大量研究表明,肠道菌群生态与胃癌、肝癌、肠癌及胰腺癌等紧密关联.通常情况下,肠道菌群处于稳定状态,当肠道菌群组成发生改变时,会对代谢系统以及免疫系统产生影响,也会影响药物的吸收、代谢及转化,这对癌症的发生、发展以及癌症治疗都存在一定的影响,这也提示肠道菌群是潜在的癌症诊断与治疗的靶标.通过靶向调节肠道菌群对癌症进行治疗,能够有效地避免放化疗药物带来的副作用,有望成为癌症治疗的一种更加有效且低副作用的治疗方式.本文综述了肠道菌群影响癌症发生、发展以及不同治疗方式的研究进展,同时对肠道菌群在癌症诊断与治疗方面的作用和方式进行展望.

延长健康寿命的跨度对每个人都有重要意义,百岁老人存在独特的肠道菌群特征,肠道微生物群是许多年龄相关变化的核心,菌群特征以及菌群基因组成改变都能影响机体寿命.一些饮食和药物要发挥延寿效果也离不开微生物的参与,微生物具有重要的介导和转化作用,益生菌和粪便移植等措施在动物模型中已被明确可以影响机体寿命.越来越多的研究表明微生物不仅能产生小分子化合物促进健康寿命跨度的增加乃至延长个体寿命如γ-氨基丁酸、荚膜异多糖酸,还能影响宿主的生物合成代谢如5-羟色胺,甚至间接参与宿主信号通路的调控.目前对于这些微生物的生物学功能以及对宿主寿命的影响还没有系统的总结,对肠道微生物影响寿命的证据以及生理机制进行综述,为改善老年期健康状况的干预措施提供参考.

2型糖尿病(type 2 diabetes mellitus,T2DM)是一种因胰岛素分泌不足或胰岛素抵抗而引起的慢性代谢疾病,T2DM患病人数的快速增长使治疗和预防T2DM成为世界上亟待解决的医学问题.随着微生物组学技术的进步,肠道菌群及其代谢产物与T2DM的研究亦逐渐深入,肠道菌群可能成为治疗和预防T2DM的靶点.肠道菌群及其代谢产物作用于T2DM的潜在机制,主要是参与体内炎症反应、增加肠道短链脂肪酸产量、调节肠道胆汁酸的代谢、调节支链氨基酸的代谢等.目前,治疗T2DM的药物可能会产生一些副作用,而基于肠道菌群干预T2DM的措施相对安全无害.例如,可通过严格控制的特定结构饮食长期摄入或增加益生菌的长期摄取控制血糖,或通过口服可影响肠道菌群生态结构的降糖药物(二甲双胍、阿卡波糖)有效地调控血糖水平.综述基于肠道菌群及其代谢产物诱发T2DM的潜在机制,研讨基于肠道菌群干预T2DM的措施,从肠道菌群的新视角探索治疗T2DM的新方法,为彻底治疗T2DM提供一种新可能.

糖尿病是一个世界性问题,在中国就有超过1.3亿人患有糖尿病.糖尿病主要分为1型糖尿病和2型糖尿病.遗憾的是,糖尿病至今尚未达成有效的预防和治愈手段.但是,近年来的一系列突破性的研究成果,让我们看到了治愈糖尿病的希望.在这里我们回顾了目前关于1型糖尿病和2型糖尿病可能的治愈途径的研究进展.这些途径包括胰岛移植和1型糖尿病的干细胞治疗,以及抗体诱导的α细胞向β细胞分化,以及1型糖尿病中某些类型的β细胞能逃逸免疫攻击;糖尿病早期胰岛素长期注射治疗、GABA以及青蒿素长期诱导促进α细胞转化为β细胞从而恢复胰岛的结构和功能;研究还表明,长期增加维生素D受体的活性有利于减少炎症反应从而保护β细胞.但是在青蒿素诱导治愈2型糖尿病方面仍然存在争议.

