Guaiane type of sesquiterpene with NO inhibitory activity from the root of Wikstroemia indica.

Roots of Wikstroemia indica is widely used in China as a folk medicine in treatment of many diseases. However, active compounds of guaiane type of sesquiterpene remain largely unknown. In the present work, five new guaiane of type sesquiterpene compounds wikstronone A-E, along with one known guaiane type of sesquiterpene compound were isolated from the petroleum and CH2Cl2 fraction of roots of Wikstroemia indica. Structures of these compounds including absolute configuration were determined by extensive NMR and CD spectroscopic analysis. The inhibitory activity of all isolated compounds were assayed against LPS-induced NO production in RAW 264.7 macrophages by Griess reagent. Among all compounds, wikstronone A (1) showed remarkable NO inhibitory activity comparable to that of positive control Indometacin. Wikstronone D and E (4 and 5) showed weak NO inhibitory activity. The isolated guaiane type of sesquiterpene may be potent NO synthetase inhibitors.