Bioactive Constituents of Ziziphora clinopodioides

Abstract

Ziziphora clinopodioides Lam. (Labiatae), a medicinal and edible plant, is mainly distributed in Xinjiang of China, Iran, Turkey, Mongolia, and Central Asia. It is commonly used in traditional Uyghur medicine for the treatment of fever, edema, neurasthenic, insomnia, tracheitis, lung abscess, hemorrhoids, hypertension, angina pectoris, coronary artery disease, and other cardiovascular diseases [1–4]. Phytochemical investigations on the genus Ziziphora have mainly focused on essential oil components as well as a few flavonoids, caffeoyl derivatives, fatty acids, phenolic acids, triterpenoids, and sterols [4]. In our previous studies, Z. clinopodioides Lam. was shown to acquire notable antihypertensive, antidiabetic, and antioxidant effects. In order to explore the antihypertensive constituents of this plant, the commonly adopted in vitro model of rat thoracic aortic rings [4] were applied for the bioassay-guided fractionation of active components from Z. clinopodioides Lam., with 11 compounds isolated from the 70% EtOH extract. Based on spectroscopic analyses, their structures were identified as diosmetin (1), apigenin (2), luteolin (3), caffeic acid (4), 5,7,2 -trihydroxyflavone 2 -O-D-glucopyranoside (5), methyl rosmarinate (6), betulinic acid (7), dibutyl phthalate (8), oleanolic acid (9), acacetin (10), and 5,6,4 -trihydroxy-7,8,3 -trimethoxyflavone (thymonin, 11), respectively, among which compounds 7 and 8 were obtained from the genus Ziziphora for the first time. Apigenin (2), luteolin (3), methyl rosmarinate (6), and oleanolic acid (9) were identified as potential vasorelaxant principles. Methyl rosmarinate (6), caffeic acid (4), and luteolin (3) possessed significant antioxidant capacities. Ziziphora clinopodioides along with the active principle oleanolic acid (9) were also reported to possess exciting antidiabetic properties herein for the first time.