Design,synthesis and antifungal activity evaluation of isocryptolepine derivatives

In this paper, the nitrogen atom was inserted into the anthracycline system of the isocryptolepine nucleus to obtain the “Aza”-type structure benzo[4,5]imidazo[1,2-c] quinazoline. A series of “Aza”-type derivatives were designed, synthesized and evaluated for their antifungal activity against six plant fungi in vitro. Among all derivatives, compounds A-0, B-1 and B-2 showed significant antifungal activity against B. cinerea with the EC₅₀ values of 2.72 μg/mL, 5.90 μg/mL and 4.00 μg/mL, respectively. Compound A-2 had the highest activity against M. oryzae with the EC₅₀ values of 8.81 μg/mL, and compound A-1 demonstrated the most control efficacy against R. solani (EC₅₀, 6.27 μg/mL). Moreover, compound A-0 was selected to investigate the in vivo tests against B. cinerea and the results indicated that the preventative efficacy of it up to 72.80% at 100 μg/mL. Preliminary mechanism studies revealed that after treatment with A-0 at 5 µg/mL, the B. cinerea mycelia appeared curved, collapsed and the cell membrane integrity may be damaged. The reactive oxygen species production, mitochondrial membrane potential and nuclear morphometry of mycelia have been changed, and the membrane function and cell proliferation of mycelia were destroyed. Compounds A-0, A-1, B-1 and B-2 presented weaker toxicities against two cells lines than isocryptolepine. This study lays the foundation for the future development of isocryptolepine derivatives as environmentally friendly and safe agricultural fungicides.     

Comparative screening of plant essential oils: phenylpropanoid moiety as basic core for antiplatelet activity

Essential oils extracted from different plants (Anthemis nobilis L., Artemisia dracunculus L., Cannabis sativa L., Cupressus sempervirens L., Cymbopogon citratus (DC.) Stapf., Curcuma longa L., Foeniculum vulgare L., Hypericum perforatum L., Hyssopus officinalis L., Mentha spicata L., Monarda didyma L., Ocimum basilicum L., Ocotea quixos Kosterm., Origanum vulgare L., Pinus nigra J.F. Arnold, Pinus silvestris L., Piper crassinervium Kunth., Rosmarinus officinalis L., Salvia officinalis L., Salvia sclarea L., Santolina chamaecyparissus L., Thymus vulgaris L., Zingiber officinaie L.) were screened in guinea pig and rat plasma in order to assess antiplatelet activity and inhibition of clot retraction. The oils were chemically analysed and a relationship between components and ability to affect hemostasis was evidenced. O. quixos, F. vulgaris, and A. dracunculus showed the highest antiplatelet activity against ADP, Arachidonic Acid and the Thromboxane A2 agonist U46619 (IC50, 4-132 microg ml(-1)), and a good ability to destabilize clot retraction (IC50, 19-180 microg ml(-1)). For these oils a significant correlation between antiplatelet potency and phenylpropanoids content (54-86%) was evidenced thus suggesting a key role for this moiety in the prevention of clot formation. These findings provide the rationale to take in account the antiplatelet activity in the pharmacological screening of natural products containing phenylpropanoids.     

The phytotoxic lichen metabolite, usnic acid, is a potent inhibitor of plant p-hydroxyphenylpyruvate dioxygenase

The lichen secondary metabolite usnic acid exists as a (−) and a (+) enantiomer, indicating a or β projection of the methyl group at position 9b, respectively. (−)-Usnic caused a dose-dependent bleaching of the cotyledonary tissues associated with a decrease of both chlorophylls and carotenoids in treated plants whereas no bleaching was observed with the (+) enantiomer. (−)-Usnic acid inhibited protophorphyrinogen oxidase activity (I₅₀=3 μM), but did not lead to protoporphyrin IX accumulation. Bleaching appears to be caused by irreversible inhibition of the enzyme 4-hydroxyphenylpyruvate dioxygenase by (−)-usnic acid (apparent IC₅₀=50 nM).     

植物天然产物微生物重组合成研究进展

植物天然产物是小分子药物、营养品、化妆品、香精香料等的主要来源之一,在国民经济中发挥重要的作用。目前植物天然产物主要依赖于植物提取,这种生产方式占用耕地、生长周期长,而且植物活性成分往往含量低、生产成本高。通过解析植物天然产物生物合成途径,在微生物细胞中重构,创建细胞工厂,实现利用可再生原料发酵合成,为植物天然产物的供给提供了新的路线。本文重点介绍了中国科学院天津工业生物技术研究所在萜类、黄酮类、苯丙素类等重要类型植物天然产物微生物重组合成方面的研究进展,简要探讨了当前研究面临的挑战及未来前景。     

Modulation of Anopheles gambiae Epsilon glutathione transferase activity by plant natural products in vitro

