肉苁蓉的化学成分及药理作用研究进展

以近10年国内外发表的文献为依据,对肉苁蓉的生物学特性及其分布作了概述,并特别对化学成分及各种主要化学成分所具有的药理作用作一综述,并展望其发展前景。     

药用真菌桑黄的研究进展

以近年来国内外发表的文献为依据 ,从形态特征、生物学生长特性、主要化学成分、药理学研究等方面综述了文献中称为“桑黄”[包括 :鲍氏针层孔菌 (Phellinusbaumii)、火木针层孔菌 (P .igniarius)、裂蹄针层孔菌 (P .linteus) 3种 ]的药用菌子实体、发酵菌丝体、发酵胞外物的研究进展。结果 :桑黄的人工栽培 (日本、韩国学者采用的室外荫棚段木埋畦栽培法 ) ,固体、液体发酵培养均已获成功。其主要化学成分是子实体、菌丝体多糖以及发酵液中的胞外多糖 ,此外还有黄酮及其衍生物、香豆素类、甾醇类化合物。其子实体、菌丝体及提取物 (主要为多糖 )、胞外多糖在抗发炎、抗氧化、抑制肿瘤生成、增强免疫力、保护肝脏、预防和治疗关节炎等方面有显著的功效。桑黄的各种产品 (包括 :子实体、菌丝体微粉末、提取物浸膏、桑黄茶、桑黄口服液等 )市场需求量很大 ,表明桑黄有广阔的发展前景。     

Aggregation of Leslie matrix models with application to ten diverse animal species

Some grouping is necessary when constructing a Leslie matrix model because it involves discretizing a continuous process of births and deaths. The level of grouping is determined by the number of age classes and frequency of sampling. It is largely unknown what is lost or gained by using fewer age classes, and I address this question using aggregation theory. I derive an aggregator for a Leslie matrix model using weighted least squares, determine what properties an aggregated matrix inherits from the original matrix, evaluate aggregation error, and measure the influence of aggregation on asymptotic and transient behaviors. To gauge transient dynamics, I employ reactivity of the standardized Leslie matrix. I apply the aggregator to 10 Leslie models developed for animal populations drawn from a diverse set of species. Several properties are inherited by the aggregated matrix: (a) it is a Leslie matrix; (b) it is irreducible whenever the original matrix is irreducible; (c) it is primitive whenever the original matrix is primitive; and (d) its stable population growth rate and stable age distribution are consistent with those of the original matrix if the least squares weights are equal to the original stable age distribution. In the application, depending on the population modeled, when the least squares weights do not follow the stable age distribution, the stable population growth rate of the aggregated matrix may or may not be approximately consistent with that of the original matrix. Transient behavior is lost with high aggregation.     

Structural insights into the half-of-sites reactivity in homodimeric and homotetrameric metalloenzymes

Half-of-sites reactivity in many homodimeric and homotetrameric metalloenzymes has been known for half a century, yet its benefit remains poorly understood. A recently reported cryo-electron microscopy structure has given some clues on the less optimized reactivity of Escherichia coli ribonucleotide reductase with an asymmetric association of α2β2 subunits during catalysis. Moreover, nonequivalence of enzyme active sites has been reported in many other enzymes, possibly as a means of regulation. They are often induced by substrate binding or caused by a critical component introduced from a neighboring subunit in response to substrate loadings, such as in prostaglandin endoperoxide H synthase, cytidine triphosphate synthase, glyoxalase, tryptophan dioxygenase, and several decarboxylases or dehydrogenases. Overall, half-of-sites reactivity is likely not an act of wasting resources but rather a method devised in nature to accommodate catalytic or regulatory needs.     

延龄草皂苷类成分及其药理活性、资源保育的研究进展

延龄草是土家族四大名药之一,具有活血祛瘀、镇静安神、治疗跌打损伤等功效,现代药理研究表明其在改善阿尔茨海默症等中枢神经退化性疾病方面具有一定疗效。由于早年的大量采挖及现代保育工作尚未完善,延龄草资源稀缺,已被列为国家三级珍稀濒危保护植物。本文归纳了延龄草皂苷类成分及其结构分类、药理活性以及资源保育方面的研究进展,剖析了目前延龄草资源发展中亟待解决的问题,旨在为延龄草资源的可持续利用和产业发展提供基础和依据。     

Nanotechnology Formulations Designed with Herbal Extracts and Their Therapeutic Applications – A Review

