Towards a better understanding of commonly used medicinal plants from Turkiye: Detailed phytochemical screening and biological activity studies of two Teucrium L. species with in vitro and in silico approach.

ETHNOPHARMACOLOGICAL RELEVANCE: Since ancient times, Teucrium L. species have been among the most commonly used traditional medicinal plants mainly in the Mediterranean region. From tackling gastrointestinal problems to maintaining the healthy functioning of endocrine glands, and from treating malaria to severe dermatological disorders, Teucrium species are known to have extensive therapeutic applications. Teucrium polium L. and Teucrium parviflorum Schreb. are the two members of the genus that have been used in Turkish folk medicine for various medicinal purposes. AIM OF THE STUDY: To determine the phytochemical compositions of the essential oils and ethanol extracts of Teucrium polium and Teucrium parviflorum collected from different locations in Turkiye along with the investigation of in vitro antioxidant, anticancer, antimicrobial activities, and both in vitro and in silico enzyme inhibitory activities of the extracts. MATERIALS AND METHODS: Ethanol extracts of Teucrium polium aerial parts and roots, and aerial parts of Teucrium parviflorum were prepared. Volatile profiling of the essential oils by GC-MS, phytochemical profiling of the ethanol extracts by LC-HRMS, antioxidant activity by DPPH radical scavenging, ABTS cation radical scavenging, CUPRAC, and metal chelating activity assays, anticholinesterase, antityrosinase, antiurease, activities by different enzyme inhibitory activity assays, anticancer activity by SRB cell viability assay, and antimicrobial activity against a standard panel of bacteria and fungi by the microbroth dilution technique. Molecular docking studies were performed by Autodock Vina (Ver. 1.1.2). RESULTS: The studied extracts were found to be quite rich in various biologically important volatile and phenolic compounds. (-)-Epigallocatechin gallate, which is a molecule renowned for having great therapeutic potential, was the major compound of all extracts. Teucrium polium aerial parts extract was revealed as a great source for naringenin with 16327 ± 685.23 µg/g extract. All extracts exerted significant antioxidant activity by different methods. All extracts demonstrated antibutrylcholinesterase, antityrosinase, and antiurease activities by in vitro and in silico assays. Teucrium polium roots extract stood out with remarkable tyrosinase and urease inhibitory and cytotoxic activities. CONCLUSION: The obtained results from this multi-disciplinary study proves that the traditional use of these two Teucrium species is justified, and the mechanisms behind are enlightened.

Aminated Quinolinequinones as Privileged Scaffolds for Antibacterial Agents: Synthesis, In Vitro Evaluation, and Putative Mode of Action.

Our previous studies have revealed that the aminated 1,4-quinone scaffold can be used for the development of novel antibacterial and/or antifungal agents. In this study, the aminated quinolinequinones (AQQ1-9) were designed, synthesized, and evaluated for their antimicrobial activity against a panel of seven bacterial strains (three Gram-positive and four Gram-negative bacteria) and three fungal strains. The structure-activity relationship (SAR) for the QQs was also summarized. The antibacterial activity results indicated that the two aminated QQs (AQQ6 and AQQ9) were active against Enterococcus faecalis (ATCC 29212) with a MIC value of 78.12 µg/mL. Besides, the two aminated QQs (AQQ8 and AQQ9) were active against Staphylococcus aureus (ATCC 29213) with MIC values of 4.88 and 2.44 µg/mL, respectively. The most potent aminated QQs (AQQ8 and AQQ9) were identified as promising lead molecules to further explore their mode of action. The selected QQs (AQQ8 and AQQ9) were further evaluated in vitro to assess their potential antimicrobial activity against each of 20 clinically obtained methicillin-resistant S. aureus isolates, antibiofilm activity, and bactericidal activity using time-kill curve assay. We found that the molecules prevented adhesion of over 50% of the cells in the biofilm. Molecular docking studies were performed to predict the predominant binding mode(s) of the ligands. We believe that the molecules need further investigation, especially against infections involving biofilm-forming microbes.

Exploring the Relationships between Structure and Antimicrobial Potency of Quinolinequinones.

