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Background and Aims: Stachys L. species, which are members of the Lamiaceae family, have long been applied for their therapeutic benefits especially to cure cough, infection, genital tumors, ulcers, inflammatory illnesses, and wounds in Anatolian traditional medicine. In the current study, various extracts prepared from the aerial parts of Stachys cretica subsp. butgarica Rech.f. (SC), Stachys byzantina K. Koch (SB), Stachys thirkei K. Koch and were tested for their in vitro antioxidant, antibacterial, and anticandidat properties. Methods: The aerial parts of three Stachys species were sequentially extracted using n-hexane, chloroform, and methanol. Aqueous extracts of each sample was also prepared by infusion process. The total phenolic content of each extract was determined and the contribution of the biological activities in the samples was evaluated. To assess the antioxidant capacity, samples were studied using CUPRAC activity, DPPH center dot free radical scavenging, and FRAP methods. The antimicrobial activity of the extracts was tested against 7 bacteria and 3 yeast. Results: The infusion and methanol extract exhibited the strongest antioxidant potential and also had the highest percentage of phenolics among the studied extracts. The n-hexane extracts of all studied species showed considerable antifungal activity with MIC values ranging from 312.5-78.12 mg/L. Conclusion: According to our results, three Stachys species were found to be beneficial for their antioxidant and antimicrobial properties. Background and Aims: Stachys L. species, which are members of the Lamiaceae family, have long been applied for their therapeutic benefits especially to cure cough, infection, genital tumors, ulcers, inflammatory illnesses, and wounds in Anatolian traditional medicine. In the current study, various extracts prepared from the aerial parts of Stachys cretica subsp. butgarica Rech.f. (SC), Stachys byzantina K. Koch (SB), Stachys thirkei K. Koch and were tested for their in vitro antioxidant, antibacterial, and anticandidat properties. Methods: The aerial parts of three Stachys species were sequentially extracted using n-hexane, chloroform, and methanol. Aqueous extracts of each sample was also prepared by infusion process. The total phenolic content of each extract was determined and the contribution of the biological activities in the samples was evaluated. To assess the antioxidant capacity, samples were studied using CUPRAC activity, DPPH center dot free radical scavenging, and FRAP methods. The antimicrobial activity of the extracts was tested against 7 bacteria and 3 yeast. Results: The infusion and methanol extract exhibited the strongest antioxidant potential and also had the highest percentage of phenolics among the studied extracts. The n-hexane extracts of all studied species showed considerable antifungal activity with MIC values ranging from 312.5-78.12 mg/L. Conclusion: According to our results, three Stachys species were found to be beneficial for their antioxidant and antimicrobial properties. WOS:000744167900009

Serious bacterial infections could be caused by Gram-positive microorganisms, in particular methicillin-resistant Staphylococcus aureus and Staphylococcus epidermidis. Aiming to address this challenging issue by developing the potent and selective antimicrobial lead structures against methicillin-resistant Staphylococcus spp., herein, we report in vitro evaluation of quinolinequinones (QQ1-QQ10) against the Gram-negative and Gram-positive strains using the broth microdilution technique. The design principle of the quinolinequinones was based on the variation of the structures attached to the 1,4-quinone moiety and substituent(s) within amino phenyl moiety. A series of ten quinolinequinones displayed activity mainly against the Gram-positive strains with a minimal inhibitory concentration (MIC=1.22-1250 mg/L) within the Clinical and Laboratory Standards Institute (CLSI) levels. Interestingly, QQ3, QQ5, and QQ6 displayed equal antibacterial inhibitory activity against S. aureus (MIC=1.22 mg/L), respectively, to the standard positive control Cefuroxime-Na. QQ2, QQ3, and QQ5 had the best inhibitory activity with the MIC value of 1.22 mg/L (4-fold more potent compared reference standard Cefuroxime) against S. epidermidis. On the other hand, QQ3 was the most effective quinolinequinone against fungi, in particular C. albicans. The identified lead quinolinequinones (QQ3 and QQ5) with a comprehensive analysis of structure-activity relationships and further studies showed high activity against methicillin-resistant Staphylococcus spp. It is worth noting that the isopropyl group has importance for excellent bioactivity. Remarkably, the in vitro antibiofilm and bactericidal activities (each of 32 clinically obtained strains of Gram-positive bacteria) of the selected two quinolinequinones (QQ3 and QQ5) have been evaluated for the mode of action in addition to the time-kill curve study.

