Possible antioxidant mechanism of melanoidins extract from Shanxi aged vinegar in mitophagy-dependent and mitophagy-independent pathways

Melanoidin-like carbohydrate-containing macromolecules from Shanxi aged vinegar exert immunoenhancing effects on macrophage RAW264.7 cells

Bioactive macromolecule mining is important for the functional chemome analysis of traditional Chinese vinegar. In this study, we isolated and characterized carbohydrate-containing macromolecules from Shanxi aged vinegar (CCMSAV) and evaluated their immunomodulatory activity. The isolation process involved ethanol precipitation, deproteinization, decolorization, and DEAE-650 M column chromatography, resulting in the acquisition of four sub-fractions. All sub-fractions exhibited a molecular weight range of 6.92 to 16.71 kDa and were composed of 10 types of monosaccharides. Comparative analysis of these sub-fractions with two melanoidins exhibited similarities in elemental composition, spectral signature, and pyrolytic characteristics. Immunological assays confirmed the significantly enhanced cell viability, phagocytic activity, and secretion of nitric oxide, tumor necrosis factor (TNF)-α and interleukin (IL)-6 in RAW264.7 cells by all four sub-fractions. Further investigation of the immunomodulatory mechanism revealed that SAV-RP70-X, the most potent purified sub-fraction, enhanced aerobic glycolysis in macrophages and activated Toll-like receptor 2 (TLR2), TLR4, mannose receptor (MR), scavenger receptor (SR), and the dendritic cell-associated C-type lectin-1 receptor (Dectin-1). Furthermore, the activation of macrophages was associated with the MyD88/PI3K/Akt/NF-κB signaling pathway. Methylation analysis revealed that 1,4-Xylp was the most abundant glycosidic linkage in SAV-RP70-X.

Melanoidins present in traditional fermented foods and beverages

Traditional fermented foods and beverages (TFFB) are an important dietary component consumed in large quantities worldwide. Currently, much attention has been focused on the health benefits of TFFB. Melanoidins, a class of bioactive substance produced in the final stage of the Maillard reaction, not only have a significant impact on sensory properties of TFFB but also contribute to the health effects. Melanoidins formed in the fermentation system with a long reaction time at low temperature could be different from those obtained from high-temperature, short-duration roasted systems due to the multiple formative stages and involvement of microorganisms and enzymes. In this paper, the current state of knowledge regarding the formation, distribution, extraction and purification, physicochemical properties, structure characteristics, and biological activities of TFFB melanoidins are comprehensively reviewed, with predominant focus on TFFB that are typically brown like douchi, miso, cheonggukjang, soy sauce, huangjiu (Chinese rice wine), beer, vinegar, and sweet wine. The current challenges and prospective recommendations for the research of melanoidins in fermented systems are also presented. In future, people should pay more attention to the basic research on TFFB melanoidins, especially purification methods and formation mechanisms, further substantiation of health properties of TFFB melanoidins in vivo, and development of specific melanoidins to fulfill technological, productive, or health needs of consumers.

Melanoidins, extracted from Chinese traditional vinegar powder, inhibit alcohol-induced inflammation and oxidative stress in macrophages via activation of SIRT1 and SIRT3

Alcohol induces inflammation and oxidative stress with the dysregulation of proinflammatory cytokines, which are implicated in the pathogenesis of alcoholic liver injury. Melanoidins are known to exert an antioxidant effect, however, their function in inhibiting alcohol-induced inflammation is unclear. In this study, we examined the role of melanoidins from Chinese traditional vinegar powder in terms of their anti-inflammatory and antioxidant properties in RAW 264.7 macrophages and elucidated their mechanisms of function. In macrophages, melanoidins significantly suppress the mRNA expression of interleukin (Il)-6, Il-1β and tumor necrosis factor α (Tnf-α) with a concomitant inhibitory effect on IL-1β, IL-6 and TNFα secretion, which are increased by ethanol. In addition, ethanol significantly increases the cellular reactive oxygen species (ROS) levels and the expression of cytochrome β-245 and beta polypeptide (Cybb), which are repressed by melanoidins to basal level. However, the expression of genes related to oxidative stress significantly decreases in response to ethanol, while it is significantly increased by melanoidins. Importantly, treatment with ethanol led to significant decreases in SIRT1 and SIRT3 transcription, translation, and activation, as well as the nicotinamide adenine dinucleotide (NAD⁺) levels. Interestingly, all the decreases were markedly attenuated by melanoidins. Ethanol promoted the expression of proinflammatory genes, whereas coincubation with resveratrol (a potent SIRT agonist) inhibited this effect. Conversely, the addition of sirtinol (a known SIRT inhibitor) augmented the proinflammatory gene expression. Taken together, our findings suggest that melanoidins exert anti-inflammatory and antioxidant functions via abolishing decreases in SIRT1 and SIRT3 expression and cellular NAD⁺ levels in ethanol-induced macrophages and may serve as a new therapeutic agent for the prevention of alcohol-induced cell damage.