Microorganisms are responsible for hospital infections, and methicillin-resistant Staphylococcus aureus is one of them. In looking for the most effective lead structures to cope with the rise of antimicrobial (antibiotic) resistance, we evaluated the antimicrobial profile of quinolinequinones for potential antimicrobial applications. 1,4-quinone molecules fused with heteroatom have been studied extensively for many years as a source of drugs and lead structures. The aims of this study were to evaluate the antimicrobial activity of quinolinequinones against bacterial and fungal strains, and to probe for potential lead structures. For this reason, the activity of these compounds against three different strains of Candida fungi (C. albicans, C. parapsilosis, and C. tropicalis) and Gram-positive and Gram-negative pathogenic bacteria were investigated, searching for potential lead compounds. Five of nine quinolinequinones showed activity mainly against the Gram-positive strains with a minimal inhibitory concentration within the Clinical and Laboratory Standards Institute (CLSI) levels. The results revealed that quinolinequinones have significant activity against bacteria including Staphylococcus aureus and Staphylococcus epidermidis, and fungi including Candida albicans and Candida parapsilosis. QQ1, QQ2, QQ3, QQ5, and QQ6 exhibited the highest growth inhibition against two essential species of the Gram-positive strains (Staphylococcus epidermidis and Staphylococcus aureus). Among these, four molecules (QQ2, QQ3, QQ5, and QQ6) were also active against Enterococcus faecalis, the other member of the Gram-positive strains. The antifungal profile of two quinolinequinones (QQ7 and QQ8) indicated that they were as effective as the reference drug Clotrimazole against Candida albicans. The same molecules also have potential inhibitory antifungal activity against Candida tropicalis. For better understanding, the most active two quinolinequinones (QQ2 and QQ6) were examined for biofilm inhibition and a time-kill kinetic study.

Natural-product-inspired design and synthesis of thiolated coenzyme Q analogs as promising agents against Gram-positive bacterial strains: insights into structure-activity relationship, activity profile, mode of action, and molecular docking.

In an attempt to develop effective and potentially active antibacterial and/or antifungal agents, we designed, synthesized, and characterized thiolated CoQ analogs (CoQ1-8) with an extensive antimicrobial study. The antimicrobial profile of these analogs was determined using four Gram-negative bacteria, three Gram-positive bacteria, and three fungi. Because of the fact that the thiolated CoQ analogs were quite effective on all tested Gram-positive bacterial strains, including Staphylococcus aureus (ATCC® 29213) and Enterococcus faecalis (ATCC® 29212), the first two thiolated CoQ analogs emerged as potentially the most desirable ones in this series. Importantly, after the evaluation of the antibacterial and antifungal activity, we presented an initial structure-activity relationship for these CoQ analogs. In addition, the most promising thiolated CoQ analogs (CoQ1 and CoQ2) having the lowest MIC values on all tested Gram-positive bacterial strains, were further evaluated for their inhibition capacities of biofilm formation after evaluating their in vitro potential antimicrobial activity against each of 20 clinically obtained resistant strains of Gram-positive bacteria. CoQ1 and CoQ2 exhibited potential molecular interactions with S. aureus DNA gyrase in addition to excellent pharmacokinetics and lead-likeness profiles. Our findings offer important implications for a potential antimicrobial drug candidate, in particular for the treatment of infections caused by clinically resistant MRSA isolates.

Discovery of quinolinequinones with N-phenylpiperazine by conversion of hydroxyquinoline as a new class of antimicrobial agents targeting resistant pathogenic microorganisms.

