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1.
Although germin-like proteins (GLPs) have been demonstrated to participate in plant biotic stress responses, their specific functions in rice disease resistance are still largely unknown. Here, we report the identification and characterization of OsGLP3-7, a member of the GLP family in rice. Expression of OsGLP3-7 was significantly induced by pathogen infection, jasmonic acid (JA) treatment, and hydrogen peroxide (H2O2) treatment. OsGLP3-7 was highly expressed in leaves and sublocalized in the cytoplasm. Overexpression of OsGLP3-7 increased plant resistance to leaf blast, panicle blast, and bacterial blight, whereas disease resistance in OsGLP3-7 RNAi silenced plants was remarkably compromised, suggesting this gene is a positive regulator of disease resistance in rice. Further analysis showed that OsGLP3-7 has superoxide dismutase (SOD) activity and can influence the accumulation of H2O2 in transgenic plants. Many genes involved in JA and phytoalexin biosynthesis were strongly induced, accompanied with elevated levels of JA and phytoalexins in OsGLP3-7-overexpressing plants, while expression of these genes was significantly suppressed and the levels of JA and phytoalexins were reduced in OsGLP3-7 RNAi plants compared with control plants, both before and after pathogen inoculation. Moreover, we showed that OsGLP3-7-dependent phytoalexin accumulation may, at least partially, be attributed to the elevated JA levels observed after pathogen infection. Taken together, our results indicate that OsGLP3-7 positively regulates rice disease resistance by activating JA and phytoalexin metabolic pathways, thus providing novel insights into the disease resistance mechanisms conferred by GLPs in rice.  相似文献   

2.
Many selenoorganic compounds play an important role in biochemical processes and act as antioxidants, enzyme inhibitors, or drugs. The effects of five new synthesized selenoorganic compounds (2-(5-chloro-2-pyridyl)-7-azabenzisoselenazol-3(2H)-one; 2-phenyl-7-azabenzisoselenazol-3(2H)-one; 2-(pyridyl)-7-azabenzisoselenazol-3(2H)-one; 7-azabenzisoselenazol-3(2H)-one; bis(2-aminophenyl) diselenide) on oxidative changes in human blood platelets and in plasma were studied in vitro and compared with those of ebselen, a well known antioxidant. Our studies demonstrated that bis(2-aminophenyl) diselenide has distinctly protective effects against oxidative stress in blood platelets and in plasma. It might have greater biological relevance and stronger pharmacological effects than ebselen.  相似文献   

3.
为了解柯拉斯那(Aquilaria crassna)的化学成分,从其所产沉香中分离得到10个化合物,经波谱分析分别鉴定为:6,8-羟基-2-(2-苯乙基)色酮(1),6,8-二羟基-2-[2-(4-甲氧基苯)乙基]色酮(2),rel-(1a R,2R,3R,7b S)-1a,2,3,7b-tetrahydro-2,3-dihydroxy-5-(2-phenylethyl)-7H-oxireno[f][1]benzopyran-7-one(3),rel-(1a R,2R,3R,7b S)-1a,2,3,7b-tetrahydro-2,3-dihydroxy-[2-(4-methoxyphenyl)-ethyl]-7H-oxireno[f][1]benzopyran-7-one(4),rel-(1a R,2R,3R,7b S)-1a,2,3,7b-tetrahydro-2,3-dihydroxy-5-[2-(3-hydroxy-4-methoxyphenyl)-ethyl]-7H-oxireno[f][1]benzopyran-7-one(5),oxidoagarochromone B(6),oxidoagarochromone C(7),(5S,6R,7S,8R)-2-[2-(3′-hydroxy-4′-methoxyphenyl)ethyl]-5,6,7,8-tetrahydroxy-5,6,7,8-tetrahydrochromone(8),6,7-cis-dihydroxy-2-(2-phenylethyl)-5,6,7,8-tetrahydrochromone(9),N-trans-feruloyltyramine(10)。化合物3~5和8~10为首次从柯拉斯那沉香中分离得到。化合物1,3,6,7,9和10对乙酰胆碱酯酶具有一定的抑制活性,化合物4对人慢性髓原白血病细胞株K-562和人胃癌细胞株SGC-7901均具有较小的抑制作用,化合物1和3对人肝癌细胞株BEL-7402也有抑制活性。  相似文献   

