Antioxidant, antiinflammatory activities and HPLC analysis of South African Salvia species

Abstract

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 2,20- 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 value ranging from 1.6 to 74.5 lg/ml using DPPH_, whilst the IC50 values ranged from 11.9 to 69.3 lg/ml, when tested with ABTS_+. The extract of Salvia schlechteri, with an IC50 value of 1.6 lg/ml, was three times more active than the reference compound, Trolox_ (IC50 value: 2.51 lg/ml). The antiinflammatory activity was evaluated using the 5-lipoxygenase assay. With the exception of Salvia radula (IC50 value: 78.8 lg/ml), the extracts displayed poor inhibition of the 5-lipoxygenase enzyme, with all IC50 values being greater than 100 lg/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 211 mg of GAE per g 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.