In Silico Approach for Phytocompound-Based Drug Designing to Fight Efflux Pump-Mediated Multidrug-Resistant Mycobacterium tuberculosis

Synthesis, Characterization, and Antioxidant Activity Evaluation of New N-Methyl Substituted Thiazole-Derived Polyphenolic Compounds

Reactive oxygen species play a significant role in various pathological conditions, driving the need for novel, potent antioxidants. While polyphenols are known for their antioxidant properties, their limited stability and bioavailability present challenges for therapeutic applications. To address these limitations, a series of novel thiazolyl-polyphenolic compounds was synthesized via a multi-step synthetic route incorporating Hantzsch heterocyclization in the final step. The synthesized compounds 7a-k were structurally characterized using spectroscopic techniques, including NMR, MS, and IR. In silico thermodynamic calculations, including HOMO-LUMO gap and bond dissociation enthalpy (BDE) calculations, revealed a promising antioxidant profile for these compounds and indicated that the substitution in position 2 of the thiazole ring does not substantially influence the antioxidant activity conferred by the catechol moiety in position 4. The antioxidant capacity of the synthesized compounds was experimentally validated using a panel of six distinct assays: two radical scavenging assays (ABTS and DPPH) and four electron transfer-based assays (RP, TAC, FRAP, and CUPRAC). The in vitro evaluation demonstrated that compounds 7j and 7k exhibited significantly enhanced antioxidant activity compared to the established antioxidant standards, ascorbic acid and Trolox. These findings suggest that the strategic modifications in position 2 of the thiazole scaffold represent a promising direction for future research aimed at developing novel therapeutic agents with enhanced antioxidant properties. The present study is limited to the in vitro evaluation of compounds based on the N-methyl substituted thiazole scaffold, but future studies can include modifications such as changing the substituent on the thiazole nitrogen, the hydrazone linker or possible insertion of substituents in position 5 of thiazole ring of substituents with various electronic or physico-chemical properties.

Antimicrobial Activity of Silver Nanoparticles Against Common Bovine Mastitis Pathogens: A Comparative Analysis

Bovine mastitis is one important metabolic disease in dairy cows caused by S. aureus and E. coli impacting huge economic losses worldwide. Silver Nanoparticles (AgNPs) possess unique electrical, thermal, optical, and biological properties, scrutinizing them as more effective antimicrobial agents. This study aimed to synthesize and evaluate AgNPs as effective antimicrobial compounds against S. aureus and E. coli. In the present work, the extract of citrus limon was analysed with gas chromatography-mass spectrometry (GC-MS) analysis, citric acid was found abundant in methanolic solvent. Synthesis of AgNPs was made by both green and chemical synthesis method, charctererized by UV‒visible spectroscopy, electron microscopy, zeta sizing and infrared spectroscopy. The result confirmed that both green and chemical AgNPs are in nanoscale range with average size ranged from 10 to 20 nm. The zeta potential was found negative and green synthesized AgNPs resulted significantly (P ≤ 0.05) higher antimicrobial activities than chemical synthesized AgNPs and also commercial available antibiotics. The minimum inhibitory concentration (MIC) was also evaluated and green synthesized AgNPs resulted MIC50 value of 46.10 and 49.93 while chemical synthesized AgNPs showed MIC50 value of 77.39 and 86.50 μg mL-1 against S. aureus and E. coli respectively. Additionally, green synthesized AgNPs demonstrated more cell viability (%) against RAW264.7 cells. Therefore, green AgNPs would be a potential antimicrobial agent in place commercially available antibiotics against aforesaid organisms in nearest future.

Study of Glabranin as an Inhibitor Against Prostate Cancer: Molecular Docking, Molecular Dynamics Simulation, MM-PBSA Calculation and QSAR Prediction

Prostate cancer is the World's second most frequent malignancy, with the fifth-highest male mortality rate. In advanced prostate cancer patients, point mutations such as T877A and W741L are prevalent, imparting treatment resistance and hence promoting cancer development. The emergence of drug resistance in prostate cancer necessitates the development of suitable ligands to allow for stronger interactions with the receptors, which can inhibit cancer progression. The present study focuses on flavonoids produced by plants, which may act as inhibitors of point mutations like T877A and W741L in prostate cancer. This research was conducted using an in-silico method where the compound Glabranin and its derivatives were virtually screened to identify potential drugs for combating such point mutations. Thirty-five Molecular Dockings were performed to find the ligand-receptor complexes with the lowest binding energy. Moreover, employing a variety of tools, ligands were evaluated for drug-likeness and toxicity, indicating a promising drug candidate. Based on the results of Molecular Docking, Drug-likeness, and ADMET testing, eight structures were subjected to a 100 ns Molecular Dynamics simulation. A QSAR analysis was also performed based on the simulation findings. In this study, it was revealed that GlaMod2 phytocompound was effective against T877A and W741L mutations in prostate cancer. It was observed that the phytocompound was stable and had potential properties for the development of a novel drug to combat prostate cancer and drug resistance This phytocompound may therefore be effective in the development of prostate cancer inhibitors for patients with mutant androgen receptors.

Graphical Abstract

Supplementary Information

The online version contains supplementary material available at 10.1007/s12291-023-01134-3.