4.
5.
6.
Chemical investigation of the ethanol extract of the branch and leaves of Illicium majus resulted in the isolation of four new phenylpropanoid glycosides ( 1 – 4 ) and one new phenolic glycoside ( 9 ), along with 13 known ones. Spectroscopic techniques were used to elucidate the structures of the new isolates such as 3-[(2R,3S)-7-hydroxy-2-(4-hydroxy-3-methoxyphenyl)-3-(hydroxymethyl)-2,3-dihydro-1-benzofuran-5-yl]propyl β-D-glucopyranoside ( 1 ), [(2R,3S)-7-hydroxy-2-(4-hydroxy-3-methoxyphenyl)-5-(3-hydroxypropyl)-2,3-dihydro-1-benzofuran-3-yl]methyl 2-O-α-L-rhamnopyranosyl-β-D-glucopyranoside ( 2 ), [(2R,3S)-7-hydroxy-2-(4-hydroxy-3-methoxyphenyl)-5-(3-hydroxypropyl)-2,3-dihydro-1-benzofuran-3-yl]methyl 2-O-α-L-rhamnopyranosyl-β-D-xylopyranoside ( 3 ), 3-[(2R,3S)-3-({[2-O-(4-O-acetyl-α-L-rhamnopyranosyl)-β-D-xylopyranosyl]oxy}methyl)-7-hydroxy-2-(4-hydroxy-3-methoxyphenyl)-2,3-dihydro-1-benzofuran-5-yl]propyl acetate ( 4 ), and 4-(2-hydroxyethyl)phenyl 3-O-β-D-glucopyranosyl-β-D-glucopyranoside ( 9 ). Free radical scavenging activities of the isolates were elucidated through the DPPH assay method. The most active compounds, 1-O-caffeoyl-β-D-glucopyranose ( 17 ) and soulieana acid 1 ( 18 ), exhibited moderate radical scavenging activities (IC50=37.7±4.4 μM and IC50=97.2±3.4 μM, respectively). The antibacterial activities of the isolates against Staphylococcus aureus and Escherichia coli were also assessed, and no activity was shown at the measured concentration (<32 μg/mL).  相似文献   

7.
Sphaeranthus africanus L. is native in Vietnam. Little is known about α-glucosidase inhibition of Sphaeranthus africanus and its isolated compounds. A bioactive-guided isolation was applied to the Vietnamese Sphaeranthus africanus to find α-glucosidase inhibitory components. Eight compounds were detected and structurally elucidated. They are 3-angeloyloxy-5-[2′′,3′′-epoxy-2′′-methylbutanoyloxy]-7-hydroxycarvotacetone, 3-angeloyloxy-5-[3′′-chloro-2′′-hydroxy-2′′-methylbutanoyloxy]-7-hydroxycarvotacetone, 3-angeloyloxy-5-[2′′R,3′′R-dihydroxy-2′′-methyl-butanoyloxy]-7-hydroxycarvotacetone, 3-angeloyloxy-5-[2′′S,3′′R-dihydroxy-2′′-methylbutanoyloxy]-7-hydroxycarvotacetone, 3-angeloyloxy-5-[2′′S,3′′S-dihydroxy-2′′-methylbutanoyloxy]-7-hydroxycarvotacetone, 5-angeloyloxy-7-hydroxy-3-tigloyloxycarvotacetone, 3-O-methylquercetin, and chrysosplenol D. Their chemical structures were elucidated by extensive 1D and 2D NMR analysis and high-resolution mass spectroscopy as well as comparisons in literature. 3-Angeloyloxy-5-[2′′S,3′′S-dihydroxy-2′′-methylbutanoyloxy]-7-hydroxycarvotacetone is a new compound. Isolated compounds were evaluated for the α-glucosidase inhibition. Isolated compounds showed moderate activity with IC50 values ranging from 128.9–274.3 μM while others are weak. A molecular docking study was conducted, indicating that isolated compounds are potent α-glucosidase inhibitory compounds.  相似文献   

8.
In order to define binding interactions of Kdo-specific monoclonal antibodies directed against the chlamydial α-(2→8)-linked Kdo disaccharide epitope on a molecular level, modifications at the 7-position of the proximal and distal Kdo unit were investigated. The synthesis of 7-O-methyl and 7-azido-7-deoxy-7-epi-Kdo monosaccharide derivatives was achieved via an 8-O-TBS protected derivative, whereas methylation of O-7 at the proximal Kdo unit of the α-(2→8)-linked Kdo disaccharide was conveniently accomplished via a 4,5; 4′,5′; 7′,8′-tri-O-carbonyl-protected disaccharide intermediate. Attempted epimerization at C-5 of the inner unit of a α-(2→4)-linked Kdo disaccharide, however, resulted in formation of the corresponding 5,6-dehydro derivative, which was fully deprotected. Treatment of unprotected α-(2→8)- as well as α-(2→4)-linked Kdo disaccharides in neat acetic acid furnished the corresponding interresidue lactone derivatives. The lactones displayed limited stability under neutral conditions and were hydrolyzed at pH 7 within 3 days. Access to the lactones, however, provides a means for selective derivatization of the carboxylic group located at the distal Kdo residue, which was demonstrated by methanolysis of the lactone to afford the monomethyl ester of the α-(2→8)-linked Kdo disaccharide. ELISA inhibition experiments of the ligands with two Kdo-specific monoclonal antibodies showed slightly reduced reactivity for the binding of the α-(2→8) Kdo-specific antibody S25-2, whereas the 7-O-methyl disaccharide antigen displayed high binding affinity toward the Kdo monosaccharide-specific antibody S67-27.  相似文献   

