Four compounds, luteolin (1), 6-γ,γ-dimethylallylquercetin 7-O-β-D-glucopyranoside (2), 6-γ,γ-dimethylallylkaempferol 7-O-β-D-glucopyranoside (3), and 6-γ,γ-dimethylallyldihydrokaempferol 7-O-β-D-glucoside (4), were isolated for the first time from AcOEt extract of the O. integerrima flower. We then evaluated the antioxidant effects of AcOEt, butanol, and MeOH extracts and their effects on H2 O2 against oxidative stress in HaCaT keratinocyte cell lines. Furthermore, 2,2-diphenyl-1-picrylhydrazyl hydrate (DPPH⋅) radical scavenging activities of 1-4 were determined and their mechanisms of action on tyrosinase were predicted by in silico studies. The results revealed that the AcOEt extract and 1-3 exhibited good DPPH⋅ radical scavenging activity. Furthermore, this extract also had a significant protective effect against H2 O2 -induced oxidative stress in HaCaT cells. In silico studies indicated that the activity of 1-3 may be due to tyrosinase inhibition with MM-GBSA free binding energies of -78.9, -70.1, and -71.1 kcal mol-1 , respectively, compared to 4 with an energy -56.9 kcal mol-1 .
Keywords: HaCaT keratinocyte cells; Ochna integerrima; antioxidant properties; cytotoxicity; in silico.
© 2022 Wiley-VHCA AG, Zurich, Switzerland.