DETERMINATION OF THE ANTIOXIDANT CAPACITY OF SIDERITIS SCARDICA SPECIMENS COLLECTED AT DIFFERENT REGIONS IN BULGARIA

Antioxidant capacity of leaves and flower extracts of Sideritis scardica was determined by the DPPH center dot. (free radicals scavenging activity) and FRAP (Ferric Reducing Antioxidant Power) assays, total phenolics and flavonoids content, and the level of water-soluble (WS-AOC) antioxidant capacity, expressed as equivalents of ascorbate. The results revealed that antioxidant capacity of leaves and flowers extracts from wild S. scardica grown at peak Alibotush (Slavyanka Mountains) was much higher than other herbal samples. Also, a difference greater than 6-fold among the total antioxidants measured by FRAP in the wild growing S. scardica flowers harvested in two different locations of Slavianka Mountains (specimen 7 and 8) was found; a similar trend was observed in the total antioxidant capacity assessed by DPPH center dot where the difference was about two-fold. Out of all studied specimens, plants harvested from Alibotush Peak (Slavyanka Mountains) was differentiated based on the high measured FRAP, DPPH center dot and phenolic and flavonoids content in comparison with the same parameters of seven other specimens. Great differences in total phenolic and flavonoids content (up to several times between separate specimens) always corresponded to the same differences in FRAP and DPPH center dot measured. The results suggested that both leaves and flowers from S. scardica have a high level of ascorbic acid and, therefore, they might be used by native people in the traditional way of intake of plant-derived antioxidants such as herbal infusions rich in vitamin C.