Elucidation of pseudopterosin biosynthesis: Oxidations of erogorgiaene and the intermediacy of seco-pseudopterosins

The pseudopterosins and seco-pseudopterosins are diterpene glycosides isolated from the marine octocoral Pseudopterogorgia elisabethae . These compounds exhibit potent anti-inflammatory and analgesic properties superior to the industrial standard indomethacin. The overall goal of this work was to complete biosynthetic studies for the development of a biotechnological production method of the pseudopterosins and seco-pseudopterosins. The aim of this project was to identify all intermediates involved in pseudopterosin biosynthesis. Previously, the Kerr lab has shown that elisabetatriene and erogorgiaene are the first two committed steps in pseudopterosin biosynthesis. In a continuation of those metabolic studies, the isolation and utilization of 7-hydroxyerogorgiaene, 7,8-dihydroxyerogorgiaene, seco-pseudopterosin J, amphilectosins A and B in pseudopterosin biosynthesis is reported. The utilization of these compounds in pseudopterosin biosynthesis was assessed by incubating these compounds in radiolabeled form with viable cell-free extracts of P. elisabethae and monitoring for the incorporation of a radiolabel in the pseudopterosins. We also report the isolation of the pseudopterosin aglycone from extracts of P. elisabethae and identified the aglycone as the end product of this metabolic pathway.