Green synthesis of silver nanoparticles from Kedrostis nana (Lam.) Cogn. extracts and its biological activities

The medicinal plant Kedrostis nana is a relatively understudied species that belongs to the Cucurbitaceae family. It is important to understand the pharmacological potential of traditional medicinal plants such as K. nana as it could have potential in various clinical applications, especially since there have been so many advancements in the biomedical sector. Nanoparticles have also become of interest due to their size and various applications as antimicrobial agents, anticancer agents, and drug delivery agents. This study evaluated the biosynthesis of silver nanoparticles (AgNPs) from K. nana aqueous leaf, stem and tuber extracts. Characterization was accomplished using ultra-violet visible spectrometry, energy-dispersive x-ray spectroscopy (EDX), Fourier transform infrared spectroscopy (FTIR), high resolution transmission electron microscopy (HRTEM), dynamic light scattering (DLS) and zeta potential analysis. The synthesized AgNPs were explored for their antioxidant, antibacterial and cytotoxic potential. The results showed that the AgNPs were stable, negatively charged and polydispersed with sizes ranging from 21 to 28 nm. FTIR results revealed various functional groups present which could be attributed to the capping of the AgNPs by the plant's phytochemicals. The stem and tuber AgNPs displayed significant antioxidant potential at 200 μg/mL which were similar to the known antioxidant, ascorbic acid. When tested against five bacterial strains, the tuber AgNPs appeared to outperform all other biosynthesized AgNPs as well as the positive control, neomycin. The cytotoxicity investigation exhibited the possibility of the tuber AgNPs being used as an anticancer agent. At 200 μg/mL, the AgNPs derived from the tuber displayed toxicity to the HeLa cell line. The tuber AgNPs also exhibited toxicity to the non-cancerous cell line, Hek293, however, further investigations are necessary such as apoptosis detection and gene expression profiling. These results corroborate the benefit of this plant's use in traditional medicine.