Antimicrobial Activity of Solanum torvum Crude Extracts against Important Mycobacterial Strains.

Aims and objectives: Tuberculosis (TB) caused by Mycobacterium tuberculosis complex remains a leading cause of morbidity and mortality worldwide. The zoonotic infectious condition represents a never-ending challenge towards which drug discovery efforts are needed. The current study was designed to evaluate the in vitro antimycobacterial activity of ethanolic extracts from roots, stem bark, leaves and unripe fruits derived from Solanum torvum, a shrub traditionally used against respiratory tract illnesses, including tuberculosis. Methods: The phenotypic colorimetric micro plate alamar blue assay (MABA) was used to study the antimycobacterial activity of the ethanolic extracts against six mycobacterial strains. Each experiment was run in triplicate. Data generated was analyzed using descriptive statistics to obtain mean minimum inhibitory concentration values. Results: The roots, stem bark, leaves and unripe fruits exhibited minimum inhibitory concentration values of 1.250 mg/mL, 0.078 mg/mL, 1.250 mg/mL and 0.625 mg/mL against the pathogenic mycobacterial strain, M. tuberculosis H37Rv (ATCC 27294) respectively. Conclusions: In conclusion, Solanum torvum stem bark has demonstrated moderate activity against the pathogenic Mycobacterium tuberculosis strain. This observation validates the ethno pharmacological use of the plant species against tuberculosis. Further studies are required to isolate, elucidate the structure and characterize the antimycobacterial compounds responsible for the observed activity. These will potentially contribute towards bioprospecting for a new class of ligands with activity against sensitive and drug resistant strains of M. tuberculosis.

Tuberculosis (TB) caused by Mycobacterium tuberculosis complex remains a leading cause of morbidity and mortality worldwide. The zoonotic infectious condition represents a never-ending challenge toward which drug discovery efforts are needed. The current study was designed to evaluate the in vitro antimycobacterial activity of hydroethanolic extracts from Allium sativum and Allium cepa bulbs and leaves, traditionally used against respiratory tract illnesses, including TB. The phenotypic colorimetric microplate Alamar blue assay was used to study the antimycobacterial activity of the ethanolic extracts against six mycobacterial strains. Each experiment was run in triplicate. Data generated were analyzed using descriptive statistics to obtain mean minimum inhibitory concentration (MIC) values. The A. sativum bulbs, A. sativum leaves, A. cepa bulbs, and A. cepa leaves exhibited MIC values of 19.5 µg/mL, 78.1 µg/mL, 78.1 µg/mL, and 19.5 µg/mL against the pathogenic mycobacterial strain, M. tuberculosis H37Rv (ATCC 27294), respectively. In conclusion, the tested A. sativum and A. cepa bulbs and leaves have demonstrated significant activity against the pathogenic M. tuberculosis strain. This observation validates the ethnopharmacological use of the Allium species against TB. Further studies are required to isolate, elucidate the structure, and characterize the antimycobacterial compounds responsible for the observed activity. These will potentially contribute toward bioprospecting for a new class of ligands with activity against sensitive and drug-resistant strains of M. tuberculosis.

In vitro antimycobacterial activity and toxicity of eight medicinal plants against pathogenic and nonpathogenic mycobacterial strains

peer reviewed

Ethanolic and aqueous extracts of three local medicinal plants viz Alchornea cordifolia, Nauclea latifolia and Spondias mombin were screened against Pseudomonas aeruginosa, Escherichia coli, Staphylococcus aureus and Salmonella typhi. The results reveal that ethanolic extract of A. cordifolia showed activity against P. aeruginosa, E coli and S .typhi with mean minimum inhibitory concentration (MIC) values of 2.733, 2.887 and 0.602 mg/ml respectively, while its aqueous extract was active against S .typhi only, (MIC 0.912 mg/ml). Ethanolic extract of S. mombin was only active against S. typhi (MIC 1.445 mg/ml) while its aqueous extract exhibited activity against S. aureus and S. typhi with MIC values of 0.622 and 1.514 mg/ml respectively. Results of Independent Samples t-test infer that there was no significant difference (P > 0.05) in the susceptibilities to the plant extracts between antibiotic–resistant and sensitive P. aeruginosa. These findings underscore the possibility of using A. cordifolia and S. mombin extracts in developing alternative drugs for cases of drug resistance in infections caused by S. aureus and S. typhiKeywords: Pseudomonas aeruginosa, Alchornea cordifolia, Spondias mombin, Nauclea latifolia, antibacterial activity

