Reactions of polyphenols in pomegranate peel with nitrite under simulated stomach conditions

Digestive interaction between dietary nitrite and dairy products generates novel nitrated linolenic acid products

Nitrated fatty acids are important anti-inflammatory and protective lipids formed in the gastric compartment, with conjugated linoleic acid (rumenic acid, RA, 9Z,11E-18:2) being the primary substrate for lipid nitration. The recently reported identification of nitrated rumelenic acid (NO2-RLA) in human urine has led to hypothesize that rumelenic acid (RLA, 9Z,11E,15Z-18:3) from dairy fat is responsible for the formation of NO2-RLA. To evaluate the source and mechanism of NO2-RLA formation, 15N labeled standards of NO2-RLA were synthesized and characterized. Afterward, milk fat with different RA and RLA levels was administered to mice in the presence of nitrite, and the appearance of nitrated fatty acids in plasma and urine followed. We confirmed the formation of NO2-RLA and defined the main metabolites in plasma, urine, and tissues. In conclusion, RLA obtained from dairy products is the main substrate for forming this novel electrophilic lipid reported to be present in human urine.

Inhibitory effects and reactions of gallic acid, catechin, and procyanidin B2 with nitrosation under stomach simulating conditions

Nitrite widely exists in meat products, and has the functions of bacteriostasis, antisepsis, and color development. However, in an acidic environment, nitrite will react with amines, and further generate nitrosamines with carcinogenic and teratogenic effects. Polyphenols have good antioxidant and nitrite-scavenging effects. This study aimed to evaluate the inhibitory effects of gallic acid, catechin, and procyanidin B2 on the nitrosation reaction under stomach simulating conditions and discuss the potential inhibitory mechanism. The nitrite scavenging rate and nitrosamine synthesis blocking rate of gallic acid, catechin, and procyanidin B2 under different reaction times and contents was determined by UV-vis spectrophotometry. The possible products of the reaction of the three polyphenols with nitrite were analyzed by high-performance liquid chromatography-mass spectrometry (HPLC-MS) to reveal the mechanism of inhibiting nitrification. The results showed that the scavenging rate of the three polyphenols on nitrite and the blocking rate of nitrosamine synthesis increased with the increase of the content and reaction time. The ability of the three polyphenols to inhibit nitrosation was catechin > procyanidin B2 > gallic acid. HPLC-MS analysis showed that under simulated gastric juice conditions, the three phenolics were oxidized by nitrous acid to form their semiquinone radicals as the intermediates and nitrosated derivatives, while nitrite might be converted to ˙NO. These results suggested that gallic acid, catechin, and procyanidin B2 could inhibit nitrosation reactions in an acidic environment and may be used as food additives to reduce nitrite residues and nitrosamines in food.

A comprehensive review on Ellagic acid in breast cancer treatment: From cellular effects to molecular mechanisms of action

Globally, breast cancer (BC) is the leading cause of cancer-related deaths in women. Hence, developing a therapeutic plan to overcome the disease is crucial. Numerous factors such as endogenous hormones and environmental factors may play a role in the pathophysiology of BC. Regarding the multi-modality treatment of BC, natural compounds like ellagic acid (EA) received has received increased interest in antitumor efficacy with lower adverse effects. Based on the results of this comprehensive review, EA has multiple effects on BC cells including (1) suppresses the growth of BC cells by arresting the cell cycle in the G0/G1 phase, (2) suppresses migration, invasion, and metastatic, (3) stimulates apoptosis in MCF-7 cells via TGF-β/Smad3 signaling axis, (4) inhibits CDK6 that is important in cell cycle regulation, (5) binds to ACTN4 and induces its degradation via the ubiquitin-proteasome pathway, inducing decreased cell motility and invasion in BC cells, (6) inhibits the PI3K/AKT pathway, and (7) inhibits angiogenesis-associated activities including proliferation (reduces VEGFR-2 tyrosine kinase activity). In conclusion, EA exhibits anticancer activity through various molecular mechanisms that influence key cellular processes like apoptosis, cell cycle, angiogenesis, and metastasis in BC. However, further researches are essential to fully elucidate its molecular targets and implications for clinical applications.

