Chemical Constituents And Bioactivities From Twigs Of Myricaria Germanica, A Tibetian Medicine

The twigs of Myricaria germanica, a Tibetian medicine in folk, belongs to the genus Tamaricaceae, distributed in the Qinghai-tibet plateu , used to treat of arthritis. Modern pharmacological studies showed that Myricaria germanica have the antibacterial effects , inflammation, antifatigue and antioxidation. This paper studied on chemical consitituents and bioactivation of Myricaria germanica.(1) Chemical consitituents of Myricaria germanicaTwenty-two compounds were isolated from the 60% aq. acetone extract of the air-dried twigs of Myricaria germanica (Tamaricaceae), a famous Tibetian medicine, by repeat column chromatography of Diaion HP20SS, Sephadex LH-20, silica gel and MCI CHP20P. Their structures were elucidated by IR, ESI-MS, 1D,2D 1H-NMR, 1D,2D 13C-NMR spectroscopic analysis and identified as 3,5,4'-trihydroxy-7,3'- dimethoxyflavone (1), 3,5,4'-trihydroxy-7-meth--oxyflavone (2), rhamnetin (3), 3,5,7-trihydroxy-4'-methoxyflavone (4), tamarixetin (5), kaempferol (6), quercetin-3- O-β-D-glucoside (7), kaempferol-3-O-β-D-glucuronic acid (8), quercetin-3-O-β-D- glucuronicacid (9), quercetrin (10), afzelin (11), ferulic acid (12), coniferol (13), feruloyl glucose (14), isolariciresinol (15), caffeic acid (16), p-hydroxy cinnamic acid (17), gallic acid (18), 3,5-dihydroxy-4-methoxyb-enzoic acid (19), 4-hydroxy-α- methylbe-nzeneepropanol (20), 4-hydroxy-3-methoxybenzoic acid (21) , 3,5,4- trihydroxycin--nanic acid (22), 3,4-dimethoxygallic acid (23) and gypsogenic acid 3-O-[β-D-xylopy-ranoside] (24), respectively. All compounds were obtained from M. germanica for the first time, and compounds 1-6,8-11,14,15 and 17-24 were obtained from the genus Myricaria for the first time.(2) Bioactivation of the twenty-four compoundsThis paper studied on bioactivation of twenty-four compounds, seven compounds exhibited significant DPPH radical scavenging activities (stronger than vitamin C ). Compound's activities of scavenge DPPH radical was closely related to the number of Phenol hydroxyl. The number of Phenol hydroxyl more in molecules, the activity of scavenge DPPH radical is stronger. The position of 3-hydroxy in flavonoids is polyglucosides, the activity of scavenge DPPH radical was significantly decreased. The total antioxidant capacity of FRAP and ABTS test results show that flavonoids have weak antioxidant capacity, and simple phenolic compounds have strong total antioxidant capacity. The experiment of inhibitory activities on tyrosinase show that all compounds were smaller than Kojic acid.