The occurrence of resistant bacteria to specific heavy metals can be associated with increasing load of the metals in the environment. River Yamuna is polluted by various toxic heavy metals discharged by several industrial and agricultural sources. Therefore, the use of heavy metal-resistant bacteria as an indicator of metal pollution was tested in the present study. For the purpose of the study, the heavy metal resistance status of 42 Escherichia coli strains isolated from River Yamuna water from 7 sampling sites within a span of 2years was determined using growth curves and plate dilution method in terms of minimum inhibitory concentration (MIC) values by comparing with MIC value of control strain. Seasonally, the lowest mean MIC value was observed for bacterial strains isolated in post-monsoon (December) 2013 and highest mean MIC value was observed for bacterial strains isolated in monsoon (August) 2015. Site-wise analysis of the maximum mean MIC values for all the isolated strains showed the highest mean Ni MIC value for the bacterial strains isolated from site S4 (ITO), highest mean Cu MIC, Cr MIC, and Fe MIC values for the bacterial strains isolated from site S2 (Najafgarh drain intermixing zone) and highest mean Cd MIC, Pb MIC, and Zn MIC values for the bacterial strains isolated from site S7 (Shahdara drain intermixing zone). Correlation analysis between mean MIC site-wise results with mean heavy metal site-wise concentrations showed significant positive correlation indicating that the higher the mean concentration of a given heavy metal at a given site, the higher the mean MIC value for the strains isolated from the same site indicating higher level of resistance. Overall, the present study has shown that the presence of heavy metals in River Yamuna caused due to indiscriminate discharge of various effluents from different kind of sources as well as due to insufficient treatment capacity of sewage treatment plants as well as common effluent treatment plants, has serious impacts on its bacterial microflora as it leads to the development of resistant strains.

Positive allosteric modulators (PAMs) of the GABAB receptor constitute a new class of GABAB-receptor ligands. GABAB PAMs reproduce several pharmacological effects of the orthosteric GABAB receptor agonist, baclofen, although displaying a better safety profile. This paper reviews the reducing or, frequently, even suppressing effects of all GABAB PAMs tested to date on multiple alcohol-related behaviours in laboratory rodents exposed to validated experimental models of human alcohol use disorder. Acute or repeated treatment with CGP7930, GS39783, BHF177, rac-BHFF, ADX71441, CMPPE, COR659, ASP8062, KK-92A, and ORM-27669 reduced excessive alcohol drinking, relapse- and binge-like drinking, operant alcohol self-administration, reinstatement of alcohol seeking, and alcohol-induced conditioned place preference in rats and mice. These effects closely mirrored those of baclofen; notably, they were associated to remarkably lower levels of tolerance and toxicity. The recent transition of ASP8062 to clinical testing will soon prove whether these highly consistent preclinical data translate to AUD patients.

Herein we report a new class of hemilabile ligands with boron-dipyrromethene (Bodipy) fluorophores that, when complexed to Pt(II), can signal changes in coordination mode through changes in their fluorescence. The ligands consist of phosphino-amine or phosphino-thioether coordinating moieties linked to the Bodipy's meso carbon via a phenylene spacer. Interestingly, this new class of ligands can be used to signal both ligand displacement and chelation reactions in a fluorescence "turn-on" fashion through the choice of weakly binding heteroatom in the hemilabile moiety, generating up to 10-fold fluorescence intensity increases. The Pt(II) center influences the Bodipy emission efficiency by regulating photoinduced electron transfer between the fluorophore and its meso substituent. The rates at which the excited Bodipy-species generate singlet oxygen upon excitation suggest that the heavy Pt(II) center also influences Bodipy's emission efficiency by affecting intersystem crossing from the Bodipy excited singlet to excited triplet states. This signaling strategy provides a quantitative read-out for changes in coordination mode and potentially will enable the design of new molecular systems for sensing and signal amplification.

