Microbial models of mammalian metabolism: biotransformations of phenacetin and its O-alkyl homologues with Cunninghamella species

Ethenesulfonamide derivatives, a novel class of orally active endothelin-A receptor antagonists

In the present article we wish to report the discovery of a novel class of ET(A)-selective endothelin (ET) receptor antagonists through the modification of the ET(A)/ET(B) non-selective antagonist, Ro47-0203 (Bosentan, 1). Replacement of the benzenesulfonamide group of 1 with a 2-phenylethenesulfonamide group gave compound 5a and resulted in improvement in ET(A)-selectivity. Optimization of the alkoxy side chain attached to the core pyrimidine ring yielded the 2-fluoroethoxy derivative (5n) with further improvement of ET(A)-selectivity. [IC50=2.1 nM for ET(A) receptor, ET(B)/ET(A) ratio=1200]. After oral administration, compound 5n inhibited the big ET-1 induced pressor response in pithed rats with a DR2 value of 2.6 mg/kg and also exhibited a potent antagonistic activity in conscious rats.

Microbial models for drug metabolism

This review describes microbial transformation studies of drugs, comparing them with the corresponding metabolism in animal systems, and providing technical methods for developing microbial models. Emphasis is laid on the potential for selected microorganisms to mimic all patterns of mammalian biotransformations and to provide preparative methods for structural identification and toxicological and pharmacological studies of drug metabolites.

Biotransformation of tri-substituted methoxyamphetamines by Cunninghamella echinulata

1. Four trimethoxyamphetamine analogues were incubated with the filamentous fungus Cunninghamella echinulata. 2. 2,4,5-Trimethoxyamphetamine and 2,5-dimethoxy-4-ethoxyamphetamine were poorly metabolized by C. echinulata ATCC 9244 and C. echinulata var. elegans ATCC 9245. 2,5-Dimethoxy-4-(n)-propoxyamphetamine was mainly metabolized through N-acetylation and O-dealkylation with minor amounts of several aliphatic hydroxylation metabolites formed. 2,5-Dimethoxy-4-methylthioamphetamine was extensively metabolized to the corresponding sulphoxide. 3. 2,5-Dimethoxy-4-methylthioamphetamine metabolism was inhibited by ethanol and quinidine. Sparteine did not inhibit the formation of the sulphoxide and may have shunted the substrate through alternate metabolic pathways. 4. Incubation conditions can affect the rate and extent of fungal biotransformation of 2,5-dimethoxy-4-methylthioamphetamine, and influence dextrose utilization, ammonia formation and pH.