Purpose: To prepare and evaluate some 2-piperidinomethylamino-4-(7-H/substitutedcoumarin-3-yl)-6-
chlorosubstitutedphenyl pyrimidines as antimicrobial agents.
Methods: Some 2-piperidinomethylamino-4-(7-H/substitutedcoumarin-3-yl)-6-chlorosubstitutedphenyl
pyrimidines were prepared by reacting 2-amino-4-(7-H/substitutedcoumarin-3-yl)-6-
(chlorosubstitutedphenyl) pyrimidines with piperidine and formaldehyde. The chemical structures of the
synthesized compounds were elucidated by Fourier transform infrared (FTIR),
1H-nuclear magnetic
resonance (
1H-NMR), mass spectrometry and elemental analysis. These compounds were investigated
for their antimicrobial activity against ten bacteria and five fungi by serial plate dilution method using
standard drugs, namely, ofloxacin and ketoconazole, respectively, and their minimum inhibitory
concentrations (MICs) were also determined.
Results: A total of eighteen new compounds (1a-18a) were synthesized. Compound 6a (MIC = 50
μg/mL; p < 0.05 or less) displayed the highest activity against
S. aureus
,
E. faecalis
, S.
epidermidis
,
B. subtilis
, and
B. cereus
. Compound 6a further showed good activity (MIC = 25 μg/mL; p < 0.05 or less)
against
E. coli
;
P. aeruginosa
K. pneumonia
,
B. bronchiseptica
, and
P. vulgaris
. Compounds 6a (MIC =
25 μg/mL; p < 0.0001) and 17a (MIC = 25 μg/mL; p < 0.0001) displayed very good activity against
C. albicans
,
A. niger
,
A. flavus
,
M. purpureous
, and
P. citrinum
, respectively. Analysis of structure-activity
relationship revealed that the presence of bromo group at 7-postion of the coumarin moiety along with
the 4-chlorophenyl group at position-6 of the pyrimidine ring is critical for antimicrobial activity against
Gram-positive bacteria, Gram negative bacteria and fungi.
Conclusion: The synthesized 2-piperidino derivatives are better antifungal and antibacterial agents
than the earlier reported 2-morpholino derivatives, but require further investigations against other
microbial strains to ascertain their broad spectrum antimicrobial activity.
