Marine sterols. V. sterols of some tunicata. The occurrence of saturated ring sterols in these filter-feeding organisms

The sterols present in one oceanic and two coastal tunicates have been determined by combined gas chromatography-mass spectrometry techniques.Very complex sterol profiles were found in a Pyrosoma sp. and Ascidia mentula O. F. Müller, with 25 and 27 sterols, respectively, in which a high proportion of the sterols were identified as saturated ring compounds. The analyses established the presence of related pairs of 5α-stanols and Δ5-sterols with identical sidechains, whereas Δ7-sterols were almost absent in these extracts. A number of the 5α-stanols found are very uncommon in the marine environment and the presence of new C31 and C32 sterols with long sidechains indicated in the Ascidia mentula extracts is notable.Extracts of the coastal species, Ciona intestinalis L., were much simpler and contained only 13 sterols, some of which were saturated ring compounds.     

Marine sterols X. Minor constituents of the sterols of the soft coral Sarcophyton glaucum

The sterol mixture of the southern Japan soft coral $\text{Sarcophyton glaucum}$ was found to contain a variety of minor components overlooked in a previous study. Five 4α-methylsterols ($\text{1}$ to $\text{5}$) and three 4-demethyl-sterols ($\text{6}$ to $\text{8}$) were isolated and their structures were confirmed.     

On the sterols of some ascidians.

The lipid content of sea squirts is low, namely less than a half percent of the fresh weight. Lipids consist of about seventy percent of saponifiable lipids and of about twenty percent of non-saponifiable lipids. Both types of these lipids, including sterols, can be synthesized from acetate by these animals. Small amounts of C30 sterols were observed only in Microcosmus sulcatus and Halocynthia papillosa, the species with a low content of C27 sterols and a high content of C28 sterols. In addition these species contained considerable higher amounts of sterols with a double bond at the C22 position than Ciona intestinalis and Styela plicata did.     

Interaction of steptolysin O with sterols.

A quantitative study of the specific inhibitory power of cholesterol and other sterols on the hemolytic properties of streptolysin O is reported. This streptococcal exocellular protein is a cytolytic toxin which disrupts cytoplasmic membranes of eukaryote cells. The structural characteristics, particularly the stereochemical ones required for a steroid molecule to inhibit the cytolytic activity of streptolysin O, have been investigated in detail. By immunodiffusion techniques, in agar gel plates or tubes containing sterols, the formation of hydrophobic complexes between streptolysin O and inhibitory steroids, but not non-inhibitory steroids except lanosterol, is shown. Upon interaction with inhibitory steroids streptolysin O loses its immunoreactive properties towards neutralizing and precipitating homologous antibodies. An interpretation of the mechanism of biomembrane disorganization by streptolysin O is discussed in the light of its steroid binding properties.     

Synthesis of sterols with modified side chains.

Synthesis of sterols with side chain containing from four to nine carbons are described.     

Acid-labilization of sterols for extraction from yeast.

A wild type strain of yeast, Saccharomyces cerevisiae, pretreated with a mild acid hydrolysis, exhibited a 4-fold increase in sterol yield upon saponification and extraction. This increased yield is reflected in both major and minor sterols (ergosterol; zymosterol) and sterol esters.     

Marine sterols. XV. Sterols of some oceanic holothurians

Mature and immature individuals of the deep-water detritus-feeder Benthodytes lingua Perrier and mature specimens of the mid-water detritus-feeders Stichopus tremulus (Gunnerus) and Mesothuria verrilli (Theel) have been analysed by gas chromatographic-mass spectrometric techniques for their component sterols. The results indicate a highly variable sterol and stanol composition amongst holothurians irrespective of water depth, probable diet or even life stage. It is suggested that the complex sterol mixtures found reflect specific structural requirements of holothurians for both component sterols and stanols.