Simultaneous determination of hydroxyanthraquinones in rhubarb and experimental animal bodies by high-performance liquid chromatography.

A simple and reliable high-performance liquid chromatographic (HPLC) method was developed for the simultaneous determination of five hydroxyanthraquinones (aloe-emodin, rhein, emodin, chrysophanol, and physcion) in Rhubarb and experimental animal bodies. A Zorbax SB-C18 column (250 mm x 4.6 mm i.

Isolation and enzyme determination of Candida tropicalis mutants for DCA production.

Techniques, named two-step enrichment and double-time replica-plating method (TEDR), are described that allow a mutated population of Candida tropicalis to be enriched efficiently for mutants deficient in the alkane degradation pathway (Alk(-)) and to be selected easily for mutants increasing in the DCA (dicarboxylic acids) excretion pathway. After C. tropicalis was mutated with ethyl methane sulphonate and ultraviolet, the Alk(-) mutants were enriched (the first step enrichment, up to eightfold in one round of enrichment) by treatment with nystatin in medium SEL1-1.