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136'

FIGURE 14.145 Formation of optically active 2a-hydroxycineole from 1,4-cineole (131) and terpinene-4-ol (342) by Aspergillus niger TBUYN-2, Gibberella cyanea, and Glomerella cingulata. (Modified from Abraham, W.-R. et al., 1986. Appl. Microbiol. Biotechnol., 24: 24-30; Miyazawa, M. et al., 1991c. Chem. Express, 6: 771-774; Miyazawa, M. et al., 1995b. Proc. 39th TEAC, pp. 352-353; Noma, Y. and Y. Asakawa, 2007b. Proc. 51st TEAC, pp. 299-301.)

(+)-8-hydroxycarvotanacetone (44) (Bhattacharyya et al., 1960; Prema and Bhattacharyya 1962 (Figure 14.146).

The degradation of (+)-a-pinene (4) by a soil Pseudomonas sp. (PL strain) was investigated by Hungund et al. (1970). A terminal oxidation pattern was proposed, leading to the formation of organic acids through ring cleavage. (+)-a-Pinene (4) was fermented in shake cultures by a soil Pseudomonas sp. (PL strain) that is able to grow on (+)-a-pinene (4) as the sole carbon source, and borneol (36), myrtenol (5), myrtenic acid (84), and a-phellandric acid (65) (Shukla and Bhattacharyya, 1968) (Figure 14.147) were obtained.

The degradation of (+)-a-pinene (4) by Pseudomonas fluorescens NCIMB11671 was studied and a pathway for the microbial breakdown of (+)-a-pinene (4) was proposed as shown in Figure 14.148 (Best et al., 1987; Best and Davis, 1988). The attack of oxygen is initiated by enzymatic oxygenation of the 1,2-double bond to form a-pinene epoxide (38), which then undergoes rapid rearrangement to produce a unsaturated aldehyde, occurring as two isomeric forms. The primary product of the reaction (Z)-2-methyl-5-isopropylhexa-2,5-dien-1-al (39, isonovalal) can undergo chemical isomer-ization to the E-form (novalal, 40). Isonovalal (39), the native form of the aldehyde, possesses citrus, woody, spicy notes, whereas novallal (40) has woody, aldehydic, and cyclone notes. The same biotransformation was also carried out by Nocardia sp. strain P18.3 (Griffiths et al., 1987a, b).

Pseudomonas PL strain and PIN 18 degradated a-pinene (4) by the pathway proposed in Figure 14.149 to give two hydrocarbon, limonene (68) and terpinolene (346), and neutral metabolite,

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FIGURE 14.146 Biotransformation of (+)-a-pinene (4) by Aspergillus niger NCIM 612. (Modified from Bhattacharyya, P.K. et al., 1960. Nature, 187: 689-690; Prema, B.R. and P.K. Bhattachayya, 1962. Appl. Microbiol., 10: 524-528.)

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