Generation of trans-arachidonic acid under nitrative stress is associated with upregulation of thromponsdin-1 in diabetic rats.

BACKGROUND: Trans-arachidonic acids (TAAs), newly discovered markers of nitrative stress and the major products of nitrogen dioxide (NO2(·))-mediated isomerization of arachidonic acid (AA), represent a new mechanism of NO2(·)-induced toxicity. It has been reported that TAAs were generated in oxygen-induced microvascular degeneration model and TAAs were also generated in a diabetic retinopathy (DR) model. In this study, we examined high glucose-induced nitrative stress damage and TAAs levels and explored the possible mechanisms for DR caused by reactive nitrogen species. METHODS: Diabetic rats were induced by intraperitoneal injection of streptozotocin (STZ) at 60 mg/kg. Bovine retinal capillary endothelial cells (BRECs) were selectively cultured and incubated with normal or high glucose. The serum TAAs and AA in diabetic rats were measured by the gas chromatography and mass spectrometry (GC/MS) method. The ratio of peak area of TAAs to AA with selected ion of 79 was estimated by a group t-test. Thrombospondin-1 (TSP-1) in the rat retinas and BRECs extracts were examined by Western blotting. The phosphorylation of extracellular signal-regulated kinase 1/2 (ERK1/2) protein was examined by Western blotting in BRECs incubated with high glucose. RESULTS: The TAAs to AA ratio (TAAs/AA) was significantly increased in the serum at 8, 12 and 16 weeks after STZ injection (P < 0.05), with no noticeable change found at 2 or 4 weeks (P > 0.05). Expression of TSP-1 in the retina of diabetic rats was progressively elevated according to the duration of diabetes. TSP-1 expression was increased in BRECs incubated with high glucose at 48 hours. Moreover, high glucose also increased ERK1/2 expression, which peaked at 30 minutes and then decreased in the following 48 hours. CONCLUSION: An elevation of TAAs/AA is associated with high glucose-induced nitrative stress, which probably involves upregulation of TSP-1 through activating ERK1/2.

Tuning the acyclic ether moiety of anticancer agent AA005 with conformationally constrained fragments.

A new series of anticancer annonaceous acetogenin mimetics were designed, synthesized, and evaluated based on our previously developed compound AA005, in which a variety of conformationally constrained fragments were introduced. Parallel syntheses of all new compounds were accomplished by replacement of the acyclic bis-ether functionality of AA005 with certain conformationally constrained fragments. Slight effects to the anticancer activity were exerted by altering stereochemistries in the middle modification region. Similar to AA005, most newly synthesized mimetics were found to exhibit potent activities against breast cancer cells, and showed satisfactory selectivities between cancerous and non-cancerous cells. An N,N'-dimethyl bis-amide compound 67 exhibits 30 times more potency against MDA-MB-468 cells than its parent molecule AA005. This study indicates that the introduction of appropriate conformational constraints is a useful optimizing tool for this class of anticancer agents. Successes in the bis-amide analogues of AA005 make this unique class of anticancer agents much simpler and more flexible for future further developments.