Phytochemical and biological activity investigation of endemic Onosma onur-koyuncui Sezer

In this study, comprehensive phytochemical and biological activity investigations were conducted on the endemic plant species Onosma onur-koyuncui Sezer. For this purpose, extracts were prepared from the herb, flower, and seed parts of the plant using n-hexane and 70% methanol as solvents. These extracts were then subjected to extensive chemical analyses to evaluate their biological activities. The chemical composition of the plant was analyzed in detail using gas chromatography (GC-FID/MS) and liquid chromatography (UHPLC-HRMS/MS), enabling the identification of volatile compounds and fixed fatty acids. To assess antioxidant capacity, various methods including DPPH, CUPRAC, FRAP, ORAC, TEAC, and β-carotene bleaching assays were employed. Regarding antidiabetic potential, α-amylase enzyme inhibition activity was examined. In the analyses conducted using the micro-scale MSD-SPME technique, the main compounds were identified as cuminaldehyde in the herb, palmitic acid in the flower, and γ-terpinene in the seed. In fatty acid composition, methyl linolenate was identified as the predominant component in the seed and herb, while methyl palmitate was dominant in the flower. The UHPLC-MS/MS results revealed the presence of major phenolic compounds mainly luteolin, kaempferol, and chlorogenic acid. Additionally, the presence of Fe, Mg, Ca, and K elements was also shown in mineral analysis. These findings demonstrate that O. onur-koyuncui has a rich chemical composition and holds significant pharmacological potential. This study represents the first scientific investigation on this plant species and also highlights the importance of evaluating endemic plants for their phytochemical and therapeutic value.