for analyzing drug combination data and to have a view of the various steps and offer different results based on the model chosen.

The present study aimed to evaluate the antileishmanial effect, the mechanisms of action and the association with miltefosine of Vernonia brasiliana essential oil against Leishmania infantum promastigotes. This essential oil was obtained by hydrodistillation and its chemical composition was determined by gas chromatography-mass spectrometry (GC–MS). The antileishmanial activity against L. infantum promastigotes and cytotoxicity on DH82 cells were evaluated by MTT colorimetric assay. Ultrastructural alterations were evaluated by transmission electron microscopy. Changes in mitochondrial membrane potential, in the production of reactive oxygen species, and analysis of apoptotic events were determined by flow cytometry. The association between the essential oil and miltefosine was evaluated using the modified isobologram method. The most abundant component of the essential oil was β-caryophyllene (21.47 %). Anti-Leishmania assays indicated an IC50 of 39.01 ± 1.080 μg/mL for promastigote forms after 72 h of treatment. The cytotoxic concentration for DH82 cells was 63.13 ± 1.211 μg/mL after 24 h of treatment. The effect against L. infantum was proven through the ultrastructural changes caused by the oil, such as kinetoplast and mitochondrial swelling, vesicles in the flagellar pocket, discontinuity of the nuclear membrane, nuclear fragmentation and condensation, and loss of organelles. It was observed that the oil leads to a decrease in the mitochondrial membrane potential (35.10 %, p = 0.0031), increased reactive oxygen species production, and cell death by late apoptosis (17.60 %, p = 0.020). The combination of the essential oil and miltefosine exhibited an antagonistic effect. This study evidences the antileishmanial action of V. brasiliana essential oil against L. infantum promastigotes.

The present study investigated the synergistic potential of methanol extract/fractions of Camellia sinensis (L.) Kuntze (CSM) leaves and orlistat on inhibition of Pancreatic Lipase (PL). Since PL is responsible for 50–70% of dietary fats digestion, its inhibition is considered as a promising target for the management of obesity. A synergy guided fractionation strategy has been incorporated with the help of combination index (CI) and isobologram methods. CSM exhibited a potential synergistic activity in combination with orlistat (CI value: 0.66). Amongst the subfractions of CSM, polyphenol-rich fraction exhibited a greater synergistic potential (CI-0.35) than remaining fractions. HPLC analysis identified epicatechin gallate (ECG) and epigallocatechin gallate (EGCG) as major phytochemicals in polyphenol-rich fraction and the most active subfractions (F6 and F7). Two drug and three-drug combinations of these phytochemicals were investigated by partnering with orlistat. The three-drug combination (orlistat-EGCG-ECG) exhibited a greater synergistic potential (CI value-0.17) than the two-drug combinations of EGCG-orlistat and ECG-orlistat (CI values of 0.40 & 0.71, respectively). The resultant orlistat-EGCG-ECG combination resulted in a 12.11-fold dose reduction index for orlistat. Thus, synergistic drug combinations of polyphenol-rich fraction along with orlistat offers the prospect to enhance the orlistat anti-obesity efficacy in a decreased dose level, that will help to reduce its associated toxicities while maintaining its efficacy. Image, graphical abstract • Methanol extract of C. sinensis was subjected to synergy guided fractionation. • Polyphenol rich fraction showed synergistic potential than the subsequent fractions. • A three-drug synergy of EGC: EGCG: orlistat was performed. • A 12.11-fold dose reduction of orlistat was achieved. • First report on the role of phytochemicals as potential synergists for orlistat. [ABSTRACT FROM AUTHOR]

