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Stratmann K , Moore RE , Bonjouklian R , Deeter JB , Patterson GML , Shaffer S , Smith CD , Smitka TA
Welwitindolinones, Unusual Alkaloids from the Blue-Green-Algae Hapalosiphon-Welwitschii and Westiella-Intricata - Relationship to Fischerindoles and Hapalindoles
Journal of the American Chemical Society. 1994 Nov 2;116(22) :9935-9942
PMID: ISI:A1994PP75400015   
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Abstract
N-Methylwelwitindolinone C isothiocyanate (7), the major indole alkaloid in the blue-green algae (cyanobacteria) Hapalosiphon welwitschii W. & G. S. West UH IC-52-3 and Westiella intricata Borzi UH HT-29-1 (Stigonemataceae), is responsible for some of the multiple-drug-resistance (MDR) reversing activity in H welwitschii and most of the insecticidal activity in W. intricata. The oxindole was isolated from the lipophilic extracts of the two cyanophytes and its structure and absolute stereochemistry determined by X-ray crystallography. Fourteen additional alkaloids were isolated from H. welwitschii as minor constituents, viz. a novel spiro oxindole, welwitindolinone A isonitrile (1), five tetracyclic oxindoles (1-6) related to 7, and eight biogenetically-related fischerindoles (8-11) and hapalindoles (12-15). In addition to 1, five other alkaloids were isonitriles and these six compounds collectively accounted for the fungicidal activity of H. welwitschii. The gross structures and relative stereochemistries of 1-6 and 8-15 were elucidated by spectral analysis. The biogenesis of these alkaloids is discussed.
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English Article PP754 J AMER CHEM SOC