The development of new antimicrobial agents is necessary to overcome the emerging antimicrobial resistance among infectious microbial pathogens. Herein, we successfully designed and synthesized quinolinequinones (QQs) with N-phenylpiperazine (QQ1-7) containing strong or weak EDG in the amino moiety by converting hydroxyquinoline (HQ) to the dichloroquinolinequinone (QQ) via chlorooxidation. We performed an extensive antimicrobial activity assessment of the QQs with N-phenylpiperazine (QQ1-7). Among the seven quinolinequinones (QQs) with N-phenylpiperazine tested, QQ3 and QQ4 were the most active molecules against Staphylococcus aureus (ATCC® 29213) with a MIC value of 1.22 µg/mL. In addition to this, while QQ4 was more than six (6) times more effective towards Enterococcus faecalis (ATCC® 29212), QQ3 was twenty-six (26) times more effective against same strain. Furthermore, the evaluation of antimicrobial activity indicated that six of seven synthesized QQs (QQ1-4, QQ6, and QQ7) exhibited superior biological potency, eight (8) times for five of them (QQ1-4 and QQ6) and two (2) times for QQ7, against Staphylococcus epidermidis (ATCC® 12228). Besides, all QQs except QQ5 displayed excellent antifungal activity against the fungi Candida albicans (ATCC® 10231). Among these, the two QQs (QQ3 and QQ4), which showed the lowest values against gram-positive bacterial strains (Staphylococcus aureus (ATCC® 29213), Staphylococcus epidermidis (ATCC® 12228), and Enterococcus faecalis (ATCC® 29212)) as well as fungal strains (Candida albicans (ATCC® 10231) and Candida parapsilosis (ATCC® 22019)), were further evaluated for their biofilm inhibition properties and their mode of action with in vitro potential antimicrobial activity against each of 20 clinically obtained resistant strains of gram-positive bacteria, and bactericidal activity using time-kill curve assay. In this study, we investigated the bactericidal effects of QQ3 against methicillin-resistant Staphylococcus aureus (MRSA) and Candida albicans strains. The findings of this study suggest that a significant bactericidal effect was seen with all tested 1 × MIC and 4 × MIC concentrations used within 24 h. Our findings present significant implications for an antimicrobial drug candidate for treating infections, especially those caused by clinically resistant MRSA isolates.

The Therapeutic Potential of Ethnomedicinally Important Anatolian Thyme Species: A Phytochemical and Biological Assessment.

Thyme has been used for various therapeutic purposes in many different cultures, which makes it one of the most riveting medicinal plants throughout history. From its beneficial effects on the respiratory tract or the gastrointestinal system, to its unique skin-related activities, the investigation of the medicinal properties of thyme has always been an alluring topic for researchers aiming to develop conventional medications from this traditional herb. With an incentive to contribute to the extensive thyme research, three Thymus L. species namely Thymus cariensis Hub-Mor. & Jalas (endemic), Thymus praceox subsp. grossheimii (Ronniger) Jalas, and Thymus pubescens Boiss. et Kotschy ex Celak from Turkey were deeply investigated within this study. The analysis of the phytochemical constituents of the extracts was conducted by LC-MS/MS. 12 biologically important secondary metabolites (p-coumaric acid, caffeic acid, salicylic acid, quinic acid, fumaric acid, vanillin, malic acid, rutin, apigenin, naringenin, and nicotiflorin) were detected in all extracts. Their total phenolic and flavonoid contents were calculated (11.15 ± 0.17-61.12 ± 2.59 µg PEs/mg extract, 2.53 ± 0.04-40.28 ± 0.92 µg QEs/mg extract, respectively), and the antioxidant potential of the extracts was evaluated by DPPH and ABTS radical scavenging and CUPRAC activity methods, accordingly, the extracts were shown to possess significant antioxidant activity. Among them, Thymus cariensis Hub-Mor. & Jalas was the most active with IC50 values of 34.97 ± 1.00 µg/ml and 9.98 ± 0.04 µg/ml regarding the DPPH and ABTS radical scavenging assays, respectively, and an A0.5 value of 5.80 ± 0.02 µg/ml according to CUPRAC activity method. Their anticholinesterase, antityrosinase, and antiurease activities were also tested, Thymus cariensis Hub-Mor. & Jalas (35.61 ± 1.20%) and Thymus pubescens Boiss. et Kotschy ex Celak aerial part extract (33.49 ± 1.39%) exhibited moderate antibutyrylcholinesterase activity at 200 µg/ml concentration. The results of the cell viability assay indicated that the extracts demonstrated moderate-to-low cytotoxicity on A498 human renal cell lines. Furthermore, all studied extracts exerted noteworthy antimicrobial activity, especially against Candida tropicalis (MIC values: 19.53-78.12 µg/ml). The presented data substantiates the use of thyme extracts as therapeutic agents in both ethnomedicine and conventional therapies.