Opioid analgesics represent a critical treatment for chronic pain in the analgesic ladder of the World Health Organization. However, their use can result in a number of unwanted side-effects including incomplete efficacy, constipation, physical dependence, and overdose liability. Cannabinoids enhance the pain-relieving effects of opioids in preclinical studies and dampen unwanted side-effects resulting from excessive opioid intake. We recently reported that a CB1 positive allosteric modulator (PAM) exhibits antinociceptive efficacy in models of pathological pain and lacks the adverse side effects of direct CB1 receptor activation. In the present study, we evaluated whether a CB1 PAM would enhance morphine’s therapeutic efficacy in an animal model of chemotherapy-induced neuropathic pain and characterized its impact on unwanted side-effects associated with chronic opioid administration. In paclitaxel-treated mice, both the CB1 PAM GAT211 and the opioid analgesic morphine reduced paclitaxel-induced behavioral hypersensitivities to mechanical and cold stimulation in a dose-dependent manner. Isobolographic analysis revealed that combinations of GAT211 and morphine resulted in anti-allodynic synergism. In paclitaxel-treated mice, a sub-threshold dose of GAT211 prevented the development of tolerance to the anti-allodynic effects of morphine over 20 days of once daily dosing. However, GAT211 did not reliably alter somatic withdrawal signs (i.e., jumps, paw tremors) in morphine-dependent neuropathic mice challenged with naloxone. In otherwise naïve mice, GAT211 also prolonged antinociceptive efficacy of morphine in the tail-flick test and reduced the overall right-ward shift in the ED50 for morphine to produce antinociception in the tail-flick test, consistent with attenuation of morphine tolerance. Pretreatment with GAT211 did not alter somatic signs of μ opioid receptor dependence in mice rendered dependent upon morphine via subcutaneous implantation of a morphine pellet. Moreover, GAT211 did not reliably alter μ-opioid receptor-mediated reward as measured by conditioned place preference to morphine. Our results suggest that a CB1 PAM may be beneficial in enhancing and prolonging the therapeutic properties of opioids while potentially sparing unwanted side-effects (e.g., tolerance) that occur with repeated opioid treatment.

Chlorpyrifos (CPF) and aflatoxin B1 (AFB1) are each known to adversely affect hepatic tissue individually, but their combined hepatic effects have never been previously investigated. HepG2 cell viability, oxidative status, and genetic impairment were examined after exposing HepG2 cells to: (1) CPF alone, (2) AFB1 alone, and (3) CPF and AFB1 combined (20:1). CPF exposure decreased cell viability, reduced glutathione (GSH) content, and superoxide dismutase (SOD) activity but increased both glutathione peroxidase (GPx) and paraoxonase 1 activity. AFB1 exposure decreased cell viability and GSH content but increased reactive oxygen species (ROS) production. CPF and AFB1 combined exposure decreased GSH content (p < 0.05) further over individual CPF and AFB1 exposures. Induction of micronucleus formation was detected in AFB1-treated cells but undetected in both CPF and combination-treated cells. In conclusion, cytotoxic effects caused by combined exposure were antagonistic, as shown by a combination index value of 1.67. Although no change in ROS production was observed in CPF groups, the overall results confirmed the occurrence of oxidative stress through the alterations of GSH content, GPx, and SOD activity. Only intracellular GSH was evidently changed upon exposure to CPF and AFB1 combined. Thus, this study suggested cellular GSH as a potential indicator for detecting the combined effects of CPF and AFB1 in HepG2 cells, the detection of which could be adapted to estimate the potential toxicity of additional multiple toxicant exposures. [ABSTRACT FROM AUTHOR]