In our pursuit of developing the novel, potent, and selective antimicrobial agents, we managed to obtain the quinolinequinone for their antimicrobial profile with minimal inhibitory concentrations (MICs) determined against a panel of seven bacterial strains (three gram-positive and four gram-negative bacteria) and three fungi. The structure-activity relationship (SAR) for the quinolinequinone class of antimicrobials was determined. Interestingly, QQ1, QQ4, QQ6-9, QQ12, and QQ13 displayed equal antibacterial potential against S. aureus (MIC = 1.22 mg/L), respectively, to the standard positive control Cefuroxime-Na. QQ10 had the best inhibitory activity with the MIC value of 1.22 mg/L (fourfold more potent compared to reference standard Clotrimazole) against Candida albicans. On the other hand, while QQ10 is not too effective against gram-positive bacteria as much as the other analogs, QQ10 was the most effective quinolinequinones against fungi. Selected quinolinequinones were further evaluated for the mode of action, using in vitro antibiofilm activity, bactericidal activity by using time-kill curve assay, antibiofilm activity, and potential antimicrobial activity against each of 32 clinically obtained resistant strains of Gram-positive Bacteria. The results also revealed that the QQ14 had specific antifungal activity against fungi in particular C. albicans. Our results clearly showed that quinolinequinones are much more active in the inhibition of the biofilm attachment process than the inhibition of mature biofilm formation. Thus, as treatment options are narrowing for Methicillin-resistant Staphylococcus spp., Vancomycin-resistant Staphylococcus spp. daily, the quinolinequinones reported herein display promise as the lead candidates for further clinical applications against serious infections.

Being widely used in the food industry, thyme is one of the most valuable plants in many aspects, and Turkey is one of the hotspots for thyme industry. Five thyme species, Thymus convolutus (endemic), Thymus fallax, Thymus haussknechtii Velen (endemic), Thymus kotschyanus var. kotschyanus, and Thymus sipyleus from Turkey were subjected in this study. Their essential oils and the extracts of aerial and root parts were obtained. GC-MS analyses showed that camphor was the major compound in T. convolutus (12.7%), and in T. sipyleus (13.1%) essential oils. The major volatile compound of T. fallax was bicyclogermacrene (21.5%), whereas the T. kotschyanus var. kotschyanus essential oil showed a predominance of carvacrol (48.5%), and thymol (22.5%). Carvacrol was also the major compound of T. haussknechtii with 28.2%. LC-MS/MS analyses showed that nicotiflorin (293.28-4201.15 mu g/mL), caffeic (516.41-851.28 mu g/mL), quinic (344.37-4410.94 mu g/mL), rosmarinic (1800.18-9631.71 mu g/mL), and fumaric acid (350.88-682.10 mu g/mL) were detected as the main compounds in the extracts. All extracts exerted strong antioxidant activity, and the highest radical scavenging activity was demonstrated by T. haussknechtii root extract. T. convolutus and T. haussknechtii aerial parts extracts showed significant antimicrobial activity against C. tropicalis at MIC of 19.53 mu g/mL. The extracts were found to be nontoxic against COLO205 and KM12 human colon, and UO-31, and A498 human renal cell lines. Their enzyme inhibitory activities were also evaluated against cholinesterase, tyrosinase and urease enzymes and T. fallax aerial part extract was the most effective with 34.48 +/- 0.60% in antibutyrylcholinesterase activity. These species with strong antioxidant and antifungal properties and no toxicity could be beneficial to be used as preservatives in the food processing industry.

WOS: 000471951900029 PubMed ID: 30576787 Objectives: Infections caused by multidrug-resistant (MDR) Acinetobacter baumannii (A. baumannii) are a growing problem because of the limited options for treatment. The number of antimicrobials that are currently being developed is still insufficient to control this global threat. Combination therapies of antibiotics with different antimicrobial mechanisms have been proposed as the best options for treating MDR A. baumannii infections. The objective of this study was to investigate the in-vitro effectiveness of ceftazidime/avibactam alone or in combination with antibiotics against MDR A. baumannii isolates using time-kill assays. Methods: Forty clinical MDR strains were screened, and minimum inhibitory concentrations (MIC) and minimum bactericidal concentrations (MBC) of ceftazidime/avibactam, colistin, levofloxacin, meropenem, tigecycline, and tobramycin were determined by microbroth dilution method. The in-vitro synergistic activities of ceftazidime/avibactam with antibiotic combinations were determined by time-kill assays at 1 x MIC and 4 x MIC against five MDR A. baumannii isolates. Results: Based on MIC results, all isolates of A. baumannii were resistant to ceftazidime/avibactam, except for AB-5. All isolates were found to be resistant to meropenem and levofloxacin. At 4 x MIC, all of the tested antibiotics showed bactericidal effect (>= 3 log(10)killing). The synergistic activities of ceftazidime/avibactam + colistin, ceftazidime/avibactam + tobramycin and ceftazidime/avibactam + tigecycline combinations at 1 x MIC were observed against studied 5/5, 4/5 and 4/5 strains, respectively. Furthermore, all of the tested combinations at 4 x MIC were additive at 24 h. No antagonism was observed. Conclusions: The findings of this study suggest that a significant bactericidal effect was seen with all tested combinations. These findings present significant implications for antibiotic choice for the treatment of infections caused by MDR A. baumannii. (C) 2018 International Society for Chemotherapy of Infection and Cancer. Published by Elsevier Ltd. All rights reserved. Research Fund of the University of Istanbul (Istanbul, Turkey) [21897] This work was supported by a grant from the Research Fund of the University of Istanbul (Istanbul, Turkey). Project number: 21897.