Green synthesis of silver nanoparticles from Guava (Psidium guajava Linn.) leaf for antibacterial, antioxidant and cytotoxic activity on HT-29 cells (Colon cancer)

Abstract

In this study, biocompatible silver nanoparticles synthesized from aqueous leaf extract of Psidium guajava Linn. The green synthesized AgNPs were characterized by various spectroscopic and microscopic techniques (UV Spectroscopy, FTIR, XRD and SEM). The UV-visible spectroscopic analysis showed the absorbance peak at 418nm, which confirmed the synthesis of silver nanoparticles. Identification of functional groups present in the plant extract, which involved in the reduction of silver ion to AgNPs was analyzed by Fourier transform infrared spectroscopy (FTIR). X-ray diffraction (XRD) analysis confirmed crystalline nature of the synthesized nanoparticles. The synthesized AgNPs were round and spherical shape and 20nm size were confirmed by scanning electron microscopy (SEM). Initial phytochemical analysis revealed the presence of secondary metabolites in the aqueous guava leaf extract. The antibacterial activity of guava leaf extract and AgNPs was dose-dependent manner and it was revealed synthesized silver nanoparticles showed potential antibacterial activity than guava leaf extract. The antioxidant activity of synthesized AgNPs showed highest free radical inhibition (80.2%) at 250 µg/ml as compared to guava leaf extract (62.21 %). The biosynthesized silver nanoparticles were observed to possess high cytotoxicity against colon (HT-29) cancer cells with IC50- 68.26 µg/ml. In conclusion, the results obtained in the present study revealed the green synthesized silver nanoparticles from guava leaf extract exhibited considerable antioxidant, antibacterial and anticancer potential.