Opioid analgesics represent a critical treatment for chronic pain in the analgesic ladder of the World Health Organization. However, their use can result in a number of unwanted side-effects including incomplete efficacy, constipation, physical dependence, and overdose liability. Cannabinoids enhance the pain-relieving effects of opioids in preclinical studies and dampen unwanted side-effects resulting from excessive opioid intake. We recently reported that a CB1 positive allosteric modulator (PAM) exhibits antinociceptive efficacy in models of pathological pain and lacks the adverse side effects of direct CB1 receptor activation. In the present study, we evaluated whether a CB1 PAM would enhance morphine's therapeutic efficacy in an animal model of chemotherapy-induced neuropathic pain and characterized its impact on unwanted side-effects associated with chronic opioid administration. In paclitaxel-treated mice, both the CB1 PAM GAT211 and the opioid analgesic morphine reduced paclitaxel-induced behavioral hypersensitivities to mechanical and cold stimulation in a dose-dependent manner. Isobolographic analysis revealed that combinations of GAT211 and morphine resulted in anti-allodynic synergism. In paclitaxel-treated mice, a sub-threshold dose of GAT211 prevented the development of tolerance to the anti-allodynic effects of morphine over 20 days of once daily dosing. However, GAT211 did not reliably alter somatic withdrawal signs (i.e., jumps, paw tremors) in morphine-dependent neuropathic mice challenged with naloxone. In otherwise naïve mice, GAT211 also prolonged antinociceptive efficacy of morphine in the tail-flick test and reduced the overall right-ward shift in the ED50 for morphine to produce antinociception in the tail-flick test, consistent with attenuation of morphine tolerance. Pretreatment with GAT211 did not alter somatic signs of μ opioid receptor dependence in mice rendered dependent upon morphine via subcutaneous implantation of a morphine pellet. Moreover, GAT211 did not reliably alter μ-opioid receptor-mediated reward as measured by conditioned place preference to morphine. Our results suggest that a CB1 PAM may be beneficial in enhancing and prolonging the therapeutic properties of opioids while potentially sparing unwanted side-effects (e.g., tolerance) that occur with repeated opioid treatment. [ABSTRACT FROM AUTHOR]

Aim/Background: Chloroquine (CQ) resistance that appeared among different strains of Plasmodium falciparum is considered as the worst catastrophe in the realm of malaria chemotherapy. CQ is still the most favorable drug among other antimalarials especially in the poor endemic areas due to its high potency and cost-effectiveness. This urged the scientists to explore for other alternatives or sensitizers for CQ. Materials and Methods: In this experiment, the antiplasmodium and the CQ resistance reversing effects of mangostin were tested using the in vitro SYBRE green-1-based drug sensitivity assay and the isobologram technique, respectively. Furthermore, its safety level toward two types of mammalian cells, namely Vero cells and red blood cells (RBCs), was screened using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide-based drug sensitivity and the RBCs hemolysis assays, respectively. On the other hand, its effect against hemozoin formation was screened using β-hematin formation. Meanwhile, its molecular characters were determined the in silico on-line free chemi-informatic Molinspiration software for the molecular characterization as well as the standard testes for the measurement of the antioxidant effect. Results: Mangostin was moderately effective and selective toward the plasmodium so it is unsuitable to be a substituent for CQ. But it improved the sensitivity of the parasite to CQ. The molecular elucidation suggests that its CQ resistance reversal effect can be ascribed to its ability to interfere with hemozoin formation or the intravacuolar accumulation of CQ. Conclusion: Overall, the study suggests mangostin as a possible pharmacophore to develop new CQ resistance reversing agents but further studies are recommended to confirm this notion. [ABSTRACT FROM AUTHOR]

