Evaluation of antioxidant activity, total phenols and phenolic compounds in thyme (Thymus vulgaris L.), sage (Salvia officinalis L.), and marjoram (Origanum majorana L.) extracts

Abstract

The antioxidant properties and total phenolic of different extracting solvents of thyme, sage, and marjoram were examined using the stable 2,2-diphenyl-1-picrylhydrazyl-hydrate (DPPH) free radical scavenging method and Folin–Ciocalteu method, respectively. Methanol exhibited the highest extraction ability for such phenolic compound, where the total phenols were 8.10, 5.95, and 5.20 (mg gallic acid equivalent/g dry weight) for thyme, sage, and marjoram, respectively and also exhibited the strongest antioxidant capacity. On the basis of the results obtained, thyme, sage, and marjoram have a potential use as natural antioxidants due to their significant antioxidant activity. HPLC analysis of methanolic extract showed the presence of: rosmarenic acid, methyl rosmarenate, caffeic acid, cinnamic acid, chlorogenic acid and quinic acid as phenolic acids, besides some flavonoids such as ferulic acid, apigenin, luteolin and quercetin. The results demonstrated that thyme methanol extract possessed the best antioxidative activity, which were better than those of other plants, α-tocopherol and BHA.