Flavonoid and phenolic compounds from Salvia palaestina L. growing wild in Jordan and their antioxidant activities

Abstract

Investigation of the butanol fraction of Salvia palaestina Benth. from Jordanian origin resulted in the isolation and characterization of nine compounds, three of which are reported here for the first time in Nature. These compounds included the two phenolics: salpalaestinin (1), methyl 3-O-methylrosmarinate (3) and the flavonoid luteolin 7-O-(2″-p-hydroxybenzoyl)-β-glucuronide) (8). In addition, 3,4-dihydroxyphenyl caffeate (2), diosmetin (4), apigenin-7-O-(6″-butyryl-β-glucopyranoside) (5), luteolin-3'-O-methyl-7-O-(6″-butyryl-β-glucopyranoside) (6) and clinopodic acid B (7) were also obtained from the butanol fraction of the plant. The structures of the isolated compounds were elucidated by different spectroscopic methods including NMR (1D and 2D), UV, IR and MS (HRESIMS and EIMS). The DPPH radical scavenging activity for compounds 1, 3, 5, 6 &8 was evaluated. Compound 3 had the highest antioxidant activity (91.9±1.30% inhibition) with an IC₅₀ value of 1.0±0.23(μg/mL).

Keywords: Antioxidant activity; Luteolin 7-O-(2″-p-hydroxybenzoyl)-β-glucuronide; Methyl 3-O-methylrosmarinate; Salpalaestinin; Salvia palaestina.