Cholangiocarcinoma (CCA) exhibits poor response to the present chemotherapeutic agents and frequently develops drug resistance. Finding novel anticancer drugs might enhance patient outcomes. Tiliacorinine, a bisbenzylisoquinoline alkaloid from the Thai medicinal plant Tiliacora triandra , effectively induced apoptosis of human CCA cell lines and inhibited tumor growth in mice. Here, we elucidate further the molecular mechanisms underlining the cytotoxicity of tiliacorinine and its implication in overcoming gemcitabine-resistance of CCA cells. Cytotoxicity of tiliacorinine against CCA cell lines was assessed using MTT assay. The molecular signaling was determined using Western blot analysis. Molecular docking simulations were applied to predict the binding affinity and orientation of tiliacorinine to the possible binding site(s) of the target proteins. Tiliacorinine induced apoptotic cell death of CCA cells in a dose- and time-dependent manner. Tiliacorinine significantly suppressed the expression of anti-apoptotic proteins, Bcl-xL and XIAP; activated apoptotic machinery proteins, caspase-3, caspase-9, and PARP; and decreased the levels of pAkt and pSTAT3. EGF/EGFR activation model and molecular docking simulations revealed EGFR, Akt, and STAT3 as potent targets of tiliacorinine. Molecular docking simulations indicated a strong binding affinity of tiliacorinine to the ATP-binding pockets of EGFR, PI3K, Akt, JAK2, and SH2 domain of STAT3. Tiliacorinine could synergize with gemcitabine and restore the cytotoxicity of gemcitabine against gemcitabine-resistant CCA cells. Tiliacorinine effectively induced apoptosis via binding and blocking the actions of EGFR, Akt, and STAT3. Tiliacorinine is a novel multi-kinase inhibitor and possibly a potent anti-cancer agent, in cancers with high activation of EGFR. [Display omitted] • Tiliacorinine (TC) exhibits potent cytotoxicity against human CCA cell lines. • TC induces cell apoptosis by reducing Bcl-xL/XIAP and activating caspase activity. • TC simultaneously suppresses EGF/EGFR, PI3K/Akt, and JAK/STAT3 signaling. • ATP-binding pockets of EGFR, Akt, and SH2 domain of STAT3 are the recognition sites. • TC synergizes/restores gemcitabine toxicity in CCA and gemcitabine-resistant cells. [ABSTRACT FROM AUTHOR]

Plant bioactive compounds have antimicrobial and antioxidant activities that allow them to be used as a substitute for synthetic chemical additives in both food and food packaging. To improve its sensory and bactericidal effects, its use in the form of effective combinations has emerged as an interesting possibility in the food industry. In this study, the antimicrobial activities of essential oils (EOs) of cinnamon bark, cinnamon leaves, and clove and the pure compounds vanillin, eugenol, and cinnamaldehyde were investigated individually and in combination against Listeria monocytogenes and Escherichia coli O157:H7. The possible interactions of combinations of pure compounds and EOs were performed by the two-dimensional checkerboard assay and isobologram methods. Vanillin exhibited the lowest antimicrobial activity (MIC of 3002 ppm against L. monocytogenes and 2795 ppm against E. coli O157:H7), while clove and cinnamon bark EOs exhibited the highest antimicrobial activity (402–404 against L. monocytogenes and 778–721 against E. coli O157:H7). For L. monocytogenes, pure compound eugenol, the main component of cinnamon leaves and clove, showed lower antimicrobial activity than EOs, which was attributed to the influence of the minor components of the EOs. The same was observed with cinnamaldehyde, the main component of cinnamon bark EO. The combinations of vanillin/clove EO and vanillin/cinnamon bark EO showed the most synergistic antimicrobial effect. The combination of the EOs of cinnamon bark/clove and cinnamon bark/cinnamon leaves showed additive effect against L. monocytogenes but indifferent effect against E. coli O157:H7. For L. monocytogenes, the best inhibitory effects were achieved by cinnamon bark EO (85 ppm)/vanillin (910 ppm) and clove EO (121 ppm)/vanillin (691 ppm) combinations. For E. coli, the inhibitory effects of clove EO (104 ppm)/vanillin (1006 ppm) and cinnamon leaves EO (118 ppm)/vanillin (979 ppm) combinations were noteworthy. Some of the tested combinations increased the antimicrobial effect and would allow the effective doses to be reduced, thereby offering possible new applications for food and active food packaging.

