Biological activity studies on some Hypericum L. species

In this thesis, two varieties of Hypericum origanifolim Willd., which is naturally occurring in our country, namely H. origanifolium var. origanifolium Willd. (HOR) and H. origanifolium var. depilatum (Freyn & Bornm.) N. Robson (HOD) were investigated. Methanol (MeOH) and ethyl acetate (EtOAc) extracts were prepared from the above-ground parts of these plants, and the total phenolic content, DPPH• radical scavenging activity, antimicrobial, and cytotoxic activities of the extracts were explored. Additionally, the glandular structures of the plants were anatomically examined, volatile oils were obtained from the aerial parts, and the chemical compositions of volatile oils and extracts were qualitatively and quantitatively determined using GC-GC/MS and LC-MS/MS, respectively. The highest total phenolic content (245.46 ± 9.41 GAE/g extract) and DPPH• scavenging activity (Inh %=84.85 ± 0.08) were found in HOD-MeOH. The HOR-EtOAc extract exhibited the highest antimicrobial activity (MIC value < 0.19 mg/mL) against B. cereus, S. typhimurium, and B. subtilis and the highest cytotoxic activity (IC50 =13.364 ± 0.563 mg/mL) against MCF-7 cell line. In anatomical studies, various types of secretory canals, which are important for diagnosis, were observed. In the analysis of essential oils, nonacosane and germacrene D have been highlighted as common major compounds in both taxa. Additionally, HOR has been found to be rich in α and β-selinene, as well as tricosane. In LC-MS/MS analysis, it was observed that kersitrin was the most abundant chemical compound in HOR-MeOH (35712.48 mg/kg extract) and HOR-EtOAc (15123.88 mg/kg extract), while hyperoside was predominant in HOD-MeOH (75741.45 mg/kg extract) and HOD-EtOAc (42331.12 mg/kg extract).