Antioxidant capacity and polyphenolic content of seven Saudi Arabian medicinal herbs traditionally used in Saudi Arabia

The using of plants of Saudi Arabia for the cure of many ailments is ancient and still available among the tribal and local people and medicinal healers. In this study, alcoholic extract of seven plants from Tanhat protected area, Saudi Arabian, were studied for their antioxidant properties. The antioxidant properties were evaluated using different antioxidant tests, including inhibition of lipid peroxidation, reducing power, metal ion chelation, scavenging of free radical, superoxide anion radical, hydrogen peroxide and nitric oxide as well as total antioxidant capacity. Trigonella hamosa and Ducrosia anethifolia had powerful antioxidant activity, had 100% inhibition on peroxidation of linoleic acid emulsion at 200 μg/ml while Cleome ambliocarpa was the most efficient as scavenger. The presence of phenolic compounds and flavonoids in the extracts, which were detected by Folin-Ciocalteu may be responsible for the antioxidant activities of Heliotropium ramosissimum which exhibited the highest reduction capability with highest polyphenolic content (48mg/100mg extract as chlologenic acid). Moreover, Trigonella hamosa and Convolvulus prostates had effective metal chelating activity (100% ion chelation at 100μg/ml). Those various antioxidant activities were compared to standard antioxidants such as butylatedhydroxytoluene (BHT) and vitamin C.