Background: The altitudinal and geographical variability of the Aurès mountains of Algeria favored the existence of some endemic and rare varieties of medicinal plants. The aim of the present work is to determine the chemical composition, antimicrobial and antibiofilm properties of the essential oils (EOs) from aerial parts of four medicinal plants from Aurès region of Algeria; Juniperus thurifera L., Juniperus oxycedrus L., Salvia officinalis L. and Thymus ciliatus ssp. munbyanus (Boiss. & Reut.) Batt. on coagulase negative staphylococci (CoNS) isolates.
 Methodology: Extraction of EOs from the four plant materials was carried out by hydro-distillation, and the EO yield expressed in gram of the distillate per 100 grams of dry matter. The chemical composition of the EOs was analyzed by gas chromatography-mass spectrometry (GC-MS) method. In vitro antibacterial and antibiofilm activities of the EOs were evaluated against CoNS previously isolated at the Anti-Cancer Center of Batna, Algeria using the agar disc diffusion assay and biofilm inhibition study, respectively. Minimum inhibitory concentration (MIC) and minimum bacterial concentration (MBC) of the EOs of S. officinalis L. and T. ciliatus ssp. munbyanus were determined by the dilution method.
 Results: Twenty-seven and 41 compounds rich in monoterpene hydrocarbons were identified from J. oxycedrus and J. thurifera plants respectively, while 45 and 32 compounds, constituted mainly by oxygenated monoterpenes, were identified from S. officinalis L. and T. ciliatus ssp. munbyanus, respectively. The EOs of T. ciliatus ssp. munbyanus showed the most inhibitory activity of all the four plants on CoNS isolates (n=66) with mean inhibition zone diameter of 24.99±6.29mm, and mean MIC and MBC values of 2.65±3.77mg/ml and 5.31±7.41mg/ml respectively, followed by S. officinalis L., with mean inhibition zone diameter of 13.38± 6.52mm, and mean MIC and MBC values of 27.53±28.2 mg/ml and 31.97±33.19 mg/ml respectively (p<0.0001 by one-way ANOVA). Also, percentage biofilm inhibition of CoNS isolates (n=59) was high for EOs of T. ciliatus ssp. munbyanus (65.63±10.71%) and S. officinalis L. (53.13±5.83%), although was significantly higher for T. ciliatus ssp. munbyanus compared to S. officinalis L. (p<0.0001, t=7.874).
 Conclusion: Essential oils from T. ciliatus ssp. munbyanus and S. officinalis L. could represent an alternative to classical antibiotics against planktonic cells and biofilms of CoNS.

Tuberculosis (TB) remains a major global threat, with 10 million new cases and 1.5 million deaths each year. In multidrug-resistant tuberculosis (MDR-TB), resistance is most commonly observed against isoniazid (INH) and rifampicin (RIF), the two frontline drugs. Isoniazid resistance is predominantly linked to mutations in the InhA gene, which encodes an enzyme involved in mycolic acid synthesis, a vital component of the mycobacterial cell wall. Mutations in InhA reduce drug binding, rendering INH ineffective. These morbidity and mortality figures, along with the fact that the rise and global spread of drug-resistant TB, underscores the need for the discovery of novel therapeutics. In this direction, we have previously synthesized, characterized, and screened a library of diaryl ether dehydrozingerone derivatives against mycobacteria and identified two best hits, 7 and 14, based on bacteriostatic activities. The present study aimed to thoroughly investigate the antituberculosis potential of these compounds, particularly regarding drug-resistant TB. Our findings revealed that both compounds exhibited tuberculocidal activity against the standard laboratory strain Mycobacterium tuberculosis (M. tb) H37Rv, with minimal bactericidal concentrations (MBC) of 4μg/ml for compound 7 and 8μg/ml for compound 14. Next, concentration vs time-kill kinetics of both these compounds showed concentration-dependent bactericidal activities against M. tb and complete pathogen eradication from culture at just 16× MIC. Both compounds were found to be suitable for combination regimens as their interactions with isoniazid and rifampicin against M. tb were observed to be synergistic. Additionally, 7 and 14 exhibited minimal hemolysis against human RBCs and less cytotoxicity was observed against three human cell lines up to 1000μM. Molecular docking revealed that these compounds bind more effectively to M. tb InhA, including its mutant forms where isoniazid binding is impaired, outperforming both isoniazid and triclosan in binding affinity. Importantly 7 and 14 showed potent activity against drug-susceptible clinical isolates and two isoniazid-resistant M. tb clinical isolates equivalent to that against M. tb H37Rv. The most interesting observation was that both compounds were found to be effective against three multi-drug resistant (MDR) strains of M. tb, thereby depicting their potential against drug-resistant TB. An ex vivo assay on RAW 264 cells infected with M. tb demonstrated a significant reduction in bacterial load at 8× MIC, revealing the fact that these compounds are highly effective against intracellular M. tb H37Rv. To the best of our knowledge, this is the first study that reports promising antimycobacterial potential of 7 and 14 against drug-susceptible, isoniazid-resistant, and MDR tuberculosis which warrants further exploration considering the need for new anti-TB medicine.

