Quinolone degradation

Transformation of quinolones has been reported especially with fungal cells of diverse species, even obtaining partial mineralization, though LAC also proved relative efficiency in the removal of some of them. The abundance of metabolites described, many times analogous from one compound to another, has led to the proposal of several degradation pathways, which usually involve breakdown of the parental molecules and reactions of hydroxylation, acetylation, or formylation, among others. 

Further investigation showed that some amounts of both the quinolones investigated could also leak out into the boiling water or the juice exuded from the baked fish. Therefore, cooking may reveal residues of quinolones that could not be detected in the raw fish muscle before preparation. It is of value to note that none of the quinolones used in this study showed any degradation at the temperatures reached when the fish were cooked. 

Perhaps the only contribution of much chemical interest in the Cinchona group during the year concerns the biotransformation of quinidine (234) in man, and the partial synthesis of one of the metabolites. The two metabolites identified were 3-hydroxyquinidine (235) and 2 -quinidinone, the 2-quinolone analogue of quinidine the former of these was prepared from quinidine by degradation to the ketone (236) (not previously prepared), and re-introduction of the vinyl group by a Grignard synthesis (Scheme 32). 

Methoxy-l-methyl-2-quinolone (1) was isolated from Hesperethusa crenulata M. Roem. (12) and from the wood of Fagara boninensis (13). The alkaloid folimine from Haplophyllum foliosum Vved. (14) was identified as 4,8-dimethoxy-l-methyl-2-quinolone (2), which had been obtained earlier during the degradation of foliosine (Volume IX, p. 225). Folifidine from H. dubium Eug. Kor (15) and from H. foliosum (16) is the 8-hydroxy-2-quinolone 3. 

Yunusov and his collaborators (87) obtained the alkaloid haplamine from Haplophyllum perforatum. Spectroscopic data indicated that haplamine was a methoxyflindersine, and it was assigned structure 143 on the basis of its reaction with base, followed by methylation, to give 4,6-dimethoxy-l-methyI-2-quinolone, although evidence for the structure of this degradation product was not recorded. The constitution of the alkaloid has since been confirmed by synthesis (see Section III,G,2). 

Confirmation of the isoprenoid nature of the furan rings of dictamnine (328) and of N-methylplatydesminium salt (326) in S. japonica was provided indirectly by Grundon and his co-workers (224), who showed that the 3-prenylquinolones 321 and 322 labeled at - with 14C were good precursors of both alkaloids (3.6-4.8% incorporation). Specific incorporation of the precursors into dictamnine was indicated by oxidative degradation by a method similar to that used previously. N-Methylplatydesminium salt was counted as its base-cleavage product edulinine (256), which was converted into isodictamnine (Section IV,B,3) oxidation via 3-carboxy-4-hydroxy-l-methyl-2-quinolone gave 14C-labeIed carbon dioxide. 

Dechlorination followed hy further reactions on the quinolone ring, degradation of the pyrrolidine side-chain (Deionized water pH 4)... 

Photosensitized degradation of histidine was measured in the presence of 0.25, 0.50,1.0, and 1.5 10 M solution of compounds 1 to 10 (in etanol/ H O 1 10). These solutions were mixed with an equal quantity of L-histidine solution at 0.60 to 0.74 mM in phosphate buffer 0.01 M, pH 7.4. Samples of these mixtures were irradiated with an illuminator Cole Palmer 41720-series keeping a distance of 10 cm between the lamp surface and the solution at 25 °C, with a emission maximum in UV-A-Vis 320—400 nm (3-3 mW/cm2,45-575 Lux/seg) at time intervals from 45 to 60 min, with the respective controls being protected from l ht. The concentration of histidine was determined by a colorimetric reaction. The optic density was read on a spectrophotometer at 440 nm t ainst a blank reagent (L-histidine/p-nitrosodimethylaniline/ quinolone derivatives without irradiation) by... 

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