Pentacyclic triterpenoid ketones in peat from Gannan Marsh, China

Abundant terrigenous triterpenoid ketones and a series of hopanoid ketones were detected in a peat sample from the recent Gannan Marsh. The identifica tions of pentacyclic triterpenoid ketones are discussed in detail. Based on the compositional features of pentacyclic triterpenoid ketones in the samp le, it Is proposed that terrigenous triterpenoid kentones originate directl y from organism or are diagenetic oxidation products of their alcohols, and hopanoid ketones are formed from hopanoids (e.g. hopanoid alcohols and hop enes) by chemical and biochemical processes. These data provide evidence fo r the applied studies of pentacyclic triterpenoid ketones as biomarker comp ounds.