Green route synthesis of highly stable zinc oxide nanoparticles using root extract of Andrographis paniculata and evaluation of their potential activities

Abstract

In this study, bioinspired nanoscale zinc oxide particles (ZnONPs), synthesized using the root extract of Andrographis paniculata, were evaluated for various biological activities, including antioxidant, anticancer, and anti-inflammatory effects. The root extract of Andrographis paniculata was used to reduce the metal precursor, zinc acetate dihydrate, into highly stable zinc oxide nanoparticles, following simple, in situ green chemistry principles. The synthesized zinc oxide nanoparticles exhibited high stability and had a hierarchical nano-structured form, resembling flowers and flakes, with a diameter of 100 nm. X-ray diffraction (XRD) analysis revealed highly crystalline nature indicating hexagonal wurtzite phase of ZnO nanoparticles. The potential anticancer activity of the nanoparticles was confirmed by a significant reduction in the viability of MCF-7 cells, with an IC₅₀ value of 9.706 µg mL^-1. The antioxidant potential was assessed through DPPH free radical scavenging activity (74.56 %), phosphomolybdenum assay (73.4 %), and reducing power efficacy (71.2 %), confirming the high antioxidant capability of the zinc oxide nanoparticles. The anti-inflammatory activity was demonstrated by the high albumin denaturation inhibition rate (51.35 %) and a notable cytotoxic effect on RAW 267.4 cells (69.61 %). The ecotoxicity of synthesized zinc oxide nanoparticles was evaluated by measuring the germination index of mungbean seeds, revealing no significant impact on seed germination. This study confirms that biogenically synthesized ZnO nanoparticles exhibit a range of beneficial activities, making them promising candidates for various medical and industrial applications.