9.
Prion protein (PRNP) gene is well known for affecting mammal transmissible spongiform encephalopathies (TSE), and is also reported to regulate phenotypic traits (e.g. growth traits) in healthy ruminants. To identify the insertion/deletion (indel) variations of the PRNP gene and evaluate their effects on growth traits, 768 healthy individuals from five sheep breeds located in China and Mongolia were identified and analyzed. Herein, four novel indel polymorphisms, namely, Intron-1-insertion-7bp (I1-7bp), Intron-2-insertion-15bp (I2-15bp), Intron-2-insertion-19bp (I2-19bp), and 3′ UTR-insertion-7bp (3′ UTR-7bp), were found in the sheep PRNP gene. In five analyzed breeds, the minor allelic frequencies (MAF) of the above indels were in the range of 0.008 to 0.986 (I1-7bp), 0.113 to 0.336 (I2-15bp), 0.281 to 0.510 (I2-19bp), and 0.040 to 0.238 (3′ UTR-7bp). Additionally, there were 15 haplotypes and the haplotype ‘II2-15bp-D3’UTR-7bp-DI2-19bp-DI1-7bp’ had the highest frequency, which varied from 0.464 to 0.629 in five breeds. Moreover, association analysis revealed that all novel indel polymorphisms were significantly associated with 13 different growth traits (P < 0.05). Particularly, the influences of I2-15bp on chest width (P = 0.001) in Small Tail Han sheep (ewe), 3′ UTR-7bp on chest circumference (P = 0.003) in Hu sheep, and I2-19bp on tail length (P = 0.001) in Tong sheep, were highly significant (P < 0.01). These findings may be a further step toward the detection of indel-based typing within and across sheep breeds, and of promising target loci for accelerating the progress of marker-assisted selection in sheep breeding.  相似文献   

10.

Objectives  

Natural products have played a significant role in drug discovery and development. Inflammatory mediators such as inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) have been suggested to connect with various inflammatory diseases. In this study, we explored the anti-inflammatory potential of aciculatin (8-((2R,4S,5S,6R)-tetrahydro-4,5-dihydroxy-6-methyl-2H-pyran-2-yl)-5-hydroxy-2-(4-hydroxyphenyl)-7-methoxy-4H-chromen-4-one), one of main components of Chrysopogon aciculatis, by examining its effects on the expression and activity of iNOS and COX-2 in lipopolysaccharide (LPS)-activated macrophages.  相似文献   

11.
3-Nitrobenzanthrone (3-nitro-7H-benz[d,e]anthracen-7-one, 3-NBA) is a powerful mutagen and a suspected human carcinogen existing in diesel exhaust and airborne particulates. Recently, one of the major presumed metabolites of 3-NBA, 3-aminobenzanthrone (3-ABA), was detected in human urine samples. Here we analyzed DNA adducts formed in 3-NBA-exposed human hepatoma HepG2 cells by a 32P-postlabeling/thin layer chromatography (TLC) method and a 32P-postlabeling/polyacrylamide gel electrophoresis (PAGE) method. With HepG2 cells exposed to 3-NBA (0.36–36.4 μM) for 3 h, we obtained three spots or bands corresponding to adducted nucleotides. Two were assigned as 2-(2′-deoxyadenosin-N6-yl)-3-aminobenzanthrone-3′-phosphate (dA3′p-N6-C2-ABA) and 2-(2′-deoxyguanosin-N2-yl)-3-aminobenzanthrone-3′-phosphate (dG3′p-N2-C2-ABA), with identical mobilities to those of synthetic standards on PAGE analysis. The chemical structure of the substance corresponding to the other spot or band could not be identified. Quantitative analyses revealed that the major adduct was dA3′p-N6-C2-ABA and its relative adduct labeling (RAL) value at 36.4 μM of 3-NBA was 200.8 ± 86.1/108 nucleotide.  相似文献   

