Analysis of discorhabdins from the New Zealand marine sponge Latrunculia sp

Abstract

The aim of the project is to develop an efficient preparative method to isolate discorhabdins in milligram quantities, and to develop an analytical method to measure the levels of discorhabdins present in the New Zealand marine sponge Latrunculia. Discorhabdins are novel secondary metabolites produced by several species of marine sponges of the genus Latrunculia. Discorhabdins show selective activity against several solid tumour lines including colon and small cell lung cancer cells. The preparative isolation method was developed using a novel technique called "cyclic loading" and polystryene-divinyl benzene reverse phase packing material. This method is superior to the methods described in the past since it involves fewer steps, avoids the liquid/liquid extraction, and reduces the number of evaporation steps. Total analytical procedure was developed by scaling down the preparative isolation method. Using samples of 0.5 g of the dry weight sponge, six discorhabdins were identified and the four major components discorhabdins A, B, C, and J were quantifies. The reproducibility of the total analytical procedure was found to be 10% which compares favourably to the non-specific bio-assays. Although the resolution of discorhabdins was not complete, the HPLC analysis provides a "discorhabdin profile" of a sponge which can be used in comparative studies. The analytical procedure was used to examine the discorhabdin content of twenty Latrunculia specimens collected at various locations around the New Zealand coast.