Anti-Infective Agents - Volume 23, Issue 1, 2025

For more than six decades, the use of metronidazole has been limited to anaerobic microorganisms. However, there are accounts of metronidazole derivatives exhibiting strong effectiveness against facultative anaerobic bacteria, suggesting that there may be another mechanism of action for metronidazole. Recent studies have shown that the enzyme FabH (β-ketoacyl-acyl carrier protein synthase III), responsible for the first step of fatty acid biosynthesis (FAB), is a promising target for nitroimidazole derivatives that can be used as an effective anti-infective agent.

This study aimed to synthesize 1-(2-ethyl acetate)-2-styryl nitroimidazole derivatives and evaluate their in vitro and in silico antibacterial activity.

We synthesized 2-styryl 5-nitroimidazole derivatives by first condensing metronidazole with benzaldehydes and then carrying out an acetylation reaction. We evaluated the antimicrobial activity of the synthesized compounds against three Gram-positive bacterial strains (Staphylococcus aureus, Staphylococcus epidermidis, and Streptococcus agalactiae) and three Gram-negative bacterial strains (Escherichia coli, Pseudomonas aeruginosa and Klebsiella pneumoniae) using a two-fold serial dilution MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay.

Compounds 2 and 4 exhibited the highest level of antibacterial effectiveness, with minimum inhibitory concentrations (MIC) of 1.56 μg/mL against S. agalactiae and 3.13 μg/mL against P. aeruginosa. Compounds 2 and 4 also exhibited potent activity against K. pneumonia, with an MIC value of 6.25 μg/mL and 12.5 μg/mL, respectively. Molecular docking studies revealed that both compounds have favorable hydrophobic and electrostatic interactions with conserved residues in the binding site of the E. coli β-Ketoacyl-acyl carrier protein synthase III (FabH) complex.

Acetylation of 2-styryl-5-nitroimidazoles improved both their biological activity and binding interaction with the target protein.

HIV utilizes a reverse transcriptase (RT) enzyme to convert the HIV-RNA into DNA. Inhibition of the reverse transcription mechanism of HIV-RT may serve as a potential therapeutic approach to impede the proliferation of HIV in those who are infected. Non-nucleoside reverse transcriptase inhibitors (NNRTIs) are a type of medication that directly and non-competitively bind to the allosteric site of HIV-RT, inhibiting its polymerase activity.

This study was aimed at the synthesis of hydrazine derivatives and their evaluation for HIV- reverse transcriptase inhibition using RT-qPCR-based assay.

The objective of this study was to determine the HIV- reverse transcriptase inhibition using chemical compounds as non-nucleoside reverse transcriptase inhibitors in RT-qPCR.

This study involved the synthesis of five distinct hydrazine derivatives, which were subsequently tested for their capacity to inhibit HIV-RNA polymerization by targeting HIV-derived reverse transcriptase. For the determination of the study assay, commercially available HIV-RT was subjected to treatment with derivatives and utilized in an RT-qPCR experiment to determine the activity or inhibitory effects of HIV-RT for HIV-RNA polymerization.

The in-vitro assay results demonstrated a reduction in viral load due to suppression of reverse transcriptase activity when compared to the pre-quantified values obtained from untreated RT. Among the five compounds, 4-N, N-dimethylamino benzaldehyde hydrazine (C18H22N4) had the highest ability to suppress HIV-RT. This molecule reduced HIV-RNA reverse transcription by more than 90% during RT-qPCR, which is a novel and promising strategy.

N, N-dimethylamino benzaldehyde hydrazine (C18H22N4) can suppress the activity of HIV-RT, and this effect becomes more pronounced as the concentration of the compound increases.

A series of schiff bases(3-8) were synthesized by the reaction of cefradine with six different aldehydes/ketones.

These Schiff bases (3-8) were treated with different bases/salts (NaOH, KOH, Ca(OH)2, Ba(OH)2, Ag(NO)3) to get their metal salts. The structures of the products were ascertained by spectroscopic data. The synthesized compounds were tested for biological activities against Staphylococcus aureus (gram-positive bacterium) and Escherichia coli (gram-negative bacterium).

In general, low activities in most of the synthesized compounds were observed.

A general reduction in the activities of most of the synthesized compounds in comparison to cefradine can be linked to the unavailability of the free amino group of cefradine by its involvement in the synthesis of imine derivatives.

Cyphostemma cyphopetalum is a herbaceous climber species within the Vitaceae family, found in various tropical and subtropical regions of Africa. It has a history of traditional use in Ethiopia for treating various health issues in humans and livestock, including snake bites, rabies, and eczema. Despite its reported ethnomedicinal uses, there is a lack of sufficient scientific literature regarding the isolation and characterization of its bioactive chemical compounds.

The objective of this work was to isolate bioactive compounds from the leaves of Cyphostemma cyphopetalum, characterize their chemical structures using FTIR and NMR spectroscopy, and evaluate their antimicrobial activities.

Isolation was done using column chromatographic separation techniques. Spectroscopic techniques, including Fourier transform infrared and nuclear magnetic resonance, were used for functional group identification and structural elucidation. Moreover, the paper disc diffusion bioassay method was used to evaluate the antibacterial activity of the isolated bioactive compounds.

