trans-3,5,4′-Trihydroxystilbene (trans-resveratrol) is a phytochemical present in peanuts, grapes and wine with beneficial effects such as protection against cardiovascular disease and cancer prevention. The purpose of this study was to evaluate whether high doses of trans-resveratrol have harmful effects on Sprague-Dawley rats. trans-Resveratrol was administered orally to male rats for 28 d at a dose of 20 mg/(kg · d), 1000 times the amount consumed by a 70-kg person taking 1.4 g of trans-resveratrol/d. Body weight, and food and water consumption did not differ between rats treated with trans-resveratrol and the control group. Hematologic and biochemical variables were not affected by the treatment. Histopathologic examination of the organs obtained at autopsy did not reveal any alterations. These results support the view that repeated consumption of trans-resveratrol at 20 mg/(kg · d) does not adversely affect the variables tested in rats.

In chickens, elevated environmental temperature reduces food intake. We have previously reported that, during heat stress, the intestinal mucosa has an increased capacity to take up sugars. To investigate whether the effects of warm environment on sugar uptake are an intestinal adaptation to lower energy intake or a response attributable to heat stress, we examined the glucose transport kinetics of apical and basolateral membranes of the jejunum and the mucosal morphology of broiler chickens maintained in climatic chambers for 2 wk. Experimental groups were 1) control ad libitum (CAL), fed ad libitum and in thermoneutral conditions (20°C); 2) heat stress ad libitum (HSAL), fed ad libitum and kept in a heated environment (30°C); and 3) control pair-fed (CPF), maintained in thermoneutral conditions and fed the same amount of food as that consumed by the HSAL group. Both the CPF and the HSAL groups showed reduced body weight gain, but only the HSAL chickens had lower plasma thyroid hormones and higher corticosterone than CAL and CPF groups. The fresh weight and length of the jejunum were only reduced in the HSAL group. The activity and expression of apical sodium-dependent glucose transporter 1 (SGLT-1) were increased by ∼50% in the HSAL chickens, without effects in the CPF group. No changes in K_d or in SGLT-1 and glucose transporter-2 K_m were observed in the pair-fed and heated birds. These results support the view that increased intestinal hexose transport capacity is entirely dependent on adaptations of apical SGLT-1 expression to heat stress and is not due to reduced food intake.

We have previously reported the anticarcinogenic effects of an olive fruit extract composed of pentacyclic triterpenes, the main components of which are maslinic acid (73·25 %) and oleanolic acid (25·75 %). Here we examined the effects of the individual components on proliferation, necrosis and apoptosis rates by fluorescence-based techniques in human HT-29 colon cancer cells. Oleanolic acid showed moderate antiproliferative activity, with an ec₅₀ of 160·6 (se 10·6) μmol/l, and moderate cytotoxicity at high concentrations ( ≥ 250 μmol/l). On the other hand, maslinic acid inhibited cell growth with an ec₅₀ of 101·2 (se 7·8) μmol/l, without necrotic effects. Oleanolic acid, which lacks a hydroxyl group at the carbon 2 position, failed to activate caspase-3 as a prime apoptosis protease. In contrast, maslinic acid increased caspase-3-like activity at 10, 25 and 50 μmol/l by 3-, 3·5- and 5-fold over control cells, respectively. The detection of ROS in the mitochondria, which serve as pro-apoptotic signal, evidenced the different bioactivity of the two triterpenes. Confocal microscopy analysis revealed that maslinic acid generated superoxide anions while oleanolic acid-treated cells did not differ from the control. Completion of apoptosis by maslinic acid was confirmed microscopically by the increase in plasma membrane permeability, and detection of DNA fragmentation. In conclusion, the anticancer activity observed for olive fruit extracts seems to originate from maslinic acid but not from oleanolic acid. Maslinic acid therefore is a promising new compound for the chemoprevention of colon cancers.

Maslinic acid is a pentacyclic triterpene found in a variety of natural sources, ranging from herbal remedies used in traditional Asian medicine to edible vegetables and fruits present in the Mediterranean diet. In recent years, several studies have proved that maslinic acid exerts a wide range of biological activities, i.e. antitumor, antidiabetic, antioxidant, cardioprotective, neuroprotective, antiparasitic and growth-stimulating. Experimental models used for the assessment of maslinic acid effects include established cell lines, which have been often used to elucidate the underlying mechanisms of action, and also animal models of different disorders, which have confirmed the effects of the triterpene in vivo. Overall, and supported by the lack of adverse effects in mice, the results provide evidence of the potential of maslinic acid as a nutraceutical, not only for health promotion, but also as a therapeutic adjuvant in the treatment of several disorders.