Alicyclic metabolic pathways

Trudgill PW (1984) Microbial degradation of the alicyclic ring structural relationships and metabolic pathways. In Microbial Degradation of Organic Compounds (Ed DT Gibson), pp. 131-180. Marcel Dekker Inc, New York. 

Several metabolic pathways for the biosynthesis of aromatic compounds are now known, (a) The aromatization of alicyclic and isoprenoid compounds derived from mevalonic acid, as in the formation of estrone (I) from testosterone (II). A very common example of this process, which has not yet been experimentally demonstrated, is probably the aromatization of a O OH... 

The major metabolic pathway of the 5,5-disubsti-tuted barbiturates is hydroxylation, usually of the larger of the two substituents, e.g. the phenyl group in phenobarbitone, the 1-methylbutyl group in pentobarbitone, and the alicyclic group in cyclobar-bitone. Hydroxylation ofaliphatic groups at the position is usually at the W—1 (penultimate)... 

Naphthalene is toxic to the lung and these metabolic pathways are important in this toxicity (see below). There are many types of substrates for glutathione conjugation including aromatic, aliphatic, heterocyclic and alicyclic epoxides, halogenated aliphatic and aromatic... 

Various studies regarding the biotransformation of xenobiotic ketones have established that ketone reduction is an important metabolic pathway in mammalian tissue. Because carbonyl compounds are lipophilic and may be retained in tissues, their reduction to the hydrophilic alcohols and subsequent conjugation are critical to their elimination. Although ketone reductases may be closely related to the alcohol dehydrogenases, they have distinctly different properties and use NADPH as the cofactor. The metabolism of xenobiotic ketones to free alcohols or conjugated alcohols has been demonstrated for aromatic, aliphatic, alicyclic, and unsaturated ketones (e.g., naltrexone, naloxone, hydromorphone, and daunorubicin). The carbonyl reductases are distinguished by the stereospecificity of their alcohol metabolites. 

The ability of the methanotrophs to oxidize methane has been recognized for over 80 years, but the detailed studies of their metabolism started in the 1970s [16]. The oxygenation initiates the metabolic pathway that supplies the total carbons and energy required by the methanotrophs. In the methanotrophs, the enzyme MMO can also oxidize a variety of other alkanes, alkenes, ethers, and alicyclic, aromatic, and heterocyclic compounds as substrates to provide corresponding primary, secondary, or tertiary alcohols, epoxides, cyclic alcohols, and phenols, although these substrates do not participate in the growth of the bacteria [17]. 

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