Highly Active Small Aminated Quinolinequinones against Drug-Resistant Staphylococcus aureus and Candida albicans.

Two subseries of aminated quinolinequinones (AQQs, AQQ1-16) containing electron-withdrawing group (EWG) or electron-donating group (EDG) in aryl amine moiety were successfully synthesized. Antimicrobial activity assessment indicates that some of the AQQs (AQQ8-10 and AQQ12-14) with an EDG in aryl amine exhibited strong antibacterial activity against Gram-positive bacterial strains, including Staphylococcus aureus (ATCC® 29213) and Enterococcus faecalis (ATCC® 29212). In contrast, AQQ4 with an EWG in aryl amine displayed excellent antifungal activity against fungi Candida albicans (ATCC® 10231) with a MIC value of 1.22 µg/mL. To explore the mode of action, the selected AQQs (AQQ4 and AQQ9) were further evaluated in vitro to determine their antimicrobial activity against each of 20 clinically obtained resistant strains of Gram-positive bacteria by performing antibiofilm activity assay and time-kill curve assay. In addition, in silico studies were carried out to determine the possible mechanism of action observed in vitro. The data obtained from these experiments suggests that these molecules could be used to target pathogens in different modes of growth, such as planktonic and biofilm.

Promising Antibacterial and Antifungal Agents Based on Thiolated Vitamin K3 Analogs: Synthesis, Bioevaluation, Molecular Docking.

In the present study, we designed and synthesized thiolated VK3 analogs (VK3a-g) along with an extensive antimicrobial study. After the evaluation of the antibacterial and antifungal activity against various bacterial and fungal strains, we presented an initial structure-activity relationship study on these VK3 analogs. In particular, four thiolated VK3 analogs exhibited superior biological potency against some Gram-positive bacterial strains, including Staphylococcus aureus (ATCC® 29213) and Enterococcus faecalis (ATCC® 29212). Next, all thiolated VK3 analogs were evaluated for their potential of cell growth inhibition on the NCI-60 cancer cell lines panel. This screening underlined that the thiolated VK3 analogs have no visible cytotoxicity on different cancer cell lines. The selected two thiolated VK3 analogs (VK3a and VK3b), having minimal hemolytic activity, which also have the lowest MIC values on S. aureus and E. faecalis, were further evaluated for their inhibition capacities on biofilm formation after evaluating their potential in vitro antimicrobial activity against each of the 20 clinically obtained resistant strains of Staphylococcus aureus. VK3b showed excellent antimicrobial activity against clinically resistant S. aureus isolates. Furthermore, the tested molecules showed nearly two log10 reduction in the viable cell count at six hours according to the time kill curve studies. Although these molecules decreased biofilm attachment about 50%, when sub-MIC concentrations were used these molecules increased the percentage of biofilm formation. The molecular docking of VK3a and VK3b in S. aureus thymidylate kinase was conducted in order to predict their molecular interactions. VK3a and VK3b exhibited excellent lead-likeness properties and pharmacokinetic profiles that qualify them for further optimization and development. In conclusion, since investigating efficient novel antimicrobial molecules is quite difficult, these studies are of high importance, especially in the present era of antimicrobial resistance.

Active Quinolinequinones against Methicillin-Resistant Staphylococcus spp.

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.

Discovery and structure-activity relationships of the quinolinequinones: Promising antimicrobial agents and mode of action evaluation.

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.

Exploration of brominated Plastoquinone analogs: Discovery and structure-activity relationships of small antimicrobial lead molecules.

