Egg white hydrolysate promotes neuroprotection for neuropathic disorders induced by chronic exposure to low concentrations of mercury

Chitosan based fluorescent interpenetrating network polymeric probes for the sensitive detection and efficient removal of Hg+ ions

Chitosan (CS) based interpenetrating polymer network (IPN) is formed by cross-linking of CS with another polymer. It exhibits the ability of detecting environmental pollutants. In this work, the cross-linked CS was used as the network skeleton, the RAFT agent could produce an interpenetrating network with CS during the polymerization process, thereby forming a fluorescent hydrogel-type IPN (CS-Cy-PMAm and CS-Cy-PHD). The basic properties of CS-based hydrogels were analyzed by NMR, MS, FT-IR, SEM, TEM, AFM, and so on. This hydrogel prepared by in-situ synthesis technology not only has excellent film-forming properties but also EGME and toluene solvent molecules can significantly enhance the fluorescence of the hydrogel by infiltrating or squeezing the CS network. Due to the chelation of CN, CO, and thioester bonds with Hg+ to block the PET process, the hydrogel exhibited a highly sensitive 46-fold fluorescence enhancement up the Hg+ addition. The detection limit (LOD) of Hg+ was 13 nM, and the adsorption capacity was 84.0 mg·g-1. At the same time, the fluorescent film is made into a colorimetric card, which can realize real-time and portable detection of Hg+. This method expands the application of CS-based IPNs in environmental science and engineering.

Metal-Organic Framework (MOF)-Based Sensors for Mercury (Hg) Detection: Design Strategies and Recent Progress

Monitoring mercury (Hg) is critical for environmental and public health. Metal-organic framework (MOF)-based sensors demonstrate the advantage of high sensitivity and rapid response. We summarize the advances of MOF sensors for Hg2+ detection from the perspective of MOF type and role in the sensors. First, we introduce three MOFs used in Hg sensors-UIO, ZIF, and MIL-that have demonstrated superior performance. Then, we discuss the specifics of MOF-based sensors for Hg2+ detection in terms of the recognition and signal elements. Currently, the recognition elements include T-rich aptamers, noble metal nanoparticles, central metal ions, and organic functional groups inherent to MOFs. Sensors with fluorescence and colorimetric signals are the two main types of optical MOF sensors used for Hg detection. Electrochemical sensors have also been fabricated, but these are less frequently reported, potentially due to the limited conductivity and cycling stability of MOFs. Notably, dual-signal sensors mitigate background signals interference and enhance the accuracy of Hg2+ detection. Furthermore, to facilitate portability and user-friendliness, portable devices such as microfluidics, paper-based devices, and smartphones have been developed for Hg2+ detection, showcasing potential applications. We also address the challenges related to MOF-based sensors for Hg2+ and future outlook.

Red Quinoa Hydrolysates with Antioxidant Properties Improve Cardiovascular Health in Spontaneously Hypertensive Rats

In recent years, quinoa has been postulated as an emerging crop for the production of functional foods. Quinoa has been used to obtain plant protein hydrolysates with in vitro biological activity. The aim of the present study was to evaluate the beneficial effect of red quinoa hydrolysate (QrH) on oxidative stress and cardiovascular health in an in vivo experimental model of hypertension (HTN) in the spontaneously hypertensive rat (SHR). The oral administration of QrH at 1000 mg/kg/day (QrHH) showed a significant reduction in SBP from baseline (-9.8 ± 4.5 mm Hg; p < 0.05) in SHR. The mechanical stimulation thresholds did not change during the study QrH groups, whereas in the case of SHR control and SHR vitamin C, a significant reduction was observed (p < 0.05). The SHR QrHH exhibited higher antioxidant capacity in the kidney than the other experimental groups (p < 0.05). The SHR QrHH group showed an increase in reduced glutathione levels in the liver compared to the SHR control group (p < 0.05). In relation to lipid peroxidation, SHR QrHH exhibited a significant decrease in plasma, kidney and heart malondialdehyde (MDA) values compared to the SHR control group (p < 0.05). The results obtained revealed the in vivo antioxidant effect of QrH and its ability to ameliorate HTN and its associated complications.

