Total Coumarin Content and Antioxidant Activity in Different Parts of Obazema, a Yi Medicine

[Objectives] This study aimed to determine the total coumarin content and antioxidant activity in vitro of Obazema, a Yi Medicine. [Methods] The extraction process of coumarin from Obazema was optimized by response surface method, and the total contents of coumarin in different sources and different parts of Obazema were compared. With Vc, chlorogenic acid and citric acid as positive controls, the antioxidant activity of the ethanol extracts of different parts of Obazema was determined. [Results] The optimum extraction process for coumarin from Obazema were as follows: 80% ethanol, solid to liquid ratio 1∶67, extraction time 120 min and extraction temperature 57 ℃. The total contents of coumarin in roots, stems, leaves, flowers and fruit of Boenninghausenia sessilicarpa Levl. and B. albiflora(Hook.) Reichb. were 7.75, 6.50, 33.45 and 44.35, and 8.1, 4.6, 17.8 and 18.7 mg/g, respectively. The free radicle-scavenging activity of coumarin from Obazema had certain dose-effect relationship, and was slightly stronger than that of the positive drugs. Under the phenanthroline-Femethod, the free radicle-scavenging activity ranked as B. albiflora(Hook.) Reichb.>B. sessilicarpa Levl.>Vc>citric acid>chlorogenic acid; under the DPPH method, the free radicle-scavenging activity ranked as B. albiflora(Hook.) Reichb.>B. sessilicarpa Levl.>Vc>chlorogenic acid>citric acid; and under the ABSTS~+ method, the free radicle-scavenging capacity ranked was in the order as B. albiflora(Hook.) Reichb.>B. sessilicarpa Levl.>Vc>chlorogenic acid>citric acid. [Conclusions] There are significant differences in coumarin content between different sources and different parts of Obazema. When coumarin is used as the main active substance, Obazema is better harvested during the flowering period, and the free radicle-scavenging activity of B. sessilicarpa Levl. is higher than that of B. albiflora(Hook.) Reichb. The antioxidant activity of the flower-fruit ethanol extracts of B. sessilicarpa Levl. and B. albiflora(Hook.) Reichb. is stronger than that of the commonly used antioxidants such as Vc, chlorogenic acid and citric acid, which is related to antioxidant components in the ethanol extracts.