OBJECTIVES Involvement of tyrosinase in the synthesis of melanin and cell signaling pathway has made it an attractive target in the search for therapeutic inhibitors for treatment of different skin hyperpigmentation disorders and melanoma cancers. MATERIALS AND METHODS In the present study, we conducted a comprehensive kinetic analysis to understand the mechanisms of inhibition imposed by 2-a...

We have developed a simplified assay for the enzyme N-acetyltransferase, based upon the loss of fluorescence after acetylation of the substrate p-aminobenzoic acid. This method is sufficiently sensitive to permit the quantitation of N-acetyltransferase activity in 10(5) human lymphocytes. Using this method, we have compared the level of N-acetyltransferase activity in lymphocytes from adult per...

The fact that urethane, a structurally unrelated compound, can inhibit sulfanilamide action has caused Johnson (1942) to question the competitive metabolite hypothesis developed by McIntosh and Whitby (1939), Stamp (1939), Fildes (1940), Green (1940), Woods (1940) and Woods and Fildes (1940). He would explain the antagonism of p-aminobenzoic acid on the basis of the well-known fact that narcoti...

The biosynthesis of candicidin has been studied with various carbon-14 labeled precursors. The aromatic moiety of candicidin is evidently synthesized from glucose via shikimate to ^-aminobenzoic acid, which is then incorporated into candicidin. The synthesis of candicidin was partially inhibited by the presence of L-phenylalanine, L-tryptophane and L-tyrosine in the growing culture. The implica...

A screening method was established to detect inhibitors of the biosynthetic pathways of aromatic amino acids and para-aminobenzoic acid, the precursor of folic acid, using an agar plate diffusion assay modified as an antagonism test. By this screening method, a family of three novel polycyclic polyketides named as abyssomicins was isolated from a marine strain of Verrucosispora. The main compon...

Phorbol ester-induced promotion of initiated NMRI mouse skin keratinocytes to papillomas could be largely prevented when nicotinamidelike inhibitors of poly(ADP-ribose)polymerase (nicotinamide, benzamide, 3-aminobenzamide) were applied simultaneously with 12-O-tetradecanoylphorbol-13-acetate(TPA). A similar suppression of tumor promotion by nicotinamide analogues was demonstrated in clone 41 JB...

Chagas, or American trypanosomiasis, remains an important public health problem in developing countries. In the last decade, trans-sialidase has become a pharmacological target for new anti-Chagas drugs. In this work, the aims were to design and find a new series of benzoic acid derivatives as trans-sialidase (TS) inhibitors and anti-trypanosomal agents. Three compounds (14, 18, and 19) sharing...

We investigated whether the yield of the B vitamin folic acid could be elevated in Bacillus subtilis. Strategies for increasing the folic acid yield were investigated by employing computer-aided flux analysis and mutation. Controlling the activity of the enzyme pyruvate kinase by placing it under inducible control was one strategy devised to elevate yield while insuring that a rapid growth rate...

Abstract: The stability of aqueous and non-aqueous papaverine hydrochloride solutions exposed to the UV radiation is poor. In order to enhance its photo-stability suitable light absorbers may be used. There werefour photo-protectors considered in this work: 4-aminobenzoic acid, sodium benzoate, methyl 4-hydroxybenzoate and propyl 4-hydroxybenzoate, whose UV absorption spectra characteristics ma...