Comparative Study on Quantitative Analysis and In Vitro Antioxidant Potential of Leaf and Stem of Salvadora oleoides (Decne.) and Optimization of Flavonoids Using RSM.

This study quantitatively estimated bioactive compounds in leaves and stem of Salvadora oleoides (S. oleoides) and evaluated in vitro antioxidant activity of aqueous and organic extracts (petroleum ether, benzene, chloroform, ethyl acetate, and ethanol) using 1,1-diphenyl-2-picrylhydrazyl (DPPH), MC, FRAP, RP, and TAC methods. The response surface methodology (RSM) was also used to optimize extractive value and total flavonoid contents. Aqueous leaf extract contained the highest saponin (13.36 ± 0.19 mg/g), whereas ethanolic leaf extract had the highest flavonoid (12.61 ± 1.03 mg/g) with strongest antioxidant effects (DPPH IC50 0.39 ± 0.02 µg/mL; MC IC50 0.27 ± 0.01 µg/mL; RP 1.25 ± 0.04 mg/g; TAC 1.16 ± 0.01 mg/g). Ethyl acetate extract of stem showed pronounced DPPH (IC50 0.41 ± 0.02 µg/mL), MC (IC50 0.15 ± 0.02 µg/mL), and RP (1.05 ± 0.01 mg/g), whereas ethanolic extract showed highest FRAP (1.13 ± 0.01 mg/g), yielding the highest TAC (1.13 ± 0.58 mg/g) for chloroform extract. One-way analysis of variance (ANOVA) revealed highly significant relationships among antioxidant measures (p < 0.0001), and RSM optimization identified the conditions that maximize extractive yield and flavonoid contents. These findings indicate that the leaves and stem of S. oleoides are rich sources of flavonoids and saponins with strong antioxidant potential, supporting their use in herbal formulations and nutraceutical development.