Evaluation of in-vitro wound healing effects, biological activities and phytochemical components of aqueous extracts of Hypericum heterophyllum

Taxa belonging to the genus Hypericum L. are widely used in traditional medicine worldwide. Hypericum heterophyllum, one of the species of this genus, is endemic to our country and is commonly known as "wound flower." Due to insufficient research on both Hypericum heterophyllum and other endemic species found in our country, their contributions to public health and potential economic potential remain elusive. Investigating and elucidating the composition and biological/pharmacological activities of these species, elucidating their potential mechanisms for disease healing, and identifying potential industrial applications are crucial for assessing our country's assets. Therefore, the presented thesis aims to investigate the wound-healing, anticarcinogenic, antimicrobial, and antioxidant potential of aqueous extracts of the endemic species Hypericum heterophyllum in Türkiye, and to determine their phytochemical components. For this purpose, three different aqueous extracts (HHMix and HHFlower, and HHBranch-leaf) were prepared by using the flower, branch-leaf, and aerial parts (mix) of Hypericum heterophyllum. The presence of 53 different phytochemical standard substances likely to be present in the extracts was determined qualitatively and quantitatively by LC-MS/MS system. Total phenolic content, total antioxidant status (TAS), total oxidant status (TOS), and oxidative stress index (OSI) levels of the extracts were determined by spectrophotometric method. The antimicrobial activities of the extracts were determined by disk diffusion and minimal inhibitory concentration (MIC) determination methods using Staphylococcus aureus, Escherichia coli, and Candica albicans reference strains. For the determination of cytotoxic and anticarcinogenic activities, human gingival fibroblast (HGF) cells were used as a healthy cell line, and non-small cell lung cancer (A549) cells and skin cancer (G-361) cells were used as cancer cells. Different concentrations of extracts were applied to the cells and cytotoxicity levels were determined by the MTT (3-(4,5-dimethylthiazolyl-2-yl)-2,5-diphenyltetrazolium bromide) method. Media containing the lowest concentrations of extracts (100 µg/mL), which were determined to be non-cytotoxic, were applied to HGF and G-361 cells created in a cell scratch wound model. Thus, the effects of the extracts on wound healing, cell renewal (proliferation), and cell migration were determined. The results obtained indicated that the extracts contained varying amounts of bioactive substances, mostly phenolic in structure, including 5-dicaffeoylquinic acid, vanillin, caffeic acid, 4-OH benzoic acid, syringic acid, syringic aldehyde, and vanillic acid. The 4-OH benzoic acid levels were found to be 9.56% in HHBranch-leaf extract and 7% in HHMix extract, suggesting that Hypericum heterophyllum can be used as a natural source of 4-OH benzoic acid (p-hydroxybenzoic acid). Among the extracts, antioxidant activities were particularly high in HHMix and HHFlower extracts, while TOS levels were high in HHBranch-leaf extract. Based on these data, HHBranch-leaf extract was determined to have the highest antimicrobial activity against E. coli. HHMix, which was found to have higher TAS levels, was found to have better wound healing activity than other extracts in HGF cells. In G-361 cells, HHflower extract increased cell proliferation and migration, making it unsuitable for use in individuals with skin cancer. However, in G361 cells, HHBranch-leaf extract was found to reduce cell proliferation and migration and induce cell death. These data indicate that HHBranch-leaf extract, which did not cause any toxicity in healthy HGF cells but exhibited cytotoxic effects against melanoma (G361) cells, may offer new alternatives in the treatment of skin cancer. The data obtained from the presented thesis indicate that Hypericum heterophyllum, an endemic species in our country, may have economic value due to its components and biological/pharmacological effects, potentially contributing to both public health and welfare. In this context, it is recommended that fundamental studies on endemic species such as Hypericum heterophyllum, a rich resource for our country, be conducted, and that further studies with experimental animal models or volunteers, based on the data obtained, can contribute to the national economy and public health by developing species deemed necessary or innovative products.