Metabolites of Aspergillus versicolor

Systematic fractionations of crude extracts from various strains of Aspergillus versicolor were carried out by a combination of techniques, including liquid-liquid partition, column chromatography and thin-layer chromatography. As a result of these fractionations a total of eleven metabolites were obtained in pure form. Ten of these were identified as the known compounds, sterigmatocystin, de-0-methylsterigmatocystin, 5-methoxysterigmatocystin, versicolorin A, versicolorin C, aversin, averufin, griseofulvin, dechlorogriseofulvin and 3,8- dihydroxy-6 -methoxy-1-methylxanthone. A new metabolite was isolated and identified as 6,8-di-O-methylnidurufin. Two high-performance liquid chromatography systems were developed for the analysis of these metabolites, using microparticle silica gel and microparticle polar bonded phase columns. Studies were also carried out on the reduction of the hemi-acetal derivatives of sterigmatocystin and versicolorin A. Reduction with a limited amount of sodium borohydride yielded in each case a mixture of two major products. The fully reduced products were identified as diols, while the partially reduced products were found to be new hemiacetals. The structure elucidation of these compounds was carried out with the aid of carbon magnetic resonance spectroscopy and of chemical conversions. A modified pathway for the biosynthesis of versicolorin A from averufin is proposed that incorporates nidurufin as an intermediate.

Name thesis:degree_name

Ph. D.

Level thesis:degree_level

doctoral

Discipline thesis:degree_discipline

Chemistry

Department dc:contributor.department

Chemistry

Grantor dc:publisher

Virginia Polytechnic Institute and State University

Year dc:date.issued

1977

Author dc:creator

• Chen, Paul Ning-Chuan

Statement dc:rights

• In Copyright

Licence dc:rights.uri

• http://rightsstatements.org/vocab/InC/1.0/

Language dc:language.iso

en_US

Handle dc:identifier.uri

http://hdl.handle.net/10919/87334

OAI identifier oai:identifier

oai:vtechworks.lib.vt.edu:10919/87334