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Biomedical subjects

G L Kaplan

Publications and source records attributed to G L Kaplan.

3 recordsLinked to original sources

Propenyl carboxamide derivatives as antagonists of platelet activating factor.

A series of N-[4-(3-pyridinyl)butyl] 3-substituted propenyl carboxamide derivatives bearing an unsaturated bicyclic moiety in the 3-position was prepared and evaluated for PAF (platelet activating factor) antagonist activity. These compounds represent conformationally constrained direct analogues of the corresponding potent 5-aryl-pentadienecarboxamides (5). Most of the new compounds were active in a PAF-binding assay employing whole, washed dog platelets as the receptor source and inhibited PAF-induced bronchoconstriction in guinea pigs after intravenous administration. However, oral activity in the PAF-induced bronchoconstriction model was highly sensitive to the nature and substitution of the bicyclic ring system. The most interesting compounds included [R-(E)]-(1-butyl-6-methoxy-2-naphthyl)-N-[1-methyl-4-(3- pyridinyl)butyl]-2-propenamide (4b), [R-(E)]-(3-butyl-6-methoxy-2- benzo[b]thiophene-yl)-N-[1-methyl-4-(3-pyridinyl)butyl]-2-propenamide (4k), and [R-(E)]-(3-butyl-6-methoxy-1-methyl-2-indoly)-N-[1-ethyl-4- (3-pyridinyl)butyl]-2-propenamide (4l) which inhibited PAF-induced broncho-constriction in guinea pigs with IC50s of 3.0-5.4 mg/kg, when the animals were challenged 2 h after drug treatment. They were also highly effective 6 h after a 50 mg/kg oral dose. This study supports the notion that the key remote aromatic ring present in the 5-arylpentadienecarboxamides (5) is preferentially coplanar with the diene system for good PAF antagonist activity.

Administration, Oral↗

Pentadienyl carboxamide derivatives as antagonists of platelet-activating factor.

A series of N-[4-(3-pyridinyl)butyl]-5,5-disubstituted-pentadienamides was prepared and evaluated for PAF-antagonist activity. Compounds were assayed in vitro in a PAF-binding assay employing washed, whole dog platelets as the receptor source and in vivo after intravenous or oral administration for their ability to prevent PAF-induced bronchoconstriction in guinea pigs. Criteria required for good oral activity in the latter model include an (E,-E)-5-phenyl-2,4-pentadienamide, a second phenyl or a four- or five-carbon alkyl moiety in the 5-position of the diene, and an (R)-[1-alkyl-4-(3-pyridinyl)butyl] substituent on the carboxamide nitrogen atom. The alkyl substituent on this side chain can be methyl, ethyl, or cyclopropyl. Two members of this series, [R-(E)]-5,5-bis(4-methoxy-phenyl)-N- [1-methyl-4-(3-pyridinyl)butyl]- 2,4-pentadienamide (31) and [R-(E,E)]-5-(4-methoxyphenyl)-N-[1-methyl-4- (3-pyridinyl)butyl]-2,4-decadienamide (58), were selected for further pharmacological evaluation. Both were found to be substantially longer acting after oral administration than the corresponding S enantiomers in the guinea pig bronchoconstriction assay. A second in vivo model used to evaluate PAF antagonists determines the ability of test compounds to decrease the area of skin wheals induced by an intradermal injection of PAF. In this model, using both rats and guinea pigs, compounds 31 and 58 were found to be as active as the reference PAF antagonist 3-[4-(2-chlorophenyl)-9-methyl-6H- 1-(4-morpholinyl)-1-propanone (45).

Amides↗