Microbial conversion of jasmonates-hydroxylations by Aspergillus niger.

Aspergillus niger is able to hydroxylate the pentenyl side chain of (-)-jasmonic acid (JA) leading to (11S)-(-)-hydroxy-JA/(11R)- (-)-hydroxy-JA (2:1) and (-)-11,12-didehydro-JA. Methyl (-)-jasmonate (JA-Me) is converted upon hydrolysis. During prolonged cultivation or at non-optimized isolation procedures, the 11-hydroxy-(9Z)-pentenyl side chain may isomerize to (10E)-9-hydroxy- and (9E)-11-hydroxy-compounds by allylic rearrangement. The fungus hydroxylates (+/-)-9,10-dihydro-JA at position C-11 into 11 xi-hydroxy-9,10- dihydro-JA. As JA-ME, the methyl dihydro-JA is hydroxylated only upon hydrolysis into the free acid.