近年来,肠道微生物与机体健康之间关系的研究越来越受关注.研究发现,肠道微生物对身体免疫系统的调节、食物的消化、药物的代谢,以及很多疾病的发生与治疗都密切相关.事实上,微生物不仅仅在肠道中大量存在,而且在皮肤、眼睛、口腔、子宫等身体其他部位也存在,且具备丰富的多样性;不同部位微生物与疾病的发生及其生理机制也不同.目前对于这些人体微生物的生物学功能以及紊乱导致的疾病尚未有系统的总结.文章对肠道、皮肤、眼睛、口腔、子宫在宿主健康和生理代谢活动方面进行综述,为相关疾病的预防和治疗提供参考.

慢性疼痛是一种能给人们身心健康带来伤害的慢性疾病.特别在中老年人群中,慢性疼痛的发生率仍然很高.慢性疼痛不仅会损害身心健康,而且还会严重影响人们的正常工作和生活.目前研究发现了多种炎症因子及其通路与慢性疼痛的痛觉敏化过程相关,同时这类炎症因子也被发现参与细胞衰老过程,其中p38有丝分裂原激活蛋白激酶(p38 MAPK)通路及其相关的核转录因子(NF-κB)、肿瘤坏死因子-α(TNF-α)可能是关联慢性疼痛和衰老的关键点.阐明慢性疼痛与细胞衰老的关系有利于进一步探究治疗慢性疼痛及延缓衰老的新思路,同时提高患者及相关医务工作者、科研人员对慢性疼痛的重视程度.

采用全自动顶空固相微萃取(headspace solid-phase microextraction,HS-SPME)和气相色谱-质谱(gas chromatography-mass spectrometry,GC-MS)对我国2种不同省份的白茶(云南月光白茶和福建白毫银针白茶)的香气成分进行了研究,并比较了它们在香气化学成分及含量上的差异.结果在2种白茶中共鉴定出香气成分92种,共有香气成分56种;两种白茶香气成分均以碳氢化合物和醇类化合物为主,其余化合物含量均较低;月光白茶的香气成分主要是芳樟醇、十三烷、咖啡因、二氢猕猴桃内酯、2,2',5,5'-四甲基-1,1'-联苯基、芳樟醇氧化物、D-柠檬烯、β-蒎烯、2,6,10,14-四甲基十五烷等;而白毫银针白茶的香气成分主要是香叶醇、芳樟醇、芳樟醇氧化物、β-蒎烯、十二烷、雪松醇、苯乙醇、(Z)-3,7-二甲基-1,3,6-辛三烯、水杨酸甲酯等.

The volatile components of Fujian Tieguanyin oolong tea and Taiwan Ruanzhi oolong tea which from different regions were extracted by fully automated headspace solid-phase microextraction (HS-SPME), and were identified by gas chromatography-mass spectrometry (GC-MS). Then comparison of volatile components and contents by chemometrics methods between the teas was made. Results showed that a total of 71 volatile constituents were identified in seven teas, and alcohol compounds, hydrocarbon compounds, ester compounds were the major volatile components in Fujian Tieguanyin oolong tea and Taiwan Ruanzhi oolong tea, while the content of other compounds were low. The major volatile compounds of Fujian Tieguanyin oolong tea were nerolidol, indole, 2-phenethyl-2-methylbutyrate, α-farnesene, phenethyl butyrate, 2-phenethyl hexanoate, cis-3-hexenyl hexanoate, jasmine lactone, phytol, phenylethyl alcohol, linalool, ylangene, jasmone, etc., while the major volatile compounds of Taiwan Ruanzhi oolong tea were geraniol, indole, linalool, nerolidol, hotrienol, α-farnesene, jasmine lactone, caffeine, jasmone, methyl jasmonate, benzeneacetonitrile, phytol, cis-3-hexenyl hexanoate, etc. Principal component analysis (PCA) and partial least squares-discriminant analysis (PLS-DA) showed that Fujian Tieguanyin oolong tea and Taiwan Ruanzhi oolong tea could be clearly distinguished according to their volatile characteristics, and found that geraniol, nerolidol, linalool, 2-phenethyl-2-methylbutyrate, methyl salicylate, α-farnesene, phenylethyl alcohol, methyl jasmonate may be the key compounds which lead to differences between the oolong teas from different regions.

