Biotransformation of 2α,5α,10β,14β-Tetraacetoxy-4(20),11-taxadiene by Cell Suspension Cultures of Catharanthus roseus

Catharanthus roseus cell suspension cultures were employed for the biotransformation of 2α,5α,10β,14β-tetraacetoxy-4(20),11-taxadiene (1), and four metabolites were obtained. Based on their physical and chemical data, the structures of the four metabolites were respectively elucidated as 10β-hydroxy-2α,5α,14β-triacetoxy-4(20),11-taxadiene (2), 5α-hydroxy-2α,10β, 14β-triacetoxy-4(20),11-taxadiene (3), 6α,10β-dihydroxy-2α,5α,14β-triacetoxy-4(20),11-taxadiene (4), and 6α,9α,10β-trihydroxy-2α,5α,14β-triacetoxy-4(20),11-taxadiene (5), among which 3 and 5 were characterized as new taxoids. The effects of the stages of substrate addition on the biotransformation were also investigated. The results revealed that the biotransformation rate for 1 reached 85.3 % and the yield of 2 70 % when 1 was administered during the mid-linear phase (9 - 12th day) of the cell growth cycle. On the other hand, the yield for 4 reached the highest level of 11.8 % when 1 was added in the early linear phase (6th day).