Block of human NaV1.5 sodium channels by novel alpha-hydroxyphenylamide analogues of phenytoin.
Voltage-gated sodium (Na) channels are a critical component of electrically excitable cells. Phenytoin (diphenylhydantoin, DPH) is an established sodium channel blocker and is a useful anticonvulsant and class 1b antiarrhythmic, and has been effectively used in the treatment of neuropathic pain. In this study, we have synthesized novel alpha-hydroxyphenylamide analogues of diphenylhydantoin and examined their ability to inhibit human Na(V)1.5 sodium channels expressed in Chinese Hamster Ovary (CHO-K1) cells. Phenyl ring substitutions were examined including para-methyl, para-fluoro, para-chloro, ortho-chloro and meta-chloro. We have found that phenyl ring substitutions with electron withdrawing properties resulted in compounds with greater activity. In comparison to diphenylhydantoin, the novel chloro-substituted alpha-hydroxyphenylamide compounds produced as much as a 20-fold greater tonic and frequency-dependent blockade of Na(V)1.5 channels with an IC(50) value of 14.5 microM. In addition, the chloro-substitutions have position specific state dependent blocking properties. The ortho-, meta- and para-chloro substitutions have an 8-, 13- and 3-fold increased affinity for the inactivated state, respectively. Molecular modeling suggests that these differences in affinity are due to a direct interaction with the receptor. Comparing models of diphenylhydantoin to the novel alpha-hydroxyphenlyamide compound suggests that the increased activity may be due to an optimized phenyl ring position and increased molecular volume. This information may be useful in the development of more potent sodium channel blockers.
T1 T2 T3 T4 T5 T6 T7 T8 T9 T10 T11 T12 T13 T14 T15 T16 T17 T18 T19 T20 T21 T22 T23 T24 T25 T26 T27 T28 T29 T30 T31 T32 T33 T34 T35 T36
CHEMICAL CHEMICAL CHEMICAL CHEMICAL CHEMICAL CHEMICAL CHEMICAL CHEMICAL CHEMICAL CHEMICAL CHEMICAL CHEMICAL CHEMICAL CHEMICAL CHEMICAL CHEMICAL CHEMICAL CHEMICAL CHEMICAL CHEMICAL CHEMICAL CHEMICAL CHEMICAL CHEMICAL CHEMICAL CHEMICAL CHEMICAL CHEMICAL GENE-N GENE-N GENE-N GENE-Y GENE-N GENE-Y GENE-N GENE-Y
chloro diphenylhydantoin ortho-, meta- and para-chloro DPH diphenylhydantoin alpha-hydroxyphenlyamide sodium sodium phenyl sodium Na alpha-hydroxyphenylamide diphenylhydantoin sodium Phenyl para-methyl para-fluoro para-chloro ortho-chloro meta-chloro phenyl diphenylhydantoin chloro alpha-hydroxyphenylamide Phenytoin sodium alpha-hydroxyphenylamide phenytoin Voltage-gated sodium (Na) channels sodium channel sodium channel human Na(V)1.5 sodium channels Na(V)1.5 sodium channels human NaV1.5