Evaluation of in vitro antioxidant potential, anti- inflammatory activity and melanogenesis inhibition of Artocarpus hirsutus Lam. extracts

Artocarpus hirsutus Lam. belongs to Moraceae family and is endemic to Western Ghats and Kerala in India. This species is found to be effective in traditional medicine for the treatment of ulcer, diarrhea and pimples. However, extensive biological evaluation on each component of this specific species rarely appears in the literature which restricts its applicability as medicinal herb. The leaf, bark and wood of Artocarpus hirsutus Lam. were separately extracted with hot ethanol. The wood extract was further fractionated to isolate major active molecule whose structure was determined from its NMR spectra and LCMS analysis. All the extracts of A. hirsutus Lam. were then studied in vitro to evaluate their potential on tyrosinase inhibition, free radical scavenging activity by 1,1-Diphenyl-2picrylhydrazyl (DPPH) method and oxygen radical absorbance capacity (ORAC). Furthermore, their effects on melanogenesis inhibition were also evaluated by using murine melanoma cells. Activity guided fractionation of wood extract yielded a pure molecule that was characterized as oxyresveratrol. It was observed that antioxidant activity was higher in wood extract compared to the leaf and bark extracts. Isolated pure oxyresveratrol exhibited a significant antioxidant potential with ORAC value of 36,653±2570 μmol Trolox equivalent/g and having an IC50 of 4.3 μg/mL for DPPH free radical scavenging activity. This molecule was found to be effective for the tyrosinase inhibition with an IC50 of 0.1 μg/mL and melanogenesis inhibition in cultured melanoma cells by 44.62% at 0.2 μg/mL. Oxyresveratrol also exhibited significant inhibition of lipopolysaccharide (LPS) induced tumour necrosis factor alpha (TNF-α) secretion from J774A1 murine macrophage cell lines. This study provides substantial evidence for the presence of oxyresveratrol in the wood of A. hirsutus Lam. with promising anti-inflammatory, antioxidant and skin lightening property.