Comparative study of antioxidant properties of aqueous leaves extract and biogenic silver nanoparticles using Hibiscus species & Trachyspermum species

Abstract

Objective: To compare the antioxidant properties of aqueous leaf extracts and biogenic silver nanoparticles (AgNPs) synthesized from Hibiscus rosa sinensis and Trachyspermum ammi using green synthesis techniques.

Method: Aqueous leaf extracts were prepared using standard extraction methods, while AgNPs were synthesized by mixing leaf extracts with silver nitrate. Antioxidant activity was evaluated through the DPPH radical scavenging assay. Quantitative phytochemical analysis measured total flavonoid content (TFC) and total phenolic content (TPC).

Findings: The aqueous extracts exhibited superior antioxidant activity compared to their biogenic AgNP counterparts. The TFC and TPC were significantly higher in T. ammi extracts (31.12 ± 0.22 mg QE/g; 96.23 ± 0.31 mg GAE/g) than in H. rosa sinensis extracts (20.50 ± 0.15 mg QE/g; 62.42 ± 0.28 mg GAE/g). The DPPH assay showed dose-dependent antioxidant activity, with plant extracts outperforming AgNPs. The superior activity of plant extracts was attributed to their complex bioactive compounds acting synergistically. Conversely, AgNPs exhibited limited antioxidant potential, constrained by synthesis variability and stability issues.

Novelty: This study underscores the potential of traditional plant extracts as reliable and potent antioxidants compared to biogenic AgNPs. It also highlights the relevance of green synthesis and the comparative benefits of phytochemicals over nanoparticles in therapeutic applications.