Eco-Friendly Synthesis of Silver Nanoparticles from Trans-Himalayan Herbs

A Comparative Study of Biological Activities

Abstract

The current study aims to synthesise silver nanoparticles (AgNPs) using three medicinal plants-Inula racemosa, Rhodiola imbricata, and Ephedra gerardiana-native to the Trans-Himalayan region. These plants were specifically selected due to their well-documented ethnomedicinal uses and rich phytochemical profiles, particularly in phenolic compounds. The study aims to harness their bioactive potential for the development of eco-friendly, cost-effective nanomaterials with therapeutic applications. Synthesised AgNPs were characterised via UV–VIS spectrophotometer, SEM, FTIR, DLS, TEM and EDX analysis. The absorption peaks at 410 nm (I. racemosa), 440 nm (R. imbricata), and 420 nm (E. gerardiana), confirming nanoparticle formation via surface plasmon resonance. Phytochemical analysis highlighted phenolics as key agents in nanoparticle reduction and capping. Although the AgNPs showed lower antioxidant activity than the crude extracts but exhibited superior antibacterial efficacy against multidrug-resistant bacterial strains, outperforming the standard antibiotic Ampicillin. Cytotoxicity evaluation against MCF-7 breast cancer cells revealed that I. racemosa root extract and its AgNPs had the highest anticancer activity, with IC₅₀ values of 64.93 μg/mL and 55.88 μg/mL, respectively. This research proposes a sustainable approach to develop alternative antibacterial and anticancer agents, potentially addressing the rising global challenge of antibiotic resistance and cancer burden through plant-based nanotechnology.