植物多酚的防癌抗癌作用

植物多酚是植物中广泛存在的一大类多酚化合物的总称,包括多酚（如单宁）、黄酮、酚酸等。体外实验研究表明植物多酚对多种人癌细胞具有增殖抑制作用,抑制动物体内肿瘤生长。其作用机理与抗氧化、调控细胞周期、诱导肿瘤细胞凋亡和分化、影响血管生成和肿瘤细胞信号传导等有关。对植物多酚的防癌抗癌作用,值得进一步深入研究。     

植物多酚在环境保护与农业生产中的应用

植物多酚是一类广泛存在于植物体内的次生代谢物．自然界含多酚的常见植物已超过600种．随着植物多酚化学结构鉴定及其理化性状的深入研究,人类对植物多酚的应用由传统的化工和医药等领域扩展到了农业和环境等多个领域．文中就植物多酚对植物抗逆境能力以及在环境污染控制和农业生产等领域的应用进行了综述．     

植物的异黄酮合酶（IFS）

植物异黄酮是在植物次生代谢过程中产生的一类多酚混合物。其对植物自身防御病虫害和诱导根瘤形成以及人类预防或治疗激素相关的多种疾病都有作用。异黄酮合成的关键酶是异黄酮合酶（isoflavone synthase,IFS）。本文就异黄酮的代谢途径、IFS催化机制、基因克隆和转基因的研究进展作简单介绍,并讨论了IFS基因与根瘤菌之间可能的关系。     

植物多酚通过microRNA调控脂质代谢研究进展

microRNA（简称miRNA）是长度18~25个核苷酸的非编码RNA分子,具有调控mRNA的翻译和/或稳定性的功能,从而在转录后水平调节不同基因的表达。人体内约60%编码蛋白的基因的表达受到miRNA调节,其中包括脂质代谢调控相关基因。植物多酚具有良好的生物活性,可以通过调节脂质代谢相关miRNAs,如miR-122和miR-33的表达进而发挥降血脂等活性。该文综述了miRNA调控脂质代谢相关mRNA的作用机制以及植物多酚在这一过程中的可能作用。     

植物核苷二磷酸激酶研究进展

核苷二磷酸激酶(Nucleoside diphosphate kinases,NDPKs)是一类高度保守的蛋白,大小一般在70-100 k D,在生物体内大多数以六聚体形式存在,仅在少数原核生物中以四聚体形式存在。NDPK主要参与维持核苷二磷酸和核苷三磷酸的平衡。目前在植物中已发现4种NDPK:NDPKⅠ、NDPKⅡ、NDPKⅢ和NDPKⅣ,相关研究主要集中在前3种。NDPKⅠ与植物生长发育、非生物胁迫、感病应激和激素响应有关;NDPKⅡ参与光合作用和活性氧清除;NDPKⅢ参与能量代谢和细胞程序性死亡;NDPKⅣ仅在拟南芥和水稻基因组中发现,预测定位于内质网,功能未知。除了上述的主要作用外,NDPK在某些植物中还有特殊功能,如参与DNA复制、参与淀粉和纤维素的合成、参与生长素调节和发挥核酶活性等。这些作用机制是否存在物种特异性还有待进一步的研究。对NDPK的系统进化、生物功能的最新进展进行了综述。最后对NDPK的发展趋势进行了展望,有助于将来对NDPK进行更深入和全面的研究。     

