Varacin [1] and three new antimicrobial marine polysulfides, varacins A-C [3-5], have been isolated from the Far Eastern ascidian Polycitor sp. Their structures have been elucidated by spectroscopic methods and by chemical transformations.
A new fatty acid, (5Z,9Z)-22-methyl-5,9-tetracosadienoic acid (1a), and a rare fatty acid, (5Z,9Z)-23-methyl-5,9-tetracosadienoic acid (2a), the predominant constituents of the free fatty acid fraction from the lipids of the sponge Geodinella robusta, were isolated and partly separated by reversed phase high-performance liquid chromatography, followed by multifold crystallization from MeOH to give 1a and 2a in 70% and 60% purity, respectively. These fatty acids were identified as (5Z,9Z)-22- and (5Z,9Z)-23-methyl-5,9-tetracosadienoic acids by nuclear magnetic resonance techniques, including distortionless enhancement by polarization transfer, heteronuclear multiple quantum connectivity, and correlation spectroscopy experiments, as well as from mass-spectrometric data for their methyl esters, the methyl esters of their perhydro derivatives, and their pyrrolidides. Mixtures of 1a and 2a showed cytotoxic activity against mouse Ehrlich carcinoma cells and a hemolytic effect on mouse erythrocytes. The sterol fraction from the same sponge was analyzed by gas-liquid chromatography-mass spectrometry, and 24-methylenecholesterol was identified as a main constituent of this fraction. The implications of the co-occurrence of membranolytic long-chain fatty acids and 24-methylenecholesterol as a main membrane sterol are discussed in terms of the phenomenon of biochemical coordination.
New Na+,K(+)-ATPase inhibitors, sarcochromenol sulfates A [1], B [2], and C [3] and sarcohydroquinone sulfates A [4], B [5], and C [6], have been isolated from the sponge Sarcotragus spinulosus. Four of them (1, 4-6) and all six corresponding acetates 1a-6a have been isolated, and their structures have been established by spectral methods and chemical transformations.
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