Introduction: The development of multidrug resistance is a serious health problem, which demands the quest and development of many antibacterial agents. The class Actinomycetes represents best source for many antimicrobial agents. The present focus on Actinomycetes has yielded many antimicrobial agents including Nargenicin-A1. The Nargenicin-A1 belonging to class macrolides was found to have strong antibacterial activity against Staphylococcus and Streptococcus. Aim: To determine the Minimum Inhibitory Concentration (MIC) of Nargenicin-A1 against clinically isolated aerobic gram positive bacteria and comparing its antimicrobial activities with various antibiotics. Materials and Methods: A prospective, hospital-based, observational study was conducted at the Department of Microbiology, Raichur Institute of Medical Sciences, Raichur, Karnataka, India, from August 2015 to July 2016. All the clinical samples like pus, sputum, urine, ear swabs, wound swabs and body fluids received for culture and sensitivity testing at the Department of Microbiology during the study period was included. The antimicrobial activity was determined by measuring the MIC of Nargenicin-A1 by broth dilution method following standard procedure and the mean MIC was calculated. Pearson’s coefficient of correlation was calculated to find out correlation between MIC of Nargenicin-A1 and MIC of various antibiotics effective against gram positive bacteria. Results: The most common isolate was Staphylococcus followed by Enterococcus and Streptococcus. The least mean MIC of Nargenicin-A1 was observed for Streptococcus (0.017 μg/mL) followed by S. aureus (3.97 μg/mL), and the highest mean MIC value was recorded for Enterococcus (27.34 μg/ mL). Among Staphylococcus aureus, the mean MIC value of Nargenicin-A1 for Methicillin Sensitive Staphylococcus aureus (MSSA), Methicillin Resistant Staphylococcus aureus (MRSA) and Vancomycin Resistant Staphylococcus aureus (VRSA) was 0.06 μg/mL, 0.12 μg/mL and 25 μg/mL, respectively. When compared Nargenicin-A1 with various antibiotics in terms of their MICs, the activity of Nargenicin-A1 was in close proximity to that of vancomycin and linezolid against MSSA, MRSA, and Enterococci and marginally with linezolid against VRSA. Conclusion: Nargenicin-A1 exhibits strong antibacterial property against a broad spectrum of aerobic gram positive bacteria, including VRSA. The study revealed that Nargenicin-A1 can be considered as a potential alternative against multidrug resistant gram positive bacteria.

Poster session 1, September 21, 2022, 12:30 PM - 1:30 PM ObjectivesTo compare the prevalence and clinical presentation of Mucormycosis in pre-COVID era (January 2017-December 2019) and COVID era (January 2020-till date).To compare the AFST pattern of the zygomycetes causing Mucormycosis in pre-COVID era and COVID era.MethodsThis is a retrospective, hospital-based descriptive study. This study included patients admitted during the pre-COVID and COVID era at a tertiary care center, Chennai. The cases were categorized into two: (1) possible mucormycosis cases which included direct microscopy [Potassium hydroxide (KOH) and histopathological examination] positives and (2) confirmed cases which included direct microscopy and culture positives. Direct microscopic examinations like KOH wet mount and histopathological examination (H and E stain and special stains) were performed. Samples were cultured on Sabourauds dextrose agar and identification was done by analyzing the microscopic morphology using lactophenol cotton blue mount. AFST was performed for culture positive isolates with amphotericin B, itraconazole, posaconazole, voriconazole and isavuconazole by microbroth dilution method according to CLSI M38-A2.ResultsDuring the Pre-COVID era, out of the 365 samples received in the laboratory, 35 were possible mucormycosis cases. Only 17 were confirmed cases, out of which 16 grew Rhizopus oryzae and 1 grew Apophysomyces elegans. During the COVID era, among 886 samples received in the laboratory, 143 were possible mucormycosis cases, and 31 were confirmed cases that grew Rhizopus oryzae (26), Rhizomucor pusillus (2), Mucor sp (2), and Basidiobolus ranarum (1). Though the risk factors were common during the pre-COVID and COVID era, additional risk factors like steroid therapy (19.2%), and COVID infection (28.7%) were seen during the COVID era. Though clinical presentations were common during both pre-COVID and COVID era, additional complications like epistaxis (0.57%), orbital cellulitis (32.7%), and loss of smell (8.04%) were seen during COVID era. The prevalence of complications was more during COVID era compared to pre-COVID era. Treatment received during the pre-COVID era was only amphotericin B, whereas during the COVID era majority of the patients received posaconazole (74.5%) followed by liposomal amphotericin B (25.5%). The antifungal susceptibility test showed the following mean minimum inhibitory concentration (MIC) values: amphotericin B (1.8 μg/ml), itraconazole (3.6 μg/ml), posaconazole (0.31 μg/ml), and voriconazole (1.61 μg/ml) during the pre-COVID era while the mean MIC values during the COVID era had the following variations: amphotericin B (0.97 μg/mL), itraconazole (13.6 μg/ml), Posaconazole (13.4 μg/ml), voriconazole (14.5 μg/ml), and isavuconazole (1.10 μg/ml).ConclusionHigh incidence of Mucormycosis during the COVID-19 era may be related to common risk factors of COVID and mucormycosis. Though most of the risk factors and clinical presentations were similar during the pre-COVID and COVID era, serious complications like loss of vision and the percentage of complications were more during COVID era which may be attributed to the increased invasiveness of Zygomycetes during COVID infection. The high mean MIC value of amphotericin B during pre-COVID era and higher mean MIC value of posaconazole during COVID era may be contributed to the higher usage of these antifungals. Usage of the antifungal agents is the main contributor toward the resistance. Newer azole like isavuconazole which had a low mean MIC in our study, can be considered as a good therapeutic option for the future management of resistant infections. Hence timely management of the patients with an appropriate antifungal agent by performing AFST will help in the reduction of resistance in the future.

