Development of a new assay for the screening of hypochlorous acid scavengers based on reversed-phase high-performance liquid chromatography.

A new assay for the screening of hypochlorite/hypochlorous acid (XOCl) scavengers, based on the reversed-phase high performance liquid chromatographic analysis of human serum albumin (HSA, 0.2% in 100 mM sodium phosphate, pH 7), before and after oxidation by XOCl (1.6 mM), was developed. XOCl induced a significant decrease of the area under the chromatographic peak of HSA at 280 nm due to the oxidation of the aromatic amino acids tryptophan and tyrosine, as suggested by the literature and by the chromatographic analyses and the electrochemical study performed here. The assay was validated by testing known XOCl scavengers such as ascorbic acid, cysteine, glutathione, S-methylglutathione and alpha-lipoic acid and other antioxidants such as carnosine and chlorogenic acid, which inhibited the oxidation of HSA. Quantitative activities were calculated using an original formula based on the changes of the area of the albumin peak. Electrochemical data collected here in a homogeneous medium showed that the anodic potentials of the antioxidants tested are less positive (ascorbic acid, chlorogenic acid and cysteine) or similar (alpha-lipoic acid) compared with those of the aromatic residues (tryptophan and tyrosine) of HSA oxidized by XOCl. However, as expected, carnosine, glutathione and S-methylglutathione were inactive at a glassy-carbon, gold or platinum electrode.

Recent studies on lonidamine, the lead compound of the antispermatogenic indazol-carboxylic acids.

Lonidamine (LND) or [1-(2,4-dichlorobenzyl)-1H-indazole-3-carboxylic acid] is an anticancer and an antispermatogenic drug whose mechanism of action is still incompletely understood. LND is effective against a number of tumors, including head, neck and breast cancers, probably because of the inhibition of mitochondrial electron transport and the enzyme hexokinase and to the induction of apoptosis. Instead, the antispermatogenic activity of LND appeared to be related not only to its energolytic activity but also to other effects activities such as the inhibition of specific chloride channels in the epididymis and the disruption of the inter-Sertoli-germ cell junctions, leading to premature release of germ cells. In addition, we recently reported that, in the rat, LND at the dose of 100 mg/Kg b.w. p.o., a fully active but well tolerated dose, caused specific changes of the testicular and epididymal macroglobulins (alpha(2)-macroglobulin, alpha(1) inhibitor-3 and alpha(1)-macroglobulin). Further studies are needed to elucidate the mechanism of action of LND, the lead compound of an interesting class of antispermatogenic drugs based on the core structure of 1-(2,4-dichlorobenzyl)-indazole-3-carboxylic acid.

Antimicrobial and anti-lipase activity of quercetin and its C2-C16 3-O-acyl-esters.

Neither quercetin (Q), nor 3-O-acylquercetines, up to 100 microg/mL, had any significant activity on selected gram-positive strains (Staphylococcus aureus, Bacillus subtilis, Listeria ivanovi, Listeria monocytogenes, Listeria serligeri), gram-negative strains (Escherichia coli, Shigella flexneri, Shigella sonnei, Salmonella enteritidis, Salmonella tiphymurium) and yeasts (Candida albicans and Candida glabrata). In addition, we confirmed the known anti-HIV activity of Q (80% inhibition at 40 microM), which might depend on the free hydroxyl in the C-3 position, as suggested by the lack of activity of the 3-O-acylquercetines. Finally, we described an interesting inhibitory activity on Candida rugosa lipase by Q (IC(16)=10(-4) M) and its esters (3-O-acylquercetines) which, in vivo, could play an important role against lipase producing microorganisms. In particular, 3-O-acyl-quercetines, being more active (IC(16)=10(-4)-10(-6) M) and more lipophilic, could be more effective than Q when applied to the skin or mucosae, and deserve to be studied further.