Synthesis and Pharmacological Activities of 1,8-Naphthyridine Derivatives

In the present study, a series of 2-substituted-4-methyl-7-amino/4,7-dimethyl-1,8-naphthyridines were synthesized and characterized by IR, 1H-NMR and elemental analysis. The compounds were investigated for anticonvulsant (125, 250 mg/kg), cardiac and antimicrobial activities. The compounds were screened for antibacterial activity against gram (+) bacteria (Staphylococcus epidermidis, Bacillus subtilis, Enterococcus faecalis and Micrococcus luteus) and gram (−) bacteria (Proteus vulgaris, Pseudomonas aeruginosa, Escherichia coli and Salmonella typhi). All the compounds except 2-(3′-phenylaminopropyloxy)-4-methyl-7-amino-1,8-naphthyridine exhibited significant anticonvulsant activity. The anticonvulsant activity of 2-(3-morpholino-2′-hydroxypropyloxy)-4-methyl-7-amino-1,8-naphthyridine, 2-(3′-diphenylamino-2′-hydroxypropyloxy)-4-methyl-7-amino-1,8-naphthyridine and 2-(3′-diethanolamino-propyloxy)-4,7-dimethy-1,8-naphthyridine at the dose of 250 mg/kg were found to be equivalent to diazepam (5 mg/kg). Sympathetic blocking activity was observed with 2-(3′-phenylamino-2′-hydroxypropyloxy)-4-methyl-7-amino-1,8-naphthyridine, 2-(3′-diethanolamino-2′-hydroxypropyloxy)-4-methyl-7-amino-1,8-naphthyridine and 2-(3′-diphenylamino-2′-hydroxypropyloxy)-4-methyl-7-amino-1,8-naphthyridine only. All the compounds were devoid of antibacterial activity against the tested bacteria.