trans-Resveratrol (t-RESV; 1-10 M), a phenolic component of wines, had no effect on phenylephrine-(PE; 1 M) and high KCl-(60 mM) induced contractions in endothelium-denuded rat aortic rings. However, it relaxed the contractile response produced by these vasoconstrictor agents in intact rat aorta. The vasorelaxing effects of t-RESV were completely inhibited by N G -nitro-L-arginine (L-NOARG; 0.1 mM) and methylene blue (10 M), but they were unaffected by atropine (10 M) and yohimbine (1 M). The reversal effect produced by L-NOARG was antagonized by L-arginine but not by D-arginine (0.1 mM). t-RESV (1-10 M) did not significantly modify rat aorta constitutive nitric-oxide synthase activity. However, this natural compound decreased NADH/NADPH oxidase activity in rat aortic homogenates. In addition, t-RESV (1-10 M) was ineffective in scavenging superoxide anions (O 2 . ) generated enzymatically by a hypoxanthine/xanthine oxidase (HX/XO) system and/or to inhibit XO. The above data demonstrate that the characteristic endothelium-dependent vasorelaxant effect of t-RESV in rat aorta seems to be caused by the inhibition of vascular NADH/ NADPH oxidase and the subsequent decrease of basal cellular O 2 . generation and, therefore, of NO biotransformation. Under the assumption that t-RESV exhibits a similar behavior in human blood vessels and bearing in mind that an overactivity of NADH/NADPH oxidase has been found in a number of cardiovascular pathologies, the results obtained in this work suggest that t-RESV could play an important role in the cardioprotective effects induced by the long-term moderate wine consumption.

The potential vasorelaxant, antioxidant and cyclic nucleotide phosphodiesterase (PDE) inhibitory effects of the citrus-fruit flavonoids naringin and (+/-)-naringenin were comparatively studied for the first time in this work. (+/-)-Naringenin (1 microM - 0.3 mM) did not affect the contractile response induced by okadaic acid (OA, 1 microM). However, (+/-)-naringenin relaxed, in a concentration-dependent manner, the contractions elicited by phenylephrine (PHE, 1 microM) or by a high extracellular KCl concentration (60 mM) in intact rat aortic rings. Mechanical removal of endothelium and/or pretreatment of aorta rings with glibenclamide (GB, 10 microM) or tetraethylammonium (TEA, 2 mM) did not significantly modify the vasorelaxant effects of this flavanone. (+/-)-Naringenin (10 microM - 0.1 mM) did not alter the basal uptake of 4) Ca2+ but decreased the influx of 45Ca2+ induced by PHE and KCl in endothelium-containing and endothelium-denuded rat aorta. (+/-)-Naringenin (10 microM - 0.1 mM) was ineffective to scavenge superoxide radicals (O*2-) generated by the hypoxanthine (HX)-xanthine oxidase (XO) system and/or to inhibit XO activity. (+/-)-Naringenin (0.1 mM) significantly increased the production of cGMP and cAMP decreased by PHE (1 microM) and high KCl (60 mM) in cultured rat aortic myocytes. (+/-)-Naringenin preferentially inhibited calmodulin (CaM)-activated PDE1, PDE4 and PDE5 isolated from bovine aorta with IC50 values of about 45 microM, 60 microM and 68 microM, respectively. In contrast, the 7-rhamnoglucoside of (+/-)-naringenin, naringin (1 microM - 0.3 mM), was totally inactive in all experiments. These results indicate that the vasorelaxant effects of (+/-)-naringenin seem to be basically related to the inhibition of PDE1, PDE4 and PDE5 activities.

Tetrodotoxin (TTX) is a potent natural toxin causative of human food intoxications that shares its mechanism of action with the paralytic shellfish toxin saxitoxin (STX). Both toxins act as potent blockers of voltage-gated sodium channels. Although human intoxications by TTX were initially described in Japan, nowadays increasing concern about the regulation of this toxin in Europe has emerged due to its detection in fish and mollusks captured in European waters. Currently, TTX is only regularly monitored in Dutch fishery products. However, the European Food Safety Authority (EFSA) has established a safety level of 44 µg/kg TTX as the amount of toxin that did not cause adverse effects in humans. This level was extrapolated considering initial data on its acute oral toxicity and EFSA remarked the need for chronic toxicity studies to further reduce the uncertainty of future toxin regulations. Thus, in this work, we evaluated the oral chronic toxicity of TTX using the safety levels initially recommended by EFSA in order to exclude potential human health risks associated with the worldwide expanding presence of TTX. Using internationally recommended guidelines for the assessment of oral chronic toxicity, the data provided here support the proposed safety level for TTX as low enough to prevent human adverse effects of TTX even after chronic daily exposure to the toxin. However, the combination of TTX with STX at doses above the maximal exposure level of 5.3 µg/kg body weight derived by EFSA increased the lethality of TTX, thus confirming that both TTX and paralytic shellfish toxins should be taken into account to assess human health risks.

Tetrodotoxin (TTX) is one of the most potent naturally occurring neurotoxins. InitiallyTTX was associated with human food intoxications in Japan, but nowadays, concerns about thehuman health risks posed by TTX have increased in Europe after the identification of the toxin infish, marine gastropods, and bivalves captured in European waters. Even when TTX monitoring isnot currently performed in Europe, an acute oral no observable effect level (NOAEL) of 75 μg/kghas been recently established but, to date, no studies evaluating the chronic oral toxicity of TTXhave been released, even when EFSA has highlighted the need for them. Thus, in this work, thechronic effects of low oral TTX doses (below the acute lethal dose 50) were evaluated followinginternationally adopted guidelines. The results presented here demonstrate that low oral doses ofTTX have deleterious effects on renal and cardiac tissues. Moreover, alterations in bloodbiochemistry parameters, urine production, and urinalysis data were already detected at the oraldose of 75 μg/kg after the 28 days exposure. Thus, the data presented here constitute an initialapproach for the chronic evaluation of the in vivo toxicity of tetrodotoxin after its ingestion throughcontaminated fishery products.

Since the first generation of MAO inhibitors was developed, more than fifty years ago, this family of drugs has been ups and downs over the last decades. Actually, interest in MAO inhibitors is reviving and the emergence of new advances in the rational design of molecules and new techniques to predict the in vivo behavior has encouraged the research for new drugs with therapeutic potential in this area. The classic MAOIs have been widely used as antidepressants during the two decades after its introduction in clinic. Based on observations made on MAO inhibition by these drugs, it has been postulated hypothesis that have contributed to a better understanding of the mechanism and management of depressive disorders. However, exaggerated concerns about food and drug interactions relegated these drugs from the pharmaceutical landscape. The correct interpretation and the contextualization of side effects and the recent research findings, in which MAO selective inhibitors appear as promising agents in the treatment of emerging and high prevalence diseases, are placing these drugs again into the scientific and pharmacological focus.