On-Line Screening, Isolation and Identification of Antioxidant Compounds of Helianthemum ruficomum.

Many Helianthemum species (Cistaceae) are recognized for their various medicinal virtues. Helianthemum ruficomum is an endemic species to the septentrional Sahara on which no report is available so far. The purpose of this work was to investigate the chemical composition and the radical scavenging capacity of this species and its isolated components. Collected from Mougheul (south-west of Algeria), the aerial parts were macerated with 80% EtOH/H₂O, after evaporation, the remaining extract was diluted with H₂O and extracted with petroleum ether, chloroform, ethyl acetate and n-butanol. EtOAc and n-BuOH extracts were evaluated for their free radical scavenging capacity by on-line HPLC-ABTS•+ assay. The obtained data which were confirmed by TEAC and ORAC assays, allowed guiding the fractionation of these extracts by CC, TLC and reverse phase HPLC. Among the components, 14 were isolated and identified by spectroscopic analyses: protocatechuic acid (1), trans-tiliroside (2), cis-tiliroside (3), astragalin (4), picein (7), vanillic acid 4-O-β-d-glucopyranoside (8), lavandoside (9), 4-hydroxybenzoic acid 4-O-β-d-glucopyranoside (10), nicotiflorin (11), rutin (12), vicenin-2 (13), narcissin (14) and stigmasterol (5) and β-sitosterol (6) as a mixture (71% and 29%, respectively). Compounds 5, 7, 8, 9, 10 and 14 were new for the genus Helianthemum. The antioxidant power of all the isolated compounds was also evaluated by HPLC-ABTS•+, TEAC and ORAC assays. The results clearly indicated high antioxidant potential of the extracts and tested compounds of this species especially, compounds 1, 4, 8, 9, 10 and 12.