The aim of this study is to investigate the antimicrobial synergistic effect against Campylobacter jejuni, a leading foodborne pathogen that causes human gastroenteritis, by cinnamon oil, encapsulated curcumin, and zinc oxide nanoparticles (ZnO NPs). We compared three approaches to study the antimicrobial interactions, including the time-killing method, the fractional inhibitory concentration index (FICI) method, and a mathematical concentration-effect model. Isobologram analysis was performed to evaluate the synergy in different combinations, and a median-effect equation was applied to identify the combinations of synergistic effects at median, bacteriostatic, and bactericidal reduction levels. The time-killing method overestimated the synergistic interaction between antimicrobials, while the FICI method failed to detect an existing synergistic phenomenon. This lack of accuracy and sensitivity was mainly due to combining antimicrobials without a deep understanding of their concentration-effect relationships. Our results showed that each antimicrobial had a unique concentration-effect curve. Specifically, encapsulated curcumin showed a sharp sigmoidal curve unlike cinnamon oil and ZnO NPs. A mathematical model was applied to study the interaction between antimicrobials with a different shape of concentration-effect curve. We observed an additive effect of cinnamon oil/ZnO NPs and synergistic interactions of other binary combinations (cinnamon oil/encapsulated curcumin and ZnO NPs/encapsulated curcumin). The tertiary combination of cinnamon oil/ZnO NPs/encapsulated curcumin at IC25 (additive line

Background: Xylopic acid (XA), a kaurene diterpene from the dried fruits of Xylopia aethiopica, has anxiolytic- and antidepressant-like activity in mice and zebrafish. We aimed to assess the potential synergistic antidepressant-like effects of XA when combined with selected antidepressants in the mouse forced-swim test., Materials and Methods: The antidepressant-like effect of xylopic acid (XA) (10, 30, 100 mgkg -1 ), fluoxetine (Flx) (3, 10, 30 mgkg -1 ), sertraline (Sert) (3, 10, 30 mgkg -1 ), imipramine (Imi) (10, 30, 100 mgkg-1) and ketamine (Ket) (0.1, 0.3, 1.0 mgkg -1 ), was evaluated in forced swim test. The dose (ED 50 ) that achieved a 50% reduction in immobility time was determined from the respective log-dose response curves. XA and the selected antidepressants were co-administered in fixed-dose ratio combinations (1/2:1/2, 1/4:1/4, 1/8:1/8) of the ED 50 to identify the experimental ED 50 (ED 50mix ). The theoretical ED 50 (ED 50add ), of all combinations was determined using isobolograms and compared with the ED 50mix to identify the nature of the interaction. The effect of dose combinations on general locomotor activity was assessed in the open-field test., Results: The interaction index (γ) for the following XA combinations, XA/Flx, XA/Sert, XA/Imi and XA/Ket were 0.42, 0.41, 0.31 and 0.34. An independent sample t- test revealed that the experimental ED 50 (ED 50mix ) was significantly lower than the theoretical ED 50 (ED 50add ) in all combinations of XA, indicative of a synergistic antidepressant-like effect. However, combinations of XA with ketamine significantly reduced general locomotor activity at all dose combinations., Conclusion: The co-administration of xylopic acid and fluoxetine, imipramine, sertraline and ketamine produces a synergistic antidepressant-like effect in mice., Competing Interests: The authors declare no financial or non-financial competing interests., (© 2024 The Authors.)

Nonsteroidal anti-inflammatory drugs (NSAIDs) are very commonly used, but their adverse effects warrant investigating new therapeutic alternatives. Polyalthic acid, a labdane-type diterpenoid, is known to produce gastroprotection, tracheal smooth muscle relaxation, and antitumoral, antiparasitic and antibacterial activity. This study aimed to evaluate the antinociceptive, antiallodynic, antihyperalgesic and anti-inflammatory effect of polyalthic acid on rats. Moreover, the effectiveness of treating hyperalgesia with a combination of polyalthic acid and naproxen was analyzed, as well as the type of drug–drug interaction involved. Nociception was examined by injecting 1% formalin into the right hind paw and thermal hyperalgesia and inflammation by injecting a 1% carrageenan solution into the left hind paw of rats. Allodynia was assessed on an L5/L6 spinal nerve ligation model. Polyalthic acid generated significant antinociceptive (56–320 mg/kg), antiallodynic (100–562 mg/kg), and antihyperalgesic and anti-inflammatory (10–178 mg/kg) effects. Antinociception mechanisms were explored by pretreating the rats with naltrexone, ODQ and methiothepin, finding the effect blocked by the former two compounds, which indicates the participation of opioid receptors and guanylate cyclase. An isobolographic analysis suggests synergism between polyalthic acid and naproxen in the combined treatment of hyperalgesia.