Elevated glutathione transferase (GST) E2 activity is associated with DDT resistance in the mosquito Anopheles gambiae. The search for chemomodulators that inhibit the function of AgGSTE2 would enhance the insecticidal activity of DDT. Therefore, we examined the interaction of novel natural plant products with heterologously expressed An. gambiae GSTE 2 in vitro. Five of the ten compounds, epiphyllocoumarin (Tral-1), knipholone anthrone, isofuranonaphthoquinones (Mr 13/2, Mr13/4) and the polyprenylated benzophenone (GG1) were shown to be potent inhibitors of AgGSTE2 with IC₅₀ values of 1.5 μM, 3.5 μM, 4 μM, 4.3 μM and 4.8 μM respectively. Non-competitive inhibition was obtained for Tral 1 and GG1 with regards to GSH (K_i of 0.24 μM and 0.14 μM respectively). Competitive inhibition for Tral1 was obtained with CDNB (K_i = 0.4 μM) whilst GG1 produced mixed type of inhibition. The K_i and K_i' for GSH for Tral-1 and GG1 were 0.2 μM and 0.1 μM respectively. These results suggest that the novel natural plant products, particularly Tral-1, represent potent AgGSTE2 in vitro inhibitors.     

人肠道菌对天然产物代谢及转化的研究进展

天然产物的人肠道菌代谢及转化研究已引起各国学者的重视,并作为热点课题进行了大量研究工作。本文对近二十年来各国学者关于黄酮类、萜类、苯丙素类、生物碱类、甾体类及其他天然产物的人肠道菌代谢及转化研究工作进行了综述,总结了各类天然产物在人肠道菌作用下的代谢路径及转化规律,以期为该领域的进一步深入研究提供参考。     

Identification of diverse natural products as falcipain-2 inhibitors through structure-based virtual screening

Ten natural compounds are successfully identified as falcipain-2 (FP-2) inhibitors from our in-house natural products database using structure-based virtual screening, which show moderate inhibitory activities against FP-2 with IC₅₀ values ranging from 3.18 to 68.19 μM. While one of the inhibitors (compound 5) also exhibits in vitro antiplasmodial activity against chloroquine sensitive strain (3D7) and chloroquine resistant strain (Dd2) of Plasmodium falciparum in the micromolar range (IC₅₀s = 5.54 μM and 4.05 μM against 3D7 cells and Dd2 cells, respectively). Furthermore, the predicted binding poses are analyzed to explain the structure–activity relationships, which will be helpful for further structural modifications.     

Synthesis and antileishmanial activity of fluorinated rhodacyanine analogues: The ‘fluorine-walk’ analysis

In a search for potent antileishmanial drug candidates, eighteen rhodacyanine analogues bearing fluorine or perfluoroalkyl substituents at various positions were synthesized. These compounds were tested for their inhibitory activities against Leishmania martiniquensis and L. orientalis. This ‘fluorine-walk’ analysis revealed that the introduction of fluorine atom at C-5, 6, 5′, or 6′ on the benzothiazole units led to significant enhancement of the activity, correlating with the less negative reduction potentials of the fluorinated analogues confirmed by the electrochemical study. On the other hand, CF₃ and OCF₃ groups were found to have detrimental effects, which agreed with the poor aqueous solubility predicted by the in silico ADMET analysis. In addition, some of the analogues including the difluorinated species showed exceptional potency against the promastigote and axenic amastigote stages (IC₅₀ = 40–85 nM), with the activities surpassing both amphotericin B and miltefosine.     

Effects of intrinsic fluorescence and quenching on fluorescence-based screening of natural products

To evaluate the effects of intrinsic (natural) fluorescence and quenching as confounding variables in fluorescence-based enzyme inhibition assays of natural products, we measured the fluorescence and quenching properties of 25 components of popular herbal products. The analyses were performed under conditions typically employed in drug-drug interaction studies that use c-DNA-derived P450 isoforms and surrogate fluorogenic substrates. Four of the 25 compounds tested (isorhamnetin, quercetin, vitexin, and yangonin) fluoresced or quenched sufficiently to interfere with these assays. Intrinsic fluorescence had a greater effect on these assays than quenching and for one compound, yangonin, was sufficient to mask inhibition and potentially produce a false negative result. Quenching had less of an effect on these assays, but was significant enough for one compound, quercetin, to mimic "weak" inhibition. Therefore, because intrinsic fluorescence or quenching could render some natural products unsuitable for testing in certain fluorometric assays, it would be prudent to include an evaluation of these properties in experimental protocols.     

