Eight new diterpenoids from soft coral Cespitularia hypotentaculata

Chemical investigation of the soft coral Cespitularia hypotentaculata resulted in the isolation of eight new diterpenes, cespihypotins E–L (1–8). The new metabolites comprise of six verticillene-type diterpenes, one cespitularane derivative, and one derivative with 14-membered lactone ring. The structures were determined through detailed spectroscopic analyses, especially high resolution ESIMS and 2D NMR techniques. The relative stereochemistry was deduced from NOESY spectrum and application of Mosherʹs ester technique. Immunomodulatory and antiviral activities of 1–8 were tested and evaluated. The biogenetic pathways for 1–8 were also proposed.