Search

Silibinin (SDH) is a flavonoid with ascertained hepatoprotective effects, which have been partially attributed to its antioxidant properties. Oxidation of blood constituents could have a role in atherogenesis and interfere with the rheologic properties of the blood. In this study we investigated, whether SDH could protect some blood constituents against oxidative modification. In human plasma we measured TBARS and fluorescence generation as indicators of copper or azobis amidinopropane hydrochloride (AAPH) at 760 mm Hg PO2-induced lipid peroxidation. SDH at 50 microM inhibited copper-induced TBARS formation by 25% and fluorescence by 47%. SDH also inhibited AAPH-induced lipid peroxidation, but at 175 microM concentration only. Oxidative modification of albumine was evaluated by fluorescence generation. SDH at 50 microM inhibited copper/hydrogen peroxide fluorescence generation by 54% and at 2.5 microM it inhibited EDTA-Fe (II)/hydrogen peroxide fluorescence generation by 31%. The protection of albumin by SDH was confirmed by SDS-PAGE electrophoresis. Copper-induced red-cell lipid peroxidation was evaluated by TBARS formation. SDH at 250 microM inhibited copper-induced lipid peroxidation and hemolysis by 45% and 94%, respectively. SDH also inhibited hemolysis in red-cell suspensions exposed to hydrogen peroxide, but not lipid peroxidation. Our results show that SDH may protect blood constituents from oxidative damage.

Glycation and free radical reactions may play a role in complications of diabetes. Vascular complications, as a consequence of atherosclerosis, are the main causes of morbidity and mortality in diabetes. The aim of this work was to study glycation and lipid peroxidation (LPO) in plasma and skin of type 2 diabetic patients. The levels of advanced glycation endproducts (AGEs) in skin collagens are considered as the sum of accumulated glycation over time. We studied 20 subjects with type 2 diabetes and 20 controls. Glycated proteins were quantified in skin and plasma by affinity chromatography in aminophenyl boronate gels. AGEs were determined on skin collagen by fluorimetry. LPO was evaluated by fluorimetry measuring TBARS in the skin and plasma. Skin collagen-linked fluorescence (CLF) was higher in diabetics (p < 0.01). CLF in diabetics with retinopathy was higher than that of diabetics without retinopathy (p < 0.02). There was a positive correlation between duration of diabetes and skin CLF (p < 0.01). TBARS were higher in skin (p < 0.01) and plasma (p < 0.001) of diabetic patients. We did not find any correlation between CLF and TBARS. This is not surprising taking into account the complexity and multifactorial aspects involved in LPO, while in glycation the main determinant factor is hyperglycemia.

UV irradiation induces lipid peroxidation (LPO) and cell damage. The aim of the present work was the study of UVB radiation effects on cultured human skin fibroblasts, concerning LPO, prostaglandine E2 (PGE2) formation and cell viability. The cells were exposed to 50, 100, and 150 mJ/cm2 of UVB irradiation. Cellular TBARS and supernatant fluorescent substances were measured spectrofluorimetrically. PGE2 was measured using an immunoenzymatic method. Cell viability was evaluated by the MTT test. All determinations were done after a 2 h incubation period post-irradiation. TBARS were increased for all doses of irradiation (p < 0.001). Fluorescent substances differed from controls at 50 mJ/cm2 (p < 0.001). UVB at 100 and 150 mJ/cm2 decreased cellular viability (p < 0.001). An increase of PGE2 was observed with UVB at 150 mJ/cm2 (p < 0.001). These results confirm the occurrence of LPO and cytotoxicity after UV irradiation; on the other hand, this study showed the formation of PGE2 induced by UV light on cultured human skin fibroblasts. We propose a relationship between these phenomena.

Pentoxifylline (PTX) is a methylxanthine derivative with hemorrheologic properties. PTX decreases neutrophil degranulation and tumor necrosis factor production. We investigated the properties of the drug as a hydroxyl radical scavenger. The aim of this study was to assess the ability of PTX to inhibit visible fluoroescence generation in albumin incubated with 50 microM cupric chloride and 880 microM hydrogen peroxide for 3 h at 37 degrees C. PTX inhibited visible fluorescence generation (ex 360, em 454 nm) by 11% at 50 microM, 13% at 100 microM and 22% at 200 microM. In conclusion, PTX inhibited fluorescence generation in proteins induced by copper/hydrogen peroxide and has potential beneficial effects by protecting proteins against oxidative damage by reactive oxygen species.