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Structure and absolute stereochemistry of two new 3-alkylpyridines, haminol-A ( 3) and haminol-B ( 4), isolated from the cephalaspidean mollusc Haminoea navicula, have been determined by means of spectral and chemical methods. Haminols are secreted by H. navicula when it is molested, and these induce an alarm response in trail-following conspecifics. [ABSTRACT FROM AUTHOR]

Five new polyoxygenated steroids, 24-methylcholesta-1,4,22E-trien-16β, 18,20ξ-triol-3-one (1), cholest-1,4,22E-trien-16β, 18,20ξ-triol-3-one (2), 24-methylcholesta-4,22E-dien-16β, 18, 20ξ-triol-3-one (3), cholesta-4,22E-dien-16β, 18,20ξ-triol-3-one (4) and 27-nor-24-methylcholesta-4,22E-dien-16β,18,20ξ-triol-3-one (5), have been found in a marine organism, the gorgonian Leptogorgia sarmentosa. [ABSTRACT FROM AUTHOR]

Several high molecular weight polyacetylenes have been isolated from the sponge Petrosia ficiformis found in dark caves. These compounds are related to, but different from, the polyacetylenes isolated from the same sponge living in its usual habitat. [ABSTRACT FROM AUTHOR]

Direct incorporation and cold trap experiments suggest that cholest-4-en-3-one is an intermediate in the conversion of cholesterol into 3β-hydroxymethyl-A-nor-cholestane in the marine sponge Axinella verrucosa. Cholest-4-en-3-one is further transformed by the sponge into cholest-4-en-3β-ol, 5α-cholestan-3-one and 5α-cholestan-3β-ol; these compounds arise from side reactions, which are not part of the major metabolic route leading to 3β-hydroxymethyl-A-norsteranes. [ABSTRACT FROM AUTHOR]

The sponge Calyx niceaensis metabolizes administered [7,7-H]-fucosterol to produce labelled calysterol, the principal sterol component of the sponge, possessing the unique feature of a cyclopropene ring bridging C. [ABSTRACT FROM AUTHOR]

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9-[5′-deoxy-5′-(methylthio)-β- d-xylofuranosyl]-adenine, the first naturally occurring analog of methylthioadenosine (MTA), was isolated from the marine nudibranch mollusc Doris verrucosa. This finding provides indirect evidence for the existence in nature of analogs of S-adenosyl- l-methionine (AdoMet), the ubiquitous naturally-occurring biological methyl donor. [ABSTRACT FROM AUTHOR]

Polygodial ( 1), the defense metabolite stored in the skin of the nudibranch Dendrodoris limbata, is toxic for the mollusc itself when injected into the hepatopancreas. Biosynthetic experiments using labeled mevalonic acid were devised to investigate a possible metabolic relationship between 1 and the mixture of sesquiterpenoidic esters 2, stored in the hepatopancreas. The results suggest that 1 and 2 are biosynthesized by independent pathways. [ABSTRACT FROM AUTHOR]

Twelve steroidal ketones have been subjected to reduction with C. acidophila resting cells, regio- and stereospecific reduction of the 3-keto groups being observed, as well as reduction of the Δ-double bond. The presence of oxo groups at C-11 or C-12 and the presence of hydrophobic side chains on the steroidal molecules inhibit the reduction. [ABSTRACT FROM AUTHOR]

Caldariella Acidophila, a thermophilic bacterium, converts porgesterone ( 1) to pregn-4-en-3,6,20-trione ( 2), 5 a-pregnan-3, 6, 20-trione ( 3), pregn-4-en-20 a-ol-3-one ( 4), pregn-4-6β-ol-3, 20-dione ( 5) and pregn-4-en-6 a-ol-3, 20-dione ( 6). Different patterns of these metabolites were obtained by modifying the incubation conditions and using differently treated biocatalysis. [ABSTRACT FROM AUTHOR]

The conversion of cholesterol into 19-nor-5α-cholestan-3β-ol by the sponge Axinella polypoides involves a partial loss (40%) of the 3α-hydrogen atom; moreover administration to the sponge of [4-C]cholesterol tritiated at C-4β and C-7 showed that the 4β- and 7-hydrogen atoms are retained in this conversion. A competitive uptake experiment, [4-C]cholesterol vs. [7-H]5α-cholestanol, showed that the sponge utilized exclusively cholesterol for the production of 19-nor-5α-cholestan-3β-ol. [ABSTRACT FROM AUTHOR]

The compound titled 1 has been isolated from the gorgonian E. cavolini and synthesized from 11α-acetoxy-progesterone ( 3). [ABSTRACT FROM AUTHOR]

During the conversion of cholesterol into 3 β-hydroxymethyl-A-nor-5 α-cholestane by the sponge Axinella verrucosa, the carbon-3 of this latter originate from carbon-4 of cholesterol. Cholestanol moreover does not seem an intermediate in this conversion. [ABSTRACT FROM AUTHOR]

Copyright of Experientia is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)