Plant-assisted green preparation of silver nanoparticles using leaf extract of Dalbergia sissoo and their antioxidant, antibacterial and catalytic applications.

Plant-mediated preparation of silver nanoparticles (AgNPs) is thought to be a more economical and environmentally benign process in comparison to physical and chemical synthesis methods. In the present study, the aqueous leaf extract of Dalbergia sissoo was prepared and utilized to reduce silver ion (Ag+) during the green synthesis of silver nanoparticles (DL-AgNPs). The formation of DL-AgNPs was verified using UV-Vis spectra, exhibiting the surface plasmon resonance (SPR) band at around 450 nm. FT-IR analysis revealed the kinds of phytochemicals that serve as reducing and capping agents while DL-AgNPs are being synthesized. Analysis of scanning electron microscope (SEM) and high-resolution transmission electron microscopy (HR-TEM) images verified the development of spherical and oval-shaped DL-AgNPs, with sizes ranging from 10 to 25 nm. The stability and particle size distribution of synthesized DL-AgNPs were ensured by zeta potential and DLS (dynamic light scattering) investigations. Additionally, X-ray diffraction (XRD) analysis confirmed the crystalline nature of DL-AgNPs. In antioxidant experiments, DL-AgNPs demonstrated significant scavenging capacities of DPPH and ABTS radicals with EC50 values of 51.32 and 33.32 µg/mL, respectively. The antibacterial activity of DL-AgNPs was shown to be significant against harmful bacteria, with a maximum zone of inhibition (21.5 ± 0.86 mm) against Staphylococcus aureus. Furthermore, DL-AgNPs exhibited effective catalytic activity to degrade environment-polluting dyes (methylene blue, methyl orange, and Congo red) and toxic chemicals (p-nitrophenol). The results of all these studies suggested that DL-AgNPs made from the leaf extract of Dalbergia sissoo have merit for application in the environmental and biomedical fields.

In vivo the antioxidative extract of Averrhoa carambola Linn. leaves induced apoptosis in Ehrilch ascites carcinoma by modulating p53 expression.

This study was designed to evaluate the antioxidant activity of methanol extract of Averrhoa carambolla Linn. leaves (MELA) using DPPH· and ABTS·+ free radical scavenging assays whereas its antineoplastic effect against Ehrlich ascites carcinoma (EAC) was assed using viable cell count, life span, body weight gain and hematological parameters of experimental mice. Results showed that rich phenolic and flavonoid content of MELA had moderate dose dependent free radical scavenging activity (IC50: 62.0 µg/mL for DPPH· and 6.0 µg/mL for ABTS·+). In vivo antineoplastic assay, MELA significantly (P < 0.05) decreased viable cells and body weight gain, increased the survival time and restored altered hematological profiles of cancer cell bearing mice. Fluorescence microscopic view of EAC cells derived from MELA-treated group showed apoptotic characteristics and this observation was also supported by overexpression of pro-apoptotic genes coding p53 and Bax proteins in treated cancer cells. The anti-apoptotic genes coding Bcl-2 protein was also absent in treated EAC cells as compared with the control. Moreover, phytochemical profiles of MELA as identified by GC/MS analysis are also consistent with its activities.