Influence of Location of Production, Season and Genotype on Caffeine and Flavan-3-ols in Young Green Tea （Camellia sinensis） Leaves in Kenya

Although tea is grown in agro-ecological regions widely varying in environmental factors affecting yield and quality, planters usually import genetic materials across the different growing regions assuming genotypes with good quality attributes in one location maintain their status in all regions. However, tea quality has not been replicated in new production regions. Black tea quality is influenced by the green leaf quality precursors including caffeine, total polyphenols and individual flavan-3-ols which are precursors of theaflavins and thearubigins, key plain black tea quality parameters. Factors influencing levels of the precursors compounds have not been quantified for popular Kenyan tea cultivars. The influence of geographical production location and seasons on levels and ratios of the quality precursors for 10 black tea popular clones grown in three locations in Kenya under uniform agronomic inputs were monitored. Caffeine varied significantly （P _〈 0.05） with clones and location but not with season. The flavan-3-ols and their ratios all varied （P 〈 0.05） with clones and site but not with season, with significant interactions （P 〈 0.05） between locations and clones, and locations and seasons. These results explain the observed variations in plain black tea quality due to clones and location of production. Thus, farmers in different locations are unlikely to produce black tea of same quality. It is therefore necessary to evaluate new tea genotypes in intended growing areas to establish cultivars suitable for producing high quality plain black teas in the locations. Seasonal variations in plain black tea in Kenya are unlikely to vary significantly due to flavan-3-ols.

A New Flavan-3-ol Glucoside from Daphniphyllum oldhami

A new flavan-3-ol glucoside, (-)-afzelechin-7-O-β-D-glucopyranoside (1), has been isolated from the stem of Daphniphyllum oldhami. The structure of the new compound was elucidated on the basis of detailed spectroscopie analysis and comparison with related compounds.

A Novel Phenylpropanoid-substituted Catechin Glycoside and a New Dihydrochalcone from Sarcandra glabra

A novel phenylpropanoid-substituted catechin glycoside glabraoside A 1 and a new dihydrochalcone 3＇-（7＂-allylphenyl）-2＇,4＇,4＂-trihydroxy-6＇-methoxydihydrochalcone 2 were isolated from the herbs of Sarcandra glabra. Their structures were elucidated on the basis of spectroscopic analyses and chiroptical methods.

Dietary flavonoid intake and risk of stomach and colorectal cancer

Stomach and colorectal cancers are common cancers and leading causes of cancer deaths.Because the alimentary tract can interact directly with dietary components,stomach and colorectal cancer may be closely related to dietary intake.We systematically searched published literature written in English via PubMed by searching for terms related to stomach and colorectal cancer risk and dietary flavonoids up to June 30,2012.Twenty-three studies out of 209 identified articles were finally selected for the analysis.Log point effect estimates and the corresponding standard errors were calculated using covariate-adjusted point effect estimates and 95%CIs from the selected studies.Total dietary flavonoid intake was not associated with a reduced risk of colorectal or stomach cancer [odds ratio(OR)(95%CI) = 1.00(0.90-1.11) and 1.07(0.70-1.61),respectively].Among flavonoid subclasses,the intake of flavonols,flavan-3-ols,anthocyanidins,and proanthocyanidins showed a significant inverse association with colorectal cancer risk [OR(95%CI) = 0.71(0.63-0.81),0.88(0.79-0.97),0.68(0.56-0.82),and 0.72(0.61-0.85),respectively].A significant association was found only between flavonols and stomach cancer risk based on a limited number of selected studies [OR(95%CI) = 0.68(0.46-0.99)].In the summary estimates from casecontrol studies,all flavonoid subclasses except flavones and flavanones were inversely associated with colorectal cancer risk,whereas neither total flavonoids nor any subclasses of flavonoids were associated with colorectal cancer risk in the summary estimates based on the cohort studies.The significant association between flavonoid subclasses and cancer risk might be closely related to bias derived from the case-control design.There was no clear evidence that dietary flavonoids are associated with reduced risk of stomach and colorectal cancer.

Dietary (poly)phenol intake is associated with cardiometabolic health parameters in adolescents

The protective role of(poly)phenols against metabolic disorders has been extensively studied in adults but not in adolescents.To assess associations of dietary(poly)phenols and their subclasses with cardiometabolic health parameters in adolescents.A cross-sectional study was conducted in 944 individuals aged 11–14 years enrolled in the SI!Program for Secondary Schools trial(NCT03504059).(Poly)phenol intake was assessed using semiquantitative food frequency questionnaires and the Phenol-Explorer database.The measured cardiometabolic parameters were waist circumference(WC)age-sex Z-score,blood pressure(BP)age-sex Z-score,blood glucose(BG),triglycerides(TG),and high-density lipoprotein cholesterol(HDL-c).Multilevel mixedeffect linear regression models were applied to examine the association between(poly)phenol quintiles and cardiometabolic health parameters.Compared to the lowest quintile,adolescents in the highest quintile of total(poly)phenol intake had lower WC Z-scores,mean arterial pressure Z-scores,and HDL-c after multivariable adjustment.The WC Z-scores and HDL-c were lower in the highest quintile of flavonoid intake compared to the lowest quintile.The highest quintile of phenolic acid intake was associated with a lower WC Z-score and TG levels,and the highest quintile of stilbene intake with lower BG and TG,and with higher HDL-c compared to the lowest quintile.A higher intake of(poly)phenols,especially flavonoids,phenolic acids,and stilbenes,was associated with better cardiometabolic parameters in adolescents.

Identification and biosynthesis of plant papanridins,a group of novel oligomeric flavonoids

The discovery of novel flavonoids and elucidation of their biosynthesis are fundamental to understanding their roles in plants and their benefits for human and animal health.Here,we report a new pathway for polymerization of a group of novel oligomeric flavonoids in plants.We engineered red cells for discovering genes of interest involved in the flavonoid pathway and identified a gene encoding a novel flavanol polymerase(FP)localized in the central vacuole.FP catalyzes the polymerization of flavanols,such as epicatechin and catechin,to produce yellowish dimers or oligomers.Structural elucidation shows that these compounds feature a novel oligomeric flaven–flavan(FF)skeleton linked by interflavan–flaven and interflaven bonds,distinguishing them from proanthocyanidins and dehydrodicatechins.Detailed chemical and physical characterizations further confirmed the novel FFs as flavonoids.Mechanistic investigations demonstrated that FP polymerizes flavan-3-ols and flav-2-en-3-ol carbocation,forming dimeric or oligomeric flaven-4→8-flavans,which we term“papanridins.”Data from transgenic experiments,mutant analysis,metabolic profiling,and phylogenetic analyses show that the biosynthesis of papanridins is prevalent in cacao,grape,blueberry,corn,rice,Arabidopsis,and other species in the plant kingdom.In summary,our study discoveries a group of novel oligomeric flavonoids,namely papanridins,and reveals that a novel FP-mediated polymerization mechanism for the biosynthesis of papanridins in plants.