| || || Kumar, Rohitesh R.|
| || || Isolation and characterization of the cytotoxic components of a Fijian sponge, hippospongia sp|
Author:Kumar, Rohitesh R.
Institution: University of the South Pacific.
Call No.: Pac QL 372 .8 .F5 K86 2010
Copyright:Under 10% of this thesis may be copied without the authors written permission
Abstract: A marine sponge of the genus Hippospongia, collected near Kia Island, off Labasa, Vanua Levu, exhibited cytotoxic activity towards brine shrimps. In order to identify the active principles, the crude extract of this sponge was subjected to a range of purification steps guided by brine shrimp bioassay. The purification steps which included solvent partitioning, Flash Column Chromatography (FCC) and High Performance Liquid Chromatography (HPLC) lead to the isolation of three known cytotoxic compounds: epi-ilimaquinone , smenospongine  and glycinylilimaquinone  Bioactive hexane and dichloromethane (DCM) extracts from solvent partitioning were subjected to normal phase (NP)-FCC and the fraction eluted with 4:1 ethyl acetate-hexane was further purified on reverse phase (RP)-HPLC with 80% acetonitrile-water and lead to the isolation of the known compound 1, epiilimaquinone. Another fraction obtained from NP-FCC of the DCM extract eluted with 1:1 ethyl acetate-hexane was subjected to RP-HPLC with the mobile phase of 80% acetonitrile-water and 0.1% trifluoroacetic acid (TFA) and yielded the second known compound, smenospongine. Compound 3 was isolated from the methanol fraction from solvent partitioning. This fraction was subjected to reverse phase vacuum liquid chromatography (RP-VLC) with methanol-water. The fraction eluted with 80% methanol-water yielded the known cytotoxic compound 3, known as glycinylilimaquinone, upon purification on RP-HPLC with 65% acetonitrile-water and 0.1% TFA. LC-MS and NMR data of the compounds isolated were used to elucidate the structures. From the 1H NMR data of the three compounds it was apparent that these compounds are related and are analogues belonging to the group of compounds known as sesquiterpene quinones or amino quinones. All the compounds isolated showed cytotoxic activity towards brine shrimps. Compound 1, epi-ilimaquinone exhibited the most cytotoxicity at 18μg/ml, compound 2, smenospongine exhibited moderate cytotoxicity of 188μg/ml while compound 3, glycinylilimaquinone was the least active with the cytotoxic activity of greater than 500μg/ml.