12.
The CHCl3-soluble fraction of the whole plant of Duranta repens showed anti-plasmodial activity against the chloroquine-sensitive (D6) and chloroquine-resistant (W2) strains of Plasmodium falciparum, with IC50 values of 8.5?±?0.9 and 10.2?±?1.5?μg/mL, respectively. From this fraction, two new flavonoid glycosides, 7-O-α-d-glucopyranosyl-3,4′-dihydroxy-3′-(4-hydroxy-3-methylbutyl)-5,6-dimethoxyflavone (1) and 7-O-α-d-glucopyranosyl(6′′′-p-hydroxcinnamoyl)-3,4′-dihydroxy-3′-(4-hydroxy-3-methylbutyl)-5,6-dimethoxyflavone (2), along with five known flavonoids, 3,7,4′-trihydroxy-3′-(4-hydroxy-3-methylbutyl)-5,6-dimethoxyflavone (3), 3,7-dihydroxy-3′-(4-hydroxy-3-methylbutyl)-5,6,4′-trimethoxyflavone (4), 5,7-dihydroxy-3′-(2-hydroxy-3-methyl-3-butenyl)-3,6,4′-trimethoxyflavone (5), 3,7-dihydroxy-3′-(2-hydroxy-3-methyl-3-buten-yl)-5,6,4′-trimethoxyflavone (6), and 7-O-α-d-glucopyranosyl-3,5-dihydroxy-3′-(4′′-acetoxy-3′′-methylbutyl)-6,4′-dimethoxyflavone (7), have been isolated as anti-plasmodial principles. Their structures were deduced by spectroscopic analysis including 1D and 2D NMR techniques. The compounds (1–7) showed potent anti-plasmodial activities against D6 and W2 strains of Plasmodium falciparum, with IC50 values in the range of 5.2–13.5?μM and 5.9–13.1?μM, respectively.  相似文献   

13.
14.
Abstract: Cross-reactions between dopamine D3 and σ receptor ligands were investigated using (±)-7-hydroxy-N,N-di-n-[3H]propyl-2-aminotetralin [(±)-7-OH-[3H]DPAT], a putative D3-selective radioligand, in conjunction with the unlabeled σ ligands 1,3-di(2-tolyl)guanidine (DTG), carbetapentane, and R(?)-N-(3-phenyl-1-propyl)-1-phenyl-2-aminopropane [R(?)-PPAP]. In transfected CCL1.3 mouse fibroblasts expressing the human D3 receptor, neither DTG nor carbetapentane (0.1 µM) displaced (±)-7-OH-[3H]DPAT binding. R(?)-PPAP (0.1 µM) displaced 39.6 ± 1.0% of total (±)-7-OH-[3H]DPAT binding. In striatal and nucleus accumbens homogenates, (±)-7-OH-[3H]DPAT labeled a single site (15–20 fmol/mg of protein) with high (1 nM) affinity. Competition analysis with carbetapentane defined both high- and low-affinity sites in striatal (35 and 65%, respectively) and nucleus accumbens (59 and 41%, respectively) tissue, yet R(?)-PPAP identified two sites in equal proportion. Carbetapentane and R(?)-PPAP (0.1 µM) displaced ~20–50% of total (±)-7-OH-[3H]DPAT binding in striatum, nucleus accumbens, and olfactory tubercle in autoradiographic studies, with the nucleus accumbens shell subregion exhibiting the greatest displacement. To determine directly (+)-7-OH-[3H]DPAT binding to σ receptors, saturation analysis was performed in the cerebellum while masking D3 receptors with 1 µM dopamine. Under these conditions (+)-7-OH-[3H]DPAT labeled σ receptors with an affinity of 24 nM. These results suggest that (a) (±)-7-OH-[3H]DPAT binds D3 receptors with high affinity in rat brain and (b) a significant proportion of (±)-7-OH-[3H]DPAT binding consists of σ1 sites and the percentages of these sites differ among the subregions of the striatum and nucleus accumbens.  相似文献   

