Myriad evidence attests to the health-promoting benefits of tea drinking.While there are multiple factors of tea influencing the effective biological properties,tea polyphenols are the most significant and valuable co...Myriad evidence attests to the health-promoting benefits of tea drinking.While there are multiple factors of tea influencing the effective biological properties,tea polyphenols are the most significant and valuable components.The chemical characterization and physical characteristics of tea polyphenols have been comprehensively studied over the previous years.Still the emergence of new chemistry in tea,particularly the property of scavenging reactive carbonyl species(RCS)and the newly discovered flavoalkaloid compounds,has drawn increasing attention.In this review,we summarize recent findings of a new class of compounds in tea-flavonoid alkaloids(flavoalkaloids),which exist in fresh tea leaves and can be generated during the process of post-harvesting,and also postulate the formation mechanism of flavoalkaloids between catechins and theanine-derived Strecker aldehyde.Additionally,we detail the up-to-date research results of tea polyphenols regarding their ability to trap RCS and their in vivo aminated metabolites to suppress advanced glycation ends products(AGEs).We further raise questions to be addressed in the near future,including the synthetic pathways for the generation of flavoalkaloids and AGEs in fresh tea leaves before processing and the concentrations of tea polyphenols that affect their RCS scavenging capability due to their pro-oxidant nature.More intensive research is warranted to elucidate the mechanisms of action underlying the biological activity of flavoalkaloids and the pharmacological application of tea polyphenols in scavenging RCS and impeding detrimental AGEs.展开更多
Oxyresveratrol(ORes,trans-2,4,3′,5′-tetrahydroxy stilbene)naturally exists in mulberry,grapes,peanuts and other plants.It belongs to stilbene polyphenolic family and has an extra hydroxyl group at 2-position compari...Oxyresveratrol(ORes,trans-2,4,3′,5′-tetrahydroxy stilbene)naturally exists in mulberry,grapes,peanuts and other plants.It belongs to stilbene polyphenolic family and has an extra hydroxyl group at 2-position comparing with resveratrol(Res).Hence,ORes has stronger antioxidant activity than resveratrol.In present study,we employed a rat hepatic fibrosis model induced by carbon tetrachloride(CCl_(4))and administrated ORes via gavage feeding to study the protective effects and potential mechanisms of ORes against hepatic fibrosis.We demonstrated that rat liver oxidative damage induced by CCl_(4)was significantly alleviated after ORes feeding.Furthermore,the mRNA transcription levels ofα-smooth muscle actinn(˛-SMA),desmin,and two MMPs(MMP2 and MMP9)were reduced and the expression levels of transforming growth factorβ1(TGF-β1),p-small mother against decapen-taplegic protein(Smad)1/2 and p-extracellular signal-regulated kinases(ERK)1/2 in the liver tissue down-regulated dramatically.In a parallel study with Res,ORes showed more efficacious protective effect than Res against rat liver fibrosis,which is attributed to extended conjugation system due to the extra hydroxyl group at 2-position on ORes making it more electron-rich and susceptible to oxidation than Res.Therefore,dietary consumption of mulberry and other fruits containing ORes may be beneficial in the prevention of liver fibrosis.展开更多
Tea(Camellia sinensis)is widely considered to promote feelings of calming and soothing.This effect is attributed to L-theanine(L-γ-glutamylethylamide)in tea,a non-protein amino acid mainly derived from tea leaves.As ...Tea(Camellia sinensis)is widely considered to promote feelings of calming and soothing.This effect is attributed to L-theanine(L-γ-glutamylethylamide)in tea,a non-protein amino acid mainly derived from tea leaves.As a naturally occurring structural analogue of glutamate,L-theanine competes for the receptors with glutamate and is able to pass the blood-brain barrier to exert its relaxation effect.This review focuses on the relaxation effect of L-theanine,including animal models and the latest human trials as well as the potential molecular mechanisms regarding neuron stem cells.The biological efficacy of dietary L-theanine in the food matrix has been further discussed in this review in relation to the physiological changes in the gastrointestinal tract and bindings of L-theanine with other food components.展开更多
