Oh

hydrolysis

125b'

125b

130b' 125b'

FIGURE 14.140 Formation of 2a-hydroxy-1,8-cineoles (125b and b') from 1,8-cineole (122) and optical resolution by Glomerella cingulata and Aspergillus niger TBUYN-2 and 125b' from (+)-limonene (68) by Pencillium digitatum. (Modified from Nishimura, H. et al., 1982. Agric. Biol. Chem., 46: 2601-2604; Abraham, W.-R. et al., 1986. Appl. Microbiol. Biotechnol., 24: 24-30; Miyazawa, M. et al., 1995b. Proc. 39th TEAC, pp. 352-353; Noma, Y. et al., 1986. Proc. 30th TEAC, pp. 204-206; Noma, Y. and Y. Asakawa, 2007a. Book of Abstracts of the 38th ISEO, p. 7.)

pregnenolone-16a-carbonitrile (PCN), recombinant CYP3A4 were determined to be 50 |mM and 90.9 nmol/min/nmol P450, 20 |M and 11.5 nmol/min/nmol P450, and 90 |M and 47.6 nmol/min/ nmol P450, respectively (Shindo et al., 2000).

Microbial resolution of racemic 2a-hydroxy-1,8-cineoles (125b and b') was carried out by using Glomerella cingulata. The mixture of 125b and b' was added to a culture of Glomerella cingulata and esterified to give after 24 h (1R,2R,4S)-2a-hydroxy-1,8-cineole-2-yl-malonate (130b') in 45% yield (ee 100%). The recovered alcohol showed 100% ee of the (1S,2S,4R)-enantiomer (125b) (Miyazawa et al., 1995b). On the other hand, optically active (+)-2a-hydroxy-1,8-cineole (125b) was also formed from (+)-limonene (68) by a strain of Citrus pathogenic fungus Penicillium digitatum (Saito and Miyazawa 2006, Noma and Asakawa 2007a) (Figure 14.140).

Esters of racemic 2a-hydroxy-1,8-cineole (125b and b') were prepared by a convenient method (Figure 14.141). Their odours were characteristic. Then products were tested against antimicrobial activity and their microbial resolution was studied (Hashimoto and Miyazawa, 2001) (Table 14.15).

1,8-Cineole (122) was glucosylated by Eucalyptus perriniana suspension cells to 2a-hydroxy-1,8-cineole monoglucoside (404, 16.0% and 404', 16.0%) and diglucosides (405, 1.4%) (Hamada et al., 2002) (Figure 14.142).

Regarding the biotransformation of 1,4-cineole (131), Streptomyces griseus transformed it to 8-hydroxy-1,4-cineole (134), whereas Bacillus cereus transformed 1,4-cineole (131) to 2a-hydroxy-1,4-cineole (132b, 3.8%) and 2ß-hydroxy-1,4-cineoles (132a, 21.3%) (Liu et al., 1988) (Figure 14.144). On the other hand, a strain of Aspergillus niger biotransformed 1,4-cineole (131) regiospecifically to 2a-hydroxy-1,4-cineole (132b) (Miyazawa et al., 1991c) and (+)-3a-hydroxy-1,4-cineole (133b) (Miyazawa et al., 1992b) along with the formation of 8-hydroxy-1,4-cineole (134) and 9-hydroxy-1,4-cineole (135) (Miyazawa et al., 1992c) (Figure 14.144).

34a 34a'

MCPBA in dichloromethane

H<Xl IJOH

34a 34a'

MCPBA in dichloromethane

Acid chloride, Pyridine

125b' 125b

Acid chloride, Pyridine

125b' 125b

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