Sterol Ring System Oxidation Pattern in Marine Sponges

Abstract

Abstract:The marine sponges (Porifera) are a unique group of sedentary organisms from which several novel natural products are reported, many of which have useful biological activities. In producing unusual sterols, they occupy a preeminent position among the various groups of organisms. The polar sterols of sponges reported as at the end of the year 2002 number about 250; their ring structure changing a hundred times. The oxidation pattern in the sterol ring system, from the point of view of biogenesis seems to be mainly of four types. Each sponge species is able to produce sterols fitting into one of the four main biogenetic pathways viz., (i) 3β-hydroxy-∆ 5 -sterol pathway, (ii) 3β-hydroxy-∆ 7 -sterol pathway, (iii) 3β-hydroxy-∆ 5,7 -sterol pathway, and (iv) 3α-hydroxy sterol pathway.

An epoxysterol and other constituents of Tanzania soft corals

“…The 1 H-NMR spectrum of each of the gums exhibited signals which were comparable with 1 H-NMR chemical shifts of known sterols (Sarma et al, 2005), Thus the spectra exhibited absoptions at δ -0.13 (dd, J = 4 and 6 Hz), 0.06-0.44 (m) and 0.45 (dd, J = 4.8 and 9 Hz) which fitted well with reported l H-NMR spectral values for sterols which bear a cyclopropyl ring in the side chain (Kerr and Baker, 1991). In addition to these signals the 1 H-NMR spectra of the three gums also revealed absorptions at δ 3.53 (m) and 5.35 (m) with highest intensities, these being due to the 3α-hydroxymethine and H-6 of the sterols in the mixtures (Zurcher, 1963).…”

“…The 1 H-NMR spectrum exhibited peaks at δ 0.678 (s, 3H) and 1.18 (s, 3H) which are characteristic of C-19 and C-18 quaternary methyl groups in sterols (Zurcher, 1963). Two doublets at δ 0.876 and 0.917 (both J = 6.47 Hz, each 3H) and one singlet at δ 1.39 (3H) indicated that the sterol side chain is trimethylated, and hence the compound consists of a 24-norcholestane skeleton (Kerr and Baker, 1991;Sarma et al, 2005). Apart from a signal at δ 170.49, the l3 C-NMR spectrum exhibited peaks due to a quaternary C-O carbon at δ 85.95 and two secondary C-O carbons at δ 76.06 and 67.63.…”

“…Therefore in accordance with the 1 H-and l3 C-NMR and mass spectral data discussed above, the gums from the three soft corals consist of sterols which have various modifications on the side chain. GC-MS analysis indicated that each of the substances was a mixture of at least six sterols (Table 1) (Kerr and Baker, 1991;Sarma et al, 2005). Compound 4 was obtained as white powder.…”

Bioactivities of six sterols isolated from marine invertebrates

“…Numerous new sterols have been identified in marine organisms, especially in marine sponges and corals (Blunt et al, 2012;Sarma et al, 2005). Some of these sterols possessing unique side chains and polyoxygenated core structures have been well characterized with their unusual functional groups (D'Auri et al, 1993;Feng et al, 2005).…”

Marine Sponge/H3PO4: As a Naturally Occurring Chiral Catalyst for Solvent-free Fischer-Indole Synthesis

“…Marine sponges are known as a prolific source of biologically active and structurally unique metabolites (21, 22). We described the catalytic, chirality and absorbent abilities of marine sponge powder of Iranian coast of Persian Gulf in organic reaction such as sulfonamides synthesis (23), and researches about its application in organic reactions such as various oxidation, and reduction reactions (24); therefore we decided to study shallow sponges ( Desmospongea sp.) of Qeshm and Bushehr Islands in offshore zone as an efficient chiral catalyst.…”