Benzoic acid, 4-hydroxy-3,5-dimethoxy-, 4-[(aminoiminomethyl)amino]butyl ester, hydrochloride (1:1)/4-Carbamimidamidobutyl 4-hydroxy-3,5-dimethoxybenzoate hydrochloride (1:1)/4-hydroxy-3,5-dimethoxy-benzoic acid-(4-guanidino-butyl ester),hydrochloride/4-Guanidinobutyl 4-hydroxy-3,5-dimethoxybenzoate hydrochloride/4-Hydroxy-3,5-dimethoxy-benzoesaeure-(4-guanidino-butylester),Hydrochlorid/4-(diaminomethylideneamino)butyl 4-hydroxy-3,5-dimethoxy-benzoate hydrochloride/leonurine hydrochloride/Leonurin monohydrochloride/Leonurine (hydrochloride)
Leonurine hydrochloride is an alkaloid isolated from Herba leonuri, with anti-oxidative and anti-inflammatory.
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provides coniferyl ferulate(CAS#:24735-18-0) MSDS, density, melting point, boiling point, structure, formula, molecular weight etc. Articles of coniferyl ferulate are included as well.>> amp version: coniferyl ferulate
Fredericamycin (FDM) A, a highly oxidized aromatic pentadecaketide natural product, exhibits potent cytotoxicity and has been studied as a new anticancer drug lead. The FDM biosynthetic gene cluster has been previously cloned from Streptomyces griseus ATCC 49344 and successfully expressed in the heterologous host Streptomyces albus J1074. The fdmM and fdmM1 genes code for two proteins with high sequence homology to each other but unknown function. In-frame deletion of each of the genes from the fdm cluster was accomplished in the S. albus host. Each mutant failed to produce FDM A and the key biosynthetic intermediate FDM E but produced various new metabolites, the titers of which were dramatically increased via overexpression of an fdm pathway-specific activator fdmR1. The ΔfdmM mutant strain accumulated three new compounds FDM M-1, FDM M-2, and FDM M-3, whereas the ΔfdmM1 mutant strain produced one new compound FDM M1-1. Isolation and structural characterization of these compounds enable us to propose that FdmM and FdmM1 catalyze the C-6 and C-8 hydroxylations for FDM biosynthesis, respectively. Homologs of FdmM and FdmM1 can be found in biosynthetic gene clusters of many other aromatic polyketides, ranging from dodecaketides to pentadecaketides, but to date all of them were annotated as proteins of unknown function. Based on the findings reported here for FdmM and FdmM1, we now propose similar functions for those proteins, and FdmM and FdmM1 therefore represent an emerging family of novel oxygenases responsible for hydroxylation of aromatic polyketide natural products.
Studies on natural product biosynthetic pathways have uncovered a number of intriguing oxygenases. For instance, the first reported metal- and cofactor-free monooxygenase TcmH is responsible for quinone moiety formation in tetracenomycin D3 and represents a rapidly growing family of antibiotic biosynthetic monooxygenases (1, 2). Another example is DpgC, which is involved in the biosynthesis of vancomycin building block 3, 5-dihydroxyphenylglycine. The crystal structure of DpgC has been used to understand the reaction mechanism of metal- and cofactor-free dioxygenases (3). MomA, involved in mompain biosynthesis (4) is a metal ion-dependent monooxygenase belonging to the cupin superfamily of oxidases bearing no prosthetic group. The discovery of enzymes such as TcmH, DpgC, and MomA continually encourage the community to search for and characterize new oxygenases from proteins of unknown functions involved in natural products biosynthesis.
Whereas octaketides (C-16), nonaketides (C-18), and decaketides (C-20) are the most common aromatic polyketide natural products whose biosyntheses have been extensively investigated, aromatic polyketides ranging from dodecaketides (C-24) to pentadecaketides (C-30) are also known including biologically active compounds such as fredericamycin (FDM)2 A (1) (5, 6), pradimicin A (2) (7), lysolipin X (3) (8), griseorhodin A (4) (9), benastatin A (5) (10), and γ-rubromycin (6) (Fig. 1 and Ref. 11). The highly oxidized nature of these molecules suggests their biosynthetic pathways as potential resources for the discovery of new oxygenases. We have recently cloned and sequenced the biosynthetic gene cluster of 1 from Streptomyces griseus ATCC 49344, proposing that 1 is derived from a pentadecaketide core structure (7) (Fig. 1). The complete fdm cluster was successfully expressed in the heterologous host Streptomyces albus J1074, providing another amenable system with which to perform in vivo studies (12). Based on the structures of FDM A and its biosynthetic intermediates, FDM B (8), FDM C (9) (13), and FDM E (10) (14), 1 was proposed to be generated from 8 through a benzylic acid rearrangement (Fig. 2). The biosynthetic production of 1 from 7 was proposed to include at least seven oxidative steps (14). Upon bioinformatics analysis of the fdm cluster, however, only three genes, fdmJ, fdmP, and fdmQ, were identified as candidates to encode oxygenases, and five additional genes, fdmK, fdmL, fdmM, fdmM1, and fdmU, were annotated to encode proteins of unknown function. The latter implies the existence of novel