Ferulsinaic acid attenuation of diabetic nephropathy.

BACKGROUND: Different factors are involved in the development of diabetic nephropathy (DN). Oxidative stress and inflammation play an important role in the pathogenesis of DN. Ferulsinaic Acid (FA) was isolated in 2007. In 2011, we found that FA prolonged the lifespan of C. elegans due to its antioxidative effect, and we hypothesized that FA restores the kidney function of diabetic rats via its antioxidant activity. METHODS: Male Wistar rats were injected with STZ and divided into 5 groups of 10 each: control, diabetic untreated, diabetic treated with 500, 750 and 1000 ng/kg FA. FA treatment was continued for 21 weeks after induction of diabetes. RESULTS: In the diabetic rats treated with FA, fasting blood sugar, HbA1C kidney/body weight ratio, creatinine, BUN, sodium and albuminurea were significantly decreased compared with untreated diabetic rats. Diabetic rats showed decreased activities of superoxide dismutase, glutathione peroxidase and catalase, increased concentrations of malondialdehyde and IL-6 in the kidney homogenate. In addition levels of 8-hydroxy-2'-deoxyguanosine in the urine and in the renal cortex DNA were increased. Moreover, severe destruction in glomerular and tubulointerstitial lesions such as glomerular sclerosis, atrophy, interstitial expansion and interstitial cellular infiltration was seen in the kidney of the diabetic untreated rats. Furthermore, the diabetic kidney was found to be positive for NF-κB p65 antigen in the immunohistochemistry examinations. Treatment with FA restored all the altered parameters in a dose-dependent manner. Furthermore, all the ultra-morphologic abnormalities and NF-κB activation in the kidney of diabetic rats were markedly ameliorated by FA treatment. CONCLUSION: FA confers a considerable protection against kidney injuries of the diabetic rats by increasing activities of antioxidant enzymes, attenuating the formation of AGEs, attenuating the NF-κB activation, ameliorating the inflammatory markers and inhibiting the accumulation of oxidized DNA in the kidney, suggesting a potential drug for the prevention and therapy of DN.

Loss of pain perception in diabetes is dependent on a receptor of the immunoglobulin superfamily.

Molecular events that result in loss of pain perception are poorly understood in diabetic neuropathy. Our results show that the receptor for advanced glycation end products (RAGE), a receptor associated with sustained NF-kappaB activation in the diabetic microenvironment, has a central role in sensory neuronal dysfunction. In sural nerve biopsies, ligands of RAGE, the receptor itself, activated NF-kappaBp65, and IL-6 colocalized in the microvasculature of patients with diabetic neuropathy. Activation of NF-kappaB and NF-kappaB-dependent gene expression was upregulated in peripheral nerves of diabetic mice, induced by advanced glycation end products, and prevented by RAGE blockade. NF-kappaB activation was blunted in RAGE-null (RAGE(-/-)) mice compared with robust enhancement in strain-matched controls, even 6 months after diabetes induction. Loss of pain perception, indicative of long-standing diabetic neuropathy, was reversed in WT mice treated with soluble RAGE. Most importantly, loss of pain perception was largely prevented in RAGE(-/-) mice, although they were not protected from diabetes-induced loss of PGP9.5-positive plantar nerve fibers. These data demonstrate, for the first time to our knowledge, that the RAGE-NF-kappaB axis operates in diabetic neuropathy, by mediating functional sensory deficits, and that its inhibition may provide new therapeutic approaches.

Activation of tubular epithelial cells in diabetic nephropathy.

Previous studies have shown that renal function in type 2 diabetes correlates better with tubular changes than with glomerular pathology. Since advanced glycation end products (AGEs; AGE-albumin) and in particular carboxymethyllysine (CML) are known to play a central role in diabetic nephropathy, we studied the activation of nuclear factor kappaB (NF-kappaB) in tubular epithelial cells in vivo and in vitro by AGE-albumin and CML. Urine samples from healthy control subjects (n = 50) and type 2 diabetic patients (n = 100) were collected and tested for excretion of CML and the presence of proximal tubular epithelial cells (pTECs). CML excretion was significantly higher in diabetic patients than in healthy control subjects (P < 0.0001) and correlated with the degree of albuminuria (r = 0.7, P < 0.0001), while there was no correlation between CML excretion and HbA(1c) (r = 0.03, P = 0.76). Urine sediments from 20 of 100 patients contained pTECs, evidenced by cytokeratin 18 positivity, while healthy control subjects (n = 50) showed none (P < 0.0001). Activated NF-kappaB could be detected in the nuclear region of excreted pTECs in 8 of 20 patients with pTECs in the urine sediment (40%). Five of eight NF-kappaBp65 antigen-positive cells stained positive for interleukin-6 (IL-6) antigen (62%), while only one of the NF-kappaB-negative cells showed IL-6 positivity. pTECs in the urine sediment correlated positively with albuminuria (r = 0.57, P < 0.0001) and CML excretion (r = 0.55, P < 0.0001). Immunohistochemistry in diabetic rat kidneys and a human diabetic kidney confirmed strong expression of NF-kappaB in tubular cells. To further prove an AGE/CML-induced NF-kappaB activation in pTECs, NF-kappaB activation was studied in cultured human pTECs by electrophoretic mobility shift assays (EMSAs) and Western blot. Stimulation of NF-kappaB binding activity was dose dependent and was one-half maximal at 250 nmol/l AGE-albumin or CML and time dependent at a maximum of activation after 4 days. Functional relevance of the observed NF-kappaB activation was demonstrated in pTECs transfected with a NF-kappaB-driven luciferase reporter plasmid and was associated with an increased release of IL-6 into the supernatant. The AGE- and CML-dependent activation of NF-kappaBp65 and NF-kappaB-dependent IL-6 expression could be inhibited using the soluble form of the receptor for AGEs (RAGE) (soluble RAGE [sRAGE]), RAGE-specific antibody, or the antioxidant thioctic acid. In addition transcriptional activity and IL-6 release from transfected cells could be inhibited by overexpression of the NF-kappaB-specific inhibitor kappaBalpha. The findings that excreted pTECs demonstrate activated NF-kappaB and IL-6 antigen and that AGE-albumin and CML lead to a perpetuated activation of NF-kappaB in vitro infer that a perpetuated increase in proinflammtory gene products, such as IL-6, plays a role in damaging the renal tubule.