BACKGROUND: The suppression of α‐glucosidase activity to retard glucose absorption is an important therapy for type‐2 diabetes. Corosolic acid (CRA) is a potential antidiabetic component in many plant‐based foods and herbs. In this study, the interplay mechanism between α‐glucosidase and corosolic acid was investigated by several methods, including three‐dimensional fluorescence spectra, circular dichroism spectra, and molecular simulation. RESULTS: Corosolic acid significantly inhibited α‐glucosidase reversibly in an uncompetitive manner and its IC50 value was 1.35 × 10−5 mol L−1. A combination of CRA with myricetin exerted a weak synergy against α‐glucosidase. The intrinsic fluorescence of α‐glucosidase was quenched via a static quenching course and the binding constant was 3.47 × 103 L mol−1 at 298 K. The binding of CRA to α‐glucosidase was mainly driven by hydrophobic forces and resulted in a partial extension of the protein polypeptide chain with a loss of α‐helix content. The molecular simulation illustrated that CRA bound to the entrance part of the active center of α‐glucosidase and interacted with the amino acid residues Ser157, Arg442, Phe303, Arg315, Tyr158, and Gln353, which could hinder the release of substrate and catalytic reaction product, eventually suppressing the catalytic activity of α‐glucosidase. CONCLUSIONS: These results may suggest new insights into corosolic acid from food sources as a potential α‐glucosidase inhibitor that could better control diabetes. © 2019 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

The aim of this study is to investigate the antimicrobial synergistic effect against Campylobacter jejuni , a leading foodborne pathogen that causes human gastroenteritis, by cinnamon oil, encapsulated curcumin, and zinc oxide nanoparticles (ZnO NPs). We compared three approaches to study the antimicrobial interactions, including the time-killing method, the fractional inhibitory concentration index (FICI) method, and a mathematical concentration-effect model. Isobologram analysis was performed to evaluate the synergy in different combinations, and a median-effect equation was applied to identify the combinations of synergistic effects at median, bacteriostatic, and bactericidal reduction levels. The time-killing method overestimated the synergistic interaction between antimicrobials, while the FICI method failed to detect an existing synergistic phenomenon. This lack of accuracy and sensitivity was mainly due to combining antimicrobials without a deep understanding of their concentration-effect relationships. Our results showed that each antimicrobial had a unique concentration-effect curve. Specifically, encapsulated curcumin showed a sharp sigmoidal curve unlike cinnamon oil and ZnO NPs. A mathematical model was applied to study the interaction between antimicrobials with a different shape of concentration-effect curve. We observed an additive effect of cinnamon oil/ZnO NPs and synergistic interactions of other binary combinations (cinnamon oil/encapsulated curcumin and ZnO NPs/encapsulated curcumin). The tertiary combination of cinnamon oil/ZnO NPs/encapsulated curcumin at IC25 (additive line <1-log CFU/mL) presented the greatest synergistic effect by reducing the bacterial population over 8-log CFU/mL. This mathematical model provided an alternative strategy to develop a new antimicrobial strategy. [ABSTRACT FROM AUTHOR]

