Antioxidant activity of sage (Salvia officinalis and S fruticosa) and oregano (Origanum onites and O indercedens) extracts related to their phenolic compound content

In this study the antioxidant activity of methanolic extracts of oregano and sage samples was tested. Samples of oregano belonged to Origanum onites and 0 indercedens species, whilst samples of sage belonged to Salvia officinalis and S fruticosa species. Two methods were used to evaluate the antioxidant activity of sage and oregano extracts: the crocin test and the Rancimat test. The methanolic extracts were also analysed by HPLC for the qualitative/quantitative determination of phenolic compounds. The total phenolic compound content of oregano samples showed no significant differences between the two species, but rosmarinic acid was present in higher amount in 0 indercedens. Carvacrol content sharply differentiated flowers from leaves. Samples of 0 indercedens had a higher antioxidant activity evaluated by the crocin test, whereas no differences were evidenced by the Rancimat test. For sage samples, carnosic acid and methyl carnosate showed a significant difference between the two species, with S fruticosa samples having a higher content than S officinalis samples. Samples of S fruticosa also had a higher antioxidant activity evaluated by the crocin test. The antioxidant activities of sage samples were, on average, higher than those of oregano samples. Some samples of sage had a very high antioxidant activity, with induction times more than 10-fold higher than that of lard used as the reference sample. (C) 2002 Society of Chemical Industry.