Bio-based synthesis of silver nanoparticles using leaf extract of Uraria picta (Jacq.) Desv. ex DC.: Characterization and evaluation of its activity against Leishmania donovani

Abstract

Uraria picta is used as a folk medicine to cure various ailments. Regardless of ethnobotanical application, a therapeutic study of the plant parts has yet to be reported. Aqueous leaf extract was enriched with secondary metabolites like phenols, alkaloids, and terpenoids. Total phenol (60.97 mgG−1 GAE), total flavonoid (52.36 mgG−1 RE), and antioxidant activity (IC50 2666.95 µgmL−1) of the extract were measured. Bio-based silver nanoparticles (LEUP-AgNPs) were fabricated using a secondary metabolite-enriched leaf extract of U. picta (LEUP), and characterization of LEUP-AgNPs was done. The LEUP-AgNPs were crystalline, circular (13.04 ± 5.97 nm), monodisperse (pdi 0.205), and stable (-17.8 mV). The LEUP-AgNPs surface was composed of carbon, nitrogen, oxygen, and silver. A comparative study was performed to evaluate the potential of LEUP and LEUP-AgNPs against promastigotes and intra-RAW264.7 macrophage amastigotes of Leishmania donovani. A high dose of LEUP and LEUP-AgNPs significantly inhibited the growth of promastigotes up to 53% and 68%, with an IC50 value of 47.90 µgmL−1 and 6.79 µgmL−1, respectively. LEUP and LEUP-AgNPs higher doses also inhibited intracellular amastigotes up to 53% and 80% with an IC50 value of 6.72 µgmL−1 and 1.16 µgmL−1, respectively. The microscopic examination revealed that LEUP-AgNPs lead to size reduction and aggregations of promastigotes. The LEUP-AgNPs efficiently declined the number of amastigotes per RAW 264.7 macrophages compared to LEUP. LEUP-AgNPs had no cytotoxic effects on RAW 264.7 macrophages based on the CC50 value. Findings showed LEUP-AgNPs were more efficient than LEUP in controlling L. donovani, which induces visceral leishmaniasis. © The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature 2024.