Therapeutic profiling of Saraca indica bark oil silver nanoparticles: Bioactivity and cytocompatibility in human keratinocyte (HaCaT) cells

This study explores the potential of silver nanoparticles synthesized from Ashoka ( Saraca indica ) bark oil, which has properties as a natural therapeutic agent. The silver nanoparticles (Ag-NPs) were produced using a green synthesis method from the Saraca indica bark oil and characterized through UV-Vis spectrophotometry, FTIR, and SEM techniques. Fungal infections are mainly caused by Candida spp ., especially Candida albicans , which significantly contributes to diseases like candidiasis. The antifungal and antibacterial activities were tested against Candida albicans and Bacillus subtilis . Using the disk-diffusion method, different concentrations of Ag-NPs were evaluated and compared with fluconazole and streptomycin. Results showed that the inhibition zones were concentration-dependent, with a maximum inhibition zone of 21.75 ± 1.768 mm, 21.75 ± 1.06 mm at 100 µg/mL against C. albicans and B. subtilis . The DPPH assay showed 62.17 % antioxidant activity at 80 µg/mL, and IC₅₀ values were 36.43 µg/mL for AO-Ag NPs compared to 26.88 µg/mL for crude oil. The increasing resistance to antifungal drugs and limited effective treatments highlight the need for alternatives. The DPPH antioxidant assay confirmed the nanoparticles free radical scavenging ability, indicating antioxidant potential. An albumin denaturation anti-inflammatory assay revealed notable inhibition by the nanoparticles compared to Ascorbic acid. Cytotoxicity was assessed on human keratinocyte (HaCaT) cells, showing dose-dependent cytocompatibility, with > 90 % viability at lower concentrations and 12.31 ± 1 . 62 % viability at 100 µg/mL. Compared to crude bark oil and positive controls, the nanoparticles exhibited enhanced bioactivity with reduced cytotoxicity to normal skin cells. Morphological observations also suggested apoptosis, possibly linked to ROS-mediated oxidative stress pathways. Overall, this research indicates that Saraca indica -silver nanoparticles are cost-effective, eco-friendly, and biocompatible, with antimicrobial, antioxidant, anti-inflammatory, and low cytotoxic properties. These properties support their potential use in developing nanomedicine treatments for infections and inflammation.