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1.
Flavones and flavone glycosides from Halophila johnsonii 总被引:1,自引:0,他引:1
Halophila johnsonii Eiseman is a shallow-water marine angiosperm which contains UV-absorbing metabolites. Studies on methanol extracts of H. johnsonii by means of HPLC-UV, NMR, HPLC-MS resulted in isolation and identification of seven previously unknown flavone glycosides: 5,6,7,3′,4′,5′-hexahydroxyflavone-7-O-β-glucopyranoside (1), 5,6,7,3′,4′,5′-hexahydroxyflavone-7-O-(6″-O-acetyl)-β-glucopyranoside (2), 6-hydroxyluteolin-7-O-(6″-O-acetyl)-β-glucopyranoside (3), 6-hydroxyapigenin-7-O-(6″-O-acetyl)-β-glucopyranoside (4), 6-hydroxyapigenin-7-O-(6″-O-[E]-coumaroyl)-β-glucopyranoside (5), 6-hydroxyapigenin-7-O-(6″-O-[E]-caffeoyl)-β-glucopyranoside (6) and 6-hydroxyluteolin-7-O-(6″-O-[E]-coumaroyl)-β-glucopyranoside (7). Also isolated were three known flavone glycosides, 6-hydroxyluteolin 7-O-β-glucopyranoside (8), scutellarein-7-O-β-glucopyranoside (9), and spicoside (10), and five known flavones, pedalitin (11), ladanetin (12), luteolin (13), apegenin (14) and myricetin (15). Qualitative comparison of the flavonoid distribution in the leaf and rhizome-root portions of the plant was also investigated, with the aim of establishing the UV-protecting roles that flavonoids played in the sea grass. 相似文献
2.
The oviduct is a specialized organ responsible for the storage and the transport of male and female gametes. It also provides an optimal environment for final gamete maturation, fertilization, and early embryo development. Prostaglandin (PG) E2 is involved in many female reproductive functions, including ovulation, fertilization, implantation, and parturition. However, the control of its synthesis in the oviduct is not fully understood. Cyclooxygenases (COXs) are involved in the first step of the transformation of arachidonic acid to PGH2. The prostaglandin E synthases (PGESs) constitute a family of enzymes that catalyze the conversion of PGH2 to PGE2, the terminal step in the formation of this bioactive prostaglandin. Quantitative real-time PCR was used to determine the expression of COX-1, COX-2, microsomal prostaglandin E synthase-1 (mPGES-1), microsomal prostaglandin E synthase-2 (mPGES-2), and cytosolic prostaglandin E synthase (cPGES) mRNA in various sections of the oviduct, both ipsilateral and contralateral (to the ovary on which ovulation occurred) at various stages of the estrous cycle. Furthermore, protein expression and localization of cPGES, mPGES-1, and mPGES-2 were determined by Western blot and immunohistochemistry. All three PGESs were detected at both mRNA and protein levels in the oviduct. These PGESs were mostly concentrated in the oviductal epithelial layer and primarily expressed in the ampulla section of the oviduct and to a lesser extent in the isthmus and the isthmic-ampullary junction. The mPGES-1 protein was highly expressed in the contralateral oviduct, which contrasted with mPGES-2 mostly expressed in the ipsilateral oviduct. This is apparently the first report documenting that the three PGESs involved in PGE2 production were present in the Bos taurus oviduct. 相似文献
3.
Starch, a very compact form of glucose units, is the most abundant form of storage polyglucan in nature. The starch synthesis pathway is among the central biochemical pathways, however, our understanding of this important pathway regarding genetic elements controlling this pathway, is still insufficient. Starch biosynthesis requires the action of several enzymes. Soluble starch synthases (SSs) are a group of key players in starch biosynthesis which have proven their impact on different aspects of the starch biosynthesis and functionalities. These enzymes have been studied in different plant species and organs in detail, however, there seem to be key differences among species regarding their contributions to the starch synthesis. In this review, we consider an update on various SSs with an emphasis on potato SSs as a model for storage organs. The genetics and regulatory mechanisms of potato starch synthases will be highlighted. Different aspects of various isoforms of SSs are also discussed. 相似文献
4.
