Antibacterial and antifungal properties of β-naphthol derivatives VI

Abstract

The bacteriostatic and fungistatic activities of a number of β-naphthol, 2-hydroxy-6-naphthoic acid, and 2-hydroxy-3-naphthoic acid derivatives are reported against Staphylococcus aureus, Salmonella typhosa, and Aspergillus niger. Selected compounds from the initial screening have been further tested for their activity against Staphylococcus albus, Salmonella paratyphi A, S. paratyphi B, Escherichia coli, Shigella dysenteriae, Trichophyton rubrum, Trichophyton gypseum, Candida albicans, and Candida tropicalis. Few compounds exhibited activity against the selected Gram-negative organisms at concentrations below 50 mcg./ml. For S. aureus and S. albus, the bacteriostatic concentrations of 6-alkyl-, 3-alkyl-, and 1,6-dialkyl-β-naphthols, esters of 2-hydroxy-6-naphthoic acid, and substituted anilides of 1,6-dibromo-, 1-nitro-, and 1-nitro-6-bromo-2-hydroxy-3-naphthoic acid are between 1 and 10 mcg./ml. Marked inhibition of the few fungus pathogens tested is shown by 3-propyl, 3-butyl, 1-methyl-6-ethyl-, 1-methyl-6-propyl- and 1,6-diethyl-β-naphthol, and alkyl esters of 2-hydroxy-6-naphthoic acid. The bacteriostatic and fungistatic activities of a number of β-naphthol, 2-hydroxy-6-naphthoic acid, and 2-hydroxy-3-naphthoic acid derivatives are reported against Staphylococcus aureus, Salmonella typhosa, and Aspergillus niger. Selected compounds from the initial screening have been further tested for their activity against Staphylococcus albus, Salmonella paratyphi A, S. paratyphi B, Escherichia coli, Shigella dysenteriae, Trichophyton rubrum, Trichophyton gypseum, Candida albicans, and Candida tropicalis. Few compounds exhibited activity against the selected Gram-negative organisms at concentrations below 50 mcg./ml. For S. aureus and S. albus, the bacteriostatic concentrations of 6-alkyl-, 3-alkyl-, and 1,6-dialkyl-β-naphthols, esters of 2-hydroxy-6-naphthoic acid, and substituted anilides of 1,6-dibromo-, 1-nitro-, and 1-nitro-6-bromo-2-hydroxy-3-naphthoic acid are between 1 and 10 mcg./ml. Marked inhibition of the few fungus pathogens tested is shown by 3-propyl, 3-butyl, 1-methyl-6-ethyl-, 1-methyl-6-propyl- and 1,6-diethyl-β-naphthol, and alkyl esters of 2-hydroxy-6-naphthoic acid.