Life span extension of Caenorhabditis elegans by novel pyridoperimidine derivative.

Zwitterions formed from the addition of triphenylphosphine to dialky acetylene-dicarboxylates attack the nucleus of both 1H-perimidine (1) and 1H-benzo[d]imidazole (9) to form novel pyrido[1,2,3-cd]perimidine and imidazo[4,5,1-ij]quinoline derivatives in moderate yields (64-72%). The biological activity of the products has been studied. Compound 3a was found to extend life span of wild type Caenorhabditis elegans under standard laboratory conditions. Both heat stress and induced chemical stress resistance of wild type C. elegans were improved in a reverse dose-dependent manner due to 3a treatment. In addition, treatment of worms with compound 3a significantly attenuated the formation of advanced glycation end products in a reverse dose-dependent manner.

Ferulsinaic acid attenuation of advanced glycation end products extends the lifespan of Caenorhabditis elegans.

OBJECTIVES: Ferulsinaic acid is the first member of a new rearranged class of sesquiterpene coumarins of the genus Ferula. The genus Ferula can be used for the treatment of skin infections, hysteria and for stomach disorders, such as a febrifuge and a carminative agent. The effect of ferulsinaic acid on the lifespan of the nematode Caenorhabditis elegans has been examined. Novel data explaining the effect of ferulsinaic acid on the lifespan of C. elegans and its antioxidant power were obtained. METHODS: C. elegans was cultivated under standard laboratory conditions in absence and presence of different ferulsinaic acid. Also, animals were cultivated under heat and chemical stress conditions in absence and presence of ferulsinaic acid. Life span assay, determination of protein concentration, assay of malondialdehyde and ELISA for determination of AGEs were performed. KEY FINDINGS: Under standard laboratory conditions and in presence of ferulsinaic acid (500 nm, 10 µm and 100 µm), mean life span of wild type animals was significantly lengthened in a dose-dependent manner from 18.64 ± 0.19 days (control) to 19 ± 0.19 (P = 0.695), 20.76 ± 0.25 (P = 0.043) and 22.3 ± 0.29 (P = 0.0291), respectively. Interestingly, in C. elegans resistance for heat stress at 35°C and oxidative stress induced by paraquat were significantly improved with ferulsinaic acid. Ferulsinaic acid was found to significantly attenuate both lipid peroxidation and the formation of advanced glycation end products in the wild-type animals under standard laboratory conditions. CONCLUSIONS: Ferulsinaic acid had therapeutic efficacy as an antioxidant with the possibility of its use as an antioxidant drug.

Glyoxalase-1 prevents mitochondrial protein modification and enhances lifespan in Caenorhabditis elegans.

Studies of mutations affecting lifespan in Caenorhabditis elegans show that mitochondrial generation of reactive oxygen species (ROS) plays a major causative role in organismal aging. Here, we describe a novel mechanism for regulating mitochondrial ROS production and lifespan in C. elegans: progressive mitochondrial protein modification by the glycolysis-derived dicarbonyl metabolite methylglyoxal (MG). We demonstrate that the activity of glyoxalase-1, an enzyme detoxifying MG, is markedly reduced with age despite unchanged levels of glyoxalase-1 mRNA. The decrease in enzymatic activity promotes accumulation of MG-derived adducts and oxidative stress markers, which cause further inhibition of glyoxalase-1 expression. Over-expression of the C. elegans glyoxalase-1 orthologue CeGly decreases MG modifications of mitochondrial proteins and mitochondrial ROS production, and prolongs C. elegans lifespan. In contrast, knock-down of CeGly increases MG modifications of mitochondrial proteins and mitochondrial ROS production, and decreases C. elegans lifespan.