Formation mechanisms and characterisation of the typical polymers in melanoidins from vinegar, coffee and model experiments

Melanoidins, are of increasing interest for their potential biological activities. However, little knowledge is available on their structure. In the present study, vinegar, coffee and model melanoidins were degraded by NaBH₄, and the resultant reaction products were characterised by chromatography, mass spectrometry and spectrometry methods to elucidate the mechanism of formation of melanoidin skeleton molecules. The study identified a typical polymer with a molecular weight (MW) interval of 74 Da, which was polymerised by aldol condensation and reduced by NaBH₄, followed by intermolecular dehydration. MW of the theoretically derived typical polymers matched the detected polymers, validating the speculated pathway involved in the formation of melanoidins skeleton molecules. The study also revealed that melanoidins from different sources contain polymers with the same MW and different binding preferences, contributing to the heterogeneity of melanoidins. Overall, these findings indicated that the identified polymers could be used as potential candidate biomarkers for melanoidins.

Mitophagy in Cardiovascular Diseases

Cardiovascular diseases are one of the leading causes of death. Increasing evidence has shown that pharmacological or genetic targeting of mitochondria can ameliorate each stage of these pathologies, which are strongly associated with mitochondrial dysfunction. Removal of inefficient and dysfunctional mitochondria through the process of mitophagy has been reported to be essential for meeting the energetic requirements and maintaining the biochemical homeostasis of cells. This process is useful for counteracting the negative phenotypic changes that occur during cardiovascular diseases, and understanding the molecular players involved might be crucial for the development of potential therapies. Here, we summarize the current knowledge on mitophagy (and autophagy) mechanisms in the context of heart disease with an important focus on atherosclerosis, ischemic heart disease, cardiomyopathies, heart failure, hypertension, arrhythmia, congenital heart disease and peripheral vascular disease. We aim to provide a complete background on the mechanisms of action of this mitochondrial quality control process in cardiology and in cardiac surgery by also reviewing studies on the use of known compounds able to modulate mitophagy for cardioprotective purposes.

Effects of Plant and Animal Natural Products on Mitophagy

Mitophagy is a protected cellular process that is essential for autophagic removal of damaged mitochondria and for preservation of a healthy mitochondrial population. In the last years, a particular interest has been devoted in studying the effects of natural compounds on mitophagy. Different natural compounds may modulate mitochondrial oxidative phosphorylation, the production of mitochondrial reactive oxygen species, the expression of mitophagy- and autophagy-related genes, and the activities of transcription factors which regulate the expression of mitochondrial proteins, thereby controlling mitochondrial damage and mitophagy. Remarkably, since mitochondrial function has a crucial role in the pathogenesis of various diseases (e.g., cancer, atherosclerosis, Duchenne muscular dystrophy, diabetes complications, Alzheimer's disease, and hepatic steatosis), these effects might have important therapeutic implications. In this review, preclinical studies investigating the role of different natural compounds in the modulation of mitophagy will be discussed.