α-神经毒素(α-neurotoxin,α-NTX)是眼镜蛇科和海蛇科蛇毒的主要毒性成分之一,属一种非酶类多肽,能以特异的、几乎不可逆的状态与烟碱型乙酰胆碱受体(nicotinic acetylcholine receptor,nAChR)结合.nAChR在生物学、病理学、生理学等方面发挥着重要作用,与感觉、认知、疼痛、保护神经元和递质释放等关系密切.神经型nAChR参与多种脑功能,与多种神经退行性疾病的发生密切相关,如阿尔茨海默病(AD)、帕金森病(PD)和精神分裂症(Sz)等.因此,研究α-NTX与nAChR的相互作用关系及其作用机制,对深入研究神经活动机制及相关疾病的治疗机理和寻找新型药物等具有重要意义.对α-NTX、nAChR的结构以及它们之间相互作用的研究进展进行了归纳和评述,对其相互作用位点作了较为详细的介绍.

Baking is the last, and yet most essential, step in the formation of the final distinct flavour of most black tea products. In this study, the influence of baking on the volatile components of Dianhong black tea, which is one of the most popular black teas in China, was investigated. As a very fast, effective, and simple method for collecting volatiles, headspace solid-phase microextraction (HS-SPME) with a 65 mu m PDMS/DVB fibre was used to extract the volatile compounds of Dianhong black tea, and the volatile components were further separated and identified by gas chromatography-mass spectrometry (GC-MS). The results showed that the peak areas of alcohols, aldehydes, esters, and ketones were increased, but that those of some alkanes, acids, and nitrogen compounds did not demonstrate an obvious increase after baking. The differences generated by baking process actually result in the distinct flavour of most black teas and can be used as a model for analysing the chemical composition of special flavours, and for quality improvement and process control.

Pu-erh ripe tea is one of the main tea products in China, which has a unique woody, chestnut fragrance flavour, distinct from other teas. Because of the largely excessive production capacity, it is now possible and necessary to utilise it to produce tea essential oil. In this study, the extraction efficiency of Soxhlet extraction (Soxhlet), ultrasonic-assisted extraction (UAE), simultaneous distillation extraction (SDE), and steam distillation extraction (SD) for extraction oil of Pu-erh ripe tea was investigated. GC-MS and HS-SPME/GC-MS were then applied to identify the volatile compounds in the essential oils and tea samples. The results showed that the extraction ratios of the essential oil were 0.81 +/- 0.01 g/kg (Soxhlet), 0.36 +/- 0.01 g/kg (UAE), 0.11 +/- 0.01 g/kg (SDE), and 0.59 +/- 0.01 g/kg (SD). GC-MS identified 40, 38, 35, and 47 volatile compounds in the essential oils extracted by the different methods, whereas 55 compounds were identified by HS-SPME/GC-MS. Therefore, when both the essential oil extraction rate and oil flavour are considered, the best method is SD.

