Mono- and dicyclic unsaturated triterpenoid hydrocarbons in sediments from Lake Masoko (Tanzania) widely extend the botryococcene family

摘要: Abstract A mixture of C33–C37 botryococcenes and partially reduced derivatives was isolated from ca. 32,000 year old sediment Lake Masoko, a freshwater crater lake in the Rungwe Range area (Tanzania). Botryococcenes accounted for 246 μg/g dry >92% hydrocarbon fraction; 1D 2D nuclear magnetic resonance spectroscopy (NMR) mass spectrometry allowed structure dominant botryococcene (43% fraction) to be established, after purification using high performance liquid chromatography (HPLC). The compound is novel tetraunsaturated dicyclic C34 named masokocene. Overall, structures six other four were tentatively assigned. new biomarkers, three C34–C36 (or masokocenes) seven monocyclic C34–C37 analogues are discussed along with their biosynthetic relationship. abundance such polyunsaturated compounds preserved indicates an aquatic ecosystem dominated at time by green alga Botryococcus braunii, as well very good preservation organic matter.