A review on bioactive peptides derived from meat and by-products: Extraction methods, biological activities, applications and limitations.

Meat and its by-products offer a rich source of bioactive compounds which have potential applications in both the food and pharmaceutical industries. In this review, we present several extraction methods and report the identification and properties of bioactive peptides. We also examine the challenges and limitations associated with their use in food applications. Enzymatic hydrolysis and fermentation using starts cultures are common methods for generating bioactive peptides from meat proteins. Additionally, natural gastrointestinal digestion can also produce bioactive peptides. However, emerging technologies like high hydrostatic pressure, subcritical extraction and pulsed electric fields can improve hydrolysis and increase the yield of bioactive peptides. Online bioinformatics applications have emerged as an established method for identifying potentially bioactive peptides. These tools reduce the cost and time required for traditional methods of research. Finally, incorporating bioactive peptides into diets for specific purposes such as supporting vulnerable populations like children and the elderly ensures safety and efficacy.

In vivo subchronic effects of ciguatoxin-related compounds, reevaluation of their toxicity.

Ciguatoxins are marine compounds that share a ladder-shaped polyether structure produced by dinoflagellates of the genus Gambierdiscus and Fukuyoa, and include maitotoxins (MTX1 and MTX3), ciguatoxins (CTX3C) and analogues (gambierone), components of one of the most frequent human foodborne illness diseases known as ciguatera fish poisoning. This disease was previously found primarily in tropical and subtropical areas but nowadays, the dinoflagellates producers of ciguatoxins had spread to European coasts. One decade ago, the European Food Safety Authority has raised the need to complete the toxicological available data for the ciguatoxin group of compounds. Thus, in this work, the in vivo effects of ciguatoxin-related compounds have been investigated using internationally adopted guidelines for the testing of chemicals. Intraperitoneal acute toxicity was tested for maitotoxin 1 at doses between 200 and 3200 ng/kg and the acute oral toxicity of Pacific Ciguatoxin CTX3C at 330 and 1050 ng/kg and maitotoxin 1 at 800 ng/kg were also evaluated showing not effects on mice survival after a 96 h observation period. Therefore, for the following experiments the oral subchronic doses were between 172 and 1760 ng/kg for gambierone, 10 and 102 ng/kg for Pacific Ciguatoxin CTX3C, 550 and 1760 ng/kg for maitotoxin 3 and 800, 2560 and 5000 ng/kg for maitotoxin 1. The results presented here raise the need to reevaluate the in vivo activity of these agents. Although the intraperitoneal lethal dose of maitotoxin 1 is assumed to be 50 ng/kg, without chemical purity identifications and description of the bioassay procedures, in this work, an intraperitoneal lethal dose of 1107 ng/kg was obtained. Therefore, the data presented here highlight the need to use a common procedure and certified reference material to clearly establish the levels of these environmental contaminants in food.

Estimation of the post-mortem interval: Effect of storage conditions on the determination of vitreous humour [K+].

Obtaining a reliable estimate of the post-mortem interval (PMI) has been a long-running challenge in forensic medicine. Several more or less successful techniques for making such estimates have been developed, but in recent years important advances have been made thanks to the detailed study of the relationship between the PMI and the analytes - in particular K+ - of the vitreous humour (VH). The extraction and pre-treatment of VH samples has been standardized, the influence of certain environmental factors on analytical results has been quantified, and some of the circumstances under which techniques become unreliable have been identified. The present work examines how the conditions to which VH samples are subject in routine practice may alter the results of their analysis. Exposure to light and ambient temperature was found to alter the values returned in determinations of VH [K+], [Na+] and [Cl-], while exposure to several freezing/thawing cycles (even with final heating) led to no significant modifications in determinations of VH [K+] and [Na+]. It is recommended that if analysis has to be delayed, VH should be frozen for storage in a refrigerator before bringing to room temperature for processing. It is also recommended that samples not be exposed to ambient light and temperature.

Oral Chronic Toxicity of the Safe Tetrodotoxin Dose Proposed by the European Food Safety Authority and Its Additive Effect with Saxitoxin.

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.

Reevaluation of the acute toxicity of palytoxin in mice: Determination of lethal dose 50 (LD50) and No-observed-adverse-effect level (NOAEL).

Palytoxin is an emergent toxin in Europe and one of the most toxic substances know to date. The toxin disrupts the physiological functioning of the Na+/K+-ATPase converting the enzyme in a permeant cation channel. Human intoxications by PLTX after consumption of contaminated fishery products are a serious health issue and can be fatal. Several reports have previously investigated the oral and intraperitoneal toxicity of PLTX in mice. However, in all cases short observation periods (24 and 48 h) after toxin administration were evaluated. In this work, single oral or intraperitoneal doses of PLTX were administered to healthy mice and surviving animals were followed up for 96 h. The data obtained here allowed us to calculate the oral and intraperitoneal lethal doses 50 (LD50) which were in the range of the values previously described. Surprisingly, the oral NOAEL for PLTX was more than 10 times lower than that previously described, a fact that indicates the need for the reevaluation of the levels of the toxin in edible fishery products.

Chronic In Vivo Effects of Repeated Exposure to Low Oral Doses of Tetrodotoxin: Preliminary Evidence of Nephrotoxicity and Cardiotoxicity.

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.

Transcriptomic Analysis of Ciguatoxin-Induced Changes in Gene Expression in Primary Cultures of Mice Cortical Neurons.

Ciguatoxins are polyether marine toxins that act as sodium channel activators. These toxins cause ciguatera, one of the most widespread nonbacterial forms of food poisoning, which presents several symptoms in humans including long-term neurological alterations. Earlier work has shown that both acute and chronic exposure of primary cortical neurons to synthetic ciguatoxin CTX3C have profound impacts on neuronal function. Thus, the present work aimed to identify relevant neuronal genes and metabolic pathways that could be altered by ciguatoxin exposure. To study the effect of ciguatoxins in primary neurons in culture, we performed a transcriptomic analysis using whole mouse genome microarrays, for primary cortical neurons exposed during 6, 24, or 72 h in culture to CTX3C. Here, we have shown that the effects of the toxin on gene expression differ with the exposure time. The results presented here have identified several relevant genes and pathways related to the effect of ciguatoxins on neurons and may assist in future research or even treatment of ciguatera. Moreover, we demonstrated that the effects of the toxin on gene expression were exclusively consequential of its action as a voltage-gated sodium channel activator, since all the effects of CTX3C were avoided by preincubation of the neurons with the sodium channel blocker tetrodotoxin.

History and therapeutic use of MAO-A inhibitors: a historical perspective of mao-a inhibitors as antidepressant drug.

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.

Implication of cyclic nucleotide phosphodiesterase inhibition in the vasorelaxant activity of the citrus-fruits flavonoid (+/-)-naringenin.

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.

The possible implication of trans-Resveratrol in the cardioprotective effects of long-term moderate wine consumption.

trans-Resveratrol (t-RESV; 1-10 microM), a phenolic component of wines, had no effect on phenylephrine-(PE; 1 microM) 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 microM), but they were unaffected by atropine (10 microM) and yohimbine (1 microM). The reversal effect produced by L-NOARG was antagonized by L-arginine but not by D-arginine (0.1 mM). t-RESV (1-10 microM) 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 microM) 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.