Phytochemical and biological activity studies on the underground parts of Trachystemon orientalis

Trachystemon orientalis (Boraginaceae), which is the only species of Trachystemon genus in Türkiye, known by the names of "Kaldırak, Kaldirayak, Borage, Ispıt, Kaldirik, Kaldirik, Tamara, Zılbıt Balıkotu, Acı Hodan and Doğu Hodanı" has been used as a medicinal plant. It has been proven in studies that the T. orientalis shows antiviral, antioxidant, antimicrobial, antidiabetic, antimutagenic, and herbicidal activities. In this study, isolation studies were carried out on subextracts (the chloroform, ethyl acetate and remaining aqueous) prepared from the methanol extract of the underground parts of T. orientalis using various chromatographic methods. The structures of the compounds isolated from T. orientalis extracts were elucidated using 1H-NMR, 13C-NMR, 2D-NMR (COSY, HMQC, HMBC) and MS methods. Four compounds, including rosmarinic acid, danshensu, globoidnan B and rabdosiin, were isolated from the underground parts of T. orientalis. The biological activity (antioxidant and lipase inhibitor activity) studies were conducted on the extracts and isolated compounds obtained from the underground parts of T. orientalis. FRAP and CUPRAC assays were used to determine antioxidant activity. Pancreatic lipase inhibition was determined by in vitro spectrophotometric method. In FRAP and CUPRAC assays, the ethyl acetate subextract exhibited the highest antioxidant activity among the extracts. Pancreatic lipase enzyme inhibition studies showed that the remaining aqueous subextract had the highest activity. Among the isolated compounds in FRAP and CUPRAC assays, rosmarinic acid showed the highest antioxidant activity. According to the results of pancreatic lipase enzyme inhibition studies, rosmarinic acid was found to have the highest activity. In conclusion, T. orientalis may be a promising natural product for the treatment of obesity owing to the high antioxidant capacity and pancreatic lipase inhibitory activity of its underground parts and isolated compounds.