Impact of ethylene glycol on DHEA dihydroxylation in Colletotrichum lini: increasing the expression of cytochrome P450 and 6-phosphogluconate dehydrogenase and enhancing the generation of NADPH

Abstract 3β,7α,15α-trihydroxy-5-androsten-17-one (7α,15α-diOH-DHEA), a key precursor of the novel oral contraceptive “Yasmin”, can be obtained by dihydroxylation in the 7α and 15α positions of dehydroepiandrosterone (DHEA) by Colletotrichum lini CGMCC 6051. However, the commercial-scale application of 7α,15α-diOH-DHEA is limited by the poor dihydroxylation efficiency and its low yield. This research investigated different organic solvents to improve the dihydroxylation efficiency of DHEA by C. lini CGMCC 6051. Results showed that ethylene glycol was the optimum organic solvent. With the addition of 0.5% (v/v) ethylene glycol, the molar yield of 7α,15α-diOH-DHEA increased from 26.0% to 79.4% at 12 g/L DHEA, and that of the intermediate product 7α-OH-DHEA decreased to 10.5%. We then investigated the related functional mechanism of ethylene glycol on DHEA bioconversion. Results of two-dimensional electrophoresis proteomics analysis demonstrated that the expression levels of cytochrome P450 and 6-phosphogluconate dehydrogenase were increased upon the addition of ethylene glycol. Further studies suggested that ethylene glycol played critical roles in stabilizing the pH of the transformation system and generating co-enzyme NADPH during DHEA bioconversion. Hence, the addition of ethylene glycol induced the expression level of the key hydroxylase cytochrome P450 and increased the concentration of NADPH, which aided the dihydroxylation of DHEA in C. lini CGMCC6051.