Abstract

In order to study the chemical constituents in the pigmented culture produced fromAspergillus ochraceus, solid phase extraction method was employed to isolate the pigment molecules from the primary culture, followed by fractionation on preparative liquid chromatography. Structural characterization confirmed that one of the two major pigment components in the culture was emodin (1,3,8 -trihydroxy-6-methyl-anthraquinone). It was observed that production of emodin started 2 days after the culture had reached the stationary phase. The culture conditions were subsequently optimized to improve the yield of the emodin production. It was found that optimal production of emodin was achieved when fermentation was carried out at 32°C with the pH value of the culture medium at 7.0. Other conditions were also optimized, leading to the yield reaching as high as 0.8% of dry mass of A. ochraceus. The method described here offers an efficient approach for large scale production of emodin.

Key words: Preparative liquid chromatography, solid phase extraction, emodin,Aspergillus ochraceus.

Abbreviation

Abbreviations: SPE, Solid phase extraction; HPLC, high performance liquid chromatography; PrepHPLC, preparative high liquid chromatography; DEPT,distortionless enhancement by polarization transfer; TMS, tetramethylsilane; ESI,electrosprayionization.