Consistent aroma characteristics are important for tea products. However, understanding the formation of tea aroma flavor and correspondingly proposing applicable protocols to control tea quality and consistency remain major challenges. Oolong tea is one of the most popular teas with a distinct flavor. Generally, oolong tea is processed with the leaves of tea trees belonging to different subspecies and grown in significantly different regions. In this study, Yunnan and Fujian oolong teas, green tea, black tea, and Pu-erh tea were collected from major tea estates across China. Their sensory evaluation, main water-soluble and volatile compounds were identified and measured. The sensory evaluation, total polysaccharide, caffeine, and catechin content of Yunnan oolong tea was found to be different from that of Fujian oolong tea, a result suggesting that the kinds of tea leaves used in Yunnan and Fujian oolong teas were naturally different. However, according to their aroma compounds, principal component analysis (PCA) and cluster analysis (CA) of the volatile compounds showed that the two types of oolong teas were similar and cannot be clearly distinguished from each other; they are also different from green, black, and Pu-erh teas, a result indicating that the same oolong tea processing technology applied to different tea leaves results in consistent aroma characteristics. The PCA analysis results also indicated that benzylalcohol, indole, safranal, linalool oxides, β-ionone, and hexadecanoic acid methyl ester highly contributed to the distinct aroma of oolong tea compared with the other three types of teas. This study proved that the use of the same processing technology on two kinds of tea leaves resulted in a highly consistent tea aroma.

In this study, the aroma components of six Wujiatai green teas were extracted and identified using headspace solid-phase microextraction (HS-SPME) coupled with gas chromatography-mass spectrometry (GC-MS), and principal component analysis (PCA) was further used to reveal possible differences in these teas based on their aroma components. The results showed that, although there are some similarities in the aroma composition and content between Wujiatai green tea and regular green and black teas, the former had its own unique aroma characteristics. We suggest that the 'baking' procedure of Wujiatai green tea possibly causes the formation and/or increase of some aroma components, thus resulting in a more durable and prominent aroma characteristic as well as superior quality compared with the other teas investigated in this paper.

BACKGROUND:Biluochun is a typical non-fermented tea and is also famous for its unique aroma in China. Few studies have been performed to evaluate the effect of the manufacturing process on the formation and content of its aroma. RESULTS:The volatile components were extracted at different manufacturing process steps of Biluochun green tea using fully automated headspace solid-phase microextraction (HS-SPME) and further characterised by gas chromatography-mass spectrometry (GC-MS). Among 67 volatile components collected, the fractions of linalool oxides, β-ionone, phenylacetaldehyde, aldehydes, ketones, and nitrogen compounds were increased while alcohols and hydrocarbons declined during the manufacturing process. The aroma compounds decreased the most during the drying steps. CONCLUSION:We identified a number of significantly changed components that can be used as markers and quality control during the producing process of Biluochun. The drying step played a major role in the aroma formation of green tea products and should be the most important step for quality control. © 2016 Society of Chemical Industry.

The volatile components of tea flower (Camellia sinensis var. assamica), which was collected from tea garden in Pu-erh district, were extracted by fully automated headspace solid-phase microextraction (HS-SPME), identified by gas chromatography-mass spectrometry (GC/MS), and compared with the volatile components of Pu-erh green tea from same tea garden. The results showed that 9 and 67 kinds of volatile components were identified in tea flower and Pu-erh raw tea, respectively. Among them, hydrocarbons and alcohols were two major volatile components. Comparison showed that all volatile components of the tea flower were also found in Pu-erh green tea. Our results suggests that the tea flower may have similar aroma to tea leaves, and can also be mixed with tea leaves to improve the aromatic flavor.

To evaluate the effect of the processing technology utilized on the quality of teas, the major water-soluble and volatile components of 24 Biluochun and regular green tea samples obtained in different production areas were determined using the sensory evaluation, Folin-Ciocalteu method, the phenol-sulfuric acid method, high-performance liquid chromatography, and headspace solid-phase microextraction coupled with gas chromatography-mass spectrometry. There were small differences between the contents of the major water-soluble compounds identified in these samples. Sixty-five volatile compounds were identified in these teas. These molecules included 22 hydrocarbons, 18 alcohols, 8 ketones, 6 esters, 3 aldehydes, 3 heterocyclics, 2 nitrogens, 1 lactone, 1 acid, and 1 phenolic. Statistical analyses of these 65 compounds using principal component analysis and cluster analysis revealed that the contents of the Biluochun samples were highly similar and were different from those of the regular green teas. This study suggested that, although the geographical origin and cultivar influenced the aroma characteristics of tea products somewhat, processing technologies played an important role on tea aroma.

