Reactivity of Cartilage and Selected Carbohydrates with Hydroxyl Radicals: An NMR Study to Detect Degradation Products

Abstract

It was investigated to what extent isolated, monomeric and polymeric carbohydrates as well as cartilage specimens are affected by hydroxyl radicals generated by gamma-irradiation or Fenton reaction and what products can be detected by means of NMR spectroscopy. Resonances of all protons in glucose and other monosaccharides as well as carbon resonances in 13C-enriched glucose were continuously diminished upon gamma-irradiation. Formate and malondialdehyde were found as NMR detectable products in irradiated glucose solutions under physiologically relevant (aerated) conditions. In polysaccharide solutions (e.g. hyaluronic acid) gamma-irradiation and also treatment with the Fenton reagent caused first an enhancement of resonances according to mobile N-acetyl groups at 2.02 ppm. This indicates a breakdown of glycosidic bonds in polysaccharides. Using higher radiation doses or higher concentrations of the Fenton reagent formate was also detected. The same sequence of events was observed upon treatment of bovine nasal cartilage with the Fenton reagent. First, glycosidic linkages in cartilage polysaccharides were cleaved and subsequently formate was formed. In contrast, collagen of cartilage was affected only to a very low extent. Thus, HO-radicals caused the same action on cartilage as on isolated polymer solutions, inducing a fragmentation of polysaccharides and the formation of formate.

Hydroxylated Metabolites of 2,4-Dichlorophenol Imply a Fenton-Type Reaction in Gloeophyllum striatum

“…No chemiluminescence was detected in the absence of FeSO 4 . Glucose had been shown before to strongly inhibit the formation of 3-OHPH (19).…”

“…Moreover, in a defined mineral medium lacking carbon, nitrogen, and phosphate, G. striatum expressed a degradation capacity similar to that shown on wheat straw (9,23). Here, our aim was to provide further evidence for a Fenton-type reaction in G. striatum by (i) identifying primary metabolites of 2,4-DCP formed by the fungus and in Fenton's reaction as well; (ii) testing for hydroxylation of phthalic hydrazide (PH) giving 3-hydroxyphthalic hydrazide (3-OHPH), which has been postulated to specifically indicate hydroxyl radical formation (1,2,19); and (iii) inhibiting the conversion of 2,4-[U- 14 C]DCP to 14 CO 2 as well as hydroxylation of PH under conditions antagonizing hydroxyl radical activity. Such data are intended to help to firmly establish the capability of some higher fungi to employ a Fenton-type reaction in the degradation of xenobiotics.…”

Hydrogels: Methods of Preparation, Characterisation and Applications

“…The hydroxyl radicals react with hyaluronan with a rate constant k 2 = 0.9 x 10 9 mol -1 dm 3 s -1 , whereas H atoms rate is a lower order of magnitude k 2 = 7 x 10 7 mol -1 dm 3 s -1 (Myint et al, 1987). Figure 11 shows the various hydrolysis, rearrangement, and fragmentation reactions during aqueous radiolysis of cellobiose to gives possible chain break (Sonntag, 1987 Fei et al, 2000;Liu et al, 2002b;Wach et al, 2003a;) (Fei et al, 2000;Liu et al, 2002b;Wach et al, 2001;Wach et al, 2003a;) Hydroxy ethyl cellulose (Fei et al, 2000;Wach et al, 2003a) (Fei et al, 2000;Wach et al, 2001) chitin, chitosan & derivatives (Ershov et al, 1993;Ershov, 1998;Jarry et al, 2001;Jarry et al, 2002;) (Wasikiewicz et al, 2005) Cellulose & derivatives (Ershov, 1998;Nakamura et al, 1985;Phillips, 1961;Phillips, 1963;Wach et al, 2002) (Phillips & Moody, 1959;Wach et al, 2002) Starch and derivatives (Ershov, 1998;Nagasawa et al, 2004;Phillips, 1961;Zhai et al, 2003) D-glucose (Phillips, 1963;Schiller et al, 1998) (Sharpatyi, 2003) Hyaluronan & hyaluronic acid (Al-Assaf et al, 1995;Al-Assaf et al, 2006a;Ershov, 1998;…”

Cartilage Degradation by Stimulated Human Neutrophils: Elastase Is Mainly Responsible for Cartilage Damage

“…Especially small degradation products like acetate or formate, which are formed when the polysaccharides of cartilage react with hypochlorite (11) or hydroxyl radicals (12), respectively, are difficult to detect. Here, sophisticated methods like high-resolution NMR spectroscopy are more appropriate analytical tools (16,17).…”