Identification and evaluation of in-vitro antioxidant phenolic compounds from the Calendula tripterocarpa Rupr

Calendula tripterocarpa is a medicinal plant widely used in folk medicine for treatment of minor cuts, burns and skin irritation in Saudi Arabia. Five compounds were isolated from this plant through bio-assay guided fractionation for the first time and elucidated using 1H, 13C-NMR. The extracts and isolated compounds were evaluated for in-vitro antioxidant potential using DPPH (2,2-diphenyl-1-picrylhydrazyl) radical assay. The findings of this study showed that ethyl acetate fraction exhibited the best antioxidant potential (IC50 = 14.32 μg/mL) due to its high phenolic and flavonoids contents (137.24 and 119.32 mg/g, respectively). Among the isolated compounds; scopoletin and quercetin showed promising antioxidant activity when they were compared with standard antioxidant compound, vitamin C; IC50 values were found to be 9.92, 12.15, and 3.57 μg/mL, respectively. The results obtained from this study provide evidence that C. tripterocarpa plant could be valuable due to its bioactive compounds. Further study has to be accomplished on this plant type to prove its traditional uses and its various biological activities.