Comparative NMR Spectral and Pharmacological Investigation of Some N1-(4-Substituted benzyl/butyl)-2-methyl-4-nitro-1H-imidazoles

One of the key advantages of NMR spectroscopy is its non-destructive nature, allowing researchers to analyze organic compounds without altering or damaging the samples. This characteristic makes NMR spectroscopy particularly well-suited for studying delicate or limited-quantity samples, providing researchers with a non-invasive means of exploring the molecular intricacies of organic compounds. The effect of substituents in benzyl moiety of N1-(4-substituted benzyl)-2-methyl-4-nitro-1H-imidazoles (3a-f: 4-R-C6H4-CH2-N1; 3a: C6H5-CH2; 3b: 4-Br-C6H5-CH2; 3c: 4-Cl-C6H5-CH2; 3d: 4-F-C6H5-CH2; 3e: 4-CH3-C6H5-CH2 and 3f: 4-NO2-C6H5-CH2) and the effect of substituents in N1-butyl-2-methyl-4-nitro-1H-imidazoles (3g-i: 3g: n-C4H9-, 3h: sec-C4H9- and 3i: iso-C4H9-) were investigated based on the comparative study of the effect on their chemical shift values with nine different substituents by using 1H NMR and 13C NMR spectra. This work deals with the changes in the chemical shift values with respect to an active methylene carbon (4-R-C6H4-CH2-N1) and aromatic carbons. The 4-nitrobenzyl moiety of compound 3f shown more effective deviation on its chemical shift values of the N-methylene as well as aromatic protons compared to other substituents in the six imidazoles in 1H and 13C NMR spectra. The effective deviation on its chemical shift values of 3g-i with respect to decreases the carbon chain length of the butyl groups. Compounds 3a-i were also screened for their anti-inflammatory and antidiabetic activity at different concentrations (20, 40, 80, 200 and 400 µg/mL). Diclofenac sodium and acarbose were used as standard drugs for anti-inflammatory and antidiabetic activities, respectively. The 4-nitro-1H-imidazoles (3a-i) showed good to remarkable anti-inflammatory and good to excellent antidiabetic activities compared to their corresponding standard drug.