In the fight with the antimicrobial resistance, our continuous effort to find quinone analogs with higher inhibitory activity has previously led us to the promising Plastoquinone analogs. The 1,4-quinone moiety substituted with alkoxy substituent(s) plays an important role in the field of antimicrobial and anticancer drug discovery and development. Thus, an extensive series of 1,4-quinones, substituted in different positions with a variety of alkoxy substituents, has been designed, synthesized, and evaluated for their antimicrobial activity. Here, we describe the synthesis of brominated Plastoquinone analogs (BrPQ1-15) based on the dimethyl-1,4-quinone scaffold by employing two different paths. We also present here the in vitro antimicrobial activity of these analogs (BrPQ1-15) against a panel of pathogenic organisms. These studies resulted in several new selective antibacterial inhibitors and gave valuable insights into the structure-activity relationships. Among all the analogs studied, two analogs BrPQ1 with a methoxy substituent and BrPQ14 with a cyclic dioxy stand out as the most promising antibacterial molecules against Staphylococcus aureus and Staphylococcus epidermidis. Afterwards, two analogs were selected for a further investigation for biofilm evaluation. Finally, molecular docking studies for BrPQ1 and BrPQ14 with probable target S. aureus PNPase (5XEX) and predictive ADMET studies were also carried out.

Volatile and phenolic profiling of a traditional medicinal plant, Hypericum empetrifolium with in vitro biological activities.

ETHNOPHARMACOLOGICAL RELEVANCE: Hypericum empetrifolium Willd is a member of the Hypericaceae family, mainly known in southern Greece, and western Turkey. Being a centuries-old medicinal plant, the aerial parts of the plant have been used for the treatment of herpes, kidney stones, gastric ulcer, and also for their anti-helminthic, and diuretic purposes traditionally. AIM OF THE STUDY: The current study aimed to investigate the phytochemical profiles of the essential oil, and two ethanol extracts prepared from the aerial parts (H. empetrifolium aerial parts extract - HEA), and roots of the plant (H. empetrifolium roots extract - HER), and to provide data on antioxidant, anticholinesterase, antityrosinase, antiurease, cytotoxic, and antimicrobial activities of the extracts. MATERIALS AND METHODS: In this study, volatile and phenolic compounds of the HEA and HER were analyzed by GC-MS and LC-MS/MS, respectively. Antioxidant potential of the extracts was clarified by using DPPH radical scavenging assay, ABTS cation radical assay, and the CUPRAC assay. Acetylcholinesterase, butyrylcholinesterase, urease, and tyrosinase inhibitory activity assays were used to determine enzyme inhibition capacity of the extracts. Cytotoxic activity of the extracts was established by using XTT assay. The antimicrobial activity of the extracts was determined by the microbroth dilution technique. RESULTS: The major compounds of the essential oil were revealed as alloaromodendrene (24.7%), α-pinene (14.7%), ß-pinene (10.7%), and α-terpineol (7.7%) by the GC-MS analysis. According to the LC-MS/MS analysis results, quinic acid was the most abundant constituent in both extracts with 20612.42 ± 169.02 µg/g extract in HEA extract, and with 2254.34 ± 18.49 µg/g extract in HER extract, respectively. The HEA extract was also found to be rich in terms of chlorogenic acid (5583.14 ± 38.52 µg/g extract), isoquercitrin (3076.77 ± 40.92 µg/g extract), and malic acid (2822.90 ± 31.90 µg/g extract). HEA extract exhibited a significant antioxidant effect with an IC50 value of 11.98 ± 0.22 µg/mL according to the DPPH radical scavenging assay. Similar results were obtained with the ABTS cation radical assay, and the CUPRAC assay. HER extract showed a strong butyrylcholinesterase inhibitory effect with 88.69 ± 0.62% at 200 µg/mL concentration. Both extracts were considered to have moderate anti-tyrosinase activity compared to the standard at 200 µg/mL. The best antimicrobial activity was obtained for HEA against C. parapsilosis with an MIC value of 4.88 µg/mL. HEA also exhibited antifungal activity against C. tropicalis with 19.53 µg/mL. Only HER exhibited low cytotoxicity on A498 renal cell lines with 60.6% cell viability. CONCLUSION: Unquestionably, H. empetrifolium Willd has ethnopharmacological importance according to these results, and further investigations are required to evaluate other therapeutic properties of the plant.