A colorimetric sensor array for recognition of 32 Chinese traditional cereal vinegars based on "turn-off/on" fluorescence of acid-sensitive quantum dots

Colorimetric sensor array is a sensitive, rapid, and inexpensive detection technology which simulates human olfaction system based on various organic dyes. In this work, a sensor array based on acid-sensitive CdTe QDs coupled with chemometrics method was developed and proved to be a rapid, accurate and sensitive method for identification of 32 kinds of Chinese traditional cereal vinegars (CTCV). The specificity of identification of this method was mainly depends on the organic acids and melanoidins of CTCV. Among them, organic acids can quench the fluorescence of QDs through enhancing their electron transfer (hydrogen bond) and resonance energy transfer, and the fluorescence intensity of melanoidin was closely related to the brewing technology and aging year of CTCV. The types and aging time of 32 CTCV can be 100% identified at a dilution of 1000 by partial least squares discriminant analysis, when the latent variables were 4. And only one kind of QDs is needed instead of various organic dyes to this kind of colorimetric sensor array. Except for vinegar, this method can also be used in the identification of other food which rich in organic acid.

Knowledge Domain and Emerging Trends in Vinegar Research: A Bibliometric Review of the Literature from WoSCC

Vinegar is one of the most widely used acidic condiments. In recent decades, rapid advances have been made in the area of vinegar research, and the intellectual structure pertaining to this domain has significantly evolved. Thus, it is important that scientists keep abreast of associated developments to ensure an appropriate understanding of this field. To facilitate this current study, a bibliometric analysis method was adopted to visualize the knowledge map of vinegar research based on literature data retrieved from the Web of Science Core Collection (WoSCC) database. In total, 883 original research and review articles from between 1998 and 2019 with 19,663 references were analyzed by CiteSpace. Both a macroscopical sketch and microscopical characterization of the whole knowledge domain were realized. According to the research contents, the main themes that underlie vinegar research can be divided into six categories, that is, microorganisms, substances, health functions, production technologies, adjuvant medicines, and vinegar residues. In addition to the latter analysis, emerging trends and future research foci were predicted. Finally, the evolutionary stage of vinegar research was discerned according to Shneider's four-stage theory. This review will help scientists to discern the dynamic evolution of vinegar research, as well as highlight areas for future research.

Mitophagy could fight Parkinson's disease through antioxidant action

During aging, the process of mitophagy, a system that allows the removal of dysfunctional mitochondria through lysosomal degradation, starts to malfunction. Because of this defect, damaged mitochondria are not removed correctly, and their decomposing components accumulate inside the cells. Dysfunctional mitochondria that are not removed by mitophagy produce high amounts of reactive oxygen species (ROS) and, thus, cause oxidative stress. Oxidative stress, in turn, is very harmful for the cells, neuronal cells, in particular. Consequently, the process of mitophagy plays a crucial role in mitochondria-related disease. Mitochondrial dysfunctions and oxidative stress are well-established factors contributing to Parkinson's disease (PD), one of the most common neurodegenerative disorders. In this review, we report various known antioxidants for PD treatments and describe the stimulation of mitophagy process as a novel and exciting method for reducing oxidative stress in PD patients. We describe the different mechanisms responsible for mitochondria removal through the mitophagy process. In addition, we review the functional connection between mitophagy induction and reduction of oxidative stress in several in vitro models of PD and also agents (drugs and natural compounds) already known to be antioxidants and to be able to activate mitophagy. Finally, we propose that there is an urgent need to test the use of mitophagy-inducing antioxidants in order to fight PD.

Characterization of Maillard reaction products micro/nano-particles present in fermented soybean sauce and vinegar

The endogenous micro/nano-particles in daily food have drawn much attention due to specific properties potential biological impact. The aim of this study was to investigate the nanoparticles in traditional fermented soybean sauces and vinegars in order to study the safety problems of nanoparticles in daily food. The transmission electron microscope results showed that all samples exhibited diverse nanostructures with diameters ranging from 10 to 400 nm. The concentration of nanoparticles in these foods was determined to be around 1.15 × 107-3.43 × 109 particles/mL. Furthermore, the absorbance at 420 nm was found in all the fermented foods, which was ascribed to Maillard reaction products. The 3-(4, 5-Dimethylthiazol-2-yl)-2, 5-diphenyl-tetrazolium bromide (MTT) results showed that nanoparticles in traditional fermented foods did not decrease cell viability in the concentration range tested (<200 μg/mL), which were equivalent to 20 L~200 L of selected soybean sauces and vinegars. However, further studies need to be performed to find out the interaction of nanoparticle with cell (food with body) after ingestion.

