VARIATION AMONG KNOWN KALIHINOL AND NEW KALIHINENE DITERPENES FROM THE SPONGE ACANTHELLA-CAVERNOSA

Seven new diterpene constituents were isolated from the sponge Acanthe lla cavernosa investigated from Fijian locations. Their structures wer e established based on a combination of spectroscopic data, x-ray crys tallographic data and biogenetic arguments. These new diterpenes, of t he kalihinane family, can be divided into the kalihinene (compounds 4 - 6) or the 6-hydroxy-kalihinene (compounds 7 - 10) frameworks. Also p resent were three known compounds, kalihinol A (1), isokalihinol F (2) and kalihinene (3). It is proposed that the kalihinane type diterpene s are a chemotaxonomic marker for A, cavernosa. Its diterpenes can be clustered into three biogenetic families based on the stereochemistry of the decalin ring forming process. The presence of different members of these biogenetic types might be used to chemically distinguish var ious populations of A. cavernosa. The compounds, 1, 3 and 7 were major constituents in both the bulk collection extracted after collection a nd in 15 specimens held in a controlled aquaculture system for seven m onths before extraction. A subtle chemical difference could be discern ed among these samples based on the content of compounds 1, 3 - 5 and 7.