Antibacterial and antibiofilm activities of ceragenins against Achromobacter species isolated from cystic fibrosis patients.

Achromobacter species, which are recognized as emerging pathogens isolated from patients with cystic fibrosis, are capable of forming biofilm in the respiratory tract in patients and innate multidrug resistance to antimicrobials. CSAs are cationic salt derivatives that mimic the activity of antimicrobial peptides and exhibit antimicrobial activity against bacteria. In this study, the in vitro activities of various ceragenins against Achromobacter-species biofilms were investigated comparatively with a conventional antibiotic (meropenem). Biofilm-formation inhibition and biofilm-adhesion inhibition were investigated on five strong biofilm-producing strains. The lowest MIC50 result was obtained with CSA-13. All of the tested CSAs showed significant biofilm inhibitory activity in the manner of a time- and concentration-dependent effect. To the best of our knowledge, this is the first article to evaluate the antibacterial and antibiofilm activities of tested CSAs against Achromobacter species.

Evaluation of antifungal and disinfectant-resistant Candida species isolated from hospital wastewater.

The present study aims to examine the in vitro antifungal susceptibility patterns of Candida species isolated from hospital wastewater, and the efficacy of widely used disinfectants (sodium hypochlorite and benzalkonium chloride) against planktonic and biofilm cells were assessed. Susceptibility testing demonstrated that the two azoles were more effective against C. albicans than non-albicans isolates. When we determine the efficiency of disinfectants against the planktonic cells, benzalkonium chloride did not show any activity in all the studied strains under tested conditions except C. albicans-1. However, sodium hypochlorite showed ≥ 4 log10 killing in viable cells for different contact times. On the other hand, while 0.1% and 1% concentrations of benzalkonium chloride showed fungicidal activity against biofilm cells, sodium hypochlorite at 1% only demonstrated fungicidal activity. Those results showed that surface water is a possible transmission path for fungi in the investigated hospital region and may be a health risk, especially for the immunocompromised host.

In Vitro Synergistic Effect and Mutant Prevention Concentrations of Cefepime Alone or in Combination with Sulbactam Against OXA-48-positive Klebsiella pneumoniae Isolates.

The aim of this study is to investigate the combination of cefepime and sulbactam. Sulbactam, when administered , will effectively inhibit all Extended-spectrum beta lactamases (ESBLs) of the microorganism, while cefepime will inhibit the growth of the resistant microorganisms since it will not be hydrolyzed by OXA-48. Forty OXA-48-producing K. pneumoniae strains were investigated for their Minimum inhibitory concentrations (MICs) for carbapenems, cefepime, and cefepime + sulbactam by broth microdilution method. Also, the mutant prevention concentration (MPC)s of cefepime alone or in combination with sulbactam was determined. Additionally, the bactericidal activities of cefepime and cefepime + sulbactam were evaluated by the time-kill curve (TKC) assay against selected strains. Also, the in vitro synergistic activity of cefepime + sulbactam combination was determined by TKC. Based on MIC results, up to 35/40 and 34/40 of the strains were resistant to carbapenems and cefepime, respectively. Cefepime + sulbactam MIC range was lower than those for cefepime alone against all the studied isolates. Moreover, cefepime + sulbactam combination presented lower MPC values than cefepime alone. The synergistic interactions of cefepime + sulbactam were also achieved against studied strains at 24 h. No antagonism was observed against studied K. pneumoniae strains. The findings of this study displayed that cefepime + sulbactam combination had synergistic or additive effect against OXA-48-producing K. pneumoniae strains. Additionally, it was first observed that this combination could display a lower MPC than cefepime alone. Further investigations may be helpful for understanding the effectiveness of cefepime + sulbactam combinations for OXA-48-positive carbapenem-resistant K. pneumoniae isolates.

Synergistic activities of ceftazidime-avibactam in combination with different antibiotics against colistin-nonsusceptible clinical strains of Pseudomonas aeruginosa.