扁蓄总黄酮含量的测定 总被引:8,自引:0,他引:8
以35%乙醇为提取溶剂,聚酰胺吸附提纯,芦丁为标准品,用分光光度法于510nm处测定了扁蓄各部位的总黄酮含量。结果表明:扁蓄全草总黄酮含量为4.349%,根为7.115%,茎为5.454%,叶为3.544%。 相似文献
5.
González-Domenech CM Muñoz-Chápuli R 《Comparative biochemistry and physiology. Part D, Genomics & proteomics》2010,5(4):295-301
Nitric oxide synthases (NOS), the enzymes responsible for the NO synthesis, are present in all eukaryotes. Three isoforms (neuronal, inducible and endothelial), encoded by different loci, have been described in vertebrates, although the endothelial isoform seems to be restricted to tetrapods. In invertebrates, a variety of NOS isoforms have been variably annotated as "inducible" or "neuronal", while others lack precise annotation. We have performed an exhaustive collection of the available NOS amino-acid sequences in order to perform a phylogenetic analysis. We hypothesized that the NOS isoforms reported in vertebrates derive from 1) different invertebrate NOS, 2) a single invertebrate ancestral gene, through an event related to the double whole genomic duplication that occurred at the origin of vertebrates, and 3) the endothelial form of NOS appeared late in the evolution of vertebrates, after the split of tetrapods and fishes. Our molecular evolution analysis strongly supports the second scenario, the three vertebrate NOS isoforms derived from a single ancestral invertebrate gene. Thus, the diverse NOS isoforms in invertebrates can be explained by events of gene duplication, but their characterization as "inducible" or "neuronal" should only be justified by physiological features, since they are evolutionarily unrelated to the homonym isoforms of vertebrates. 相似文献
6.
7.
Isoetin, 5,7,2′,4′,5′-pentahydroxyflavone, is a rare, structurally simple natural product belonging to the flavone sub-group of flavonoids. The first reports on naturally occurring isoetin derivatives were published in the 1970s though methoxy-derivatives with the same substitution pattern had already been synthesized a decade earlier. A glucoside of isoetin was first discovered in the genus Isoetes (Lycopodiopsida). In the forty years following the discovery of the new naturally occurring flavonoid aglycone, only a limited number of reports on isoetin and its derivatives have been published. Simple, i.e. non-methyl-ether derivatives of isoetin have been found in the Isoetaceae, Asteraceae, Ranunculaceae, Rosaceae, and Rubiaceae families; while methyl ethers and their derivatives have been found in the Lycopodiaceae, Asteraceae, Cucurbitaceae, Fabaceae, and Pedaliaceae. A total of 14 non-methyl-ether-derivatives (including isoetin) and the same number of methyl ether derivatives have been described, some methyl derivatives only as synthetic compounds, others even only as virtual compounds generated for in silico studies. The published NMR data of isoetin and its derivatives as well as chemosystematic studies using isoetin derivatives as markers are compiled and critically assessed. Moreover, the papers dealing with bioactivities of isoetin and its derivatives are summarized. 相似文献
8.
Abstract 1,3-β- and 1,4-β-glucan synthases from Saprolegnia were inhibited in vitro by Congo red. This dye was found to be a non competitive inhibitor which prevented initiation and elongation of polymer chains. 相似文献
9.
10.
