Chemistry and Biology of Mycotoxins and Related Fungal Metabolites

Angucycline group antibiotics.

Naphthoquinone metabolites of the fungi

Biaryls in nature: a multi-facetted class of stereochemically, biosynthetically, and pharmacologically intriguing secondary metabolites.

In vitro leishmanicidal activity of monomeric and dimeric naphthoquinones.

Neben Xanthomegnin (16b), 3,4-Dehydroxanthomegnin (29 a), Viomellein (23) und Vioxanthin (3) wurde aus Penicillium citreo-viride unter veranderten Kulturbedingungen semi-Vioxanthin (7) isoliert. Konstitution 7 folgt aus den Spektren und dem Befund, das mit Fremy-Salz 3,4,6,9-Tetrahydro-10-hydroxy-7-methoxy-3-methyl-1,6,9-trioxo-1H-naphtho[2.3-c]pyran (9a = semi-Xanthomegnin) entsteht. – Das durch Entmethylierung von 9a zugangliche 9c lies sich mit Kaliumpersulfat/Natriumhydroxid zu 16a dimerisieren, das zu 16b methyliert wurde. Synthetisches 16b war mit nativem Xanthomegnin identisch, was die von Hofle und Roser9) revidierte Konstitution bestatigt und beweist, das die Farbstoffe der Xanthomegnin-Reihe biogenetisch einheitlich sind. – Die Stoffwechselprodukte des Stammes hemmen das Wachstum von Bakterien, 16b und 23 wirken ferner gegen Insekten.



Metabolic Products of Microorganism, 172. Isolation of the Antibiotic semi-Vioxanthin from Penicillium citreo-viride and Synthesis of Xanthomegnin



Besides xanthomegnin (16 b), 3,4-dehydroxanthomegnin (29a), viomellein (23) and vioxanthin (3) from Penicillium citreo-viride under different culture conditions semi-vioxanthin (7) was isolated. Structure 7 has been established by its spectra and the fact that oxidation with Fremy's salt gives 3,4,6,9-tetrahydro-10-hydroxy-7-methoxy-3-methyl-1,6,9-trioxo-1H-naphtho[2,3-c]pyran (9a = semi-xanthomegnin). −9c, prepared by demethylation of 9a, was dimerized by potassium peroxydisulfate/sodium hydroxide and methylated, giving 16b. Synthetic 16b and authentic xanthomegnin were identical, which verifies the structure revised by Hofle and Roser9) and shows, that the dyes of the xanthomegnin series are biogenetically homogenous. – The metabolic products of the strain inhibit the growth of bacteria. 16b and 26 furthermore have an effect against insects.

Stoffwechselprodukte von Mikroorganismen, 172. Isolierung des Antibioticums semi-Vioxanthin aus Penicillium citreo-viride und Synthese des Xanthomegnins

Tetracenomycins B3 and D3, besides tetracenomycin D (D1), were produced by a blocked mutant of the elloramycin producer Streptomyces olivaceus TU 2353. The compounds were isolated as red powders, and their structures were elucidated by comparing their physicochemical data with those of the known tetracenomycins A2, B1, B2, D and E. Tetracenomycin B3 (2), the main compound, and tetracenomycin D (3) were antibiotically inactive against Gram-positive and Gram-negative bacteria, whereas tetracenomycin D3 (1) showed a moderate activity against Bacillus subtilis and Arthrobacter aurescens. Tetracenomycin B3 (2) is the key intermediate where the biosynthesis of the elloramycins branches off from the line leading to tetracenomycin C (5) as the final product of the tetracenomycin biosynthesis branch.

Metabolic products of microorganisms. 249. Tetracenomycins B3 and D3, key intermediates of the elloramycin and tetracenomycin C biosynthesis.

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Stoffwechselprodukte von Mikroorganismen, 172. Isolierung des Antibioticums semi-Vioxanthin aus Penicillium citreo-viride und Synthese des Xanthomegnins

Metabolic products of microorganisms. 249. Tetracenomycins B3 and D3, key intermediates of the elloramycin and tetracenomycin C biosynthesis.