The mode of action of the plant antimicrobial peptide MiAMP1 differs from that of its structural homologue, the yeast killer toxin WmKT

The plant antimicrobial peptide MiAMP1 from Macadamia integrifolia and the yeast killer toxin peptide WmKT from Williopsis mrakii are structural homologues. Comparative studies of yeast mutants were performed to test their sensitivity to these two antimicrobial peptides. No differences in susceptibility to MiAMP1 were detected between wild-type and several WmKT-resistant mutant yeast strains. A yeast mutant MT1, resistant to MiAMP1 but unaffected in its susceptibility to plant defensins and hydrogen peroxide, also did not show enhanced tolerance towards WmKT. It is therefore probable that the Greek key beta-barrel structure shared by MiAMP1 and WmKT provides a robust structural framework ensuring stability for the two proteins but that the specific action of the peptides depends on other motifs.     

基于行动情景网络分析的生态产品价值实现治理体系研究——以丽水市为例

生态产品价值实现是生态文明建设的重大理论和现实命题,建立健全生态产品价值实现治理体系对于生态文明建设具有重大意义。近年来各地生态产品价值实现机制试点实践已经表明,生态产品价值实现治理具有复杂性,根据治理对象社会经济属性一一匹配治理模式,在政府与市场之间线性地寻求治理方案的传统治理逻辑已经无法有效应对其复杂性。以复杂系统视角重新审视生态产品价值实现治理,深刻把握生态产品价值实现治理体系的复杂结构,才是应对生态产品价值实现治理复杂性的治理之道。基于此,以丽水为案例,引入行动情景网络分析方法,通过识别丽水市生态产品价值实现治理体系建设的两个演进阶段,定性分析了一个完善、有效、可持续的生态产品价值实现治理体系的复杂结构。结果表明:丽水生态产品价值实现治理体系建设经历了以生态产品数量质量提升为前提、生态产业化为重点到以生态产品价值核算为切入点、生态产品市场化改革为重心的生态产品价值实现治理转型,两阶段的关键行动者均为丽水政府,但政府治理方式发生了从管理型到服务型的转变,更多市场主体和社会主体参与其中、制度规则不断完善、调节服务类生态产品经济价值得到显化。     

Recent advances in target identification of bioactive natural products

Natural products are a tremendous source of tool discovery for basic science and drug discovery for clinical uses. In contrast to the large number of compounds isolated from nature, however, the number of compounds whose target molecules have been identified so far is fairly limited. Elucidation of the mechanism of how bioactive small molecules act in cells to induce biological activity (mode of action) is an attractive but challenging field of basic biology. At the same time, this is the major bottleneck for drug development of compounds identified in cell-based and phenotype-based screening. Although researchers’ experience and inspiration have been crucial for successful target identification, recent advancements in genomics, proteomics, and chemical genomics have made this challenging task possible in a systematic fashion.     

The influence of natural mineral water on aquaporin water permeability and human natural killer cell activity

Aquaporins are the intrinsic membrane proteins functioning as water channel to transport water and/or mineral nutrients across the biological membrane systems. In this research, we aimed to clarify if the selected mineral water can affect aquaporin functions in vitro and the assumption of the mineral water can modify aquaporin expression and activate natural killer cell activity in human body. First, we expressed six human and eight plant aquaporin genes in oocytes and compared the effect of different kinds of natural mineral water on aquaporin activity. The oocyte assay data show that Hita tenryosui water could promote water permeability of almost all human and plant aquaporins in varying degrees, and freeze-dry and organic solvent extraction could reduce AQP2 activity but pH change and boiling could not. Second, each volunteer in two groups (10 in one group) received an oral Hita tenryosui or tap water load of 1000 ml/day for total four weeks. We found that these two kinds of water did not directly affect the relative expression levels of AQP1 and AQP9 in the blood cells, but intriguingly, the natural killer cell activities of the volunteers drinking Hita tenryosui water were significantly improved, suggesting that Hita tenryosui water has obvious health function, which opens a new and interesting field of investigation related to the link between mineral water consumption and human health and the therapies for some chronic diseases.     

The inhibition effects of some natural products on lactoperoxidase purified from bovine milk

In this study, inhibition profiles of some natural products, which are digoxin, L‐Dopa, dopamine, isoliquiritigenin, and 1,1,2,2‐tetrakis(p‐hydroxyphenyl)ethane (Tetrakis), were investigated against bovine lactoperoxidase (LPO) enzyme. Digoxin, L‐Dopa, and dopamine are active ingredients of some drugs, which have important functions in our body, especially in cases of heart failure. Isoliquiritigenin and tetrakis are types of natural phenolic compounds, which play an important role in cancer prevention and treatment. LPO enzyme was purified from bovine milk using sepharose‐4B‐l ‐tyrosine sulfonamide affinity column chromatography. LPO is responsible for the nonimmune biological defense system and has antibacterial activity so selection of these active substances is important. The inhibition studies are performed with the ABTS substrate. Bovine LPO enzyme was effectively inhibited by phenolic molecules. K_i values of these natural products were found as 0.20 ± 0.09, 0.22 ± 0.17, 0.49 ± 0.11, 0.49 ± 0.27, and 1.20 ± 0.25 μM, respectively. Tetrakis and digoxin exhibited noncompetitive inhibition, and other molecules showed competitive inhibition.     