Two new 5-methyl ether flavone glucosides (7,4′,5′-trihydroxy-5,3′-dimethoxyflavone 7-O-β-D-glucopyranoside and 7,4′-dihydroxy-5-methoxyflavone 7-O-β-D-glucopyranoside) were isolated from the leaves of Thai mangrove Bruguiera gymnorrhiza together with 7,3′,4′,5′-tetrahydroxy-5-methoxyflavone, 7,4′,5′-trihydroxy-5,3′-dimethoxyflavone, luteolin 5-methyl ether 7-O-β-D-glucopyranoside, 7,4′-dihydroxy-5,3′-dimethoxyflavone 7-O-β-D-glucopyranoside, quercetin 3-O-β-D-glucopyranoside, rutin, kaempferol 3-O-rutinoside, myricetin 3-O-rutinoside and an aryl-tetralin lignan rhamnoside. The structure of a lignan rhamnoside was found to be related to racemiside, an isolated compound from Cotoneaster racemiflora, and also discussed. Structure determinations were based on analyses of physical and spectroscopic data including 1D- and 2D-NMR. 相似文献
11.
Grill M Heinemann A Hoefler G Peskar BA Schuligoi R 《Journal of neurochemistry》2008,104(5):1345-1357
Systemic inflammation leads to increased expression of spinal cyclooxygenase (COX)-2 and to a subsequent increase of prostaglandin (PG) biosynthesis, which contribute to the development of hyperalgesia and allodynia. In this study, endotoxin caused a sequential induction of membrane bound prostaglandin E synthase-1 and lipocalin-type PGD synthase (L-PGDS) in the mouse spinal cord. L-PGDS expression was detected in the leptomeninges, oligodendrocytes, and interestingly, in discrete perivascular cells. Endotoxin-caused increase was most prominent in oligodendrocytes. Endotoxin-induced COX-2 and membrane bound prostaglandin E synthase-1 were restricted to the leptomeninges and perivascular cells. COX-1 was not influenced by endotoxin. We found COX-1 expressed in microglia, some of them in close proximity to L-PGDS-positive oligodendrocytes and co-localization of COX-1 with L-PGDS in perivascular and leptomeningeal cells under control conditions. It can be assumed, that PGD2 biosynthesis under control conditions is mediated via COX-1 and that during inflammation, increased PGD2 is dependent on COX-2. We found the PGD2 receptors DP1 and chemoattractant receptor homologous molecule expressed on T helper type 2 cells (CRTH2) localized in neurons of the dorsal, and motoneurons in the ventral horn. The localization of the PGD2 receptors DP1 and CRTH in spinal cord neurons, particularly in neurons of lamina I and II involved in the processing of nociceptive stimuli, supports a role of PGD2 under inflammatory conditions. 相似文献
12.
Phytochemical investigation of the roots and aerial parts of Andrographis paniculata Nees yielded a new flavone, 5-hydroxy-7,2',6'-trimethoxyflavone and an unusual 23-carbon terpenoid, 14-deoxy-15-isopropylidene-11,12-didehydroandrographolide together with five known flavonoids and four known diterpenoids. The structures of these compounds were determined on the basis of spectral and chemical studies. 相似文献
13.
Although several flavonoids have been reported to exert inhibitory effects on influenza H1N1 neuraminidase (NA), little is known about the structure-activity relationship and binding mode. Three dimensional QSAR (quantitative structure-activity relationship) and molecular docking approaches were applied to explore the structural requisites of flavone derivatives for NA inhibitory activity. A meaningful QSAR model with R(2) of 0.5968, Q(2) of 0.6457, and Pearson-R value of 0.8679, was constructed. From the QSAR model, it could be seen how 6-OH, 3'-OH, 4'-OH, and 8-position substituent affect the NA inhibitory activity. Molecular docking study between the most active compound and NA suggested that hydrogen bonds, hydrophobic and electrostatic interactions were closely related to NA inhibitory activity, 5-OH and 7-OH may be essential for this activity. The results provide a set of useful guidelines for the rational design of novel NA inhibitors. 相似文献
14.
