ISOLATION, LOCALIZATION AND BIOSYNTHESIS OF CRASSIN ACETATE INPSEUDOPLEXAURA POROSA(HOUTTUYN)

Abstract

1. The particulate portion of a homogenate of the gorgonian Pseudoplexaura porosa (Houttuyn) can be separated into fractions by repeated centrifugation and differential resuspension.2. One of these fractions is crystalline and has been identified as crassin acetate, a diterpene lactone, by the infrared absorption of the original crystals and by melting point determination after recrystallization.3. Histological sections demonstrate that crassin acetate crystals are extracellur, in part, to the gorgonain tissues, and in toto, to the symbiotic zooxanthellae of this organism. However, the crystals occur in association with gorgonian endoderm containing zooxanthellae, thus suggesting that crassin acetate is a product of host-zooxanthellae interaction.4. Quantitative determinations of crassin acetate show a minimum concentration of 10% of the organic dry weight of the cortex. It was also found that cortex from both youngest and oldest parts of the gorgonian colony contain essentially equal concentrations of crassin acetate.5. Both CO2 and acetate are precursors of the diterpene, acetate being about ten times more efficient.