Ellagic acid and its fermentative derivative urolithin A show reverse effects on the gp91-phox gene expression, resulting in opposite alterations in all-trans retinoic acid-induced superoxide generating activity of U937 cells

Dietary polyphenols and their relationship to the modulation of non-communicable chronic diseases and epigenetic mechanisms: A mini-review

Chronic Non-Communicable Diseases (NCDs) have been considered a global health problem, characterized as diseases of multiple factors, which are developed throughout life, and regardless of genetics as a risk factor of important relevance, the increase in mortality attributed to the disease to environmental factors and the lifestyle one leads. Although the reactive species (ROS/RNS) are necessary for several physiological processes, their overproduction is directly related to the pathogenesis and aggravation of NCDs. In contrast, dietary polyphenols have been widely associated with minimizing oxidative stress and inflammation. In addition to their antioxidant power, polyphenols have also drawn attention for being able to modulate both gene expression and modify epigenetic alterations, suggesting an essential involvement in the prevention and/or development of some pathologies. Therefore, this review briefly explained the mechanisms in the development of some NCDs, followed by a summary of some evidence related to the interaction of polyphenols in oxidative stress, as well as the modulation of epigenetic mechanisms involved in the management of NCDs.

Urolithins Modulate the Viability, Autophagy, Apoptosis, and Nephrin Turnover in Podocytes Exposed to High Glucose

Urolithins are bioactive compounds generated in human and animal intestines because of the bacterial metabolism of dietary ellagitannins (and their constituent, ellagic acid). Due to their multidirectional effects, including anti-inflammatory, antioxidant, anti-cancer, neuroprotective, and antiglycative properties, urolithins are potential novel therapeutic agents. In this study, while considering the future possibility of using urolithins to improve podocyte function in diabetes, we assessed the results of exposing mouse podocytes cultured in normal (NG, 5.5 mM) and high (HG, 25 mM) glucose concentrations to urolithin A (UA) and urolithin B (UB). Podocytes metabolized UA to form glucuronides in a time-dependent manner; however, in HG conditions, the metabolism was lower than in NG conditions. In HG milieu, UA improved podocyte viability more efficiently than UB and reduced the reactive oxygen species level. Both types of urolithins showed cytotoxic activity at high (100 µM) concentration. The UA upregulated total and surface nephrin expression, which was paralleled by enhanced nephrin internalization. Regulation of nephrin turnover was independent of ambient glucose concentration. We conclude that UA affects podocytes in different metabolic and functional aspects. With respect to its pro-survival effects in HG-induced toxicity, UA could be considered as a potent therapeutic candidate against diabetic podocytopathy.

Potential role of green tea amino acid L-theanine in activation of innate immune response via enhancing expression of cytochrome b 558 responsible for the reactive oxygen species-generating ability of leukocytes

L-Theanine (N-ethyl-L-glutamine) is an analog of L-glutamine and L-glutamic acid, accounts for up to 50% of all free amino acids in green tea, and elicits an umami taste. Since L-theanine also shows various physiological activities including immune response-modifying activities, it is expected as an excellent health-promoting phytochemical agent. To know the influences of L-theanine on the human innate immune response, we investigated the effect of L-theanine on the superoxide anion (O₂ ^- )-generating system of leukocytes using U937 cells. The O₂ ^- -generating system in leukocytes is consisted of membrane cytochrome b ₅₅₈ protein (a complex of p22-phox and gp91-phox proteins) and cytosolic p40-phox, p47-phox and p67-phox proteins. Addition of 500 μM L-theanine caused remarkable enhancement of the all-trans retinoic acid (ATRA)-induced O₂ ^- -generating activity (to ~470% of ATRA-treated cells), but not L-glutamine and L-glutamic acid. Semiquantitative RT-PCR showed that the transcription level of gp91-phox is significantly increased in ATRA and L-theanine-cotreated cells. Chromatin immunoprecipitation assay revealed that L-theanine enhances acetylations of Lys-9 and Lys-14 residues of histone H3 within chromatin surrounding the promoter region of gp91-phox gene. Immunoblotting demonstrated that membrane cytochrome b ₅₅₈ proteins remarkably accumulate in ATRA plus L-theanine-treated cells. These results suggested that L-theanine brings about remarkable accumulation of cytochrome b ₅₅₈ protein via up-regulating the transcription of gp91-phox gene during leukocyte differentiation, resulting in marked augmentation of the O₂ ^- -generating ability, which is one of the most important functions of leukocytes responsible for the innate immune system. This article is protected by copyright. All rights reserved.

Complexation of ellagic acid with α-lactalbumin and its antioxidant property

Ellagic acid possesses numerous bioactivities such as antioxidant activity and anti-inflammatory effect. In this work, the binding interaction between ellagic acid and α-lactalbumin was investigated by multi-spectroscopy and the results suggested that ellagic acid could change the conformation of α-lactalbumin. Chromatographic analysis proved the interaction of α-lactalbumin with ellagic acid taken place in less than 30 min and this interaction was stable. Computer simulations showed that both aromatic clusters Ⅰ and Ⅱ of α-lactalbumin were active sites for ellagic acid. Interestingly, both the results of molecular docking and molecular dynamics simulations suggested that ellagic acid tended to bind to aromatic cluster Ⅱ rather than aromatic cluster Ⅰ. Moreover, α-lactalbumin could enhance the antioxidant property of ellagic acid, indicating that the solubility of ellagic acid might be improved by combining α-lactalbumin. Overall, this work suggested that α-lactalbumin exhibited binding affinity for ellagic acid and enhanced its antioxidant property.

Maillard Browning Inhibition by Ellagic Acid via Its Adduct Formation with the Amadori Rearrangement Product

The Maillard reaction performed under a stepwise increase of temperature was applied for researching the inhibition of Maillard browning caused by ellagic acid. Ellagic acid was found effective for the inhibition of melanoidin formation in the xylose-glycine Maillard reaction but depended on its dosage and the point of time it was added in the reaction system. The lightest color of the Maillard reaction products was observed when ellagic acid was added at the 90th min, which was the point of time when the Amadori rearrangement product (ARP) developed the most. LC-ESI-MS/MS analysis results showed a significant tendency of the ellagic acid hydrolysis product to react with the predominant intermediate ARP to yield an adduct. The adduct stabilized the ARP and delayed its decomposition and inhibited the downstream reactions toward browning. After the ARP was depleted, ellagic acid also showed an effect on scavenging some short-chain dicarbonyls which contributed to the inhibition of Maillard browning.