Bioactive phenolic components and antioxidant activities of water-based extracts and flavonoid-rich fractions from Salvadora persica L. leaves

Salvadora persica L. (Sp) has been widely used as folk medicine. This study aimed to identify and assess the significant phenolics' antioxidant activities in young (S1) and old (S2) leaves of Sp. Six flavonoids; isoquercitrin, kaempferol-3-neohesperidoside, myricetin-3-galactoside, apigenin-O-hexoside, isorhamnetin and isorhamnetin-3-neohesperidoside, were identified for the first time in Sp leaves using LC-ESI-QTOF MS/MS analysis. The flavonoid-rich fraction obtained after purification of S1 (S1TF7) has the highest TFC (358.88±0.12 mg rutin equivalent/g) and TPC (180.82±0.82 mg gallic acid equivalent/g) and exhibits significant (p < 0.05) free-radical scavenging activity in DPPH(IC50% = 14.64±0.29 µg/mL) and ABTS (IC50% = 200.41±1.85 µg/mL) assays which was similar to Butylated hydroxytoluene (BHT) as a positive control (IC50% =12.94±0.10 µg/mL and IC50% = 190.47±8.93 µg/mL, respectively). Also, S1TF7 inhibits Lipopolysaccharide (LPS)-stimulated ROS production in raw-cell-264.7 with no significant toxicity at 200 µg/mL (p > 0.05). The study concludes that S1TF7 can serve as a mean to prevent oxidative diseases, and it merits further pharmacological investigations.