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At least 1,783 records · Page 99Linked to original sources
PubMed1985

Bryostatin, a non-phorbol macrocyclic lactone, activates intact human polymorphonuclear leukocytes and binds to the phorbol ester receptor.

Bryostatin, is an antineoplastic agent with activity in both solid and liquid tumors. When added to tissue culture cells this agent shares a number of similarities with phorbol esters. In this report, we evaluate Bryostatin's effect on human polymorphonuclear leukocytes. Bryostatin stimulates the release of specific granules with a parallel dose response curve to phorbol 12-myristate 13-acetate (PMA), but induces release of superoxide at a significantly slower rate than PMA. Competition experiments demonstrate that Bryostatin, although sharing little structural similarity with PMA, can bind to the PMA receptor. In addition, both Bryostatin and PMA stimulate the phosphorylation of almost identical proteins in intact PMNs. These experiments suggest that Bryostatin may activate PMNs by binding to the PMA receptor, which is currently felt to be the calcium, phospholipid-dependent protein kinase.

Binding, Competitive↗
PubMed1993

Synthesis of 3-deoxyaldulosonic acid esters by one-carbon chain extension of glycal-derived lactone precursors.

A convenient preparative route is described for 3-deoxyaldulosonic acids. Glycal precursors are oxidatively converted into 2-deoxyaldonolactones, which react with 1,3-dithian-2-yl anion to afford 1,3-propanediyl dithioacetals of higher 3-deoxyaldosuloses. Deprotection with mercuric salts in wet or dry alcohols gave high yields of the corresponding alkyl aldulosonates. Preparative reaction conditions were optimized and the anomeric configurations of the ketopyranose products were established by 13C NMR.

Deoxy Sugars↗
PubMed1995

Antifungal steroidal lactones from Withania coagulance.

Two new withanolides, 14,15 beta-epoxywithanolide I [(20S,22R) 17 beta, 20 beta-dihydroxy-14 beta,15 beta-epoxy-1-oxo-witha-3,5,24-trienolide] and 17 beta-hydroxywithanolide K (20S,22R) 14 alpha,17 beta,20 beta-trihydroxy-1-oxo-witha-2,5,24-trienolide] have been isolated from the whole plant of Withania coagulance and their structures were elucidated by spectroscopic techniques. The latter compound was found to be active against a number of potentially pathogenic fungi.

Antifungal Agents↗
PubMed1980

Studies directed toward synthesis of quassinoids VII. Conversion of chenodeoxycholic acid to a delta-lactone quassinoid analog and generation of A-ring diosphenol acetate derivatives of deoxycholic acid.

Chenodeoxycholic acid was converted to a new 5,14-epi-28,30-dinorquassinoid analog. Two isomeric A-ring diosphenol acetate derivatives of deoxycholic acid were synthesized. A 3-oxo-5 beta-steroid was transformed to a 4-acetoxy-3-oxo-delta 4-steroid by treatment with base and oxygen or to a 2-acetoxy-3-oxo-delta 2-steroid by reaction with cupric chloride in refluxing acetic acid followed by acetylation. Ketene extrusion is a characteristic mass spectral fragmentation of these diosphenol acetates.

Chemical Phenomena↗
PubMed1990

Metabolism of antimalarial sesquiterpene lactones.

Metabolism of artemisinin derivatives, which are antimalarial sesquiterpenes, appeared to lead to the production of the more polar metabolites in general. Presence of the endoperoxide moiety in the A/B ring structure seems crucial for the expression of antimalarial activity of these compounds. Microbial models served as effective predictors for the mammalian metabolism of artemisinin derivatives as well as producing quantities of metabolites for reference standards and structure elucidation studies. Combination of 2D-NMR and Thermospray HPLC/MS techniques was very useful for the structure elucidation of metabolites.

Animals↗