Phytocompounds as potential inhibitors of mycobacterial multidrug efflux pump Rv1258c: an in silico approach

The number of infections and deaths caused by multidrug resistant (MDR) tuberculosis is increasing globally. One of the efflux pumps, that makes Mycobacterium tuberculosis resistant to a number of antibiotics and results in unfavourable treatment results is Tap or Rv1258c. In our study, we tried to utilize a rational drug design technique using in silico approach to look for an efficient and secure efflux pump inhibitor (EPI) against Rv1258c. The structure of Rv1258c was built using the homology modeling tool MODELLER 9.24. 210 phytocompounds were used for blind and site-specific ligand docking against the modelled structure of Rv1258c using AutoDock Vina software. The best docked plant compounds were further analysed for druglikeness and toxicity. In addition to having excellent docking scores, two plant compounds-ellagic acid and baicalein-also exhibited highly desirable drug-like qualities. These substances outperform more well-known EPIs like piperine and verapamil in terms of effectiveness. This data shows that these two compounds might be further investigated for their potential as Rv1258c inhibitors.

Clove Buds Volatile Compounds: Inhibitory Activity on Mycobacterium Growth and Molecular Docking on Mmr Efflux Pump Drug Resistance

Syzygium aromaticum is used in traditional and modern medicine for its various and outstanding pharmacological properties. Here, we studied the chemical composition of hexane extract and non-polar fractions (NPF) obtained from the maceration and fractionation of clove buds, in order to evaluate their in vitro antimycobacterial activity, as well as their contribution against efflux pump (EP) resistance through molecular docking experiments. The gas chromatography-mass spectrometry (GC-MS) analysis of the volatile profiles revealed the presence of eugenol, followed by eugenyl acetate, and β-caryophyllene as common major compounds. According to Resazurin microtiter assay (REMA), Mycobacterium tuberculosis H37 Rv strain was sensitive to all volatile samples at concentration range between 10 and 100 μg/mL. The NPF of ethanol extract was the best inhibitor with a MIC=10 μg/mL. The in silico study revealed a strong binding affinity between eugenol and Mmr EP protein (-8.1 Kcal/mol), involving two binding modes of hydrogen bond and π-alkyl interactions. The non-polarity character of clove volatile constituents, and their potential additive or synergistic effects could be responsible for the antimycobacterial activity. In addition, these findings suggest the benefic effect of eugenol in the management of mycobacterium drug resistance, whether as potential inhibitor of Mmr drug EP, or modulator during combination therapy.

The Art of War with Pseudomonas aeruginosa: Targeting Mex Efflux Pumps Directly to Strategically Enhance Antipseudomonal Drug Efficacy

Pseudomonas aeruginosa (P. aeruginosa) poses a grave clinical challenge due to its multidrug resistance (MDR) phenotype, leading to severe and life-threatening infections. This bacterium exhibits both intrinsic resistance to various antipseudomonal agents and acquired resistance against nearly all available antibiotics, contributing to its MDR phenotype. Multiple mechanisms, including enzyme production, loss of outer membrane proteins, target mutations, and multidrug efflux systems, contribute to its antimicrobial resistance. The clinical importance of addressing MDR in P. aeruginosa is paramount, and one pivotal determinant is the resistance-nodulation-division (RND) family of drug/proton antiporters, notably the Mex efflux pumps. These pumps function as crucial defenders, reinforcing the emergence of extensively drug-resistant (XDR) and pandrug-resistant (PDR) strains, which underscores the urgency of the situation. Overcoming this challenge necessitates the exploration and development of potent efflux pump inhibitors (EPIs) to restore the efficacy of existing antipseudomonal drugs. By effectively countering or bypassing efflux activities, EPIs hold tremendous potential for restoring the antibacterial activity against P. aeruginosa and other Gram-negative pathogens. This review focuses on concurrent MDR, highlighting the clinical significance of efflux pumps, particularly the Mex efflux pumps, in driving MDR. It explores promising EPIs and delves into the structural characteristics of the MexB subunit and its substrate binding sites.

Codon usage divergence of important functional genes in Mycobacterium tuberculosis

Sequence characteristics are usually used to explain the adaptive ability to hosts, metabolism, genetic diversity, drug resistance, and infectivity of Mycobacterium tuberculosis. Exploring the codon usage pattern of coding sequences in Mycobacterium tuberculosis is of great significance. In the present study, two hundred random complete genomes of Mycobacterium tuberculosis were downloaded from the National Center for Biotechnology Information database. The important codon usage pattern, such as the codon bias index, the effective number of codons, the relative synonymous codon usage as well as the base component, of twenty one specific functional genes were counted or calculated. The differences of the relative synonymous codon usage values among those functional genes, and the summation of the standard deviations of codon usage parameters were used to evaluate the divergence degree of the concerned genes. The results show that among the concerned genes, 1) all genes are high GC sequences, the codon usage frequency corresponding to each amino acid of these functional genes had a significant bias; 2) the genes of those with high effective number of codons, such as the coding sequences of Myco-bacterial membrane protein large family, usually have higher divergences; and 3) genes with lower divergences, such as the ag85A and the sigH, are usually highly conserved and are often used as drug target genes. The findings of the present work would improve new understandings on the evolution of Mycobacterium tuberculosis and on the measures to prevent and control tuberculosis from the gene engineering.