Eco-friendly synthesis of silver nanoparticles using Senna alata bark extract and its antimicrobial mechanism through enhancement of bacterial membrane degradation.

Biological synthesis of nanomaterials has been increasingly gaining popularity due to its eco-friendly nature and cost-effectiveness. This study aimed to synthesize silver nanoparticles (AgNPs) using Senna alata bark extract as reducing and capping agents, and to evaluate their antimicrobial activities. AgNPs was characterized using UV-vis spectrophotometry, transmission electron microscopy, and Fourier transform infrared spectroscopy (FTIR). The formation of AgNPs was monitored by recording the surface plasmon resonance peak observed at 425 nm. High-resolution TEM images elucidated the formation of spherical AgNPs with an average diameter of 10-30 nm. Energy dispersive spectroscopy (EDS) revealed the presence of silver. The functional groups of biomolecules present in the extract and their interaction with AgNPs were identified through FTIR analysis. Biosynthesized AgNPs displayed antimicrobial activity against different microorganisms, including Gram-positive and Gram-negative bacteria as well as fungi, as indicated by the diameter of inhibition zones between 11.37 and 14.87 mm. Minimum inhibitory concentration of AgNPs for the tested microorganisms was in the range from 31.25 to 125 µg/mL. Potassium leakage is a primary indicator of membrane damage which is a significant mode of action of AgNPs against the tested microorganisms. The amount of potassium ions leaked from the microbial cells after 4 h contact time ranged between 0.97 and 3.05 ppm. Morphological changes were observed in all AgNPs-treated microorganisms. The green synthesized AgNPs with high antimicrobial activity has potential to be used in food packaging and biomedical research areas.

Comparative metabolome-based classification of Senna drugs: a prospect for phyto-equivalency of its different commercial products.

INTRODUCTION: The demand to develop efficient and reliable analytical methods for the quality control of nutraceuticals is on the rise, together with an increase in the legal requirements for safe and consistent levels of its active principles. OBJECTIVE: To establish a reliable model for the quality control of widely used Senna preparations used as laxatives and assess its phyto-equivalency. METHODS: A comparative metabolomics approach via NMR and MS analyses was employed for the comprehensive measurement of metabolites and analyzed using chemometrics. RESULTS: Under optimized conditions, 30 metabolites were simultaneously identified and quantified including anthraquinones, bianthrones, acetophenones, flavonoid conjugates, naphthalenes, phenolics, and fatty acids. Principal component analysis (PCA) was used to define relative metabolite differences among Senna preparations. Furthermore, quantitative 1H NMR (qHNMR) was employed to assess absolute metabolites levels in preparations. Results revealed that 6-hydroxy musizin or tinnevellin were correlated with active metabolites levels, suggesting the use of either of these naphthalene glycosides as markers for official Senna drugs authentication. CONCLUSION: This study provides the first comparative metabolomics approach utilizing NMR and UPLC-MS to reveal for secondary metabolite compositional differences in Senna preparations that could readily be applied as a reliable quality control model for its analysis.