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  • Title: Free-radical degradation of high-molecular-weight hyaluronan induced by ascorbate plus cupric ions. Testing of bucillamine and its SA981-metabolite as antioxidants.
    Author: Valachová K, Hrabárová E, Priesolová E, Nagy M, Baňasová M, Juránek I, Soltés L.
    Journal: J Pharm Biomed Anal; 2011 Nov 01; 56(3):664-70. PubMed ID: 21782370.
    Abstract:
    High-molecular-weight hyaluronan (HA) samples were exposed to free-radical chain-degradation reactions induced by ascorbate in the presence of Cu(II) ions - the so-called Weissberger's oxidative system. The concentrations of both reactants [ascorbate, Cu(II)] were comparable to those that may occur during an early stage of the acute phase of joint inflammation. The time-dependent changes of the viscosity of the HA solution in the absence of the substance tested were monitored by rotational viscometry. However, when the anti- or pro-oxidative effects of the antioxidants/drugs were investigated, their dose-dependency was also examined. Additionally, the anti-oxidative activities of these substances were screened by the well-established ABTS and DPPH decolorization assays. The actions of the disease-modifying anti-rheumatic drugs, namely bucillamine and D-penicillamine, were compared to those of L-cysteine and of SA981, the oxidized metabolite of bucillamine. The results indicated that bucillamine was the most efficient scavenger of hydroxyl- and/or peroxyl-type radicals, even at the lowest drug concentration. In contrast, SA981 demonstrated no scavenging activity against the aforementioned free radicals. D-Penicillamine and L-cysteine showed a dual effect, i.e. a pronounced anti-oxidative effect was, after a given time period, followed by a significant pro-oxidative effect.
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