Isolation of secondary metabolites of the endemic Salvia siirtica species and determination of the biological activities

Over 900 Salvia L. (Lamiaceae) species in the world and up to 98 of them in Turkey grow naturally. 53 of these 98 species are endemic. The species of Salvia are rich in terpenes and flavonoids. Salvia species have excellent antimicrobial activity in addition to their antioxidant capacity due to the variety of secondary metabolites they contain. Some of these are used against many pathological diseases such as vascular occlusion, brain dysfunction and cancer. The species belonging to the genus Salvia have been extensively researched because of their various medical uses. Many Salvia species have been used in traditional medicine as a tonic, antirheumatic and chronic painkiller and as a delicious spice since ancient times. At the same time, many studies have shown that the genus Salvia has the potential to be a significant antioxidant source. In this context, it is aimed to investigate the chemical and biological aspects of the endemic Salvia siirtica Kahraman, Celep & Doğan, which is a value of our region. In this study, chloroform and ethanol extracts of S. siirtica were prepared and antioxidant, anticholinesterase, tyrosinase, and urease enzyme activities were investigated. Then, in the light of the chemical profile of the extracts, the secondary metabolites were purified by the use of preparative HPLC and other conventional chromatographic methods and their structures were illuminated by spectroscopic methods; and after the antioxidant activity of the isolated compounds was determined, urease, anticholinesterase and tyrosinase enzyme activities were also determined. In addition, some flavonoids and phenolic compounds were quantified by LC-MS / MS in petroleum ether and chloroform extracts of mixed fractions and the ethanol extracts that were prepared by the leaves, branches, flowers, roots and the mixture of these parts of this species. Petroleum ether extract for all parts of this species was prepared, and the fatty acid profile was determined by GC-MS / MS. Generally, it was determined that ethanol extracts have a high antioxidant potential in CUPRAC, DPPH free radical removal activity and ABTS cation radical removal activity methods. It was determined that especially the polar fractions obtained from the main columns were quite active in three methods. It was determined that the obtained phenolic compounds were highly active in antioxidants and ethanol extracts have moderate to high activity against both acetyl and butyryl-cholinesterase enzymes. It was found that the obtained pure substances had low anti-cholinesterase activity. None of the extracts showed antiurease activity, and all of them had a low antityrosinase activity. When the LC-MS/MS results were evaluated, it was determined that S. siirtica was very rich in rosmarinic acid. In particular, the extracts of SS-K and SS-Y were found to be very rich in rosmarinic acid (12285.62 and 10037.49 µg analyte/g extract, respectively). The main extracts were screened by HPLC-IT-TOF-MS, and molecular formulas and possible compound names were established for 54 compounds. Fatty acid contents of samples collected from S. siirtica in 2015-2016-2017 years were analyzed by GC-MS. It was found that oleic acid, sis-11-eicosenoic acid, erucic acid and nervonic acid are major components. In the isolation studies, total 21 substances, 4 of which were new (21α-hydroxy-2α,3β-diacetoxy-urs-9(11),12-diene, 3β-hydroxy-2α-acetoxy-urs-9 (11),12-diene, 2α,3β,21α-trihydroxy-urs-9(11),12-diene and 1α,21α-dihydroxy-2,3-(1,1-dimethyl-dioximethylene)-urs-9(11),12-diene) were obtained from the root and aboveground parts of S. siirtica and which were active in antioxidant ethanol extracts. Other compounds were found to be ursolic and oleanolic acid in the triterpene structure; β-sitosterol and stigmasterol in the steroid structure; ferruginol, sugiol, and 4,12-dihydroxy sapripara-quinone in the diterpene structure. The ones who were in the phenolic-flavonoid structure were found to be salvigenin, apigenin, luteolin 7-glycoside, rosmarinic acid, fumaric acid, caffeic acid, coumaric acid, 4-hydroxybenzoic acid, bis-(2-ethyl hexyl) benzene-1,2 dicarboxylate and bis(2- ethyl hexyl) terephthalate. The results obtained from the S. siirtica, whose chemical content and biological activities were investigated for the first time, were introduced to the scientific world.