Pharmacognostical investigations on Vinca soneri Koyuncu

ABSTRACT Uyanır, E., Pharmacognostical investigation on Vinca soneri Koyuncu, Hacettepe University, Graduate School of Health Sciences, Pharmacognosy Programme, Master of Sciences Thesis, Ankara, 2023. Vinca soneri Koyuncu sp. nova belongs to the Apocynaceae family and grows in Eastern Anatolia in our country. It is a perennial, endemic plant with dark green leaves and pale blue flowers. Vinca species are used as antidiabetic, antihypertensive, carminative, emetic and hemostatic in folk medicine. In this thesis, different secondary metabolites were isolated from the butanol sub-extract of the crude methanol extract of V. soneri, which has limited phytochemical studies, and the structures of the compounds obtained were determined and their inhibitory effects on α-glucosidase enzyme were investigated. As a result of phytochemical studies, 5 flavonoids, kaempferol 3-O-α-rhamnopyranosyl (1→6)-β-galactopyranoside (VS-1, VS-2A), kaempferol 3-O-α-ramnopyranosyl (1→6)-β-glucopyranoside (VS-2B), quercetin 3-O-α-ramnopyranosyl (1→6)-β-galactopyranoside (VS-3), quercetin 3-O-[α-ramnopyranosyl(1→6)-β-galactopyranosyl]- 7-O-α-ramnopyranoside (VS-4), and quercetin-3-O-[α-ramnopyranosyl(1→6)-β-galactopyranosyl]-7-O-β-glucopyranoside (VS-5), 2 phenolic acids, 2-hydroxy-3-O-β-glucopyranosyl-benzoic acid (VS-6), and chlorogenic acid (VS-7), loganin (VS-8) and loganic acid (VS-9) were obtained. The structures of isolated compounds elucidated by means of 1D (1H and 13C) and 2D (DQF-COSY, HSQC and HMBC)-NMR techniques. When the α-glucosidase enzyme inhibitions of all obtained compounds were tested, it was observed that quercetin 3-O-α-ramnopyranosyl (1→6)-β-galactopyranoside (VS-1) with an IC50 value of 169.87±4.37 µg/mL inhibited at a similar level with acarbose used as a positive control. Keywords: Vinca soneri, flavonoid, phenolic acid, iridoid, α-glucosidase Supporting Organization: H.U. Scientific Research Projects Coordination Unit (Project No: THD- 2022-20224)