K. Okazaki et al., ANTIBACTERIAL CHARACTERISTICS OF N-ALKYL-2-ALKYLTHIOPYRIDINIUM AND N-ALKYL-4-ALKYLTHIOPYRIDINIUM SALTS, Eisei Kagaku, 43(5), 1997, pp. 251-260
N-Alkyl-2-alkylthiopyridinium (2TPX-n:X=I or Br, n=6-18) and N-alkyl-4
-alkylthiopyridinium salts (4TPX-n), which have an electron-releasing
group on the pyridine ring, were synthesized. Both 2TPBr-12 and 4TPBr-
12 showed a wide and potent bactericidal spectrum of activity against
Gram-negative bacteria (9 strains) and Gram-positive bacteria 13 strai
ns), compared with N-dodecylpyridinium iodide (P-12) which has no subs
tituents. The activity of these new compounds was not correlated with
the hydrophobicity of the bacterial cell surface. This suggests that t
he bactericidal mechanism of 2TPBr-12 and 4TPBr-12 is different from t
hat of P-12. The bactericidal and bacteriostatic activity of the new c
ompounds against Escherichia coli K12 W3110 was closely influenced by
their alkyl chain length. Since they have two hydrophobic alkyl chains
in their structure, it seems that hydrophobic association between the
molecule of 2TPX-n or 4TPX-n and medium components in the minimum inh
ibitory concentration measurement system caused the reduction in their
apparent concentration. The bactericidal activity of these compounds
was dependent on their bacterioclastic activity, and less dependent on
their hydrophobicity (R-M).