The irradiation of cholesterol ( 1 ) and the allylic alcohol ( 7 ) under various conditions gives rise to a carbonium ion [A] considered to be the primary photochemical product. This cation may: (1) add the nucleophile RO − to give 5, 6, 6′ ; (2) eliminate a proton from carbon atom 4 and induce the isomer 7; (3) undergo fragmentation to give the olefinic aldehyde ( 2 ), which, by irradiation gives rise to the oxetane ( 4 ) plus trace amounts of a radical type addition product ( 3 ). The stereochemistry of the protonation process of ( 7 ) and ( 1 ) was studied using MeOD (experiments b carried out with 1 and 7 ) and deuterium labelled cholesterol molecules 23 (4βd 1 ) and 23 (4,4′ d 2 ). It appears that the protonation of the double bond Δ-4 is stereoselective (4α), and that the deprotonation process observed during the isomerisation 1 → [A] → 7 is not stereospecific with regard to carbon atom C4.

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTFluorescent derivatives of strophanthidin. Interaction with sodium- and potassium-activated adenosine triphosphataseFranz Oesch, James A. Waters, John W. Daly, and Bernhard WitkopCite this: J. Med. Chem. 1972, 15, 7, 757–759Publication Date (Print):July 1, 1972Publication History Published online1 May 2002Published inissue 1 July 1972https://pubs.acs.org/doi/10.1021/jm00277a015https://doi.org/10.1021/jm00277a015research-articleACS PublicationsRequest reuse permissionsArticle Views52Altmetric-Citations3LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access optionsGet e-Alertsclose Get e-Alerts

The structures and absolute configuration of two unique alkaloids isolated from the Colombian frog, Dendrobates histrionicus, have been elucidated by Roentgen-ray (x-ray) crystallography. Histrionicotoxin is (2pR, 6S, 7pS, 8aS)-7-(cis-1-buten-3-ynyl)-8-hydroxy-2-(cis-2-penten-4- ynyl)-1-azaspiro[5.5] undecane, while in dihydro-isohistrionicotoxin the acetylenic 2-pentenynyl side chain is replaced by an allenic 2-(3,4 pentadienyl) substituent. Dendrobates histrionicus exhibits remarkable interpopulational variations in amounts and composition of skin toxins, in behavior, and in phenotypic characters, aspects of which are illustrated in a color plate. The histrionico-toxins are the third class of alkaloids isolated from the defensive skin secretions of Neotropical (Dendrobatidae) frogs.

Radiochemically pure stigmasterol and β-sitosterol were isolated as major products of mevalonic acid-2-C14 incubation with excised leaves of the soybean plant. Two minor biosynthetic products of this radioactive sterol precursor were partially characterized. Incubation experiments with radioactive stigmasterol and β-sitosterol indicate that the two are not directly related biosynthetically via hydrogenase-dehydrogenase enzyme systems.

Cholesterol-4-C14 and Δ4-cholesten-3-one-4-C14 were incubated with leaves from Solanum tuberosum in an aqueous medium. Radioactive transformation products were studied by thin-layer chromatography and microchemical reactions. One of the major transformation products of cholesterol was shown to be Δ4-cholesten-3-one. One product of radioactive Δ4-cholesten-3-one incubation has been identified as cholestan-3β-ol, and on the basis of Chromatographic and microchemical evidence, a second product appears to be cholestan-3α-ol.

The sterol of houseflies (Musca domestica L.) reared by the CSMA procedure, and previously designated as ‘Muscasterol’ in the literature, is a mixture of at least two sterols. The major sterol (74 per cent) was shown to be campesterol. The other component (21 per cent) was identified as β-sitosterol. Experimental results show that the housefly sterols originate from the CSMA medium and that there is a selective uptake and/or retention of campesterol by the housefly. When the housefly is reared on a diet containing more than one Δ5-3β-hydroxy sterol, there is a selective absorption or retention of that sterol in which the side-chain more nearly approximates that of cholesterol.

Quantitative analyses have been made of the dietary cholesterol requirement for the growth of the larvae of Musca domestica. The larvae will not grow on diets to which no cholesterol is added, a few pupae and adults are obtained when the concentration of cholesterol is 0·05 μmol/g of diet, but the concentration has to be raised to 0·36 μmol/g of diet before the maximum numbers of pupae and adults are obtained. Further addition of cholesterol above 0·36 μmol/g diet did not have any significant effect on the weight and growth of the larvae. However, the ratios of the cholesterol to phospholipid fractions recovered from the larvae increased rapidly when the concentration of cholesterol in the diet was raised from 0·05 to 0·56 μmol/g of diet. Above this concentration only a slight increase in the ratios was observed. Larvae reared on diets containing 0·05 μmol cholesterol/g of diet contain only 25 per cent of the cholesterol content of the larvae reared on the diets containing more than 0·28 μmol of cholesterol/g of diet, the cholesterol content being expressed relative to the weight of the larvae,The absence of cholesterol synthesis has been demonstrated in the larvae by feeding [4-14C] cholesterol. The specific activity of the cholesterol recovered from the larvae is the same as that of cholesterol added to the diet. Irrespective of the cholesterol concentration of the larval diet, approximately 97 per cent of the radioactivity recovered from the larvae behaved as free cholesterol, less than 1 per cent as cholesterol esters and the rest as unidentified ‘polar sterols’. The results are compared with those from similar studies on other insects.

A number of 4-diethylamino-2-butynyl esters and 1,4-bis-N-substituted amino-2-butynes were prepared. The compounds, in the form of their hydrochloride and/or methiodide salts, were tested in vitro against three fungi causing dermatomycoses. Several compounds exhibited good activity in comparison to the control compound, sodium undecylenate. The most effective compound in this investigation was 4- diethylamino-2-butynyl o-toluate hydrochloride.