Curcumin supplementation could improve diabetes-induced endothelial dysfunction associated with decreased vascular superoxide production and PKC inhibition

<p>Abstract</p> <p>Background</p> <p>Curcumin, an Asian spice and food-coloring agent, is known for its anti-oxidant properties. We propose that curcumin can improve diabetes-induced endothelial dysfunction through superoxide reduction.</p> <p>Methods</p> <p>Diabetes (DM) was induced in rats by streptozotocin (STZ). Daily curcumin oral feeding was started six weeks after the STZ injection. Twelve weeks after STZ injection, mesenteric arteriolar responses were recorded in real time using intravital fluorescence videomicroscopy. Superoxide and vascular protein kinase C (PKC-βII) were examined by hydroethidine and immunofluorescence, respectively.</p> <p>Results</p> <p>The dilatory response to acetylcholine (ACh) significantly decreased in DM arterioles as compared to control arterioles. There was no difference among groups when sodium nitroprusside (SNP) was used. ACh responses were significantly improved by both low and high doses (30 and 300 mg/kg, respectively) of curcumin supplementation. An oxygen radical-sensitive fluorescent probe, hydroethidine, was used to detect intracellular superoxide anion (O₂^●-) production. O₂^●-production was markedly increased in DM arterioles, but it was significantly reduced by supplementation of either low or high doses of curcumin. In addition, with a high dose of curcumin, diabetes-induced vascular PKC-βII expression was diminished.</p> <p>Conclusion</p> <p>Therefore, it is suggested that curcumin supplementation could improve diabetes-induced endothelial dysfunction significantly in relation to its potential to decrease superoxide production and PKC inhibition.</p

Linseed Oil Plasticizer Based Natural Rubber/Expandable Graphite Vulcanizates: Synthesis and Characterizations

Natural rubber (NR)/expandable graphite (EG) vulcanizates have been prepared using linseed oil plasticizer. The effects of linseed oil on the cure and mechanical properties of the NR/EG vulcanizates such as cure time, tensile strength, tear strength, modulus, elongation at break and swelling behavior have been studied to evaluate its suitability as plasticizer. Naphthenic oil was used as a reference. The linseed oil vulcanizates showed good processing behavior in terms of torques and scorch. With the incorporation of linseed oil there was improvement in the cure time and the mechanical properties of the EG/NR vulcanizates. 2-4 phr linseed oil in the NR/EG vulcanizates showed maximum tensile strengths. The higher value of cross link density at 4 phr for the linseed oil vulcanizates indicates better reinforcement of the EG-rubber matrix. The NR/EG/linseed oil vulcanizates exhibited higher thermal stability compared to NR/EG vulcanizates. The scanning electron micrographs revealed that incorporation of linseed oil up to 4 phr hinders the crack formation apparently with no major crack present in the NR/EG/LO composites minimizing the failure when compared to similar composites with naphthenic oil. The results indicate that the optimum level of linseed oil in the vulcanizates is 2-4 phr