Discovery of phthalides with vasodilating activity in stems and leaves of Ligusticum chuanxiong / 中草药

ABSTRACT

Objective: To study the phthalides with vasodilating activity of alcohol extracts from stems and leaves of Ligusticum chuanxiong. Methods: Compounds were isolated by extensive chromatographic techniques including MCI, silica gel, Sephadex LH-20, ODS, and semi-preparative HPLC. The vasodilating effect of phthalide and dimer phthalide on thoracic aortic ring in vitro was investigated. Results: Ten phthalides were isolated and identified, and their structures were elucidated as Z-3-butylidenephthalide (1), senkyunolide-E (2), Z-senkyunolide-H (3), (3Z,7β)-3-butenyl-7-hydroxy-4,5,6,7-tetrahydrophthalide (4), neoligustilide (5); Z,Z’-3.3’a,7.7’a-diligustilide (6), 3Z,3Z’-6,8’,7,3’-diligustilide (7), Z-tokinolide A (8), (3’Z)-(3S,8R,3a’S,6’R)-4,5-dehydro-3.3’a,8.6’-diligustilide (9), and (3Z)-(3aR,6S,3’R,8’S)-3a.8’,6.3’-diligustilide (10). Compound 1, 6-9 significantly reduced the strain of thoracic aortic ring in KCl preconstricted rats. The diastolic rate of compounds 6-8 were 60%, 52% and 70% at the highest concentrations (12 μmol/L), respectively. The EC50 was 9.46, 11.86 and 8.73 μmol/L, respectively. Firstly isolated from the stems and leaves of L. chuanxiong. Compounds 6, 8 are firstly isolated from L. chuanxiong. The test compounds could dilate blood vessels, and the activity of dimer phthalide was better than that of phthalide.