Assessment of the cytotoxic potential of an aqueous-ethanolic extract from Thalassia testudinum angiosperm marine grown in the Caribbean Sea.

OBJECTIVES: Reported antioxidant, anti-inflammatory and neuroprotective properties for one aqueous-ethanolic extract from Thalassia testudinum which grows in the Caribbean Sea compelled us to explore about extract cytotoxic effects. METHODS: Cell viability was assayed on tumour (HepG2, PC12, Caco-2 and 4T1) and non-tumour (VERO, 3T3, CHO, MCDK and BHK2) cell lines. The extract effects upon primary cultures of rat and human hepatocytes and human lymphocytes were assayed. KEY FINDINGS: The extract exhibited cytotoxicity against cancer cells compared to normal cells, and the IC50 values were 102 µg/ml for HepG2, 135 µg/ml for PC12, 165 µg/ml for Caco-2 and 129 µg/ml for 4T1 cells after 48 h, whereas IC50 could not be calculated for normal cells. Additional data from a high-content screening multiparametric assay indicated that after 24-h exposure, the extract (up to 100 µg/ml) induced death in HepG2 cells through oxidative stress-associated mechanism, DNA damage and hypercalcaemia. Comet assay corroborated extract-induced DNA damage. CONCLUSIONS: Thalassia testudinum extract is more cytotoxic and produced more DNA damage on human hepatoma cells than to other non-tumour cells. A possible mechanism is suggested for extract-induced cytotoxicity based on oxidative stress, nuclear damage and hypercalcaemia in HepG2 cells. T. testudinum may be a source for antitumour agents.

Resveratrol increases brown adipose tissue thermogenesis markers by increasing SIRT1 and energy expenditure and decreasing fat accumulation in adipose tissue of mice fed a standard diet.

PURPOSE: Adipose tissue is central to the regulation of energy balance. Two functionally different fat pads are present in mammals: white adipose tissue, the primary site of triglyceride storage, and brown adipose tissue (BAT), which is specialized in heat production. In this context, new strategies capable of modulating the development and function of white and BAT become relevant. In the present study, we analyzed the influence of resveratrol (sirtuin activator) on energy balance and the expression of thermogenesis markers. METHODS: Mice were divided into two groups: standard diet (ST) and standard diet plus resveratrol (ST + RSV). RESULTS: After 2 months of treatment, ST + RSV mice presented significantly decreased fat accumulation in adipose tissue, with diminished total cholesterol and glucose plasma levels. Additionally, increased oxygen consumption was observed in ST + RSV group. Analyses of mRNA of thermogenesis-related genes showed significant increase in UCP1, SIRT1, PTEN and BMP-7 expression in BAT. CONCLUSION: Our data suggest that improved metabolism produced by oral administration of resveratrol is, at least in part, associated with increased thermogenesis followed by high expression of UCP1 and SIRT1, which can mediate higher energy expenditure and decreased fat accumulation in adipose tissue.

Resting energy expenditure in peritoneal dialysis patients.

OBJECTIVES: This study aimed to evaluate whether resting energy expenditure (REE) of patients undergoing peritoneal dialysis (PD) therapy differs from that of healthy individuals, as well as to investigate the factors associated with REE in this sample of patients. DESIGN: Cross-sectional study. SETTING: Dialysis Unit of the Nephrology Division, Federal University of Sao Paulo-Oswaldo Ramos Foundation, Brazil. SUBJECTS AND METHODS: The study examined the REE of 37 patients (20 males, age 44.5 +/- 13 years) undergoing PD therapy. Only patients older than 18 years, on PD for at least 3 months, without catabolic illness, and with normal thyroid function were included. Patients were pair matched for age and gender with 37 healthy individuals. REE was measured by indirect calorimetry. Body composition was assessed by dual-energy x-ray absorptiometry in the patients and by bioelectrical impedance in the healthy individuals. RESULTS: The REE of PD patients was similar to that of pair-matched controls (1372 +/- 266 and 1453 +/- 252 kcal/day respectively, p = 0.13) even when adjusted for lean body mass and gender (p = 0.56). The REE of PD patients was positively correlated with lean body mass (r = 0.60, p < 0.01), fat mass (r = 0.43, p < 0.01), body mass index (r = 0.60, p < 0.01), serum glucose (r = 0.36, p < 0.05), and protein equivalent of nitrogen appearance (PNA; r = 0.42, p < 0.01). There were no correlations between REE and glucose absorption, dialysis-related parameters, C-reactive protein, and energy or protein intake by 3-day food diary. In the multiple linear regression analysis, using REE as the dependent variable, the final model showed that lean body mass and female gender were determinants of REE in PD patients (R(2) = 0.44). When separate analysis by gender was performed, REE correlated directly with body fat in female patients (r = 0.70, p < 0.01) but not in male patients (r = 0.29, p = 0.21). On the other hand, lean body mass was significantly correlated with REE in male patients (r = 0.78, p < 0.01) but not in female patients (r = 0.47, p = 0.06). CONCLUSIONS: This study showed that REE of PD patients did not differ from that of healthy individuals. The strong association between body fat and REE in female patients remains to be further investigated.