Publications (7) View all
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Article: Bioactive metabolites from the South African marine mollusk Trimusculus costatus.
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ABSTRACT: A reinvestigation of extracts of the endemic South African intertidal limpet Trimusculus costatus yielded the known labdane diterpenes 6beta,7alpha-diacetoxylabda-8,13 E-dien-15-ol ( 1) and 2alpha,6beta,7alpha-triacetoxylabda-8,13 E-dien-15-ol ( 2) and three new metabolites, 6beta,7alpha,15-triacetoxylabda-8,13 E-diene ( 3), 3alpha,11-dihydroxy-9,11-seco-cholest-4,7-dien-6,9-dione ( 4), and cholest-7-en-3,5,7-triol ( 5). Chiral derivatization and X-ray analysis were used to confirm the labdane absolute configuration of 2. Compounds 1, 2 and 4 exhibited moderate activity (3-25 microM) against the WHCO1 human esophageal cancer cell line.Journal of Natural Products 04/2008; 71(3):420-5. · 3.13 Impact Factor -
Article: Transformations of manool. tri- and tetracyclic norditerpenoids with in vitro activity against Plasmodium falciparum.
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ABSTRACT: The known 17-norisopimar-15-ene-8beta,13beta-diol (5) and five new semisynthetic norditerpenoids, ethyl 17-norabiet-13(15)-E-en-8beta-ol-16-oate (6), ethyl 17-norabiet-13(15)-Z-en-8beta-ol-16-oate (7), 17-norpimaran-13alpha-ethoxy-8,16-olactone (8), 17-norisopimarane-8beta,15-diol (9), and 17-norarabiet-13(15)-ene-8beta,16-diol (10), were prepared from manool (11). Standard spectroscopic data including X-ray crystal analysis were used to determine the structures of 5-10. All five compounds exhibited in vitro antiplasmodial activity against the malarial parasite Plasmodium falciparum at varying microg mL(-1) concentrations.Journal of Natural Products 09/2007; 70(8):1253-8. · 3.13 Impact Factor -
Article: Transformations of hispanolone. Novel Michael adducts with in planta activity against rice blast
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ABSTRACT: Two novel Michael adducts 9α-cyano-15,16-epoxy-7β-hydroxylabda- 13(16),14-dien-6-one (2) and 9α-cyano-15,16-epoxy-7-hydroxylabda-7,13(16), 14-trien-6-one (3) and the reduction product of 2, 9α-cyano-15,16-epoxy- 6β,7β-dihydroxylabda-13(16),14-diene (4), were synthesized from the naturally occurring labdane diterpene hispanolone (1). Compounds 2-4 exhibited in planta activity against the pathogenic rice blast fungus Magnaporthe grisea. © 2005 Elsevier Ltd. All rights reserved. -
Article: Bioactive metabolites from the South African marine mollusk Trimusculus costatus
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ABSTRACT: A reinvestigation of extracts of the endemic South African intertidal limpet Trimusculus costatus yielded the known labdane diterpenes 6β,7α-diacetoxylabda-8,13E-dien-15-ol (1) and 2α,6β, 7α-triacetoxylabda-8,13E-dien-15-ol (2) and three new metabolites, 6β,7α,15-triacetoxylabda-8,13E-diene (3), 3α,11-dihydroxy-9,11- seco-cholest-4,7-dien-6,9-dione (4), and cholest-7-en-3,5,7-triol (5). Chiral derivatization and X-ray analysis were used to confirm the labdane absolute configuration of 2. Compounds 1, 2 and 4 exhibited moderate activity (3-25 μM) against the WHCO1 human esophageal cancer cell line. © 2008 American Chemical Society and American Society of Pharmacognosy. -
Article: Lithothamnin A, the first bastadin-like metabolite from the red alga Lithothamnion fragilissimum.
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ABSTRACT: Lithothamnin A (1) is a new bastadin-like metabolite and represents the first report of this class of molecules from the red alga Lithothamnion fragilissimum. Lithothamnin A contains several novel structural features that distinguish it from other bastadins. These unique structural features include novel aromatic substitution patterns and the presence of a meta-meta linkage between aromatic rings, in addition to the meta-para linkage seen in the bastadins. Lithothamnin A is modestly cytotoxic in a panel of six human tumor cell lines.Journal of Natural Products 05/2011; 74(5):1275-80. · 3.13 Impact Factor
