iNOS-derived nitric oxide mediates the increase in TFF2 expression associated with gastric damage: role of HIF-1.

Trefoil (TFF) peptides are involved in gastrointestinal mucosal restitution. An hypoxia inducible factor 1 (HIF-1)-dependent induction of TFF genes has been reported in gastric epithelial cells. Nitric oxide (NO) is associated with mucosal damage and modulates HIF-1 activity. The aim of the present study was to analyze the role of iNOS-derived NO in HIF-1alpha stabilization and TFF gene expression in damaged gastric mucosa. Aspirin caused gastric injury that peaked 6 h after dosing and returned to normality at 24 h. iNOS mRNA expression occurs in the corpus in parallel with damage. Blockade of iNOS activity did not modify gastric lesions induced by aspirin but delayed mucosal healing. Aspirin induced HIF-1alpha stabilization and TFF2 mRNA up-regulation in the mucosa, but these effects were diminished when iNOS activity was inhibited. Results obtained using a coculture setup showed that iNOS-derived NO from activated macrophages induced HIF-1alpha stabilization, TFF gene expression, and accelerated wound healing in cultured epithelial cells. Finally, transient silencing of endogenous HIF-1alpha in epithelial cells significantly undermined activated macrophage-induced TFF gene expression. Evidence suggests that the iNOS-derived NO associated with NSAID-induced gastric injury is implicated in mucosal restitution via the HIF-1-mediated induction of TFF genes.

Protective effects of Mangifera indica L extract (Vimang), and its major component mangiferin, on iron-induced oxidative damage to rat serum and liver.

In vivo preventive effects of a Mangifera indica L extract (Vimang) or its major component mangiferin on iron overload injury have been studied in rats given respectively, 50, 100, 250 mg kg(-1) body weight of Vimang, or 40 mg kg(-1) body weight of mangiferin, for 7 days prior to, and for 7 days following the administration of toxic amounts of iron-dextran. Both Vimang or mangiferin treatment prevented iron overload in serum as well as liver oxidative stress, decreased serum and liver lipid peroxidation, serum GPx activity, and increased serum and liver GSH, serum SOD and the animals overall antioxidant condition. Serum iron concentration was decreased although at higher doses, Vimang tended to increase it; percent tranferrin saturation, liver weight/body mass ratios, liver iron content was decreased. Treatment increased serum iron-binding capacity and decreased serum levels of aspartate-amine transferase (ASAT) and alanine-amine transferase (ALAT), as well as the number of abnormal Kupffer cells in iron-loaded livers. It is suggested that besides acting as antioxidants, Vimang extract or its mangiferin component decrease liver iron by increasing its excretion. Complementing earlier in vitro results from our group, it appears possible to support the hypothesis that Vimang and mangiferin present therapeutically useful effects in iron overload related diseases.

Mangifera indica L. (Vimang) protection against serum oxidative stress in elderly humans.

BACKGROUND: We searched for the protective effect of a natural extract from stem bark of Mangifera indica L. extract (Vimang) on age-related oxidative stress. METHODS: Healthy subjects were classified in two groups, elderly (>65 years) and young group (<26 years). The elderly group received a daily dose of 900 mg of extract (three coated Vimang tablets, 300 mg each, before meals) for 60 days. Serum concentration of lipid peroxides, serum peroxidation potential, extracellular superoxide dismutase activity (EC-SOD), glutathione status (GSH, GSSG, GSSG/GSH ratio)) and total antioxidant status (TAS) were determined before (both experimental groups) and 15, 30, and 60 days after treatment (only elderly group). We confirmed the existence of an age-associated oxidative stress in human serum as documented by an age-related increase in serum lipoperoxides and GSSG and a decrease in serum antioxidant capacity and EC-SOD activity. RESULTS: Vimang tablet supplementation increased EC-SOD activity (p <0.01) and serum TAS (p <0.01). It also decreased serum thiobarbituric reactive substances (p <0.01) and GSSG levels (p <0.05). We suggested that the antioxidant components of the extract could have been utilized by the cells (especially blood and endothelial cells), sparing the intra- and extracellular antioxidant system and increasing serum peroxil scavenging capacity, thus preventing age-associated increase in GSH oxidation and lipoperoxidation. CONCLUSIONS: Vimang tablets prevent age-associated oxidative stress in elderly humans, which could retard the onset of age-associated disease, improving the quality of life for elderly persons.