Biotransformation of 4(20),11-taxadienes by cell suspension cultures of Platycodon grandiflorum

Platycodon grandiflorum cell suspension cultures were employed to biotransform the taxane diterpenoids 2alpha,5alpha, 10beta,14beta-tetraacetoxy-4(20),11-taxadiene ( 1 ) and 9alpha-hydroxy-2alpha, 5alpha,10beta,14beta-tetraacetoxy-4(20),11-taxadiene ( 2 ). One product, 10beta-hydroxy-2alpha,5alpha,14beta-triacetoxy-4(20),11-taxadiene ( 3 ) was obtained from 1 and two products, 9alpha,10beta-dihydroxy-2alpha,5alpha,14beta-triacetoxy-4(20),11-taxadiene ( 4 ) and 10beta-hydroxy-2alpha,5alpha,9alpha,14beta-tetraacetoxy-4(20),11-taxadiene ( 5 ) were obtained from 2 incubated with Platycodon cultured cells respectively, among which 5 is characterized as a new taxoid compound. The effects of the addition stage for 1 and 2 on the biotransformation were investigated and the results revealed that: (1) the optimal addition stage for 1 was in the early logarithmic phase (6th day) of the cell growth period, in which 78% of 1 was converted and the yield for 3 reached 75%; (2) the optimal addition stage for 2 was on the mid-logarithmic phase (12th day) of the cell growth period, in which 25.3% of 2 was converted and the yields for 4 and 5 reached 18.9 and 14.5%, respectively.