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Abstract Chemical and biological studies on Heteroxenia species extracts (soft coral)The work described in this thesis has been undertaken with the objective of searching for naturally occurring substances of potentially biological activities in Egyptian soft corals. Through this investigation useful information were derived from the application of the modern techniques of chromatography (column, and thin layer chromatography) and spectral measurements including IR, 1D-NMR, 2DNMR and MS. The introductory part of this thesis comprises the literature review part comprises detailed accounts of previously isolated natural products from some Xeniidae (Alcyonacea) genera especially Heteroxenia species and their structural types encountered in nature and some of their medicinal uses. Also, a brief account of ceramides (sphingolipids), their commoner structure, methods of isolation, identification, biosynthesis and biological importance. The theoretical part of the thesis describes the chemical and biological investigations of chloroform extract of Heteroxenia ghardaqensis (family Xeniidae). The original work carried out is summarized under the following titles: 1. Isolation and identification of chemical constituents of chloroform extract of Heteroxenia ghardaqensis. The frozen marine organism H. ghardaqensis was broken down into small pieces and extracted at room temperature with sufficient amount of chloroform, several times until no further residue was obtained to ensure complete extraction. The chloroform extract was chromatographed on silica gel (250 g) column (50 cm L x 6 cm D), eluted with a mixture of pet ether (40-60◦C)/ EtOAc according to increasing polarity to give eleven pure compounds (G1-G11). The structures of isolated compounds were elucidated using chemical and spectroscopic methods including IR, 1D, 2D-NMR and MS. These compounds were identified as the following: ENGLISH SUMMARY ii Compound (G1): Sterol identified as gorgosten-5(E)-3β-ol using 1D, 2D-NMR, EI-MS and spectroscopic analysis data comparing with previously reported references. This compound was isolated for the first time from Heteroxenia ghardaqensis. |