陆地生态系统植物多样性对矿质元素输入的响应

人类活动的加剧改变了陆地生态系统矿质元素(如氮、磷、钾等)循环的速度和方向,并且对生态系统的结构和功能也产生重要影响。如今,矿质元素输入量的改变及其产生的后续效应对陆地生态系统生物多样性的影响备受学者们的关注。从4个方面综述了全球氮沉降背景下主要矿质元素输入的改变对陆地植物多样性的影响及其机理:1)矿质营养元素限制的概念、确定方法以及与植物多样性的耦合关系;2)概述了氮、磷、钾等主要矿质元素输入对陆地植物多样性的影响:主要表现为负面效应;3)探讨了矿质元素输入影响植物多样性的可能机制,包括生态系统水平上的机制(如竞争排斥、酸化铝毒、物种入侵、同质性假说,间接诱导机制等)和植物个体水平上的机制(如元素失衡和环境敏感性增加等);4)根据目前研究现状,指出了已有研究的局限性,分析了未来可能的研究方向和重点。     

白藜芦醇的研究进展

白藜芦醇是一种含有芪类结构的非黄酮类多酚化合物.它不仅是植物遭受胁迫时产生的一种能提高植物抵抗病原性攻击和环境恶化的植物抗毒素,还具有抗癌,抗氧化、调节血脂,影响寿命等多方面有益于人类健康的重要功能.以下对白藜芦醇的理化特性、合成、提取、纯化与检测方法进行了全面总结,并在其作用的分子机制基础上,对其生物学活性、基因工程研究及产业化情况进行了重点介绍.发现在传统育种的基础上,借助于现代生物技术手段,将白藜芦醇的天然活性保健作用应用于保健食品的开发、作物经济附加值的提高具有广阔的前景.它的开发和利用,必将为食品及制药工业新产品的开发提供新的挑战与机遇.     

硅在植物体内的分布和吸收及其在病害逆境胁迫中的抗性作用

硅在地壳中含量位居第二位,尽管还没有被列为植物生长的必需营养元素,但它在促进植物生长发育和营养吸收、提高植物对非生物逆境胁迫和生物逆境胁迫的抗性等方面都具有重要作用。综述了近些年来国内外关于硅在植物体内的分布、吸收及其生理效应,重点介绍了硅在病害逆境胁迫中的抗性作用机理。高等植物以单硅酸[Si(OH)4]的形式吸收硅,存在硅的主动吸收和被动吸收机制。硅主要沉积在叶片及叶鞘表皮细胞,形成硅化细胞和角质-硅双层结构,能增强寄主植物细胞壁的机械强度和稳固性,从而延缓和抵御病菌的侵入和扩展。更多的证据表明,硅处理能增加植物叶片保护酶(过氧化物酶、多酚氧化酶、苯丙氨酸解氨酶等)活性和诱导寄主产生次生代谢抗性物质(如植保素、多酚类化合物、木质素),从而激活植物的防御系统,增强对病原菌的抵抗能力。分子水平上的研究显示,硅能诱导与植物防御机制相关的基因表达,参与抗病信号分子(如水杨酸、茉莉酸和乙烯)在信号传导中的作用。     

植物多酚抗逆生态作用研究进展

植物多酚是一类重要的植物次生代谢物质,具有吸收过多的太阳辐射、过滤UV(ultra-violet)和清除体内自由基等多种生理功能,有利于传播花粉、受精及传播种子,并在植物逆境生理生态上也具有重要的作用.该文对近年来国内外有关植物多酚在逆境生态中抗生物或非生物胁迫中的作用--主要包括作为缓解营养缺乏、抵抗干旱、温度变化、盐害、大气污染、食草动物和病原菌浸染等逆境胁迫时的防御物质,以及作为植物与植物之间以及植物与环境之间信息交流物质等方面的研究进展进行综述,并展望了植物多酚的应用前景.     

