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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. As l‐theanine also shows various physiological activities including immune response‐modifying activities, it is expected to be 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 consists of membrane cytochrome b558 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‐co‐treated cells. Chromatin immunoprecipitation revealed that l‐theanine enhances acetylations of Lys‐9 and Lys‐14 residues of histone H3 within the chromatin surrounding the promoter region of the gp91‐phox gene. Immunoblotting demonstrated that membrane cytochrome b558 proteins remarkably accumulate in ATRA + l‐theanine‐treated cells. These results suggested that l‐theanine brings about a remarkable accumulation of cytochrome b558 protein via upregulating the transcription of the 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. [ABSTRACT FROM AUTHOR]

This study was performed to investigate the enhanced antioxidant effects of citrus pomace (CP) extracts processed by super-heated steam (SHS). CP extracts were obtained using a closed SHS system at three different temperatures (100, 200, and 300 °C) with an extraction time of 10 or 20 min. These extracts were evaluated for their antioxidant activities by measuring their DPPH, alkyl, and hydroxyl radical scavenging activity using Electron Spin Resonance (ESR) spectroscopy and for their protective effects against H 2 O 2 -induced oxidative stress in Vero cells. All extracts exhibited strong radical scavenging activities and protective effects against H 2 O 2 -induced Vero cell damage. Especially, the SHS-CP extracts obtained at 300 °C with extraction times of both 10 min and 20 min exhibited antioxidant activities that were significantly higher than those of ethanol extracts and SHS-CP extracts obtained at other temperatures. The total phenolic and flavonoid contents of SHS-CP extracts and their antioxidant activities were found to be increased with elevated processing temperatures. Moreover, gas chromatography/mass spectrometry (GC/MS) in the presence of a methylating reagent revealed that some characteristic polyphenols and polyhydroxycyclohexanes were present in the SHS-CP extracts. Thus, this study demonstrated that SHS extraction is an efficient and environmentally friendly method for extracting antioxidants from CP. [ABSTRACT FROM AUTHOR]

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. As l-theanine also shows various physiological activities including immune response-modifying activities, it is expected to be 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 (O 2 - )-generating system of leukocytes using U937 cells. The O 2 - -generating system in leukocytes consists 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 O 2 - -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-co-treated cells. Chromatin immunoprecipitation revealed that l-theanine enhances acetylations of Lys-9 and Lys-14 residues of histone H3 within the chromatin surrounding the promoter region of the gp91-phox gene. Immunoblotting demonstrated that membrane cytochrome b 558 proteins remarkably accumulate in ATRA +  l-theanine-treated cells. These results suggested that l-theanine brings about a remarkable accumulation of cytochrome b 558 protein via upregulating the transcription of the gp91-phox gene during leukocyte differentiation, resulting in marked augmentation of the O 2 - -generating ability, which is one of the most important functions of leukocytes responsible for the innate immune system., (© 2022 The Societies and John Wiley & Sons Australia, Ltd.)

Ellagitannins (esters composed of glucose and ellagic acid) are hydrolyzed to generate ellagic acid in gut followed by conversion of ellagic acid to urolithins such as urolithin A by intestinal bacteria. Since urolithins are absorbed by gut easier than ellagitannins and ellagic acid, and show various physiological activities (e.g. anti-cancer, anti-cardiovascular disease, anti-diabetes mellitus, anti-obesity and anti-Alzheimer disease activities), they are expected as excellent health-promoting phytochemicals. Here, using human monoblast U937 cells, we investigated the effect of ellagic acid and urolithin A on the superoxide anion (O 2 - )-generating system of phagocytes, which is consisted of five specific protein factors (membrane proteins: p22-phox and gp91-phox, cytosolic proteins: p40-phox, p47-phox and p67-phox). Twenty micromolar of urolithin A enhanced the all- trans retinoic acid (ATRA)-induced O 2 - -generating activity (to ~175%) while 20 μM ellagic acid inhibited the ATRA-induced O 2 - -generating activity (to ~70%). Semiquantitative RT-PCR showed that transcription level of gp91-phox was certainly decreased (to ~70%) in ATRA plus ellagic acid-treated cells, while that of gp91-phox was significantly increased (to ~160%) in ATRA plus urolithin A-treated cells. Chromatin immunoprecipitation assay suggested that urolithin A enhanced acetylations of Lys-9 residues of histone H3 within chromatin surrounding the promoter region of gp91-phox gene, but ellagic acid suppressed the acetylations. Immunoblotting also revealed that ATRA plus urolithin A-treatment up-regulated protein levels of p22-phox (to ~160%) and gp91-phox (to ~170%) although ATRA plus ellagic acid-treatment down-regulated protein levels of p22-phox (to ~70%) and gp91-phox (to ~60%). These results suggested that conversion of ellagic acid to urolithin A in gut may bring about reverse effects on the gp91-phox gene expression, resulting in opposite alterations in O 2 - -generating activity of intestinal macrophages., Competing Interests: The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: This work was supported in part by JSPS KAKENHI Grant Number 19K02329 (to H. K.) and 18K07804 (to F. K.)., (© 2021 The Authors.)