Reduction of carbonylic and carboxylic groups by plant cell cultures

The transformation of aliphatic and aromatic acids to their corresponding alcohols, involving two reductive steps, is difficult to perform biologically due to its low redox potential. For this reason, the reduction of nonactivated carboxylic acids has been described for only a limited number of substrates and confined to a few microbial groups (fungi, clostridia, and archea). Nine species of cultured plant cells were able to reduce cinnamic, hexanoic, and octanoic acids to the corresponding primary alcohols with yields ranging from 2 to 80% (w/w). Aldehyde was detected only for three species during the reduction of cinnamic acid, confirming that the second reductive step from aldehyde to alcohol is faster than the first, from acid to aldehyde. Lyophilized cells from some of the cultures were used in buffer and solvent-water systems to obtain the reduction of carbonylic (ethyl acetoacetate) and carboxylic (cinnamic and hexanoic acids) groups.