Novel strategies for controlling nitrite content in prepared dishes: Current status, potential benefits, limitations and future challenges

Sodium nitrite is commonly used as a multifunctional curing ingredient in the processing of prepared dishes, especially meat products, to impart unique color, flavor and to prolong the shelf life of such products. However, the use of sodium nitrite in the meat industry has been controversial due to potential health risks. Finding suitable substitutes for sodium nitrite and controlling nitrite residue have been a major challenge faced by the meat processing industry. This paper summarizes possible factors affecting the variation of nitrite content in the processing of prepared dishes. New strategies for controlling nitrite residues in meat dishes, including natural pre-converted nitrite, plant extracts, irradiation, non-thermal plasma and high hydrostatic pressure (HHP), are discussed in detail. The advantages and limitations of these strategies are also summarized. Raw materials, cooking techniques, packaging methods, and storage conditions all affect the content of nitrite in the prepared dishes. The use of vegetable pre-conversion nitrite and the addition of plant extracts can help reduce nitrite residues in meat products and meet the consumer demand for clean labeled meat products. Atmospheric pressure plasma, as a non-thermal pasteurization and curing process, is a promising meat processing technology. HHP has good bactericidal effect and is suitable for hurdle technology to limit the amount of sodium nitrite added. This review is intended to provide insights for the control of nitrite in the modern production of prepared dishes.

Fat-soluble vitamin and phytochemical metabolites: Production, gastrointestinal absorption, and health effects

Consumption of diets rich in fruits and vegetables, which provide some fat-soluble vitamins and many phytochemicals, is associated with a lower risk of developing certain degenerative diseases. It is well accepted that not only the parent compounds, but also their derivatives formed upon enzymatic or nonenzymatic transformations, can produce protective biological effects. These derivatives can be formed during food storage, processing, or cooking. They can also be formed in the lumen of the upper digestive tract during digestion, or via metabolism by microbiota in the colon. This review compiles the known metabolites of fat-soluble vitamins and fat-soluble phytochemicals (FSV and FSP) that have been identified in food and in the human digestive tract, or could potentially be present based on the known reactivity of the parent compounds in normal or pathological conditions, or following surgical interventions of the digestive tract or consumption of xenobiotics known to impair lipid absorption. It also covers the very limited data available on the bioavailability (absorption, intestinal mucosa metabolism) and summarizes their effects on health. Notably, despite great interest in identifying bioactive derivatives of FSV and FSP, studying their absorption, and probing their putative health effects, much research remains to be conducted to understand and capitalize on the potential of these molecules to preserve health.

Antioxidant and Fatty Acid Changes in Pomegranate Peel With Induced Chilling Injury and Browning by Ethylene During Long Storage Times

Pomegranate (Punica granatum) is a non-climacteric fruit with a high antioxidant content in arils and peels, of which 92% are anthocyanins and tannins. However, it is susceptible to chilling injury (CI), a physiological disorder concentrated in the peel, which can affect the organoleptic quality of the fruit. To understand the effects of modified atmosphere and ethylene in responses to stress on the antioxidant quality of the fruit and composition of fatty acids in the peel under CI conditions, the exogenous ethylene treatments (0.5, 1.0, and 1.5 μg L^-1), 1-methylcyclopropene (1-MCP; 1 μl L^-1), modified atmosphere packaging (MAP: XTend™ bags), combined strategy MAP/1-MCP, and package in macroperforated bags (MPB-control treatment) were evaluated. The assay was performed in cold conditions (2 ± 1°C; 85% RH) to stimulate damage and was sampled for 120 days (+3 days at 20°C). During cold storage, CI symptoms began at 20 days in MPB and at 60 days for all treatments with exogenous ethylene; CI symptoms were delayed up to 120 days in MAP, 1-MCP, and the combined MAP/1-MCP treatment. Damage was concentrated in the peel. Ethylene and MPB-control treatments induced significant electrolyte leakage, lipid peroxidation, and oxidative damage. In contrast, MAP alone or in combination with 1-MCP successfully delayed CI symptoms. However, no significant differences were observed between treatments in fatty acid content, e.g., in the peel, oleic acid, linoleic acid, palmitic acid, but a significant loss was noted after 60 days of storage. Cold storage caused an increase in anthocyanin concentration in the peel and arils, increasing up to 12 times in the peel of the fruit treated with ethylene at the final stage of storage (120 days + 3 days at 20°C), with non-significant differences in the tannin content in the peel. During long-term cold storage of pomegranate, MAP and 1-MCP treatments delay and reduce the appearance of CI symptoms. This long cold storage induces an important decrease in the unsaturated/saturated fatty acid ratio, which is not reversed by any postharvest treatment. A higher unsaturated/saturated fatty acid ratio after 1-MCP treatments showed a protective effect in peel tissues. In addition, it was possible to increase the concentration of anthocyanins in the peel of cold-storage pomegranates treated with ethylene.