A new iridoid glycoside and other secondary metabolites from Sideritis dichotoma Huter and their chemotaxonomic significance

The phytochemical studies on the aerial parts of Sideritis dichotoma led to the isolation and identification of a new iridoid glycoside (1), along with four known iridoid glycosides (2-5), three phenylethanoid glycosides (6–8), two flavone glycosides (9 and 10), one neolignan (11) and a megastigmane glycoside (12). Their structures were elucidated by spectroscopic techniques. Compounds 2, 3 and 12 have never been found in the Sideritis genus before. Furthermore, eleven compounds (1–5, 7–12) were characterized for the first time from S. dichotoma. The chemotaxonomic importance of isolated compounds was discussed. This is the first phytochemical study on the polar constituents of S. dichotoma, an endemic species to Türkiye.