Tropic acid, degradation

Several pathways are used for the aerobic degradation of aromatic compounds with an oxygenated C2 or C3 side chain. These include acetophenones and reduced compounds that may be oxidized to acetophenones, and compounds including tropic acid, styrene, and phenylethylamine that can be metabolized to phenylacetate, which has already been discussed. 

A strain of Pseudomonas sp. ATS degraded tropic acid, which has a -CH-(CH20H)-COjH side chain to phenylacetate (Long et al. 1997). 

The degradation of L-tropic acid will be discussed as an example (Fig. 11). L-Tropic acid originates from L-phenylalanine by an intramolecular shift of the carboxy group (D 22). To determine the isotope content in the individual carbon atoms of the side chain, L-tropic acid is first oxidatively converted to benzoic acid which is then decarboxylated. This separates carbon atom 2 from the other carbon atoms as CO2. Conversion of L-tropic acid to atropic acid which is then decarboxylated releases carbon atom 1 as CO2. The methylene group can, in addition, be cleaved off by a periodate oxidation so that carbon atom 3 is removed as formaldehyde. The isotope content of each degradation product can be determined to give the isotope distribution within the L-tropic acid side chain. 

Fig. 11, Degradation of L-tropic acid to obtain separately the carbon atoms 1-3 of the side chain...

Scheme 13.1. Degradation and partial synthesis determining the structure of tropic acid. After Ladenburg, A. Riigheimer, L. Chem. Ber., 1880,13, 373.

The phannacokinetics of S- and / -enantiomers of hyoscyamine in humans have been examined by LC-ESI-MS/MS [13]. Plasma supplemented with atropine was incubated with human serum (not containing atropinesterase (AtrE)) and with rabbit serum possessing AtrE (EC 3.1.1.10), which stereospecificaUy hydrolyzes 5-hyoscyamine into tropine and tropic acid while leaving / -hyoscyamine unaffected. The estimation of the differences between the total hyoscyamine content in the aliquots incubated with human and rabbit sera allowed the determination of the remaining / -hyoscyamine and hydrolyzed S-hyoscyamine. Both enantiomers were detected in the MRM mode. The method proved to be reproducible, precise (RSD 2-9 %), accurate (93-101 %), and selective. The enantioselective assay was applied to the analysis of atropine degradation in rabbit semm in vitro as well as to human in vivo plasma samples from a pesticide-poisoned patient treated with atropine. The method was also applied for kinetic studies of atropine administered to swine, where no obvious stereoselective elimination was found [82]. 

Phenylacetic acid is another compound which has served as a precursor of tropic acid. Good incorporations (compared with phenylalanine) of [l- C]phenylacetic acid into tropic acid have been reported. Degradations carried out on this tropic acid were consistent with all the activity being located at C-3. In view of the work with the doubly labelled phenylalanine, it is unlikely that phenylacetic acid is an intermediate between phenylalanine and tropic acid. The incorporation of phenylacetic acid can be rationalized if it is assumed that it undergoes a carboxylation leading to phenylpynivic acid and thence to phenylalanine by transamination. This reaction has been observed by Allison in ruminal bacteria and photosynthetic anaerobic bacteria. He showed that phenylalanine derived from [I- C]phenylacetic was labelled solely at C-2. ... 

The example of a total extract composition of a tropical soil from the Amazon, Brazil, shows mycose as the major compound, numerous other monosaccharides, lipid components such as fatty acids and fatty alcohols, and natural product biomarkers (Fig. 9a). The mycose and elevated levels of the other saccharides reflect the efficient fungal/microbial degradation of plant detritus in the tropics. This can be compared to the saccharides in the soil from an almond orchard in California, where glucose and mycose are the main sugars with lipids, sterols and triterpenoids (Fig. 9b, ). 

Table IV. Catalytic Efficiency for Phenol Degradation of Candida tropical is Cells Entrapped in Copoly(styrene-maleic acid)/Al 3+ Networks for Various Particle Radius R, Initial Cell Concentration X. and Reaction Temperature T...

Entrapment of Candida tropical is whole cells in ionic polymeric networks has been achieved using different types of polyelectrolyte polymers (alginates, carbomethylcellulose, synthetic maleic acid copolymers) and multivalent counterions (e.g.. Ar ). Oxidative degradation of phenol served as a model reaction for a multienzyme catalytic process. 

GRIFFITH S.M. and SCHNITZER M. 1975. Oxidative degradation of humic and fulvic acids extracted from tropical volcanic soils. Canadian Journal of Soil Science, 55, 251-267. 

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