Isoprenoids of Okinawan mangroves as lipid input into estuarine ecosystem

Isoprenoids in the nonsaponifiable lipids (NSL) fraction of Okinawan mangroves were analyzed with special reference to their importance as lipid input into estuarine ecosystems. Triterpenoids and phytosterols comprised the major proportion of NSL. Identifications of the triterpenoids and phytosterols in NSL fraction were based on the interpretation of C-13-NMR and GC-MS spectra. The triterpenoids and phytosterols mainly comprised 11 and 6 compounds, respectively. The major components were lupeol, beta-amyrin and taraxerol for triterpenoids, and beta-sitosterol and stigmasterol for phytosterols. The diversity in the terpenoid composition was noted in both leaves and roots of mangrove species, implying the chemotaxonomic utility of terpenoids. Terpenoid compositions of the root are not always similar to that of leaf, suggesting that terpenoids in the root are produced by biosynthesis in situ, not by translocation of the synthate from the leaf. Terpenoids existed in greater proportion in the outer parts of the root. These data are likely to contribute to estimating the lipid input from mangrove trees adjacent to estuarine sediments and the ocean.