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Combination therapy at appropriately suitable doses presents a promising alternative to monotherapeutic drugs. In this study, Cinnamomum verum and Syzygium aromaticum essential oils and their major compounds have exhibited substantial leishmaniacidal potential against both promastigote and amastigote forms of Leishmania (L.) major . However, they displayed high cytotoxicity against Raw264.7 macrophage cells. Interestingly, when combined with each other or with amphotericin B, they demonstrated a synergistic effect (FIC<0.5) with low cytotoxicity. These combinations are able to modulate the production of nitric oxide (NO) by macrophages. Notably, the combination of S. aromaticum Essential oil with amphotericin B stimulates macrophage cells by increasing NO production to eliminate leishmanial parasites. Furthermore, investigation of the molecular mechanism of action of these synergistic combinations reveals potent inhibition of the sterol pathway through the inhibition of the CYP51 gene expression. The findings suggest that combination therapy may offer significant therapeutic benefits in both food and pharmaceutical fields.

The present study aimed to evaluate the leishmanicidal potential of the essential oil (EO) of Micromeria ( M. ) nervosa and to investigate its molecular mechanism of action by qPCR. Furthermore, in silicointeraction study of the major M. nervosa EO compounds with the enzyme cytochrome P450 sterol 14α-demethylase (CYP51) was also performed. M. nervosa EO was analyzed by gas chromatography-mass spectrometry (GC-MS). Results showed that α-pinene (26.44%), t -cadinol (26.27%), caryophyllene Oxide (7.73 ± 1.04%), and α-Cadinene (3.79 ± 0.12%) are the major compounds of M. nervosa EO. However, limited antioxidant activity was observed, as this EO was ineffective in neutralizing DPPH free radicals and in inhibiting β-carotene bleaching. Interestingly, it displayed effective leishmanicidal potential against promastigote (IC 50 of 6.79 and 5.25 μg/mL) and amastigote (IC 50 of 8.04 and 7.32 μg/mL) forms of leishmania (L.) infantum and L. major , respectively. Molecular mechanism investigation showed that M. nervosa EO displayed potent inhibition on the thiol regulatory pathway. Furthermore, a docking study of the main components of the EO with cytochrome P450 sterol 14α-demethylase (CYP51) enzyme revealed that t -cadinol exhibited the best binding energy values (-7.5 kcal/mol), followed by α-cadinene (-7.3 kcal/mol) and caryophyllene oxide (-7 kcal/mol). These values were notably higher than that of the conventional drug fluconazole showing weaker binding energy (-6.9 kcal/mol). These results suggest that M. nervosa EO could serve as a potent and promising candidate for the development of alternative antileishmanial agent in the treatment of leishmaniasis.

Current study aims to evaluate the effect of essential oil on the conservation of chicken fillets. Following a screening, Tetraclinis articulata was selected for its antimicrobial ( Enterococcus feacalis ATCC 29212, MIC < 0.031 mg/mL) and antioxidant (IC 50  = 1000 µg/mL) potentials with no cytotoxicity effect towards murine macrophage cells. The treatment of chicken fillets, especially with 200 ppm of T. articulata essential oil per 100 g of product reduced significantly ( p   <   0.05 ) lipid oxidation during 12 days of refrigerated storage. Microbial flora charges decreased significantly ( p   <   0.05 ) with a rate of 50.31% for 200 ppm of essential oil from the 6 th day of storage. The acidity of treated fillets was lower than control samples (1.3 g/kg) from the 3 rd day of storage. In addition, a clear effect was recorded by reducing water losses during cooking under the tested doses of essential oil. Withall, findings encouraged the use of T. articulata to extend poultry meat product shelf life.

Nanoencapsulation is widely considered as a highly effective strategy to enhance essential oils' (EO) stability by protecting them from oxidative deterioration and evaporation. The present study aims to optimize and characterize an efficient technique for encapsulating Cinnamomum (C.) verum essential oil into chitosan nanoparticles using response surface methodology (RSM). Moreover, the optimized C. verum EO nanoparticle was investigated for its antibacterial (against Gram-positive and Gram-negative bacteria), antifungal (against Candida albicans ), and antiparasitic activity (against Leishmania parasites). Five parameters were investigated using a Plackett-Burman and Box-Behnken statistical design: the chitosan molecular weight, TPP concentration, C. verum EO/chitosan ratio, mixing method, and the duration of the reaction. Encapsulation efficiency and anti-candida activity were considered as responses. The antibacterial, anticandidal, and anti-leishmanial activities were also assessed using a standard micro-broth dilution assay and the cytotoxicity assay was assessed against the macrophage cell line RAW 264.7. The optimized nanoparticles were characterized using Fourier transform infrared spectroscopy, Zeta potential, and scanning electron microscopy. The study results indicated that under optimal conditions, the nanoencapsulation of C. verum EO into chitosan nanoparticles resulted in an encapsulation efficiency of 92.58%, with a regular distribution, a nanoparticle size of 480 ± 14.55 nm, and a favorable Zeta potential of 35.64 ± 1.37 mV. The optimized C. verum EO/chitosan nanoparticles showed strong antifungal activity against C. albicans pathogens (CMI = 125 µg mL -1 ), notable antibacterial activity against both Gram-positive and Gram-negative bacteria (ranging from 125 to 250 µg mL -1 ), high leishmanicidal potential against the promastigotes form of L. tropica and L. major (IC50 = 10.47 and 15.09 µg mL -1 , respectively), and a four-fold cytotoxicity reduction compared to non-encapsulated essential oil. These results suggest that C. verum EO-loaded chitosan nanoparticles could be a promising delivery system for the treatment of cutaneous Candida albicans infections.