Health Functions of Egg Protein

Egg protein is a remarkably abundant source of protein, with an amino acid score of 100 and the highest net protein utilization rate. However, there have been relatively fewer studies investigating the health benefits of egg protein. In this review, we have summarized the available information regarding the health benefits of egg proteins based on human studies. In particular, studies conducted on the characteristics of egg whites, as they are high in pure protein, have reported their various health functions, such as increases in muscle mass and strength enhancement, lowering of cholesterol, and visceral fat reduction. Moreover, to facilitate and encourage the use of egg white protein in future, we also discuss its health functions. These benefits were determined by developing an egg white hydrolysate and lactic-fermented egg whites, with the latter treatment simultaneously improving the egg flavor. The health benefits of the protein hydrolysates from the egg yolk (bone growth effect) and eggshell membrane (knee join pain-lowering effect) have been limited in animal studies. Therefore, the consumption of egg protein may contribute to the prevention of physical frailty and metabolic syndromes.

Potential benefits of egg white hydrolysate in the prevention of Hg-induced dysfunction in adipose tissue

Aim: To investigate the effects of egg white hydrolysate (EWH) on the lipid and glycemic metabolism disruption in the white adipose tissue (WAT) dysfunction induced by mercury (Hg). Experimental: Wistar rats were treated for 60 days: control (saline, intramuscular - i.m.); hydrolysate (EWH, gavage, 1 g kg^-1 day^-1); mercury (HgCl₂, i.m., 1^st dose 4.6 μg kg^-1, subsequent doses 0.07 μg kg^-1 day^-1) and hydrolysate-mercury (EWH-HgCl₂). Hg level and histological analyses were performed in epididymal WAT (eWAT), pancreas and liver. GRP78, CHOP, PPARα, PPARγ, leptin, adiponectin, and CD11 mRNA expressions were analyzed in eWAT. The plasma lipid profile, glucose, and insulin levels were measured. Antioxidant status was also evaluated in the plasma and liver. Results: EWH intake prevented the reduced eWAT weight, adipocyte size, insulin levels, and antioxidant defenses and the increased glucose and triglyceride levels induced by Hg exposure; hepatic glutathione levels were higher in rats co-treated with EWH. The increased mRNA expression of CHOP, PPARα, and leptin induced by Hg was reduced in co-treated rats. EWH did not modify the elevated mRNA expression of GRP78, PPARγ and adiponectin in Hg-treated rats. Increased levels of Hg were found in the liver; the co-treatment did not alter this parameter. EWH prevented the morphological and metabolic disorder induced by Hg, by improving antioxidant defenses, inactivating pro-apoptotic pathways and normalizing the mRNA expression of PPARs and adipokines. Its effects enabled an increase in insulin levels and a normal balance between the fat storage and expenditure mechanisms in WAT. Conclusions: EWH may have potential benefits in the prevention and management of Hg-related metabolic disorders.

Epitope mapping and the effects of various factors on the immunoreactivity of main allergens in egg white

Egg white has high protein content and numerous biological/functional properties. However, reported allergenicity for some of the proteins in egg white is an issue that needs to be paid exclusive attention. A consideration of the structure of IgE epitopes and their sequences, as well as a comprehensive understanding of the effects of various processes on epitopes and the impact of the gastrointestinal tract on them, can help target such issues. The current study focuses on the identified IgE epitopes in egg white proteins and evaluation of the effects of the gastrointestinal digestion, carbohydrate moiety, food matrix, microbial fermentation, recombinant allergen, heat treatment, Maillard reaction and combination of various processes and gastrointestinal digestion on egg white allergenicity. Although the gastrointestinal tract reduces the immunoreactivity of native egg white proteins, some of the IgE epitope-containing fragments remain intact during the digestion process. It has been found that the gastrointestinal tract can have both positive and negative impacts on the IgE binding activities of egg white proteins. Elimination of the carbohydrate moiety leads to a reduction in the immunoreactivity of ovalbumin. But, such effects from the carbohydrate parts in the IgE binding activity need to be explored further. In addition, the interaction between the egg white proteins and the food matrix leads to various effects from the gastrointestinal tract on the digestion of egg white proteins and their subsequent immunoreactivity. Further on this matter, studies have shown that both microbial fermentation and Maillard reaction can reduce the IgE binding activities of egg white proteins. Also, as an alternate approach, the thermal process can be used to treat the egg white proteins, which may result in the reduction or increase in their IgE binding activities depending on the conditions used in the process. Overall, based on the reported data, the allergenicity levels of egg white proteins can be mitigated or escalated depending on the conditions applied in the processing of the food products containing egg white. So far, no practical solutions have been reported to eliminate such allergenicity.

