Ho

123b Minor

123a

123a

FIGURE 14.135 Biotransformation of 1,8-cineole (122) by Streptomyces bottropensis SY-2-1 and Streptomyces ikutamanensis Ya-2-1. (Modified from Noma, Y. and H. Nishimura, 1980. Annual Meeting of Agricultural and Biological Chemical Society, Book of abstracts, p. 28; Noma, Y. and H. Nishimura, 1981. Annual Meeting of Agricultural and Biological Chemical Society, Book of abstracts, p. 196.)

Streptomyces bottropensis, SY-2-1 biotransformed 1,8-cineole (122) stereochemical^ to (+)-2a-hydroxy-1,8-cineole (125b) as the major product and (+)-3a-hydroxy-1,8-cineole (123b) as the minor product. Recovery ratio of 1,8-cineole metabolites as ether extract was ca. 30% in Streptomyces bottropensis, SY-2-1 (Noma and Nishimura, 1980, 1981) (Figure 14.135).

In case of Streptomyces ikutamanensis, Ya-2-1 1,8-cineole (122) was biotransformed regioselec-tively to give (+)-3a-hydroxy-1,8-cineole (123b, 46%) and (+)-3b-hydroxy-1,8-cineole (123b, 29%) as the major product. Recovery ratio as ether extract was ca. 8.5% in Streptomyces ikutamanensis, Ya-2-1 (Noma and Nishimura, 1980, 1981) (Figure 14.135).

When (+)-3a-hydroxy-1,8-cineole (123b) was used as substrate in the cultured medium of Streptomyces ikutamanensis, Ya-2-1, (+)-3b-hydroxy-1,8-cineole (123a, 32%) was formed as the major product together with a small amount of (+)-3-oxo-1,8-cineole (126a, 1.6%). When (+)-3b-hydroxy-1,8-cineole (123a) was used, (+)-3-oxo-1,8-cineole (126a, 9.6%) and (+)-3a-hydroxy-1,8-cineole (123b, 2%) were formed. When (+)-3-oxo-1,8-cineole (126a) was used, (+)-3 a-hydroxy- (123b, 19%) and (+)-3b-hydroxy-1,8-cineole (123a, 16%) were formed.

Based on the above results, it is obvious that (+)-3b-hydroxy-1,8-cineole (123b) is formed mainly in the biotransformation of 1,8-cineole (122), (+)-3a-hydroxy-1,8-cineole (123b), and (+)-3-oxo-1,8-cineole (126a) by Streptomyces ikutamanensis, Ya-2-1. The production of (+)-3b-hydroxy-1,8-cine-ole (123b) is interesting, because it is a precursor of mosquito repellent, p-menthane-3,8-diol (142aa') (Noma and Nishimura, 1981) (Figure 14.136).

When Aspergillus niger TBUYN-2 was cultured in the presence of 1,8-cineole (122) for 7 days, it was transformed to three alcohols [racemic 2a-hydroxy-1,8-cineoles (125b and b'), racemic 3a-hydroxy- (123b and b'), and racemic 3b -hydroxy-1,8-cineoles (123a and 123a')] and two ketones [racemic 2-oxo- (126 and 126') and racemic 3-oxo-1,8-cineoles (124 and 124')] (Figure 14.135). The formation of 3a-hydroxy- (123b and b') and 3b -hydroxy-1,8-cineoles (123a and 123a') is of great interest not only due to the possibility of the formation of p-menthane-3,8-diol (142 and 142'), the mosquito repellents and plant growth regulators that are synthesized chemically from 3a-hydroxy-(123b and b') and 3b-hydroxy-1,8-cineoles (123a and 123a'), respectively, but also from the viewpoint of the utilization of Eucalyptus adiata var. australiana leaves oil as biomass. An Et2O extract of the culture broth (products and 122 as substrate) was recovered in 57% of substrate (w/w) (Nishimura et al., 1982; Noma et al., 1996) (Figure 14.137).

FIGURE 14.136 Biotransformation of 1,8-cineole (122), (+)-3a-hydroxy-1,8-cineole (123b), (+)-3b-hydroxy-1,8-cineole(123a), and (+)-3-oxo-1,8-cineole (126a) by Streptomyces ikutamanensis, Ya-2-1. (Modified from Noma, Y. and H. Nishimura, 1981. Annual Meeting of Agricultural and Biological Chemical Society, Book of abstracts, p. 196.)

FIGURE 14.136 Biotransformation of 1,8-cineole (122), (+)-3a-hydroxy-1,8-cineole (123b), (+)-3b-hydroxy-1,8-cineole(123a), and (+)-3-oxo-1,8-cineole (126a) by Streptomyces ikutamanensis, Ya-2-1. (Modified from Noma, Y. and H. Nishimura, 1981. Annual Meeting of Agricultural and Biological Chemical Society, Book of abstracts, p. 196.)

FIGURE 14.137 Biotransformation of 1,8-cineole (122) by Aspergillus niger TBUYN-2. (Modified from Nishimura, H. et al., 1982. Agric. Biol. Chem, 46: 2601-2604; Noma, Y. et al., 1996. Proc. 40th TEAC, pp. 89-91.)

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