Since the origin of an "'International Collaborative Study on Antibiotic Sensitivity Testing'" in 1971, considerable advancement has been made to standardize clinical susceptibility testing procedures of antimicrobial agents. However, a consensus on the methods to be used and interpretive criteria was not reached, so the results of susceptibility testing were discrepant. Recently, the European Committee on Antimicrobial Susceptibility Testing achieved a harmonization of existing methods for susceptibility testing and now co-ordinates the process for setting breakpoints. Previously, breakpoints were set by adjusting the mean pharmacokinetic parameters derived from healthy volunteers to the susceptibilities of a population of potential pathogens expressed as the mean minimum inhibitory concentration (MIC) or MIC90%. Breakpoints derived by the deterministic approach tend to be too high, since this procedure does not take the variabilities of drug exposure and the susceptibility patterns into account. Therefore, first-step mutants or borderline susceptible bacteria may be considered as fully susceptible. As the drug exposure of such sub-populations is inadequate, resistance development will increase and eradication rates will decrease, resulting in clinical failure. The science of pharmacokinetics/pharmacodynamics integrates all possible drug exposures for standard dosage regimens and all MIC values likely to be found for the clinical isolates into the breakpoint definitions. Ideally, the data sets used originate from patients suffering from the disease to be treated. Probability density functions for both the pharmacokinetic and microbiological variables are determined, and a large number of MIC/drug exposure scenarios are calculated. Therefore, this method is defined as the probabilistic approach. The breakpoints thus derived are lower than the ones defined deterministically, as the entire range of probable drug exposures from low to high is modeled. Therefore, the amplification of drug-resistant sub-populations will be reduced. It has been a long journey since the first attempts in 1971 to define breakpoints. Clearly, this implies that none of the various approaches is right or wrong, and that the different approaches reflect different philosophies and mirror the tremendous progress made in the understanding of the pharmacodynamic properties of different classes of antimicrobials.

A new class of β-amino alcohol and diamine ligands has been prepared from isosorbide as a chiral renewable source. The efficiency of these ligands has been evaluated for the metal-catalyzed enantioselective reduction of aromatic ketones by transfer hydrogenation, giving excellent conversion and good enantioselectivity.

Arginine-containing peptides R3, R8, and R16 were obtained by solid-phase peptide synthesis, and their binding to nicotinic acetylcholine receptors (nAChRs) of muscle and neuronal (α7) types was studied by competitive radioligand assay with the use of 125I-α-bungarotoxin. The resulting peptides exhibited a significantly greater binding activity with respect to the muscle-type nAChRs than to the α7 receptor. Thus, we have discovered a new class of nAChR ligands. The affinity of the synthesized oligoarginines for nAChR depended on the number of amino acid residues in the chain. The highest affinity was exhibited by the R16 peptide, which contained 16 arginine residues.