Investigation on Anti-inflammatory Effect and Chemical Constituents of Total Flavonoid Aglycones from Tibetan Medicine Oxytropisfalcata

Oxytropis falcata is a wild growing Leguminosae plant which distributes Qinghai-Tibet Plateau in China. The herb of this plant has been known as one of “Three Anti-inflammatory Drugs” in Chinese Tibetan medicine, and used to treat inflammation and nociception for thousands years[1,2]. In order to make the active material foundation corresponding to its anti-inflammatory effect clear, several main ingredients including essential oil, alkaloids, flavonoid aglycones and saponins were isolated, respectively, and then anti-inflammatory effect was evaluated and compared by TPA-induced ear oedema and carrageenan-induced peritonitis in mice. Subsequently, column chromatographic method was used to separate chemical constituents from the most active anti-inflammatory ingredient, whose structures were elucidated by NMR spectral data and physical and chemical properties. Oral administration of total flavonoid aglycones (1200 mg dry raw material/kg) could significantly (p < 0.01, compare to vehicle) inhibit the ear oedema induced by TPA and peritoneal leukocyte migration in mice at a rate of 61.1% and 56.4%, and indomethacin (10 mg/kg) showed 58.6% and 60.1% inhibition, respectively. Furthermore, pinostrobin, pinocembrin, 7-hydroxy flavonone, liquiritigenin, 2ʹ,4ʹ-dihydroxy dihydrochalcone, 2ʹ,4ʹ-dihydroxy chalcone, 2ʹ-methoxy-4ʹ-hydroxy chalcone, 2ʹ-hydroxy-4ʹ-methoxy chalcone, 2ʹ,4-dihydroxy-4ʹ-methoxy chalcone, isoliquiritigenin, 3ʹ,7-dihydroxy-2ʹ,4ʹ-dimethoxy isoflavane, genistein, Ψ-baptigenin, formononetin, 7-hydroxy flavone, kaempferol, isorhamnetin, quercetin, myricetin, chrysin, apigenin, luteolin were isolated and elucidated from active ingredient. The results suggested that the total flavonoid aglycones possess most strong anti-inflammatory activity of main ingredients from Oxytropis falcata, and 12 flavonoids were isolated from which for the first time. Acknowledgements: Financial support for this research from the Scientific Research Foundation for the Returned Overseas Chinese Scholars, State Education Ministry, is gratefully acknowledged. Reference: [1] Jiang H, et al. (2006) Chin Tradit Herb Drugs, 37: 314. [2] Mao JZ, et al. (1986), Jing Zhu Herbal, Shanghai Science and Technology Press, Shanghai, China.