Evaluation of Nutritional Compositions, Bioactive Compounds, and Antioxidant Activities of Shanxi Aged Vinegars During the Aging Process

Shanxi aged vinegar (SAV) is known as famous fermented food in China. During the brewing process, a large number of nutritional substances and bioactive compounds are produced, which have beneficial effects on human body. In this study, the contents of nutritional compositions including proteins, fats, carbohydrates, organic acids, and amino acids were determined in SAV samples. The antioxidant compounds and properties of SAV with different aging time were also evaluated. The results showed that the contents of proteins, crude fats, and carbohydrates in SAV were not changed with the aging time. Moreover, Alanine was the main component of amino acids in SAV, and the total contents of amino acids were increased with the aging time. Acetic acid and lactic acid were the predominant organic acids in SAV. The contents of acetic acid and lactic acid accounted for more than 90% of the total organic acids in SAV, which were increased during the aging process of 5 years. Furthermore, total phenols, flavonoids contents, and browning index in SAV were also increased during the aging time. These antioxidant compounds showed a high correlation with the antioxidant activities of SAV measured by ferric reducing antioxidant power and 2,2'-azino-bis(3-ethylbenzthi azoline-6-sulfonic acid) assays. The contribution of polyphenolic fractions and high molecular weight melanoidins to total antioxidant activities was similar (about 49% and 48%, respectively). Our findings would provide new insights to further explore the development of new vinegar-based functional foods.

PRACTICAL APPLICATION

The analysis of nutritional compositions, bioactive compounds, and antioxidant capacities in vinegars provides a theoretical basis for the function of SAV. It also provides references for further explore the development of new-type functional and healthy vinegars.

Mitophagy Transcriptome: Mechanistic Insights into Polyphenol-Mediated Mitophagy

Mitochondria are important bioenergetic and signalling hubs critical for myriad cellular functions and homeostasis. Dysfunction in mitochondria is a central theme in aging and diseases. Mitophagy, a process whereby damaged mitochondria are selectively removed by autophagy, plays a key homeostatic role in mitochondrial quality control. Upregulation of mitophagy has shown to mitigate superfluous mitochondrial accumulation and toxicity to safeguard mitochondrial fitness. Hence, mitophagy is a viable target to promote longevity and prevent age-related pathologies. Current challenge in modulating mitophagy for cellular protection involves identification of physiological ways to activate the pathway. Till date, mitochondrial stress and toxins remain the most potent inducers of mitophagy. Polyphenols have recently been demonstrated to protect mitochondrial health by facilitating mitophagy, thus suggesting the exciting prospect of augmenting mitophagy through dietary intake. In this review, we will first discuss the different surveillance mechanisms responsible for the removal of damaged mitochondrial components, followed by highlighting the transcriptional regulatory mechanisms of mitophagy. Finally, we will review the functional connection between polyphenols and mitophagy and provide insight into the underlying mechanisms that potentially govern polyphenol-induced mitophagy.

Vinegar Functions on Health: Constituents, Sources, and Formation Mechanisms

Vinegars are one of only a few acidic condiments throughout the world. Vinegars can mainly be considered grain vinegars and fruit vinegars, according to the raw materials used. Both grain vinegars and fruit vinegars, which are fermented by traditional methods, possess a variety of physiological functions, such as antibacteria, anti-infection, antioxidation, blood glucose control, lipid metabolism regulation, weight loss, and anticancer activities. The antibacteria and anti-infection abilities of vinegars are mainly due to the presence of organic acids, polyphenols, and melanoidins. The polyphenols and melanoidins also provide the antioxidant abilities of vinegars, which are produced from the raw materials and fermentation processes, respectively. The blood glucose control, lipid metabolism regulation, and weight loss capabilities from vinegars are mainly due to acetic acid. Besides caffeoylsophorose (inhibits disaccharidase) and ligustrazine (improves blood circulation), other functional ingredients present in vinegars provide certain health benefits as well. Regarding anticancer activities, several grain vinegars strongly inhibit the growth of some cancer cells in vivo or in vitro, but related functional ingredients remain largely unknown, except tryptophol in Japanese black soybean vinegar. Considering the discovering of various functional ingredients and clarifying their mechanisms, some vinegars could be functional foods or even medicines, depending on a number of proofs that demonstrate these constituents can cure chronic diseases such as diabetes or cardiovascular problems.