Biology subjects

khan, S.

Publications and source records attributed to khan, S..

3 recordsLinked to original sources

bioRxiv2026

In vitro investigation and evaluation of the antidiabetic potential of the ethanolic extract of Asparagus racemosus using starch digestion, glucose diffusion, glucose uptake, and DPPH assays

Asparagus racemosus commonly known as Shatamull, is a medicinal plant with pharmacological applications documented in both Indian and British Pharmacopoeias and various traditional medicinal practices. Previous studies have reported that A. racemosus reduces hyperglycemia by enhancing insulin secretion. The aim of the current study was to assess the antihyperglycemic actions and explore the underlying mechanisms of action of A. racemosus utilizing in vitro carbohydrate digestion, glucose diffusion, glucose uptake, 2,2-Diphenyl-1-picrylhydrazyl (DPPH) and preliminary phytochemical screening. The inhibition of carbohydrate digestion was assessed using -amylase and -glucosidase enzyme assays. The effect on glucose diffusion was evaluated using cellulose ester dialysis tube. Subsequently, glucose uptake was measured in a yeast cell model at different glucose concentrations, and the antioxidant potential was evaluated by measuring DPPH radical scavenging activity. A. racemosus significantly reduced (p<0.05- 0.01) glucose release during in vitro starch digestion by 21.11%, whereas glucose absorption decreased by 22.75% (p<0.05-0.001). The most significant enhancement (p<0.05-0.001) in glucose uptake by 65.03%, was observed at 5 mM glucose concentration. Furthermore, it showed significant antioxidant activity by scavenging DPPH (p<0.05, 0.001) radicals by 42.46%. Preliminary phytoconstituent screening indicated the existence of flavonoids, tannins, steroids, glycosides and saponins. In conclusion, A. racemosus shows an inhibitory effect on carbohydrate digestion and absorption, enhances glucose uptake and demonstrates significant DPPH radical scavenging activity, potentially due to the presence of naturally occurring phytochemicals. Thus, A. racemosus may contribute as a promising antidiabetic drug for the treatment of diabetes mellitus. More investigations are needed to determine the active compounds in A. racemosus that contribute to its antidiabetic effects.

pharmacology and toxicology↗

bioRxiv2025

Sec and Tat mediated secretion safeguards Mycobacterium tuberculosis membrane homeostasis

Protein secretion drives Mycobacterium tuberculosis (Mtb) physiology and pathogenesis, yet a unified picture of the machinery and its role in cell membrane homeostasis is still lacking. By comprehensively curating published evidence, we assembled a systems-level map of Mtb secretion encompassing 92 components and 198 mechanistic reactions across Sec, Tat, and ESX pathways. The secretory components identified were integrated with high-throughput ChIP-Seq and transcriptome datasets to elucidate the regulation of the secretion system. Using CRISPRi, conditional depletion of SecA1 or TatA impaired growth in vitro and survival ex vivo. Quantitative secretome revealed decreased export of SecA1- and TatA-dependent substrates, with enrichment of cytosolic proteins in culture filtrates, indicating increased membrane permeability. Membrane proteomics showed depletion dependent increased metabolic/lipid-degrading proteins and decreased cell-wall/cell-process proteins, consistent with loss of membrane stability. Ultrastructural defects and increased ethidium bromide uptake confirmed impaired membrane integrity. Together, our multi-omics and functional genetics established SecA1 and TatA as essential guardians of Mtb membrane integrity which provided valuable datasets and a framework for secretion-dependent Mtb pathogenesis.

microbiology↗

bioRxiv2022

The Solvation of the E. coli CheY Phosphorylation SiteMapped by XFMS

The Escherichia coli CheY protein belongs to a large bacterial response regulator superfamily. X-ray hydroxy radical foot-printing with mass spectroscopy (XFMS) has shown that allosteric activation of CheY by its motor target triggers a concerted internalization of aromatic sidechains. We reanalyzed the XFMS data to compare polar versus non-polar CheY residue positions. The polar residues around and including the 57D phosphorylated site had an elevated hydroxy radical reactivity. Bioinformatic measures revealed that a water-mediated hydrogen bond network connected this ring of residues with the central 57D. These residues solvated 57D to energetically stabilize the apo-CheY fold. The abundance of these reactive residues was reduced upon activation. This result was supported by the bioinformatics and consistent with the previously reported activation-induced increase in core hydrophobicity. It further illustrated XFMS detection of structural waters. Direct contacts between the ring residues and the phosphorylation site would stabilize the aspartyl phosphate. In addition, we report that the ring residue, 18R, is a constant central node in the 57D solvation network and that 18R non-polar substitutions determine CheY diversity as assessed by its evolutionary trace in bacteria with well-studied chemotaxis. These results showcase the importance of structured water dynamics for phosphorylation-mediated signal transduction.

biochemistry↗