Abstract Opioid and neurotensin (NT) receptors are expressed in both central and peripheral nervous systems where they modulate nociceptive responses. Nowadays, opioid analgesics like morphine remain the most prescribed drugs for the treatment of moderate to severe pain. However, despite their daily used, opioids can produce life-threatening side effects, such as constipation or respiratory depression. Besides, NT analogs exert strong opioid-independent analgesia. Here, we thus hypothesized that the combined use of opioid and NT agonists would require lower doses to produce significant analgesic effects, hence decreasing opioid-induced adverse effects. We used isobologram analyses to determine if the combination of a NT brain-penetrant analog, An2-NT(8-13) with morphine results in an inhibitory, synergistic or additive analgesic response. We found that intravenous administration of An2-NT(8-13) reduced by 90% the nocifensive behaviors induced by formalin injection, at the dose of 0.018 mg/kg. Likewise, subcutaneous morphine reduced pain by 90% at 1.8 mg/kg. Importantly, isobologram analyses revealed that the co-injection of An2-NT(8-13) with morphine induced an additive analgesic response. We finally assessed the effects of morphine and An2-NT(8-13) on the gastrointestinal tract motility using the charcoal meal test. As opposed to morphine which significantly reduced the intestinal motility at the analgesic effective dose of 1.8 mg/kg, An2-NT(8-13) did not affect the charcoal meal intestinal transit at 0.018 mg/kg. Interestingly, at the dose providing 90% pain relief, the co-administration of morphine with An2-NT(8-13) had a reduced effect on constipation. Altogether, these results suggest that combining NT agonists with morphine may improve its analgesic/adverse effect ratio. [ABSTRACT FROM AUTHOR]

Abstract The aim of the study was to investigate the analgesic effects of adding serotonin to oxybuprocaine or proxymetacaine preparations. We employed a rat model of the cutaneous trunci muscle reflex (CTMR) to conduct the dose-response curves and duration of drugs (oxybuprocaine, proxymetacaine, or serotonin) as an infiltrative anesthetic. The use of isobolographic methods to analyze the drug-drug interactions. We showed that oxybuprocaine and proxymetacaine, as well as serotonin produced dose-dependent skin antinociception. On the basis of 50% effective dose (ED 50), the rank order of drug potency was serotonin [7.22 (6.45–8.09) μmol/kg] < oxybuprocaine [1.03 (0.93–1.15) μmol/kg] < proxymetacaine [0.59 (0.53–0.66) μmol/kg] (P < 0.01 for each comparison). The sensory block duration of serotonin was longer (P < 0.01) than that of oxybuprocaine or proxymetacaine at the equipotent doses (ED 25 , ED 50 , and ED 75). The mixture of serotonin with oxybuprocaine or proxymetacaine produced a better analgesic effect than the drug itself. We have concluded that oxybuprocaine, proxymetacaine, or serotonin displays dose-related cutaneous analgesia. Oxybuprocaine or proxymetacaine is more potent and has a shorter duration of cutaneous analgesia than serotonin. Serotonin produces a synergistic antinociceptive interaction with oxybuprocaine or proxymetacaine. [ABSTRACT FROM AUTHOR]

Introduction: Flavonoids are a class of plant-derived compounds that have been shown to exhibit a variety of health benefits, including anti-inflammatory effects. Previous studies demonstrated that flavonoids could inhibit the production of pro-inflammatory mediators, such as nitric oxide (NO), prostaglandin E2 (PGE2), and tumor necrosis factor-alpha (TNF-α). However, it is unclear whether the anti-inflammatory effects of flavonoids are additive or synergistic when they are combined. Methods: The inhibitory effects of seven flavonoids against NO, PGE2 and TNF-α secretion from lipopolysaccharides (LPS)-induced macrophage cells (RAW 264.7) were assessed. The IC50 values were obtained. Flavonoids that showed significant inhibitory effects were combined in a series of fixed IC50 ratios and re-evaluated for synergistic effects. Dose-response curves were generated, and interactions were analysed using isobolograms. To study the effects of combination treatment on severe sepsis, mice were subjected to cecal ligation and puncture (CLP) procedure. Septic mice survival was monitored, and the levels of key pro-inflammatory mediators and markers, such as aspartate aminotransferase (AST), TNF-α, myeloperoxidase (MPO), and NO in sera samples were determined at different time points after CLP. Results: The experiments showed that chrysin, kaempferol, morin, and silibinin have highly significant synergistic effects. Conclusion: The findings of this study suggest that flavonoid combinations may be a promising new approach for the treatment of inflammatory disorders. Particularly, chrysin and kaempferol significantly synergised in their inhibitory effect upon NO, PGE2 and TNF-α secretion. Further research is needed to identify more optimal flavonoids combinations for therapeutic use. [ABSTRACT FROM AUTHOR]