oxygenases responsible for the some of the oxidative steps in FDM biosynthesis (12).FdmM and FdmM1, showing 30.8% identity to each other, are two of five proteins of unknown function involved in biosynthesis of 1 on the basis of bioinformatics analysis. Homologs of FdmM and FdmM1 can be found in biosynthetic gene clusters of many other aromatic polyketides ranging from dodecaketides to pentadecaketides. However, all of them to date were annotated as proteins of unknown functions. These include Prm-Orf5 (29.5% identity to FdmM, 42.3% identity to FdmM1) in the pradimicin A (2) biosynthetic pathway (7), LlpB (30.1% identity to FdmM, 50% identity to FdmM1), and LlpQ (41.2% identity to FdmM, 36.1% identity to FdmM1) in the lysolipin X (3) biosynthetic pathway (8), GrhM (42.2% identity to FdmM, 31% identity to FdmM1) in the griseorhodin A (4) biosynthetic pathway (9), BenG (28.6% identity to FdmM, 26.5% identity to FdmM1) in the benastatin A (5) biosynthetic pathway (10), and RubQ (43.8% identity to FdmM, 31.6% identity to FdmM1) in the γ-rubromycin (6) biosynthetic pathway (supplemental Fig. S1 and Ref. 11). Like 1, inspection of those aromatic polyketides reveals the crucial role of oxygenation in their biosynthesis (Fig. 1). It should be noted that although no oxygenation is needed in the biosynthesis of benastatin (5), its biosynthetic congener BE43767A (11) contains a C-8 hydroxyl group (15).
We report here in vivo investigations of the roles of FdmM and FdmM1 in the biosynthesis of 1 by (i) construction of ΔfdmM and ΔfdmM1 mutants, respectively and (ii) structural characterization of the accumulated metabolites for each mutant. These data provide new insights into the biosynthesis of 1 and unveil FdmM and FdmM1 as members of an emerging family of novel oxygenases involved in aromatic polyketide biosynthesis.
In Vivo Investigation of the Roles of FdmM and FdmM1 in Fredericamycin Biosynthesis Unveiling a New Family of Oxygenases*An external file that holds a picture, illustration, etc. Object name is sbox.jpg
Yihua Chen,‡ Evelyn Wendt-Pienkoski,‡ Scott R. Rajski,‡ and Ben Shen‡§¶,1
2009 Sep 11
A new method for in vivo neural activation using low-intensity, pulsed infrared light exhibits advantages over standard electrical means by providing contact-free, spatially selective, artifact-free stimulation. Here we investigate the biophysical mechanism underlying this phenomenon by careful examination of possible photobiological effects after absorption-driven light-tissue interaction. The rat sciatic nerve preparation was stimulated in vivo with a Holmium:yttrium aluminum garnet laser (2.12 μm), free electron laser (2.1 μm), alexandrite laser (750 nm), and prototype solid-state laser nerve stimulator (1.87 μm). We systematically determined relative contributions from a list of plausible interaction types resulting in optical stimulation, including thermal, pressure, electric field, and photochemical effects. Collectively, the results support our hypothesis that direct neural activation with pulsed laser light is induced by a thermal transient. We then present data that characterize and quantify the spatial and temporal nature of this required temperature rise, including a measured surface temperature change required for stimulation of the peripheral nerve (6°C-10°C). This interaction is a photothermal effect from moderate, transient tissue heating, a temporally and spatially mediated temperature gradient at the axon level (3.8°C-6.4°C), resulting in direct or indirect activation of transmembrane ion channels causing action potential generation.
Biophysical Mechanisms of Transient Optical Stimulation of Peripheral Nerve
Jonathon Wells,* Chris Kao,* Peter Konrad,* Tom Milner,† Jihoon Kim,† Anita Mahadevan-Jansen,* and E. Duco Jansen*
2007 Oct 1;
1. Experiments have been performed to determine what changes in normal constituents of extracellular fluid are necessary to generate action potentials in mammalian axons. 2. Single and multifibre preparations of rat spinal roots were tested with Krebs solutions in which Na+, K+, Ca2+, Mg2+, pH, PCO2 or osmotic pressure were varied. 3. [Ca2+] below 1.0 mM produced impulses in all preparations. Lowering [Mg2+] did not generate any impulses but did enhance the response to low [Ca2+]. 4. Increasing [Na+] or [K+] caused excitation in some of the multifibres; increased [Na+] evoked ‘off’ responses in two single fibre preparations. The response to low [Ca2+] was enhanced by increasing [Na+] and depressed by increasing [K+]. 5. Increasing the osmotic pressure (with glucose) did not generate impulses and depressed the response to low [Ca2+]. 6. Changing the pH of Krebs solution did not generate impulses, but modified the response to other stimuli. The response to low [Ca2+] was increased as pH increased from pH 7.4 to 8.2, and decreased with pH in the range pH 7.4–6.2. 7. Altering pCO2 did not have any effect on the responses to low [Ca2+] unless pH also changed.
The generation of nerve impulses in mammalian axons by changing the concentrations of the normal constituents of extracellular fluid.