Background: This study aims to analyse the effect of ceftazidime-avibactam plus various antibiotics against multidrug-resistant (MDR) Pseudomonas aeruginosa isolated from Intensive Care Units.Methods: 40 non-duplicate P. aeruginosa isolates were screened for their MICs of ceftazidime, ceftazidime-avibactam, colistin, levofloxacin, doripenem and tobramycin. MICs were determined by the broth microdilution method. The in vitro bactericidal activities of ceftazidime-avibactam compared to studied antibiotics were also determined by time-kill curve assays both at 1xMIC and at 4xMIC against carbapenemase-producing or -not producing six colistin-nonsusceptible MDR clinical strains of P.aeruginosa. Additionally, synergistic interactions were investigated by the time-kill curve assay.Results: The MIC90 values for ceftazidime, ceftazidime-avibactam, colistin, levofloxacin, doripenem and tobramycin against MDR P. aeruginosa isolates were found to be >256, 64, 8, 64, 128, and >256 mg/L, respectively. The minimum bactericidal concentration90 values for those antibiotics were also >256, 64, 16, 128, 256, and >256 mg/L, respectively. While doripenem, tobramycin and levofloxacin were bactericidal (>3 log10 killing) against the 2/6, 3/6 and 1/6 P. aeruginosa isolates at 4xMIC concentrations, respectively, levofloxacin and tobramycin were bactericidal against only one isolate (1/6) at 1xMIC concentrations at 24 h. The synergistic interactions of these antimicrobial agents were also achieved with ceftazidime/avibactam + colistin (4/6), ceftazidime/avibactam + tobramycin (3/6), and ceftazidime/avibactam + levofloxacin (3/6) combinations. No antagonism was observed against studied P. aeruginosa strains.Conclusions: The findings of this study suggest that ceftazidime/avibactam with colistin, or tobramycin, were effective against colistin-nonsusceptible strains. This combination therapy could be an alternative antibiotic therapy for resistant P. aeruginosa strains.

Evaluation of the synergy of ceftazidime/avibactam in combination with colistin, doripenem, levofloxacin, tigecycline, and tobramycin against OXA-48 producing Enterobacterales.

This study aims to analyze the effect of ceftazidime/avibactam plus various antibiotics against OXA-48-producing Enterobacterales isolated from Intensive Care Units. Seventy-four non-duplicate OXA-48-producing Enterobacterales isolates were screened for their MICs by the microbroth dilution method. The in-vitro bactericidal and synergistic activities of ceftazidime/avibactam alone or in combination with other antibiotics were determined by time-kill curve assays. According to our results, colistin was the most active drug with higher susceptibility rates in the strains. Colistin, levofloxacin, tobramycin, and doripenem showed bactericidal effects against different isolates. The best synergistic interactions were achieved with ceftazidime/avibactam + colistin, ceftazidime/avibactam + tobramycin, and ceftazidime/avibactam + tigecycline against studied strains used at 1xMIC concentrations at 24 h. No antagonism was observed against studied OXA-48-producing Enterobacterales strains.The findings of this study suggest that ceftazidime/avibactam plus colistin, tobramycin, or tigecycline were more effective against OXA-48-producing Enterobacterales strains. This combination therapy could be an alternative antibiotic therapy for carbapenemase-producing Enterobacterales strains.

Comparative In Vitro Activities of First and Second-Generation Ceragenins Alone and in Combination with Antibiotics Against Multidrug-Resistant Klebsiella pneumoniae Strains.

