Free‐Radical Degradation of High‐Molar‐Mass Hyaluronan Induced by Ascorbate plus Cupric Ions: Evaluation of Antioxidative Effect of Cysteine‐Derived Compounds

Abstract

Based on our previous findings, the present study has focused on free-radical-mediated degradation of the synovial biopolymer hyaluronan. The degradation was induced in vitro by the Weissberger's system comprising ascorbate plus cupric ions in the presence of oxygen, representing a model of the early phase of acute synovial joint inflammation. The study presents a novel strategy for hyaluronan protection against oxidative degradation with the use of cysteine-derived compounds. In particular, the work objectives were to evaluate potential protective effects of reduced form of L-glutathione, L-cysteine, N-acetyl-L-cysteine, and cysteamine, against free-oxygen-radical-mediated degradation of high-molar-mass hyaluronan in vitro. The hyaluronan degradation was influenced by variable activity of the tested thiol compounds, also in dependence of their concentration applied. It was found that L-glutathione exhibited the most significant protective and chain-breaking antioxidative effect against the hyaluronan degradation. Thiol antioxidative activity, in general, can be influenced by many factors such as various molecule geometry, type of functional groups, radical attack accessibility, redox potential, thiol concentration and pK(a), pH, ionic strength of solution, as well as different ability to interact with transition metals. Antioxidative activity was found to decrease in the following order: L-glutathione, cysteamine, N-acetyl-L-cysteine, and L-cysteine. These findings might be beneficial in future development of potential drugs in the treatment of synovial hyaluronan depletion-derived diseases.

Hyaluronan and synovial joint: function, distribution and healing

“…Subsequently, NAC exerted a modest pro-oxidative effect, more profound at 25-µM than at 100-µM concentration (Figure 10A). Application of NAC 1 h after the onset of the reaction (Figure 10B) revealed its partial inhibitory effect against formation of the peroxy-type radicals, independently from the concentration applied (Hrabarova et al, 2012). …”

“…Alkoxy-type C fragments may continue the propagation phase of the free-radical hyaluronan degradation reaction. Both fragments are represented by reduced molar masses (Kogan, 2011; Rychly et al, 2006; Hrabarova et al, 2012; Surovcikova et al, 2012; Valachova et al, 2013b; Banasova et al, 2012). …”

“…Thiol antioxidative activity, in general, can be influenced by many factors such as various molecule geometry, type of functional groups, radical attack accessibility, redox potential, thiol concentration and pK a , pH, ionic strength of solution, as well as different ability to interact with transition metals (Hrabarova et al, 2012). …”

Free radical scavenger activity of chitosan and its aminated derivative

“…the degradation kinetics when it adds after one hour of the test begging. At this time, the hydroxyl radicals will be consumed in hyaluronan degradation, and the dominated free radicals are alkoxyl, peroxyl and hyaluronan macroradicals that generated through propagation step (Valachová et al, 2011;Hrabarova et al, 2012). According to uninhibited/inhibited hyaluronan degradation method, the concept of antioxidant evaluation focused on scavenger of hydroxyl or alkoxyl radicals.…”

HYAL-2–WWOX–SMAD4 Signaling in Cell Death and Anticancer Response

“…HA can be degraded under enzyme-free conditions, including acid hydrolysis (Hair et al, 2010), heat treatment by autoclave (Pichi et al, 2012), sonication (Kubo et al, 1993), and free-radical-based cleavage (Hrabárová et al, 2012). By sonication using a fixed intensity at various durations, HA is broken down to a constant size at 11 kDa after sonication.…”