ISOLATION AND IDENTIFICATION OF TWO NEW CONSTITUENTS FROM ALGAE

AIM：To study the chemical composition in the alga Sargassum vachellianum and Ulva lactua collected from South China Sea. METHODS: Various column chromatography were used to separate the chemical constituents. MS, IR, ¹HNMR, ¹³CNMR（DEPT）, HMQC and HMBC were used to determine the structure of the isolated constituent. RESULTS: Two new compounds were isolated and their structure were elucidated as 11-methyl-1,5-diene-3,7,10-tricarbonyl-2,4,8,9-tetranitrogen-cycloundecandien(1) and cholesta-28-methyl-23,24-cyclopropane-Δ⁵-4-one-3β-ol(2) on the basis of spectral evidence. CONCLUSION: compounds 1 and 2 are new compounds.