The aroma components of sun-dried and baked black teas, three replicates each, extracted with headspace solid-phase microextraction (HS-SPME) were identified by gas chromatography-mass spectrometry (GC-MS). Their similarities and differences were compared by using principal component analysis (PCA) and clustering analysis (CA). A total of 76 aroma components were identified in these two kinds of black tea, mainly including alcohols, ketones, and esters compounds. Among them, alcohol compounds were the most abundant components in sun-dried black tea (57.43%) and baked black tea (60.45%), mainly including linalool, linalool oxides, geraniol, nerolidol, etc. The aroma components of sun-dried and baked black teas were very similar and difficult to distinguish from each other. However, PCA and CA showed that sun-dried and baked black teas could be clearly distinguished according to their volatile characteristics, which illustrated that drying methods have influences on aroma components of black tea. Therefore, HS-SPME-GC-MS in combination with multivariate statistical methods could provide a feasible and rapid technique to differentiate between sun-dried and baked black teas based on their volatile components and relative contents.

BACKGROUND:Modern instrumental analysis technology can provide various chemical data and information on tea samples. Unfortunately, it remains difficult to extract the useful information. We describe the use of chemical fingerprint similarities, combined with principal component and cluster analyses, to distinguish and recognize Pu-erh green teas, which from two tea mountains, Wuliang and Jingmai, in the Pu-erh district of Yunnan province. The volatile components of all 20 Pu-erh green teas (10 Wuliang and 10 Jingmai teas) were extracted and identified by headspace solid-phase micro extraction (HS-SPME) combined with gas chromatography-mass spectrometry (GC-MS).RESULTS:Sixty-three volatiles (including alcohols, hydrocarbons, ketones, and aldehydes) were identified in the 20 Pu-erh green teas, and differences in compound compositions between them were also observed. Through fingerprint similarity, combined with principal component and cluster analyses, the 20 Pu-erh green teas were differentiated successfully based on their volatile characteristics.CONCLUSIONS:This study demonstrates that the GC-MS combined with chemical fingerprint and unsupervised pattern recognition method is suitable for the investigation of the volatile profiling and evaluating the quality and authenticity of teas related to the different origins.Graphical abstractDifferentiate Pu-erh green teas from different tea mountains by using chemical fingerprint similarity and multivariate statistical methods.

Based on the fully automatic headspace solid-phase microextraction (HS-SPME)/gas chromatography-mass spectrometry (GC-MS) and multivariate statistical methods, a novel model of identifying and evaluating the quality of Yunnan Pu-erh green tea was constructed for the first time in this work. Twelve Pu-erh green teas from 12 typical production sites of Pu-erh district in Yunnan Province and 6 regular green teas from Zhejiang, Sichuan, Anhui, Henan, Hubei, and Jiangsu provinces of China were used to construct the model. Data from 18 green tea samples by GC-MS were processed with fingerprint technology and chemometric methods. The GC-MS fingerprints from 12 Pu-erh green teas whose correlation coefficients and congruence coefficients were over 0.850 and demonstrated Pu-erh green tea samples from different production sites in Yunnan were consistent to some extent in spite of slightly different chemical indexes. A total of 77 volatile compounds were identified in 18 green teas, mainly including linalool, linalool oxides, phytol, caffeine, geraniol, and dihydroactinidiolide, and their chemical compositions were slightly similar. Cluster analysis (CA) and principal component analysis (PCA) demonstrated that 12 Pu-erh green teas could be clearly distinguished from other six regular green teas according to their chemical characteristics. Our results thus indicate that the chromatographic fingerprint combined with multivariate statistical techniques is useful for the identity and consistency evaluation of Pu-erh green teas. Such an approach is believed to be equally applicable to other green teas.