Salix extracts show good analgesic and antiinflammatory properties in degenerative diseases of joints, e.g. arthritis, but less is know about the mode of action. In rheumatoid diseases the oxidative depolymerisation of hyaluronic acid is a side effect and xanthine oxidase causes oxidative stress. The antioxidant activity of different Salix extracts (21), a nettle extract, a devil´s claw extract and salicylic acid was determined using the xanthine/xanthine oxidase system. The inhibition of enzyme activity, the oxidation of KMB to ethene and hydroxylamine to nitrite were measured. Additionally, the oxidative depolymerisation of hyaluronic acid by Fenton-type oxidants and its inhibition by the above mentioned compounds was acquired. The Salix extracts showed different antioxidant capacities in the test systems, but this behaviour did not correlate with the total salicin content. The main antioxidant effect was provoked by subfractions containing more hydrophilic or lipophilic compounds, e.g. flavonoids. The nettle extract and salicylic acid were only weak antioxidants, the devil´s claw extract was a moderate one compared to the Salix extracts. In particular, a possible new mode of action concerning the analgesic and antiinflammatory activities in vivo was highlighted for the protective effects in case of the oxidative depolymerisation of hyaluronic acid. Carotenoids like lutein or lycopene are supposed to have beneficial effects in AMD or prostate cancer, respectively. The oxidation of low-denstiy lipoproteins (LDL) plays a crucial role in atherogenesis. In this work, the antioxidant activity of lutein and lycopene in copper-induced LDL oxidation was examined monitoring the protein part (loss of tryptophan fluorescence) and the lipid core (formation of conjugated dienes). The carotenoids were used as a suspension or in form of solubilisates and added to the assay achieving only a little protective effect in case of lutein solubilisate. Furthermore, the plasma was incubated with the carotenoids before isolating LDL. Only using solubilisates, an obvious enrichment of LDL with lutein or lycopene was possible. But even these enriched LDL particles displayed no antioxidant activity. However, combining carotenoid enriched LDL with a hydrophilic antioxidant like rutin, a synergistic protection of LDL from oxidation in case of lipid peroxidation and an additive effect in case of protein oxidation was determined. From this point of view, antioxidants should not only be assessed by their single antioxidant activity, but also by their combination effects with other compounds.
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Salix extracts show good analgesic and antiinflammatory properties in degenerative diseases of joints, e.g. arthritis, but less is know about the mode of action. In rheumatoid diseases the oxidative depolymerisation of hyaluronic acid is a side effect and xanthine oxidase causes oxidative stress. The antioxidant activity of different Salix extracts (21), a nettle extract, a devil´s claw extract and salicylic acid was determined using the xanthine/xanthine oxidase system. The inhibition of enzyme...
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