rhapontin and Inflammation

Oxidative stress and inflammation have long been considered to be responsible for the development and progression of diabetic retinopathy. On the other hand, rhaponticin (RN) has received scientific attention due to its various pharmacological properties. Keeping all these in view, the present study was performed to investigate the potential protective effects of RN on the retina in diabetic rats. Rats were randomly divided into three groups: control group rats, diabetic group rats, diabetic + RN (20 mg/kg body weight for 28 days through oral route) group rats. RN supplementation to diabetic rats significantly prevent the reduction of final body weight loss, reduced weekly fasting blood glucose levels and HbA1c levels with a significant increase in serum insulin levels. quantitative polymerase chain reaction and immunohistochemical analysis found upregulation of Nrf2, NQO-1, HO-1 and upregulation of Keap1 genes and protein distribution along with significantly reduced levels of malondialdehyde and increased activity of superoxide dismutase, catalase and glutathione peroxidase in RN-treated diabetic rats as compared to diabetic rats. Furthermore, treatment of diabetic rats with RN showed downregulated expression of tumour necrosis factor-α, matrix metalloproteinase-2 and upregulated expression of interleukin-10 (IL-10) and TIMP-1 in the retina. RN treatment decreased nuclear factor kappa-light-chain-enhancer of activated B cells distribution and increased IL-10 protein distribution in the retinae of diabetic rats. In addition, RN treatment ameliorated morphological changes observed in retinae of diabetic rats. Altogether, these results provided clear evidence that treatment of diabetic rats with RN attenuated diabetic retinal changes through its hypoglycaemic, antioxidant and anti-inflammatory effects.

Topics: Animals; Blood Glucose; Diabetes Mellitus, Experimental; Glycated Hemoglobin; Heme Oxygenase-1; Inflammation; Male; NF-E2-Related Factor 2; NF-kappa B; Oxidative Stress; Rats; Rats, Wistar; Retina; Signal Transduction; Stilbenes

Stilbenoids are a group of polyphenolic compounds found in plants, trees, berries, and nuts. Stilbenoids have been shown to serve an antimicrobial and antifungal function in plants. There is also evidence that as a part of the human diet, stilbenoids play an important role as antioxidants and may have anti-inflammatory effects. The PI3K/Akt pathway is a well-characterized signaling pathway controlling cellular functions involved in growth and cell cycle and in metabolism. There is also increasing evidence to show the involvement of this pathway in the regulation of inflammatory responses. In the present study, an attempt was made to investigate the anti-inflammatory properties of the naturally occurring stilbenoids pinosylvin (1), monomethylpinosylvin (2), resveratrol (3), pterostilbene (4), piceatannol (5), and rhapontigenin (6). Glycosylated derivatives of piceatannol and rhapontigenin, namely, astringin (7) and rhaponticin (8), respectively, were also investigated. In addition to the natural stilbenoids, pinosylvin derivatives (9-13) were synthesized and subjected to the testing of their effects on the PI3K/Akt pathway in inflammatory conditions. The investigated natural stilbenoids (except the glycosylated derivatives) were found to down-regulate Akt phosphorylation, which is a well-acknowledged marker for PI3K activity. It was also found that all of the studied natural stilbenoids had anti-inflammatory effects in vitro. The three most potent stilbenoids, piceatannol, pinosylvin, and pterostilbene, were selected for in vivo testing and were found to suppress inflammatory edema and to down-regulate the production of inflammatory mediators IL6 and MCP1 in carrageenan-induced paw inflammation in mice. When compared to the commercial PI3K inhibitor LY294002, the anti-inflammatory effects appeared to be quite similar. The results reveal hitherto unknown anti-inflammatory effects of natural stilbenoids and suggest that those effects may be mediated via inhibition of the PI3K/Akt pathway.

Topics: Animals; Anti-Inflammatory Agents; Biological Products; Cell Line; Chemokine CCL2; Down-Regulation; Inflammation; Inflammation Mediators; Interleukin-6; Macrophages; Male; Mice; Mice, Inbred C57BL; Phosphatidylinositol 3-Kinases; Phosphorylation; Proto-Oncogene Proteins c-akt; Signal Transduction

This protocol describes microsphere-based protease assays for use in flow cytometry and high-throughput screening. This platform measures a loss of fluorescence from the surface of a microsphere due to the cleavage of an attached fluorescent protease substrate by a suitable protease enzyme. The assay format can be adapted to any site or protein-specific protease of interest and results can be measured in both real time and as endpoint fluorescence assays on a flow cytometer. Endpoint assays are easily adapted to microplate format for flow cytometry high-throughput analysis and inhibitor screening.

Topics: Animals; Biotinylation; Flow Cytometry; Fluorescence Resonance Energy Transfer; Green Fluorescent Proteins; High-Throughput Screening Assays; Humans; Inflammation; Kinetics; Microspheres; Peptide Hydrolases; Peptides; Reproducibility of Results; Temperature