Purpose: Leishmaniasis is a parasitic disease found in tropical areas, and it affects up to 12 million individuals globally. Chemotherapies now available include drawbacks such as toxicity, high cost, and parasite resistance. This work aimed to evaluate the antileishmanial properties of essential oils (EOs) extracted from aerial parts of Cupressus sempervirens (C. sempervirens), Tetraclinis articulata (T. articulata), and Pistacia lentiscus (P. lentiscus) trees., Methods: The EOs were obtained by hydro-distillation, and chemical composition was determined by gas chromatography coupled to mass spectrometry at three phenological stages. The EOs were evaluated in vitro for antileishmanial activities against Leishmania major (L. major) and Leishmania infantum (L. infantum). The cytotoxicity effect was also tested against murine macrophagic cells (Raw264.7 lines)., Results: Results showed that P. lentiscus and T. articulata EOs presented low and moderate antileishmanial activity against L. infantum and L. major. However, C. sempervirens EO from the fructification stage gave an important selectivity index (23.89 and 18.96 against L. infantum and L. major, respectively). This activity was more interesting than those of amphotericin chemical drugs. Antileishmanial activity for this EO was highly correlated with germacrene D content (r = 1.00). This compound presented a SI equal to 13.34 and 10.38 for the two strains. According to the Principal Component Analysis (PCA), the distribution of the three phenological stages proved that the chemical composition of the EOs affected the antileishmanial activity. PCA revealed that SI was positively correlated with α-pinene, germacrene D and the sesquiterpene hydrocarbon class. Cupressus sempervirens EO can provide a source of germacrene D that can be used as a new alternative to chemical drugs for the treatment of antileishmanial diseases., Conclusion: C. sempervirens EO seemed to be a highly active antileishmanial agent and a natural alternative for chemical drugs to treat several leishmanial strains., (© 2023. The Author(s) under exclusive licence to Witold Stefański Institute of Parasitology, Polish Academy of Sciences.)

To explore a novel kind of green composite material having excellent antibacterial, antifungal ability and specific-targeting capability for pharmaceutical uses, a novel kind of bio-composite was prepared using sodium purified clay as carrier of Caraway essential oil (CEO). Gas chromatography-mass spectroscopy (GC-MS) analyses of CEO reveals that Carvone (68.30%) and Limonene (22.54%) are the two major components with a minimum inhibitory concentration (MIC) value equal to 125 mg/mL against Staphylococcus (S) aureus bacteria and Candida albicans fungi. Clay from Zaghouan was purified and characterized by X-ray Photoelectron Spectroscopy (XPS), X-ray diffraction (XRD), Fourier transformed infrared spectroscopy (FT-IR) and N 2 adsorption-desorption (BET method). Results obtained by chromatograph equipped with a flame ionization detector (GC-FID) show that the concentration of 130 mg/mL of essential oil and 5 h of contact with the purified clay are the optimal conditions for the bio-hybrid formation. The pseudo-second-order model can describe the kinetic study of the adsorption of Carvone and Limonene on sodium montmorillonite, and the adsorption isotherms have been established to the Langmuir type. Limonene registers a maximum adsorption value equal to 3.05 mg/g of clay however Carvone register the higher amount of adsorption (19.98 mg/g) according to its polarity and the abundance of this compound in the crude CEO. X-ray diffraction, Fourier transformed infrared spectroscopy, elemental analyses (CHN) and X-ray fluorescence characterization valid the success adsorption of CEO in sodium montmorillonite surface. The purified clay/CEO hybrid (purified clay/CEO) combined the advantages of both the clay and the essential oil used in exerting the antibacterial and antifungal activity, and thus, the composite has a double antibacterial and antifungal activity compared to the separately uses of inactive clay and CEO, suggesting the great potential application in pharmaceutical treatments., (© 2022. The Author(s).)

The present study aimed to investigate the anti-Candida activity of ten essential oils (EOs) and to evaluate their potential synergism with conventional drugs. The effect on secreted aspartic protease (SAP) activity and the mechanism of action were also explored. The antifungal properties of essential oils were investigated using standard micro-broth dilution assay. Only Cinnamomum verum, Thymus capitatus, Syzygium aromaticum, and Pelargonium graveolens exhibited a broad spectrum of activity against a variety of pathogenic Candida strains. Chemical composition of active essential oils was performed by gas chromatography-mass spectrometry (GC-MS). Synergistic effect was observed with the combinations C. verum/fluconazole and P. graveolens/fluconazole, with FIC value 0.37. Investigation of the mechanism of action revealed that C. verum EO reduced the quantity of ergosterol to 83%. A total inhibition was observed for the combination C. verum/fluconazole. However, P. graveolens EO may disturb the permeability barrier of the fungal cell wall. An increase of MIC values of P. graveolens EO and the combination with fluconazole was observed with osmoprotectants (sorbitol and PEG6000). Furthermore, the combination with fluconazole may affect ergosterol biosynthesis and disturb fatty acid homeostasis in C. albicans cells as the quantity of ergosterol and oleic acid was reduced to 52.33 and 72%, respectively. The combination of P. graveolens and C. verum EOs with fluconazole inhibited 78.31 and 64.72% SAP activity, respectively. To our knowledge, this is the first report underlying the mechanism of action and the inhibitory effect of SAP activity of essential oils in synergy with fluconazole. Naturally occurring phytochemicals C. verum and P. graveolens could be effective candidate to enhance the efficacy of fluconazole-based therapy of C. albicans infections.