Bioactive Peptides and Hydrolysates from Egg Proteins as a New Tool for Protection Against Cardiovascular Problems

The aim of the present work is to review the potential beneficial effects of dietary supplementation with bioactive egg protein hydrolysates or peptides on cardiometabolic changes associated with oxidative stress. The development of nutritionally improved food products designed to address specific health concerns is of particular interest because many bioactive food compounds can be potentially useful in various physiological functions such as for reducing oxidative stress. The results presented suggest that egg hydrolysates or derived peptides could be included in the diet to prevent and/or reduce some cardiometabolic complications associated with oxidative stress-related diseases.

Antioxidant Properties of Egg White Hydrolysate Prevent Mercury-Induced Vascular Damage in Resistance Arteries

Aim: We investigated the antioxidant protective power of egg white hydrolysate (EWH) against the vascular damage induced by mercury chloride (HgCl2) exposure in resistance arteries. Methods: Male Wistar rats received for 60 days: (I) intramuscular injections (i.m.) of saline and tap water by gavage - Untreated group; (II) 4.6 μg/kg of HgCl2 i.m. for the first dose and subsequent doses of 0.07 μg/kg/day and tap water by gavage - HgCl2 group; (III) saline i.m. and 1 g/kg/day of EWH by gavage - EWH group, or (IV) the combination of the HgCl2 i.m. and EWH by gavage - EWH + HgCl2 group. Blood pressure (BP) was indirectly measured and dose-response curves to acetylcholine (ACh), sodium nitroprusside (SNP), and noradrenaline (NE) were assessed in mesenteric resistance arteries (MRA), as in situ production of superoxide anion, nitric oxide (NO) release, vascular reactive oxygen species (ROS), lipid peroxidation, and antioxidant status. Results: Egg white hydrolysate prevented the elevation in BP and the vascular dysfunction after HgCl2 exposure; restored the NO-mediated endothelial modulation and inhibited the oxidative stress and inflammatory pathways induced by HgCl2. Conclusion: Egg white hydrolysate seems to be a useful functional food to prevent HgCl2-induced vascular toxic effects in MRA.

Nanozyme-based sensing platforms for detection of toxic mercury ions: An alternative approach to conventional methods

Mercury (Hg) is known as a poisonous heavy metal which stimulates a wide range of adverse effects on the human health. Therefore, development of some feasible, practical and highly sensitive platforms would be desirable in determination of Hg²⁺ level as low as nmol L^-1 or pmol L^-1. Different approaches such as ICP-MS, AAS/AES, and nanomaterial-based nanobiosensors have been manipulated for determination of Hg²⁺ level. However, these approaches suffer from expensive instruments and complicated sample preparation. Recently, nanozymes have been assembled to address some disadvantages of conventional methods in the detection of Hg²⁺. Along with the outstanding progress in nanotechnology and computational approaches, pronounced improvement has been attained in the field of nanozymes, recently. To accentuate these progresses, this review presents an overview on the different reports of Hg²⁺-induced toxicity on the different tissues followed by various conventional approaches validated for the determination of Hg²⁺ level. Afterwards, different types of nanozymes like AuNPs, PtNPs for quantitative detection of Hg²⁺ were surveyed. Finally, the current challenges and the future directions were explored to alleviate the limitation of nanozyme-based platforms with potential engineering in detection of heavy metals, namely Hg²⁺. The current overview can provide outstanding information to develop nano-based platforms for improvement of LOD and LOQ of analytical methods in sensitive detection of Hg²⁺ and other heavy metals.

Radiographic dose-dependency study of loperamide effects on gastrointestinal motor function in the rat. Temporal relationship with nausea-like behavior

BACKGROUND

Loperamide is a potent mu opioid receptor agonist available over the counter to treat diarrhea. Although at therapeutic doses loperamide is devoid of central effects, it may exert them if used at high doses or combined with drugs that increase its systemic and/or central bioavailability. Recently, public health and scientific interest on loperamide has increased due to a growing trend of misuse and abuse, and consequent reports on its toxicity. Our aim was to evaluate in the rat the effects of increasing loperamide doses, with increasing likelihood to induce central effects, on gastrointestinal motor function (including gastric dysmotility and nausea-like behavior).

