The Phenolic content and antioxidant and free radical scavenging activity of some hypericum species

ABSTRACTMaster of Science ThesisTHE PHENOLIC CONTENT AND ANTIOXIDANT AND FREE RADICALSCAVENGING ACTIVITY OF SOME HYPERICUM SPECIES6(9'$ø%$'29$Anadolu UniversityGraduate School of Health SciencesPharmacology ProgramSupervisor: Prof. Yusuf ÖZTÜRK2006The total phenolic content, antioxidant and free radical scavenging potentials of extracts of driedflowers and leaves of H. montbretii, H. origanifolium and H. perforatum and their fractions were evaluatedby different chemical and spectrophotometric methods. The total phenolic concentration was analyzed by theFolin-Ciocalteu method using gallic acid as a standart; also flavonoid and flavonol content was investigatedby AlCl3 and AlCl3+Na-acetate using rutin as a standart.The antioxidant potential of extracts was evaluatedby β-carotene-linoleic acid system and Rancimat method. For the free radical scavenging capacity 2,2-diphenyl-1-picrylhydrazyl (DPPH•) method was used. The results were compared to the results of thesynthetic antioxidant BHT. The highest activity was determined with all ethyl acetate extracts and it wasobserved that leaves of the studied species contain more phenolic compounds than the flowers, as well as theantioxidant capacity. It was determined that the flowers and leaves of H.origanifolium contain high amount ofphenolic compounds, consequently show the most lipid peroxidation activity on Rancimat method than thesynthetic antioxidant BHT. The flower extracts of H. montbretii and H. origanifolium exhibit higher activityon β-carotene-linoleic acid system than synthetic BHT. Also, the leaves of H. montbretii and H. perforatumdemonstrated better anti-radical activity than BHT.Keywords: Hypericum origanifolium, Hypericum montbretii, Hypericum perforatum, Antioxidant activity,Radical Scavenging Activityii