基于代谢组学的植物多酚及其肠道健康效应研究进展

综述了植物多酚的分类和来源、在代谢组学技术的驱动下,新型多酚物质的鉴定、控制植物多酚合成途径的关键因子以及多酚的功能特性的研究进展,阐述了植物多酚在肠道中的代谢以及其作为“益生元”调节肠道微生态并影响机体健康的重要功能。目前的研究表明不同植物多酚在调节肠道微生态方面存在差异,多数有促进肠道有益菌作用,并通过与肠道微生物“互作”发挥促进健康效应。总之,植物多酚作为“益生元”影响人体健康可能离不开肠道微生物的介导。各个植物多酚的益生功能也需要进一步阐析,在此过程中需要考虑宿主,膳食等混杂因素的综合影响,且需要拓展临床应用方面的研究。     

Benefits of polyphenols on gut microbiota and implications in human health

The biological properties of dietary polyphenols are greatly dependent on their bioavailability that, in turn, is largely influenced by their degree of polymerization. The gut microbiota play a key role in modulating the production, bioavailability and, thus, the biological activities of phenolic metabolites, particularly after the intake of food containing high-molecular-weight polyphenols. In addition, evidence is emerging on the activity of dietary polyphenols on the modulation of the colonic microbial population composition or activity. However, although the great range of health-promoting activities of dietary polyphenols has been widely investigated, their effect on the modulation of the gut ecology and the two-way relationship “polyphenols ? microbiota” are still poorly understood.Only a few studies have examined the impact of dietary polyphenols on the human gut microbiota, and most were focused on single polyphenol molecules and selected bacterial populations. This review focuses on the reciprocal interactions between the gut microbiota and polyphenols, the mechanisms of action and the consequences of these interactions on human health.     

The interplay between diet,gut microbes,and host epigenetics in health and disease

The mechanisms linking the function of microbes to host health are becoming better defined but are not yet fully understood. One recently explored mechanism involves microbe-mediated alterations in the host epigenome. Consumption of specific dietary components such as fiber, glucosinolates, polyphenols, and dietary fat has a significant impact on gut microbiota composition and function. Microbial metabolism of these dietary components regulates important epigenetic functions that ultimately influences host health. Diet-mediated alterations in the gut microbiome regulate the substrates available for epigenetic modifications like DNA methylation or histone methylation and/or acetylation. In addition, generation of microbial metabolites such as butyrate inhibits the activity of core epigenetic enzymes like histone deacetylases (HDACs). Reciprocally, the host epigenome also influences gut microbial composition. Thus, complex interactions exist between these three factors. This review comprehensively examines the interplay between diet, gut microbes, and host epigenetics in modulating host health. Specifically, the dietary impact on gut microbiota structure and function that in-turn regulates host epigenetics is evaluated in terms of promoting protection from disease development.     

Putative Mechanisms Underlying the Beneficial Effects of Polyphenols in Murine Models of Metabolic Disorders in Relation to Gut Microbiota

The beneficial effects of polyphenols on metabolic disorders have been extensively reported. The interaction of these compounds with the gut microbiota has been the focus of recent studies. In this review, we explored the fundamental mechanisms underlying the beneficial effects of polyphenols in relation to the gut microbiota in murine models of metabolic disorders. We analyzed the effects of polyphenols on three murine models of metabolic disorders, namely, models of a high-fat diet (HFD)-induced metabolic disorder, dextran sulfate sodium (DSS)-induced colitis, and a metabolic disorder not associated with HFD or DSS. Regardless of the model, polyphenols ameliorated the effects of metabolic disorders by alleviating intestinal oxidative stress, improving inflammatory status, and improving intestinal barrier function, as well as by modulating gut microbiota, for example, by increasing the abundance of short-chain fatty acid-producing bacteria. Consequently, polyphenols reduce circulating lipopolysaccharide levels, thereby improving inflammatory status and alleviating oxidative imbalance at the lesion sites. In conclusion, polyphenols likely act by regulating intestinal functions, including the gut microbiota, and may be a safe and suitable therapeutic agent for various metabolic disorders.     