METHODS

Male Wistar rats received an intraperitoneal injection of vehicle or loperamide (0.1, 1, or 10 mg kg^-1 ). Three sets of experiments were performed to evaluate: (a) central effects (somatic nociceptive thresholds, immobility time, core temperature, spontaneous locomotor activity); (b) general gastrointestinal motility (serial X-rays were taken 0-8 hours after intragastric barium administration and analyzed semiquantitatively, morphometrically, and densitometrically); and (c) bedding intake (a rodent indirect marker of nausea). Animals from sets 1 and 3 were used to evaluate gastric dysmotility ex vivo at 2 and 4 hours after administration, respectively.

KEY RESULTS

Loperamide significantly induced antinociception, hypothermia, and hypolocomotion (but not catalepsy) at high doses and dose-dependently reduced gastrointestinal motor function, with the intestine exhibiting higher sensitivity than the stomach. Whereas bedding intake occurred early and transiently, gastric dysmotility was much more persistent.

CONCLUSIONS AND INFERENCES

Our results suggest that loperamide-induced nausea and gastric dysmotility might be temporally dissociated.

Chronic mercury at low doses impairs white adipose tissue plasticity

INTRODUCTION

The toxic effects of mercury (Hg) are involved in homeostasis of energy systems such as lipid and glucose metabolism, and white adipose tissue dysfunction is considered as a central mechanism leading to metabolic disorders.

OBJECTIVE

The aim of this study was to determine the effects of chronic inorganic Hg exposure at low doses on the lipid and glycemic metabolism.

METHODS

Male Wistar rats were divided into two groups and treated for 60 days with: saline solution, i.m. (Untreated) and mercury chloride, i.m. - 1^st dose 4.6 μg/kg, subsequent doses 0.07 μg/kg/day - (Mercury). Histological analyses, Hg levels measurement and GRP78, CHOP, PPARα, PPARγ, leptin, adiponectin and CD11 mRNA expressions were performed in epididymal white adipose tissue (eWAT). Glucose, triglycerides, total cholesterol and insulin plasma levels were also measured.

RESULTS

Hg exposure reduced the absolute and relative eWAT weights, adipocyte size, plasma insulin levels, glucose tolerance, antioxidant defenses and increased plasma glucose and triglyceride levels. In addition, CHOP, GRP78, PPARα, PPARγ, leptin and adiponectin mRNA expressions were increased in Hg-treated animals. No differences in Hg concentration were found in eWAT between the untreated and Hg groups. These results suggest that the reduction in adipocyte size is related to the impaired antioxidant defenses, endoplasmic reticulum (ER) stress, the disrupted PPARs and adipokines mRNA expression induced by the metal in eWAT. These disturbances possibly induced a decrease in circulating insulin levels, an imbalance between lipolysis and lipogenesis mechanisms in eWAT, with an increase in fatty acids mobilization, a reduction in glucose uptake and an activation of pro-apoptotic pathways, leading to hyperglycemia and hyperlipidemia.

CONCLUSIONS

Hg is a powerful environmental WAT disruptor that influences signaling events and impairs metabolic activity and hormonal balance of adipocytes.

Pepsin egg white hydrolysate modulates gut microbiota in Zucker obese rats

There is limited information that relates the intake of food-derived bioactive peptides and the gut microbiota. We have previously described a pepsin hydrolysate of egg white (EWH) that ameliorates fat accumulation and dyslipidemia, while reducing oxidative stress and inflammation markers in obese Zucker rats. The aim of this study was to associate the beneficial effects of EWH with gut microbiota changes in these animals. Obese Zucker rats received daily 750 mg kg^-1 EWH in drinking water for 12 weeks and faeces were analysed for microbial composition and metabolic compounds in comparison with Zucker lean rats and obese controls. EWH supplementation modulated the microbiological characteristics of the obese rats to values similar to those of the lean rats. Specifically, counts of total bacteria, Lactobacillus/Enterococcus and Clostridium leptum in EWH fed obese Zucker rats were more similar to the lean rats than to the obese controls. Besides, feeding the obese Zucker rats with EWH reduced (P < 0.05) the faecal concentration of lactic acid. The physiological benefits of EWH in the improvement of obesity associated complications of Zucker rats could be associated with a more lean-like gut microbiota and a tendency to diminish total short-chain fatty acids (SCFA) production and associated obesity complications. The results warrant the use of pepsin egg white hydrolysate as a bioactive food ingredient.

