Mucuna pruriens: improvement of the biotechnological production of the anti-Parkinson drug L-dopa by plant cell selection.
Routinely grown cell suspension cultures of Mucuna pruriens L. (Fabaceae) were able to endogenously accumulate the anti-Parkinson drug L-dihydroxyphenylalanine (L-dopa) in the range between 0.2 and 2% on a dry weight (DW) basis. The green colour that developed in light-exposed cultures, appeared to be a suitable marker to select cells with an increased L-dopa biosynthesis and/or phenoloxidase activity. For this purpose, saccharose concentrations from 0 to 4% (w/v), and light intensities of 1,000 and 2,000 lux, were involved in the selection procedure. After 6 months, photomixotrophic callus cultures with a rapid growth and a high L-dopa content of 0.9% (DW) were obtained on 2% saccharose and under 1,000 lux. The cell suspensions, derived from these calli, accumulated up to 6% (DW) L-dopa, which was the highest stable content ever measured in cultures of M. pruriens. An L-dopa yield of approximately 1.2 g/l was calculated after 6 days of growth. In contrast, compared wtih the standard-grown parent cell line, the phenoloxidase activity, and consequently the bioconversion capacity as measured after entrapment in calcium alginate, of these high-producing cultures was approximately threefold lower.