The first synthesis of 4-phenylbutenone derivative bromophenols including natural products and their inhibition profiles for carbonic anhydrase,acetylcholinesterase and butyrylcholinesterase enzymes

The first synthesis of (E)-4-(3-bromo-4,5-dihydroxyphenyl)but-3-en-2-one (1), (E)-4-(2-bromo-4,5-dihydroxyphenyl)but-3-en-2-one (2), and (E)-4-(2,3-dibromo-4,5-dihydroxyphenyl)but-3-en-2-one (3) was realized as natural bromophenols. Derivatives with mono OMe of 2 and 3 were obtained from the reactions of their derivatives with di OMe with AlCl₃. These novel 4-phenylbutenone derivatives were effective inhibitors of the cytosolic carbonic anhydrase I and II isoenzymes (hCA I and II), acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) with K_i values in the range of 158.07–404.16 pM for hCA I, 107.63–237.40 pM for hCA II, 14.81–33.99 pM for AChE and 5.64–19.30 pM for BChE. The inhibitory effects of the synthesized novel 4-phenylbutenone derivatives were compared to acetazolamide as a clinical hCA I and II isoenzymes inhibitor and tacrine as a clinical AChE and BChE enzymes inhibitor.     

The inhibitory effect of vanadium oxoanions on the activity of copper-zinc superoxide dismutase

The inhibitory effect of vanadate species on the enzymatic activity of bovine copper-zinc superoxide dismutase has been investigated at different pH values and vanadium concentrations. A definite inhibitory effect, clearly related to the main negative charge of each of the vanadate solutions, has been found. The results suggest that the origin of the inhibitory effect may be similar to that found for the phosphate ion, i.e., a diminution of the effectiveness of the substrate electronic guidance mechanism by partial neutralization of the charges close to the active site. Under physiological conditions, the inhibitory effect of vanadate is somewhat smaller than the phosphate.     

The biology of insecticidal activity and resistance

Identifying insecticide resistance mechanisms is paramount for pest insect control, as the understandings that underpin insect control strategies must provide ways of detecting and managing resistance. Insecticide resistance studies rely heavily on detailed biochemical and genetic analyses. Although there have been many successes, there are also many examples of resistance that still challenge us. As a precursor to rational pest insect control, the biology of the insect, within the contexts of insecticide modes of action and insecticide metabolism, must be well understood. It makes sense to initiate this research in the best model insect system, Drosophila melanogaster, and translate these findings and methodologies to other insects. Here we explore the usefulness of the D. melanogaster model in studying metabolic-based insecticide resistances, target-site mediated resistances and identifying novel insecticide targets, whilst highlighting the importance of having a more complete understanding of insect biology for insecticide studies.     

The enduring legacy of Koji Nakanishi's research on bioorganic chemistry and natural products. Part 1: Isolation,structure determination and mode of action

In this brief review on Koji Nakanishi's remarkable career in natural products chemistry, we have highlighted a number of his accomplishments that illustrate the broad diversity of his interests. These include the isolation, structure determination, and biological mechanism of action of many natural products including the triterpenoid pristimerin; the diterpenoid ginkgolides; insect and crustacean molting hormones; phytoalexins; the toxic red tide principle brevetoxin; the vanadium tunicate pigments; philanthotoxin from killer wasps; antisickling agents; mitomycin DNA adducts; insect antifeedants; a mitotic hormone, the small molecule fish attractants from the sea anemone; new isolation and purification technologies; molecular chemistry of vision; age-related macular degeneration; and the development of the exciton circular dichroism (CD) chirality method for microscale determination of absolute configuration of natural products and chirality of other chiral molecules and supramolecular assembly.     

几类天然产物对纤溶系统的作用

在初筛天然来源的小分子ＰＡＩ－１抑制剂过程中发现一些天然产物显示出活性苗头,进一步试验和选择性试验表明这些化合物都不同程度别对纤溶系统中存在的不同的酶具有抑制作用。化合物１（ｅｘｐｏｘｙｒｏｌｉｎ Ｂ）对纤溶酶有一定的抑制,化合物２（ｍｕｒｉｃａｔｉｎｃ）对ＰＡＩ－１具有一定的抑制作用且有较好的选择性。化合物４（ｃｈｅｒｉｍｏｌｉｎ－２）对纤溶酶较强的抑制。化合物５（ｍｏｒｉｎｄｏｎｅ）对凝血酶、