Three fractions were successfully isolated using chloroform with dichloromethane and chloroform with ethyl acetate as eluting solvents and silica gel as a stationary phase. After careful interpretation of the experimental results and comparison with the literature, the isolated fractions were constituted mainly by stigmasterol (fraction 1), β-sitosterol (fraction 2), and trans-resveratrol (fraction 3). The antibacterial activities of each isolated fraction were tested against Ralstonia solanacearum, a gram-negative bacterium, and Staphylococcus aureus, a gram-positive bacterial pathogen.

Comparatively, the highest mean inhibitory value of 10.03 ± 0.13 mm was exhibited by fraction 2, which was followed by 6.25 ± 0.05 mm inhibition activity recorded for fraction 1 against R. solanacearum, while fraction 3 did not exhibit any bacterial activity against both the strains.

We have successfully isolated and characterized three compounds (1-3) from leaves of C. cyphopetalum and evaluated their antibacterial activity. A maximum mean inhibitory value of 10.03 ± 0.13 mm was exhibited by compound 2 against R. solanacearum.

Fungi produce a wide range of secondary metabolites with bactericidal or bacteriostatic properties. In search of novel antibacterial compounds recently, many fungi of marine and plant origin have been studied for their antimicrobial properties.

This work aimed to study the bioprospecting of marine and endophytic fungi for their antibacterial properties.

Intensive microbiological methods were followed for isolation, differential growth, and qualitative screening of enzyme production. The isolates were characterised and identified based on morpho-taxonomy, 18S rRNA gene sequencing, and phylogenetic analysis of the target genes. The antimicrobial activity of fungal ethyl acetate extracts against S. aureus, B. subtilis, and E. coli was evaluated using a well-diffusion method, and MIC was determined by the microdilution method. Cell lysis was observed through Transmission Electron Microscopy.

A BLAST search of 18S rRNA gene sequences of the marine isolates GSBT S13 and GSBT S14 showed 99.3% sequence similarity with A. glaucus for both isolates and that of endophyte GSBT E3 showed 99.7% sequence similarity with B. pinkertoniae. Cellulase production was comparatively higher in GSBT E3 and lipase from GSBT S13 and GSBT S14. Ethyl acetate extracts of GSBT S14 and GSBT E3 showed a clear zone of inhibition by the well-diffusion method, further confirmed by electron microscopy. HR-TEM showed that the ethyl acetate extracts of the isolates appeared to damage the cell membrane, leading to cell shrinkage and death in E. coli and S. aureus.

GSBT S13 and GSBT S14 exhibited extracellular amylase, cellulase, and lipase activities. Ethyl acetate extracts of both GSBT S14 and B. pinkertoniae GSBT E3 showed better antibacterial properties against S. aureus.

The use of commercial tinctures for the design of a formulation with improved anti-microbial activity in a polyherbal lozenge dosage form has not been described.

This study aimed to develop and evaluate the antimicrobial activity of a novel polyherbal lozenge formulation containing Ashwagandha, Neem, and Tulsi tinctures in a single-dose administration. According to previous studies, each of these herbs could be used in herbal medicine to provide relief from infection owing to their antimicrobial activity, besides other properties, such as anticancer, antidiabetic, etc.

The lozenges were prepared using the molding method using three concentrations (1, 3, and 5% w/w) of commercialized herbal tinctures. Then, they were studied using different assays, including those designed to evaluate physical properties, stability, and antimicrobial activity.

B4, containing 5% w/w of each tincture, showed the highest antimicrobial activity compared with the other batches. This batch exhibited the highest value of bacterial inhibition (17.1 ± 0.07 mm), according to the agar well diffusion method, including Escherichia coli as a test microorganism. Hence, B4 was chosen for additional analyses, including physical properties and stability tests. The results followed Indian Pharmacopeia standards and ICH guidelines, respectively. The formulation was stable after 2 weeks, and no significant changes were observed in its physical properties or antimicrobial activity.

This study shows that polyherbal lozenges have anti-microbial activity, with a disintegration period of 3.86 ± 0.07 minutes in the B4 batch.

Nowadays, most people are suffering from dandruff which when not treated becomes flaky and causes major damage to the scalp of a person. Dandruff is a common scalp illness caused by the yeast Pittosporum. It is not possible to completely eradicate dandruff; it can only be appropriately handled.

When used as indicated, a shampoo's surfactant, often referred to as a surface-active agent, in its proper form-liquid, solid, or powder-will safely remove skin fragments, dirt, and surface oil from the scalp and hair shaft. Numerous hair care solutions use a variety of anti-fungal substances to treat dandruff. Many adverse reactions to these products have been reported, including hair loss, heightened headache, nausea, scaling, itching, and irritation.

Thus, an attempt was undertaken to develop a herbal anti-dandruff shampoo form safe and more successful in treating the dandruff problem by using a marketed herbal tincture. The anti-dandruff formulation was prepared by combining natural polyherbal tincture, and these tincture shows the different medicinal effects on hair.

A number of parameters, including visual observation, pH, consistency, particle percentage, filth dispersion, surface phenomena, and foaming content were used to assess the shampoo formulations. Also, the estimation of an anti-microbial activity by using the inoculation method. The greatest zone of inhibition demonstrated a strong antimicrobial effect for the formulation.