Synthesis of silver nanoparticles from Bacillus brevis (NCIM 2533) and their antibacterial activity against pathogenic bacteria.

The present study is focused on the biological synthesis of silver nanoparticles (AgNPs) from the Bacillus brevis (NCIM 2533) was investigated. The synthesized AgNPs were characterized by various spectroscopic and microscopic techniques and confirmed the AgNPs having the surface Plasmon resonance peak at 420 nm and in the size range of 41-68 nm with spherical in shape by AFM and SEM analysis. It was confirmed and ascertained the presence of bioactive compounds in the AgNPs using TLC and FTIR. The In-vitro antibacterial activity of AgNPs showaed potential antibacterial property against multi-drug resistant pathogens such as Salmonella typhi and Staphylococcus aureus. The biosynthesized AgNPs could be utilized as antimicrobial agents for effective disease management.

The anthocyanins in black currants regulate postprandial hyperglycaemia primarily by inhibiting α-glucosidase while other phenolics modulate salivary α-amylase, glucose uptake and sugar transporters.

The hypoglycaemic effects of two Ribes sp. i.e., anthocyanin-rich black currants (BC) were compared to green currants (GC), which are low in anthocyanins to establish which compounds are involved in the regulation of postprandial glycaemia. We determined the effect of the currants on inhibiting carbohydrate digestive enzymes (α-amylase, α-glucosidase), intestinal sugar absorption and transport across CaCo-2 cells. The digestion of these currants was modelled using in vitro gastrointestinal digestion (IVGD) to identify the metabolites present in the digested extracts by LC-MS/MS. Freeze-dried BC and IVDG extracts inhibited yeast α-glucosidase activity (P<.0001) at lower concentrations than acarbose, whereas GC and IVDG GC at the same concentrations showed no inhibition. BC and GC both showed significant inhibitory effects on salivary α-amylase (P<.0001), glucose uptake (P<.0001) and the mRNA expression of sugar transporters (P<.0001). Taken together this suggests that the anthocyanins which are high in BC have their greatest effect on postprandial hyperglycaemia by inhibiting α-glucosidase activity. Phytochemical analysis identified the phenolics in the currants and confirmed that freeze-dried BC contained higher concentrations of anthocyanins compared to GC (39.80 vs. 9.85 g/kg dry weight). Specific phenolics were also shown to inhibit salivary α-amylase, α-glucosidase, and glucose uptake. However, specific anthocyanins identified in BC which were low in GC were shown to inhibit α-glucosidase. In conclusion the anthocyanins in BC appear to regulate postprandial hyperglycaemia primarily but not solely by inhibiting α-glucosidase while other phenolics modulate salivary α-amylase, glucose uptake and sugar transporters which together could lower the associated risk of developing type-2 diabetes.

Analysis of polyphenolic metabolites from in vitro gastrointestinal digested soft fruit extracts identify malvidin-3-glucoside as an inhibitor of PTP1B.

Protein-tyrosine phosphatase 1B (PTP1B, EC 3.1.3.48) is an important regulator of insulin signalling. Herein, we employed experimental and computational biology techniques to investigate the inhibitory properties of phenolics, identified from four in vitro gastrointestinal digested (IVGD) soft fruits, on PTP1B. Analysis by LC-MS/MS identified specific phenolics that inhibited PTP1B in vitro. Enzyme kinetics identified the mode of inhibition, while dynamics, stability and binding mechanisms of PTP1B-ligand complex were investigated through molecular modelling, docking, molecular dynamics (MD) simulations, and MM/PBSA binding free energy estimation. IVGD extracts and specific phenolics identified from the four soft fruits inhibited PTP1B (P < 0.0001) activity. Among the phenolics tested, the greatest inhibition was shown by malvidin-3-glucoside (P < 0.0001) and gallic acid (P < 0.0001). Malvidin-3-glucoside (Ki = 3.8 µg/mL) was a competitive inhibitor and gallic acid (Ki = 33.3 µg/mL) a non-competitive inhibitor of PTP1B. Malvidin-3-glucoside exhibited better binding energy than gallic acid and the synthetic inhibitor Dephostatin (-7.38 > -6.37 > -5.62 kcal/mol) respectively. Principal component analysis demonstrated malvidin-3-glucoside PTP1B-complex occupies more conformational space where critical WPD-loop displayed a higher degree of motion. MM/PBSA binding free energy for malvidin-3-glucoside to PTP1B was found to be higher than other complexes mediated by Van der Waals energy rather than electrostatic interaction for the other two inhibitors (-80.32 ± 1.25 > -40.64 ± 1.43 > -21.63 ± 1.73 kcal/mol) respectively. Altogether, we have established novel insights into the specific binding of dietary phenolics and have identified malvidin-3-glucoside as an PTP1B inhibitor, which may be further industrially developed for the treatment of type-2 diabetes.

Rapid biosynthesis of silver nanoparticles from Bacillus megaterium (NCIM 2326) and their antibacterial activity on multi drug resistant clinical pathogens.

The notion to fight against multi drug resistant pathogens is a great deal in the field of nanomedicine. The identifiable antimicrobial action of metal bionanoparticles on many microorganisms is reported earlier. As silver bionanoparticles (Ag-BNPs) are known to have efficient antibacterial properties they are synthesized in ecofriendly and biocompatible way. The present study is focused on the extracellular biosynthesis of highly stable Ag-BNPs from bacterial strain Bacillus megaterium (NCIM 2326) by bio-reduction of silver ion using the culture supernatant, and to determine the antibacterial efficacy on multi drug resistant clinical pathogens such as Streptococcus pneumoniae and Salmonella typhi. The biosynthesis process is rapid and Ag-BNPs are formed within few minutes if AgNO(3) comes to contact with cell filtrate. Furthermore the synthesized Ag-BNPs are characterized by UV-vis spectroscopy, Atomic Force Microscopy (AFM), Thin Layer Chromatography (TLC) and Fourier Transform Infrared Spectroscopy (FTIR).