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 identifications of pen-tacyclic triterpenoid ketones are discussed in detail. Based on the compositional features of pentacyclic triterpenoid ketones in the sample, it is proposed that terrigenous triterpenoid kentones originate directly from organisms or are diagenetic oxidation products of their alcohols, and hopanoid ketones are formed from hopanoids (e.g. hopanoid alcohols and hopenes) by chemical and biochemical processes. These data provide evidence for the applied studies of pentacyclic triterpenoid ketones as biomarker compounds.