Modulation of (Na,K)-ATPase activity by membrane fatty acid composition: therapeutic implications in human hypertension.

Abstract Oxidative stress (OS) plays a key role in the pathophysiology of essential hypertension and is associated with changes in the cell membrane fatty acid composition and fluidity. As (Na,K)-ATPase is modulated by the surrounding lipid microenvironment, lipid peroxidation could alter the interactions of this enzyme with the membrane components. Thus, modifications in the membrane fatty acid profile will translate into effects on (Na,K)-ATPase activity. Accordingly, a decrease in this enzyme activity has been reported in hypertensive patients. The aim of this study was to evaluate the relationship between membrane fluidity and fatty acid composition and (Na,K)-ATPase activity in erythrocytes of essential hypertensive patients supplemented with antioxidant vitamins C and E. A double-blind, randomized, placebo-controlled study was conducted in 120 men with essential hypertension assigned to receive vitamin C (1 g/day) +E (400 IU/day) or placebo for 8 weeks. Measurements included OS related parameters: GSH/GSSG ratio, F2-isoprostanes and antioxidant capacity of plasma, (Na,K)-ATPase activity and erythrocytes membrane fatty acid composition (PUFA, polyunsaturated fatty acids; SAFA, saturated fatty acids). Associations were assessed by Pearson correlation and the differences by Student t-test (p<0.05). Supplemented hypertensive patients showed higher activity of (Na,K)-ATPase and proportion of PUFA, and lower blood pressure, OS markers and proportion of SAFA, versus placebo. The activity of (Na,K)-ATPase correlated negatively with the proportion of SAFA, but positively with that of PUFA in both groups. Supplementation with vitamins C+E resulted in decreased OS and increased fluidity and PUFA proportion in the membrane, both of which positively modulate (Na,K)-ATPase activity, accounting for the blood pressure reduction.

Modulation of endogenous antioxidant system by wine polyphenols in human disease.

Numerous studies indicate that moderate red wine consumption is associated with a protective effect against all-cause mortality. Since oxidative stress constitutes a unifying mechanism of injury of many types of disease processes, it should be expected that polyphenolic antioxidants account for this beneficial effect. Nevertheless, beyond the well-known antioxidant properties of these compounds, they may exert several other protective mechanisms. Indeed, the overall protective effect of polyphenols is due to their large array of biological actions, such as free radical-scavenging, metal chelation, enzyme modulation, cell signalling pathways modulation and gene expression effects, among others. Wine possesses a variety of polyphenols, being resveratrol its most outstanding representative, due to its pleiotropic biological properties. The presence of ethanol in wine aids to polyphenol absorption, thereby contributing to their bioavailability. Before absorption, polyphenols must be hydrolyzed by intestinal enzymes or by colonic microflora. Then, they undergo intestinal and liver metabolism. There have been no reported polyphenol adverse effects derived from intakes currently associated with the normal diet. However, supplements for health-protection should be cautiously used as no level definition has been given to make sure the dose is safe. The role of oxidative stress and the beneficial effects of wine polyphenols against cardiovascular, cancer, diabetes, microbial, inflammatory, neurodegenerative and kidney diseases and ageing are reviewed. Future large scale randomized clinical trials should be conducted to fully establish the therapeutic use of each individual wine polyphenol against human disease.

[Antifungal effect of high molecular weight chitosan on Candida spp isolated from clinical samples]. / Efecto antifúngico de quitosán de alto peso molecular en cepas de Candida sp aisladas de muestras clínicas.

UNLABELLED: Chitosan is a D-glucosamine polysaccharide derived from chitin that displays an antimicrobial activity against bacteria and fungi. OBJECTIVE: to evaluate the antifungal effect of high molecular weight chitosan (HMWC) in clinical strains of Candida spp. METHODOLOGY: the susceptibility of forty strains of Candida spp. to HMWC was studied (16 C albicans, 11 C glabrata, 5 C. tropicalis, 5 C krusei, 2 C parapsilosis and 2 C. famata) by broth microdilution at pH 7.0 and pH 4.0. RESULTS: of 40 strains, only 2 were inhibited at pH 7.0 and corresponded to ATCC control strains (C. krusei 6258 and C parapsilosis 22019). On the other hand, 37/40 strains (92.5%) were inhibited by concentrations lower than 1.25 mg/mL of HMWC at pH 4.0. CONCLUSION: these results show that HMWC, presents activity against clinical Candida spp. strains, including C glabrata, and that this activity is present at acid pH (4.0). This compound could potentially be used in vulvovaginal candidiasis since it occurs at pH 4.0-4.5.