Antioxidant, anti-inflammatory activities and HPLC analysis of South African Salvia species

The antioxidant and antiinflammatory activities of the methanol:chloroform (1:1) extracts of 16 Salvia species indigenous to South Africa were evaluated. Antioxidant activity was measured using the 2,2′-azino-bis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) and the 2,2,-diphenyl-1-picrylhydrazyl (DPPH) scavenging assays and compared to the control values obtained with Trolox®. Nearly all the solvent extracts displayed antioxidant activity with the IC₅₀ values ranging from 1.61 to 74.50µg/ml using the DPPH·, while the IC₅₀ values ranged from 11.88 to 69.26µg/ml when tested with the ABTS·+. The extract of S. schlechteri, with an IC₅₀ value of 1.61µg/ml, was three times more active than the reference compound, Trolox® (IC₅₀ value: 2.51µg/ml). The anti-inflammatory activity was evaluated using the 5-lipoxygenase assay. With the exception of S. radula (IC₅₀ value: 78.78µg/ml), the extracts displayed poor inhibition of the 5-lipoxygenase enzyme with all IC₅₀ values being greater than 100µg/ml. The total phenolic content based on gallic acid equivalents (GAE) confirmed the presence of total soluble phenolics in the various extracts from 45 to 211mg of GAE dry sample and showed strong association (r²=0.90) with antioxidant activity. High performance liquid chromatography (HPLC) was used to identify various compounds in the extracts. Betulafolientriol oxide and rosmarinic acid were detected in all the species investigated and rosmarinic acid, carnosic acid, carnosol and oleanolic acid/ursolic acid were abundant in many species.