Biotransformations, immobilized plant

Biotransformations of morphinan alkaloids have been reported for plant, fungal, and mammalian enzymatic systems with emphasis on rather specific reactions such as the reduction of ketones, N- and O-demethylation, and perox-idative transformations. Furuya et al. used immobilized tissue culture cells of Papaver somniferum to accomplish the selective reduction of codeinone (135) to codeine (136) (207) (Scheme 30). Suspension cultures of a well-established cell line of P. somniferum were grown for one week as a source of cell mass for immobilization in calcium alginate. The cells continued to live in the alginate matrix for 6 months maintaining their biological activity. The reduction of co-... 

A number of different types of plant tissue cultures (e.g. suspension cultures, differentiated cultures, immobilized cultures, and transformed cultures) have been studied for the production of flavouring substances [14-19]. As de novo biosynthesis has been found unsuccessful in most cases (exceptions are shown in Tab. 3.5.), biotransformation of added precursors has been studied extensively. Fig. 3.4 shows some examples of biotransformation of terpenes by suspension cultures. Tab. 3.6 lists some biotransformations by suspension or immobilized cultures. 

Fixation of plant cells in a matrix of, for example, polyurethane foam or entrapment of the cells in calcium alginate beads provides an artificial surrounding for the cells, which protects them from hydrodynamic stress, high cell densities inside the matrix also allow cell to cell contact and communication. Inside the immobilized matrix nutrient and product gradients may occur. Furthermore, immobilized biomass is easily separated from the medium, which is useful in production and biotransformation systems. Immobilization of plant cells has been reviewed 103,104). 

The first reported biotransformation by means of cell cultures of P. somniferum was the conversion of thebaine to codeine (453). As P. som-nifemm cell cultures only produced alkaloids derived from (5)-reticuline (e.g., sanguinarine. Fig. 9) but none of the alkaloids derived from (/ )-reticuline, Furuya et al. 461) administered (R,S)-reticuline to the cell suspension cultures. After 3 days the alkaloids were isolated. Two alkaloids derived from (5)-reticuline were identified cheilathifoline and scoulerine. A third alkaloid isolated was identified as pure (/ )-reticuline. Thebaine, morphine, and codeine were not metabolized by these cell cultures. However, the cells were capable of stereospecifically reducing codeinone to codeine. Tam et al. 462) also found the same bioconversion. Furthermore, the conversion of thebaine to neopine was reported. Codeine, neopine, papaverine, and D,L-laudanosoline were not metabolized. Enzymatic reduction of codeinone to codeine was also achieved with cell-free preparations of whole plants of both P. somniferum and P. bracteatum 464). Yeoman and co-workers 108,465) reported the use of in reticulate polyurethane immobilized P. somniferum cells for this bioconversion. 

Johnson, T.S., Ravishankar, G.A., and Venkataraman, L.V. (1996) Biotransformation of ferulic acid and vanyllylamine to capsicin and vanillin in immobilized cell culters of Capsicum frutescens. Plant Cell Tissue Organ, Cult, 44, 117-121. 

New methods in biotechnology such as plant tissue culture, the application of recombinant DNA-techniques to plants and the biotransformation of oleo-chemlcals by immobilized enzymes and microorganisms hold promise to a)... 

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