基金supported by Hubei Science and Technology Plan Key Project(G2019ABA100)。
文摘Myriad evidence attests to the health-promoting benefits of tea drinking.While there are multiple factors of tea influencing the effective biological properties,tea polyphenols are the most significant and valuable components.The chemical characterization and physical characteristics of tea polyphenols have been comprehensively studied over the previous years.Still the emergence of new chemistry in tea,particularly the property of scavenging reactive carbonyl species(RCS)and the newly discovered flavoalkaloid compounds,has drawn increasing attention.In this review,we summarize recent findings of a new class of compounds in tea-flavonoid alkaloids(flavoalkaloids),which exist in fresh tea leaves and can be generated during the process of post-harvesting,and also postulate the formation mechanism of flavoalkaloids between catechins and theanine-derived Strecker aldehyde.Additionally,we detail the up-to-date research results of tea polyphenols regarding their ability to trap RCS and their in vivo aminated metabolites to suppress advanced glycation ends products(AGEs).We further raise questions to be addressed in the near future,including the synthetic pathways for the generation of flavoalkaloids and AGEs in fresh tea leaves before processing and the concentrations of tea polyphenols that affect their RCS scavenging capability due to their pro-oxidant nature.More intensive research is warranted to elucidate the mechanisms of action underlying the biological activity of flavoalkaloids and the pharmacological application of tea polyphenols in scavenging RCS and impeding detrimental AGEs.
基金Grant from Hubei Province,China(GRANT number 2019ABA100)。
文摘Oxyresveratrol(ORes,trans-2,4,3′,5′-tetrahydroxy stilbene)naturally exists in mulberry,grapes,peanuts and other plants.It belongs to stilbene polyphenolic family and has an extra hydroxyl group at 2-position comparing with resveratrol(Res).Hence,ORes has stronger antioxidant activity than resveratrol.In present study,we employed a rat hepatic fibrosis model induced by carbon tetrachloride(CCl_(4))and administrated ORes via gavage feeding to study the protective effects and potential mechanisms of ORes against hepatic fibrosis.We demonstrated that rat liver oxidative damage induced by CCl_(4)was significantly alleviated after ORes feeding.Furthermore,the mRNA transcription levels ofα-smooth muscle actinn(˛-SMA),desmin,and two MMPs(MMP2 and MMP9)were reduced and the expression levels of transforming growth factorβ1(TGF-β1),p-small mother against decapen-taplegic protein(Smad)1/2 and p-extracellular signal-regulated kinases(ERK)1/2 in the liver tissue down-regulated dramatically.In a parallel study with Res,ORes showed more efficacious protective effect than Res against rat liver fibrosis,which is attributed to extended conjugation system due to the extra hydroxyl group at 2-position on ORes making it more electron-rich and susceptible to oxidation than Res.Therefore,dietary consumption of mulberry and other fruits containing ORes may be beneficial in the prevention of liver fibrosis.
基金supported by Hubei Science and Technology Plan Key Project(G2019ABA100)。
文摘Tea(Camellia sinensis)is widely considered to promote feelings of calming and soothing.This effect is attributed to L-theanine(L-γ-glutamylethylamide)in tea,a non-protein amino acid mainly derived from tea leaves.As a naturally occurring structural analogue of glutamate,L-theanine competes for the receptors with glutamate and is able to pass the blood-brain barrier to exert its relaxation effect.This review focuses on the relaxation effect of L-theanine,including animal models and the latest human trials as well as the potential molecular mechanisms regarding neuron stem cells.The biological efficacy of dietary L-theanine in the food matrix has been further discussed in this review in relation to the physiological changes in the gastrointestinal tract and bindings of L-theanine with other food components.