RP-HPLC法测定芦笋中黄酮类化合物芦丁的含量 总被引:6,自引:0,他引:6
以芦丁标准品为对照,利用反相高效液相色谱法对芦笋中黄酮类化合物芦丁的含量进行定量测定。采用Agilent Eclipse XDB-C18色谱柱,柱温25℃,流动相由甲醇-水-磷酸(55∶44.5∶0.5)组成,流速为0.7 mL/min,检测波长390 nm。结果表明黄酮类化合物中各组分基线分离良好;进样量在0.07~0.7μg/20μL范围内,峰面积A与进样浓度C呈良好的线性关系,回归方程为A=1 5176C-10.388,相关系数R2=0.999 4;加样回收率为101.051%,RSD=3.306%;以保留时间和峰面积作精密度试验,RSD分别为0.199%和1.24%。该方法样品处理简单,准确度高,精密度好,适合于芦笋中芦丁含量的测定。 相似文献
15.
Ji-Young An Hwi-Ho Lee Ji-Sun Shin Hyung-Seok Yoo Jong Seon Park Seung Hwan Son Sang Won Kim Jihyun Yu Jun Lee Kyung-Tae Lee Nam-Jung Kim 《Bioorganic & medicinal chemistry letters》2017,27(11):2613-2616
In an effort to identify novel anti-inflammatory compounds, a series of flavone derivatives were synthesized and biologically evaluated for their inhibitory effects on the production of nitric oxide (NO) and prostaglandin E2 (PGE2), representative pro-inflammatory mediators, in LPS-induced RAW 264.7 cells. Their structure-activity relationship was also investigated. In particular, we found that compound 3g displayed more potent inhibitory activities on PGE2 production, similar inhibitory activities on NO production and less weak cytotoxicity than luteolin, a natural flavone known as a potent anti-inflammatory agent. 相似文献
16.
Neuroblastoma cells are capable of hypoxic adaptation, but the mechanisms involved are not fully understood. We hypothesized that caveolin-1 (cav-1), a plasma membrane signal molecule, might play a role in protecting neuroblastoma cells from oxidative injury by modulating nitric oxide (NO) production. We investigated the alterations of cav-1, cav-2, nitric oxide synthases (NOS), and NO levels in human SK-N-MC neuroblastoma cells exposed to hypoxia with 2% [O2]. The major discoveries include: (i) cav-1 but not cav-2 was up-regulated in the cells exposed to 15 h of hypoxia; (ii) NO donor 1-[N, N-di-(2-aminoethyl) amino] diazen-1-ium-1, 2-diolate up-regulated the expression of cav-1, whereas the non-selective NOS inhibitor N(G)-nitro-L-arginine methyl ester and inducible NOS (iNOS) inhibitor 1400W each abolished the increase in cav-1 expression in the hypoxic SK-N-MC cells. These results suggest that iNOS-induced NO production contributes to the up-regulation of cav-1 in the hypoxic SK-N-MC cells. Furthermore, we studied the roles played by cav-1 in regulating NO, NOS, and apoptotic cell death in the SK-N-MC cells subjected to 15 h of hypoxic treatment. Both cav-1 transfection and cav-1 scaffolding domain peptide abolished the induction of iNOS, reduced the production of NO, and reduced the rates of apoptotic cell death in the hypoxic SK-N-MC cells. These results suggest that increased expression of cav-1 in response to hypoxic stimulation could prevent oxidative injury induced by reactive oxygen species. The interactions of cav-1, NO, and NOS could be an important signal pathway in protecting the neuroblastoma cells from oxidative injury, contributing to the hypoxic tolerance of neuroblastoma cells. 相似文献
17.
