Modification of 2-acetamido-3-chloro-1,4-naphthoquinone, which has potent antiplatelet, antiallergic and antiinflammatory activities, led to a series of 2,3-disubstituted 1,4-naphthoquinones. Some of these compounds showed significant antiplatelet, antiallergic and antiinflammatory activities. Among them, 2-methoxy-3-chloro-1,4-naphthoquinone (15) and 2-ethoxy-3-chloro-1,4-naphthoquinone (17) exhibited potent inhibitory effects on neutrophil and mast cell degranulation. 2-Methoxy-1,4-naphthoquinone (20) and 2-ethoxy-1,4-naphthoquinone (21) exhibited potent inhibitory effect on neutrophil superoxide formation. These four compounds were thus selected for further evaluation.

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In this study, 18 synthetic naphthalene derivatives were tested for their inhibitory effects on the activation of neutrophils stimulated with N-formyl-methionyl-leucyl-phenylalanine (fMLP) or phorbol myristic acetate (PMA). Some of these compounds showed significant antiinflammatory activities. In general, esterification of 1-naphthalene to compound 14 (2-hydroxymethyl-1-naphthol diacetate; TAC) enhanced the antioxidant activity. Compound 15, N,N-bis(2-hydroxy-1-naphthylmethyl) amine, has moderate inhibitory activity on neutrophils stimulated with fMLP as compared to Mannich bases of naphthylene derivatives. Either substitution at 1 or 2 position, except TAC, disfavored the inhibitory effects evoked by PMA stimulation. The influence of these compounds on the release of granule enzyme lysozyme-induced by fMLP was measured. TAC had the highest potency on the inhibition of lysozyme release from rat neutrophil degranulation. The effects of TAC on ionic currents in a mouse neuroblastoma and rat glioma hybrid cell line, NG105-18, were also investigated with the aid of the whole-cell patchclamp technique. TAC caused an inhibitory effect on voltage-dependent L-type Ca 2þ current (I Ca,L ) with an IC 50 value of 0.8 mM. The inhibitory effect of TAC on I Ca,L may not be caused by its inhibition of superoxide formation. Such an effect may, also in part, affect neuronal function. Drug. Dev. Res. 60: 261-269, 2003.

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