Because of the increasing demand for natural products, the development of nanoformulations containing natural active ingredients requires in-depth knowledge of the substances used, methods of obtaining, and stability profiles to ensure product quality, efficacy, and safety. Considering this, the bibliography of the last five years presented in databases (PubMed and Science Direct) was discussed in this work, discussing the study with medicinal plants to obtain active metabolites with therapeutic properties, as well as the different nano-systems responsible for carrying these molecules. Due to the wealth of biodiversity found in the world, many species are submitted to the extraction process for several purposes. However, identifying, classifying, and quantifying the constituents of herbal matrices are crucial steps to verify their therapeutic potential. In addition, knowing the techniques of production and elaboration of nanotechnology products allows the optimization of the incorporation of herbal extracts as an innovation target. For studies to be successful, it is necessary to exhaust experimental results that guarantee the efficacy, safety, and quality of natural nanosystems, with the objective of obtaining reliable answers in nanotechnology therapy.     

Therapeutic potential of A2 adenosine receptor pharmacological regulators in the treatment of cardiovascular diseases,recent progress,and prospective

Adenosine and its analogs are of particular interest as potential therapeutic agents for treatment of cardiovascular diseases (CVDs). A2 adenosine receptor subtypes (A2a and A2b) are extensively expressed in cardiovascular system, and modulation of these receptors using A2 adenosine receptor agonists or antagonists regulates heart rate, blood pressure, heart rate variability, and cardiovascular toxicity during both normoxia and hypoxia conditions. Regulation of A2 adenosine receptor signaling via specific and novel pharmacological regulators is a potentially novel therapeutic approach for a better understanding and hence a better management of CVDs. This review summarizes the role of pharmacological A2 adenosine receptor regulators in the pathogenesis of CVDs.     

阳荷化学成分及药理作用最新研究进展

对姜科姜属植物阳荷Zingiber striolatum的栽培、化学成分及药理作用进行综述,并对其应用及生产上存在的问题进行探讨。     

Clinal and seasonal variations in initial retention capacity of virginDrosophila melanogaster females as a strategy for fitness

Summary The study of the first laboratory generation of isofemale lines ofDrosophila melanogaster, founded by wild flies collected in populations of various geographical origins, has shown that virgin females differ in their capacity to control egg deposition. This capacity to delay the ovulation process when no sexual partner is available is genetically determined. The present study shows that the frequency distribution of the various phenotypes varies progressively along a latitudinal cline from Afrotropical to European regions, or from neotropical to nearctic areas, while a few oriental populations appear off the cline. This variation in initial retention capacity, added to a similar variation in number of ovarioles conditioning a potential increase in fecundity for mated flies, induces variation in reactivity to insemination which may be an adaptation to a variable environment. Moreover, similar study of F1 virgin females from isofemale lines founded by wild flies collected in Spring, Summer and Autumn in two French populations over ten successive years revealed that seasonal genetic variations occur in this capacity to postpone egg-laying in case of non-insemination. The frequency of the different phenotypes follows cyclical seasonal variations. Long retention phenotypes are more frequent in Spring and Autumn samples, whereas short retention phenotypes, closer to the ancestral African type, are more common in Summer generations. This balancing selection temporarily modifies the genetic equilibrium of the population, enhancing its competitive ability. Temperature appears to be the primordial selective factor both in geographical and in seasonal variations.     

Effect of temperature on the acidolysis of N-acyl-N,alpha,alpha-trialkyl glycine amides as related to the nature of substituents.

The C-terminal amide bond of N-acyl-N,alpha,alpha-trialkyl glycine amides is labile to acid and this has been currently assigned to steric crowding within the amino acid residue. However, our previous work has shown that in the acidolysis of some of these compounds steric hindrance seems to play a less important role than what one would expect. Thus, the cleavage of two sets of such compounds bearing different degrees of crowding was investigated at five different temperatures in order to clarify the effect of structure on reactivity in terms of enthalpy and entropy of activation. The compounds exhibited an Arrhenius-type behaviour, and both enthalpies and entropies of activation were calculated by taking advantage of the transition state theory. In addition, the kinetic data were analysed in terms of isokinetic relationships in order to find evidence to support that the compounds react under the same mechanism. The changes in the reaction rate are governed by the changes in both the enthalpy and the entropy of activation, which are related to bond energy and steric hindrance, respectively. In general, the entropies of activation are very negative for all compounds investigated, which reflects large steric constrictions associated with the formation of the transition state. In addition, they are very sensitive to the structure of the substrates.