Antiangiogenic mechanisms of diet-derived polyphenols

Accumulating evidence demonstrates that polyphenols in natural products are beneficial against human lethal diseases such as cancer and metastasis. The underlying mechanisms of anti-cancer effects are complex. Recent studies show that several polyphenols, including epigallocatechin-3-gallate (EGCG) in green tea and resveratrol in red wine, inhibit angiogenesis when administrated orally. These polyphenols have direct effects on suppression of angiogenesis in several standard animal angiogenesis models. Because angiogenesis is involved in many diseases such as cancer, diabetic retinopathy and chronic inflammations, the discovery of these polyphenols as angiogenesis inhibitors has shed light on the health beneficial mechanisms of natural products, which are rich in these molecules. At the molecular level, recent studies have provided important information on how these molecules inhibit endothelial cell growth. Perhaps the greatest therapeutic advantage of these small natural molecules over large protein compounds is that they can be administrated orally without causing severe side effects. It is anticipated that more polyphenols in natural products will be discovered as angiogenesis inhibitors and that these natural polyphenols could serve as leading structures in the discovery of more potent, synthetic angiogenesis inhibitors.     

益生菌调控幼龄畜禽消化道微生物研究进展

益生菌是一类对宿主(人类或动物)有益的活性微生物,包括细菌、真菌(如酵母)等,具有促进动物生长、提高免疫力的作用,是潜在的抗生素替代品。益生菌可能通过与动物消化道微生物互作来发挥益生作用,但具体机制仍不明确。综述了基于高通量测序技术研究益生菌调控幼龄畜禽(仔猪、雏鸡、反刍动物)消化道微生物群落组成的最新进展,并提出了未来研究方向,包括益生菌如何通过与消化道微生物互作影响其功能,益生菌对于幼龄畜禽不同健康状态下肠道微生物的影响,以及宿主因素如何影响益生菌对于幼龄畜禽消化道微生物的作用效果。     

Improving the oral bioavailability of beneficial polyphenols through designed synergies

A substantial and growing consumer demand exists for plant-based functional foods that improve general health and wellbeing. Amongst consumed phytochemicals, the polyphenolic compounds tend to be the most bioactive. Many commonly consumed polyphenols have been shown to have specific and potent health-promoting activities when assessed by high-throughput in vitro assays and when administered to experimental animals by injection. However, very few have been shown to have any beneficial effects in animals or man when orally consumed, because of the poor bioavailability exhibited by most polyphenols following the ingestion. Consumed polyphenols, like most pharmaceuticals, are regarded as xenobiotics by the body and must overcome many barriers, including extensive enzymatic and chemical modification during digestion and absorption, to reach their site(s) of action. This is especially true for polyphenols targeting the brain, which is protected by the tightly regulated blood–brain barrier. Interestingly, many polyphenols are also known to specifically modify some of the metabolic and transport processes that govern bioavailability. Therefore, the opportunity exists to increase the bioactivity of beneficial polyphenols by designing specific synergistic interactions with polyphenols that improve their oral bioavailability. This hypothesis and review paper will discuss some of the endogenous systems that limit the bioavailability of ingested polyphenols to the body and the brain, and the means by which bioavailability may be improved by specifically designing synergies between orally consumed polyphenols.     

Efficacy of Probiotics-Based Interventions as Therapy for Inflammatory Bowel Disease: A Recent Update

Probiotics such as Lactobacillus spp. play an important role in human health as they embark beneficial effect on the human gastrointestinal microflora composition and immune system. Dysbiosis in the gastrointestinal microbial composition has been identified as a major contributor to chronic inflammatory conditions, such as inflammatory bowel disease (IBD). Higher prevalence of IBD is often recorded in most of the developed Western countries, but recent data has shown an increase in previously regarded as lower risk regions, such as Japan, Malaysia, Singapore, and India. Although the IBD etiology remains a subject of speculation, the disease is likely to have developed because of interaction between extrinsic environmental elements; the host’s immune system, and the gut microbial composition. Compared to conventional treatments, probiotics and probiotic-based interventions including the introduction of specific prebiotics, symbiotic and postbiotic products had been demonstrated as more promising therapeutic measures. The present review discusses the association between gut dysbiosis, the pathogenesis of IBD, and risk factors leading to gut dysbiosis. In addition, it discusses recent studies focused on the alteration of the gastrointestinal microbiome as an effective therapy for IBD. The impact of the COVID-19 pandemic and other viral infections on IBD are also discussed in this review. Clinical and animal-based studies have shown that probiotic-based therapies can restore the gastrointestinal microbiota balance and reduce gut inflammations. Therefore, this review also assesses the status quo of these microbial-based therapies for the treatment of IBD. A better understanding of the mechanisms of their actions on modulating altered gut microbiota is required to enhance the effectiveness of the IBD therapeutics.     