Predicted protein sequences of fungal chitin synthases can be divided into a non-homologous N-terminal region and a C-terminal region that shows significant homology among the various synthases. We have explored the function of these domains by constructing a series of nested deletions, extending from either end, in theCHS1 andCHS2 genes ofSaccharomyces cerevisiae. In both cases, most or all of the sequences encoding the non-homologous N-terminal region (one-third of the protein for Chs1p and about one-fourth for Chs2p) could be excised, with little effect on the enzymatic activity in vitro of the corresponding synthase or on its function in vivo. However, further small deletions (20–25 amino acids) into the homologous region were deleterious to enzymatic activity and function, and often led to changes in the zymogenic character of the enzymes. Similarly, relatively small (about 75 amino acids) deletions from the C-terminus resulted in loss of enzymatic activity and function of both synthases. Thus, it appears that all the information necessary for membrane localization, enzymatic activity and function resides in the homologous regions of Chs1p and Chs2p, a situation that may also apply to other chitin synthases.These authors contributed equally to this paper 相似文献
18.
Xinzhou Yang Shihao Deng Mi Huang Jialin Wang Li Chen Mingrui Xiong Jie Yang Sijiang Zheng Xinhua Ma Ping Zhao Yunjiang Feng 《Bioorganic & medicinal chemistry letters》2017,27(6):1463-1466
Bioassay-guided phytochemical investigation of the EtOAc fraction (ST-EtOAc) from the roots of Sophora tonkinensis resulted in the isolation of a new compound 6aR,11aR-1-hydroxy-4-isoprenyl-maackiain (1), along with 12 known compounds (2–13). The structure of the new compound was established by 1D and 2D NMR, MS data and circular dichroism analysis. Polyprenylated flavonoids 6–9 and 11–13 increased GLUT-4 translocation by the range of 1.35–2.75 folds. Sophoranone (8) exerted the strongest activity with 2.75 folds GLUT-4 translocation enhancement at the concentration of 10 μM. This is the first report of the GLUT-4 translocation activity of the plant Sophora tonkinensis. 相似文献
19.
Terpenoids represent the largest family of natural products. Their structural diversity is largely due to variable skeletons generated by terpene synthases. However, terpene skeletons found in nature are much more than those generated from known terpene synthases. Most promiscuous terpene synthases (i.e. those that can generate more than one product) have not been comprehensively characterised. Here, we first demonstrated that the promiscuous terpene synthases can produce more variable terpenoids in vivo by converting precursor polyisoprenoid diphosphates of different lengths (C10, C15, C20, C25). To release the synthetic potential of these enzymes, we integrated the engineered MVA pathway, combinatorial biosynthesis, and point mutagenesis to depict the comprehensive product profiles. In total, eight new terpenoids were characterised by NMR and three new skeletons were revealed. This work highlights the key role of metabolic engineering for natural product discovery. 相似文献
20.
We examined the roles of nitric oxide (NO) and NO synthase (NOS) isozymes in the healing of indomethacin-induced small intestinal ulcers in rats. Animals were given indomethacin (10 mg/kg, s.c.) and killed 1, 4 and 7 days after the administration. Indomethacin (2 mg/kg), N(G)-nitro-L-arginine methyl ester (L-NAME: a nonselective NOS inhibitor: 10 mg/kg) and aminoguanine (a relatively selective iNOS inhibitor: 20 mg/kg) were given s.c. once daily for 6 days, the first 3 days or the last 3 days during a 7-day experimental period. Both indomethacin and L-NAME significantly impaired healing of these lesions, irrespective of whether they were given for 6 days, first 3 days or last 3 days. The healing was also impaired by aminoguanine given for the first 3 days but not for the last 3 days. Expression of iNOS mRNA in the intestine was up-regulated after ulceration, persisting for 2 days thereafter, and the Ca(2+)-independent iNOS activity also markedly increased with a peak response during 1-2 days after ulceration. Vascular content in the ulcerated mucosa as measured by carmine incorporation was decreased when the healing was impaired by indomethacin and L-NAME given for either the first or last 3 days as well as aminoguanidine given for the first 3 days. These results suggest that endogenous NO plays a role in healing of intestinal lesions, in addition to prostaglandins, yet the NOS isozyme mainly responsible for NO production differs depending on the stage of healing: iNOS in the early stage and cNOS in the late stage. 相似文献