Hippocampal Dysfunction Provoked by Mercury Chloride Exposure: Evaluation of Cognitive Impairment, Oxidative Stress, Tissue Injury and Nature of Cell Death

Mercury (Hg) is a highly toxic metal, which can be found in its inorganic form in the environment. This form presents lower liposolubility and lower absorption in the body. In order to elucidate the possible toxicity of inorganic Hg in the hippocampus, we investigated the potential of low doses of mercury chloride (HgCl₂) to promote hippocampal dysfunction by employing a chronic exposure model. For this, 56 rats were exposed to HgCl₂ (0.375 mg/kg/day) via the oral route for 45 days. After the exposure period, the animals were submitted to the cognitive test of fear memory. The hippocampus was collected for the measurement of total Hg levels, analysis of oxidative stress, and evaluation of cytotoxicity, apoptosis, and tissue injury. It was observed that chronic exposure to inorganic Hg promotes an increase in mercury levels in this region and damage to short- and long-term memory. Furthermore, we found that this exposure model provoked oxidative stress, which led to cytotoxicity and cell death by apoptosis, affecting astrocytes and neurons in the hippocampus. Our study demonstrated that inorganic Hg, even with its low liposolubility, is able to produce deleterious effects in the central nervous system, resulting in cognitive impairment and hippocampal damage when administered for a long time at low doses in rats.

Aluminum exposure for 60days at an equivalent human dietary level promotes peripheral dysfunction in rats

Aluminum (Al) is a neurotoxic associated with a number of chronic human diseases. We investigated the effects of Al exposure at doses similar to human dietary levels and at a high level exposure to Al on the peripheral nervous system. Wistar male rats were divided into two major groups and received orally: 1) First group - Low level - rats were subdivided and treated for 60days: a) Control - received ultrapure water; b) AlCl₃ - received Al at 8.3mg/kg body weight (bw) for 60days; and 2) Second group - High level - rats were subdivided and treated for 42days: C) Control - received ultrapure water through oral gavage; d) AlCl₃ - received Al at 100mg/kg bw for 42days. Von Frey hair test, plantar test, the presence of catalepsy and the spontaneous motor activity were investigated. Reactive oxygen species, lipid peroxidation and total antioxidant capacity, immunohistochemistry to investigate the nerve inflammation and, the specific presence of Al in the sciatic nerve fibers were investigated. Al exposure at a representative human dietary level promotes the development of mechanical allodynia, catalepsy, increased inflammation in the sciatic nerve, systemic oxidative stress and, is able to be retained in the sciatic nerve. The effects of low-dose Al were similar to those found in rats exposed to Al at a dose much higher (100mg/kg). Our findings suggest that Al may be considered toxic for the peripheral nervous system, thus inducing peripheral dysfunction.

Egg white-derived peptides prevent male reproductive dysfunction induced by mercury in rats

Oxidative stress in known to contribute to the male reproductive dysfunction induced by mercury (Hg). Our study tested the hypothesis that the egg white hydrolysate (EWH), a potent antioxidant in vitro, is able to prevent the effects of prolonged Hg exposure on male reproductive system in rats. For this, rats were treated for 60 days with: a) Untreated - saline solution (i.m.); b) Hydrolysate - EWH (1 g/kg/day, gavage); c) Mercury - HgCl₂ (1st dose 4.6 μg/kg, subsequent doses 0.07 μg/kg/day, i.m.); d) Hydrolysate-Mercury. At the end of the treatment, sperm motility, count and morphological studies were performed; Reactive Oxygen Species (ROS) levels, lipid peroxidation, antioxidant capacity, histological and immunohistochemical assays on testis and epididymis were also carried out. As results, HgCl₂-treatment decreased sperm number, increased sperm transit time in epididymis and impaired sperm morphology. However, these harmful effects were prevented by EWH. HgCl₂-treatment also increased ROS levels, lipid peroxidation and antioxidant capacity in testis and epididymis as well as promoted testicular inflammation and histological changes in epididymis. EWH improved histological and immunohistochemical alterations, probably due to its antioxidant property. In conclusion, the EWH could represent a powerful natural alternative to protect the male reproductive system against Hg-induced sperm toxicity.