Role of plant polyphenols in genomic stability

Polyphenols are a large and diverse class of compounds, many of which occur naturally in a range of food plants. The flavonoids are the largest and best-studied group of these. A range of plant polyphenols are either being actively developed or currently sold as dietary supplements and/or herbal remedies. Although, these compounds play no known role in nutrition (non-nutrients), many of them have properties including antioxidant, anti-mutagenic, anti-oestrogenic, anti-carcinogenic and anti-inflammatory effects that might potentially be beneficial in preventing disease and protecting the stability of the genome. However not all polyphenols and not all actions of individual polyphenols are necessarily beneficial. Some have mutagenic and/or pro-oxidant effects, as well as interfering with essential biochemical pathways including topoisomerase enzyme activities, prostanoid biosynthesis and signal transduction. There is a very large amount of in vitro data available, but far fewer animal studies, and these are not necessarily predictive of human effects because of differences in bacterial and hepatic metabolism of polyphenols between species. Epidemiological studies suggest that high green tea consumption in the Japanese population and moderate red wine consumption in the French population may be beneficial for heart disease and cancer, and these effects may relate to specific polyphenols. A small number of adequately controlled human intervention studies suggest that some, but not all polyphenol extracts or high polyphenol diets may lead to transitory changes in the antioxidative capacity of plasma in humans. However, none of these studies have adequately considered long-term effects on DNA or the chromosome and unequivocally associated these with polyphenol uptake. Furthermore, clinical trials have required intravenously administered polyphenols at concentrations around 1400mg/m(2) before effects are seen. These plasma concentrations are unlikely to be achieved using the dietary supplements currently available. More focused human studies are necessary before recommending specific polyphenolic supplements at specific doses in the human population.     

Regulation of cellular signals from nutritional molecules: a specific role for phytochemicals, beyond antioxidant activity

Phytochemicals (PhC) are a ubiquitous class of plant secondary metabolites. A "recommended" human diet should warrant a high proportion of energy from fruits and vegetables, therefore providing, among other factors, a huge intake of PhC, in general considered "health promoting" by virtue of their antioxidant activity and positive modulation, either directly or indirectly, of the cellular and tissue redox balance. Diet acts through multiple pathways and the association between the consumption of specific food items and the risk of degenerative diseases is extremely complex. Recent literature suggests that molecules having a chemical structure compatible with a putative antioxidant capacity can actually "perform" activities and roles independent of such capacity, interacting with cellular functions at different levels, such as affecting enzyme activities, binding to membrane or nuclear receptors as either an elective ligand or a ligand mimic. Inductive or signaling effects may occur at concentrations much lower than that required for effective antioxidant activity. Therefore, the "antioxidant hypothesis" is to be considered in some cases an intellectual "shortcut" possibly biasing the real understanding of the molecular mechanisms underlying the beneficial effects of various classes of food items. In the past few years, many exciting new indications elucidating the mechanisms of polyphenols have been published. Here, we summarize the current knowledge of the mechanisms by which specific molecules of nutritional interest, and in particular polyphenols, play a role in cellular response and in preventing pathologies. In particular, their direct interaction with nuclear receptors and their ability to modulate the activity of key enzymes involved in cell signaling and antioxidant responses are presented and discussed.