This thesis titled "phytochemical and bioactivity studies on hypericum thymopsis boiss. (hypericaceae)

In this study, it was determined the amounts of hypericin, pseudohypericin and also phenolic acids by reversed- phase HPLC-DAD, the total phenolic and total flavonoid contents by the spectrophotometric method, of the different polarity extracts and infusions prepared from the aboveground parts of the endemic Hypericum thymopsis Boiss (Hypericaeae) collected near Sivas-Kangal-Gürün. In addition, it were carried out the antioxidant activity of extracts by DPPH• free radical scavenging effect, ABTS cation radical scavenging effect, metal chelation and reductive power determinations anti-alzheimer activities by acetylcholinesterase and butyrylcholinesterase enzyme inhibition activity determinations; antimicrobial activity by broth dilution method, cytotoxicity studies on Caco2 and 3T3 cell lines. The results were compared with Hypericum perforatum L. results. It has been determined that H. thymopsis contain less amount of hypericin and pseudohypericin compared to H. perforatum by the HPLC; volatile terpenes, α-pinene, β-pinene and limonene by the GC-MS/FID technique. Ethyl acetate extracts with the highest total phenolic substance and total flavonoid amount, compared to other extracts studied, while showing high AChE enzyme inhibition, ethyl acetate and %70 methanol extract; %70 ethanol extract high free radical scavenging effect; methanol extract and infusion high reduction power; the aqueous extract has been shown to have high ABTS radical cation decolorizing effect. In addition, while ethyl acetate and methanol extracts showed better activity against all strains studied than other extracts, it showed significant antibacterial activity compared to chloramphenicol and significant antifungal activity against Candida strains. Pseudohypericin content and anti-alzheimer, cytotoxic, antifungal and antibacterial activities of H. thymopsis, one of the endemic species of our country, were presented for the first time in this study.