OBJECTIVES: The ceragenins, or CSAs, were designed to mimic the activities of antimicrobial peptides and represent a new class of antimicrobial agent. The aim of this study was to comparatively investigate the antimicrobial activities of first/second generation ceragenins and various antibiotics against multidrug-resistant (MDR) Klebsiella pneumoniae, including colistin-resistant bacteria. Also, the synergistic effects of two ceragenins with colistin or meropenem were investigated with six K. pneumoniae strains presenting different resistant patterns. METHODS: Minimal inhibition concentrations (MICs) were determined by the microdilution method according to the CLSI. Antibiotic combination studies were evaluated by the time-kill curve method. RESULTS: MIC50 and MIC90 values of tested ceragenins ranged from 8 to 32 mg/L and 16 to 128 mg/L. Overall, among the ceragenins tested, CSA-131 showed the lowest MIC50 and MIC90 values against all microorganisms. The MICs of the ceragenins were similar or better than tested antibiotics, except for colistin. Synergistic activities of CSA-131 in combination with colistin was found for strains both at 1× MIC and 4× MIC. No antagonism was observed with any combination. CONCLUSIONS: First-generation ceragenins CSA-13 and CSA-44 and second-generation ceragenins CSA-131, CSA-138 and CSA-142 have significant antimicrobial effects on MDR K. pneumoniae. Mechanisms allowing resistance to clinical comparator antibiotics like colistin did not impact the activity of ceragenins. These results suggest that ceragenins may play a role in treating infections that are resistant to known antibiotics.

Discovery of a new family of heterocyclic amine linked plastoquinone analogs for antimicrobial evaluation.

A series of aminobenzoquinones, denoted as PQ analogs (PQ1-13), were synthesized by employing a green methodology approach using water as solvent developed by Tandon et al. Subsequently, in vitro antimicrobial potential of all PQ analogs was evaluated in a panel of seven bacterial strains (three gram positive and four gram negative bacteria) and three fungi. The antifungal profile of all PQ analogs indicated that four analogs (while PQ2, PQ9, and PQ10 were effective against Candida tropicalis, PQ11 is effective against Candida albicans) have potent antifungal activity. The results revealed that PQ9 showed similar antibacterial activity against Staphylococcus epidermidis compared clinically prevalent antibacterial drugs cefuroxime. PQ11 exhibited the highest antibacterial activity against S. epidermidis, which was about fourfold better than that of cefuroxime. Owing to their outstanding activities, PQ9 and PQ11 were chosen for a further investigation for biofilm and cytotoxicity evaluation. Based on the tests performed, there was a significant positive correlation between inhibition of the biofilm attachment and time. In addition, PQ9 and PQ11 showed cytotoxic effects at high concentrations on Balb/3T3, HaCaT, HUVEC, and NRK-52E cells (>24 and >18 µg/mL, respectively). Thus, two analogs (PQ9 and PQ11) were identified as the hits with the strong antibacterial efficiency against the S. epidermidis with low MIC values.

Comprehensive analysis of an uninvestigated wild edible medicinal garlic species from Turkey: Allium macrochaetum Boiss. & Hausskn.

The study was aimed to investigate the phenolic compounds of Allium macrochaetum by LC-MS/MS, as well as the antioxidant, antialzheimer, and antimicrobial activities of the extracts, and determination of the essential oil and fatty acid compositions by GC-MS. The results indicate that malic acid and t-caffeic acid are the major compounds in the bulbs. The main components of fatty acids were found to be linolenic (40.72%), oleic (19.79%), and palmitic (18.45%) acids. The allyl disulfide (66.97%) was found as major compound in the essential oil. The ethanol extract of the bulbs exhibited stronger ABTS cation (IC50 : 55.90 ± 1.08 µg/ml) and DPPH free (IC50 : 204.43 ± 2.17 µg/ml) radical scavenging activities than the other extracts. The extract also showed moderate cupric reducing activity with 1.52 absorbance at 100 µg/ml concentration. Only the ethanol extract of the bulbs showed weak inhibition (23.34 ± 0.11%) against butrylcholinesterase enzyme at 200 µg/ml. PRACTICAL APPLICATIONS: Allium macrochaetum is a wild and edible garlic species which grown in Turkey, Iran, Iraqi, and Syria. A. macrochaetum has been used by local people in Turkish folk medicine as an antibiotic, and for the treatment of alopecia. The health benefits and nutritional values of A. macrochaetum were clarified in the first time. Phenolic compounds of A. macrochaetum were detected by LC-MS/MS. The essential oil and fatty acid compositions of A. macrochaetum were identified by GC-MS. Antioxidant, antialzheimer, and antimicrobial activities potential of A. macrochaetum were determined.