15.
In order to produce explants of Mandevilla illustris (Vell) Woodson for the Cerrado in vitro, the Germplasm Bank of UNAERP, we carried out a micropropagation protocol using MS or MS/3 medium supplemented with different concentrations of 6-benzyladeninepurine (BA), Zeatin or 2-isopentenyladenine for nodal segment growth, and -naphthaleneacetic acid, indole-3-butyric acid (IBA) or 1,4 dithiothreitol for rooting. For nodal segments, all the cytokinins tested yielded similar results. However, 2.22 µM BA is more economical to use. MS/3 medium supplemented with 0.49 µM IBA was the most appropriate medium for rooting, resulting in 29% rooted explants. The crude aqueous extract from the subterranean system (SS) of M. illustris was assayed for its inhibitory action on the enzymatic activity of Crotalus durissus terrificus snake venom, isolated basic phospholipase A2 (CB) and crotoxin. It totally inhibited the phospholipase activity of crude Cdt venom and CB toxin and inhibited the phospholipase activity of crotoxin by 49%. The toxic action of both the crude venom and crotoxin was partially inhibited—there was a prolonged survival time and a 40.0% decrease in lethality.Abbreviations BA: 6-Benzyladeninepurine - CB: Crotalus durissus terrificus basic phospholipase A2 - Cdt: Crotalus durissus terrificus crude venom - DTT: 1,4 Dithiothreitol - IBA: Indole-3-butyric acid - 2ip: 2-Isopentenyladenine - MiHD: Minimum indirect hemolytic dose - NAA: -Naphthaleneacetic acid - PBS: Phosphate-buffered saline solution - Spermidine: (n-[3-Aminopropyl]-1,4-butanediamine) - SS: Subterranean system - TDZ: Thidiazuron - Zeatin: (6-[4-Hydroxy-3-methylbut-2-enylamino]purine) Communicated by C.F. Quiros  相似文献   

16.
Thirty-two steers orally inoculated with a four-strain mixture (1010 CFU) of nalidixic acid-resistant Escherichia coli O157:H7 had sun-dried Ascophyllum nodosum seaweed (Tasco-14™) added to their barley-based diet (860 g/kg barley grain and 90 g/kg whole crop barley silage, dry matter basis) to assess its effectiveness in reducing fecal shedding of the pathogen. Steers were housed in four groups of eight and received Tasco-14™ in the diet, in place of barley, at levels (as fed) of 10 g/kg for 14 days (T1-14), 20 g/kg for 7 days (T2-7), 20 g/kg for 14 days (T2-14), or not at all (i.e., control, CON). The dietary treatments commenced 7 days after E. coli O157:H7 inoculation and fecal shedding patterns were examined over 14 weeks. Water, water–trough interface, feed and fecal pat samples were also collected weekly and cultured for E. coli O157:H7. Detection of the pathogen in fecal samples was less frequent (P<0.05) in T1-14 (99/168) and T2-7 (84/168) versus CON (135/168) and T2-14 (115/168), and the concentrations of E. coli O157:H7 recovered in feces from T1-14 and T2-7 steers were lower (P<0.005) than from CON or T2-14 steers. Rates of decline in shedding of E. coli O157:H7 were similar among treatments, but final numbers of E. coli O157:H7 were lower (P<0.05) in T1-14 and T2-7 as compared to T2-14 and CON. Fecal volatile fatty acid concentrations and pH were similar among treatments, suggesting no fecal alterations that were antagonistic to survival. E. coli O157:H7 was present in 1 (from T2-7) of 56 cattle drinking water samples, 2 of 56 (T1-14, CON) feed samples and 32 of 56 fecal pats. A second experiment investigated effects of the dietary treatment on growth performance of non-inoculated sheep. Tasco-14™ was administered to 40 individually fed Canadian Arcott lambs beginning at day 56 of a 105-day finishing period. The lambs received Tasco-14™ at 0 g/kg (control, CON), at 10 g/kg for 14 days (T1-14), 20 g/kg for 14 days (T2-14), 10 g/kg for 28 days (T1-28) or at 20 g/kg for 7 days (T2-7) as a top-dress on their pelleted, barley grain-based diet (n = 8). E. coli O157:H7 was not isolated from fecal samples collected at 4-week intervals, but generic E. coli populations were lower (P<0.05) in T1-28 lambs than in other treatments. Average daily gain, feed intake, feed efficiency and carcass traits did not differ among treatments. Our challenge study supports past studies showing that Tasco-14™ decreases shedding of E. coli O157:H7 by cattle. The lamb study shows that this additive did not directly affect feed intake or animal growth.  相似文献   

17.
Visceral leishmaniasis affects people from 70 countries worldwide, mostly from Indian, African and south American continent. The increasing resistance to antimonial, miltefosine and frequent toxicity of amphotericin B drives an urgent need to develop an antileishmanial drug with excellent efficacy and safety profile. In this study we have docked series of febrifugine analogues (n = 8813) against trypanothione reductase in three sequential docking modes. Extra precision docking resulted into 108 ligands showing better docking score as compared to two reference ligand. Furthermore, 108 febrifugine analogues and reference inhibitor clomipramine were subjected to ADMET, QikProp and molecular mechanics, the generalized born model and solvent accessibility study to ensure the toxicity caused by compounds and binding-free energy, respectively. Two best ligands (FFG7 and FFG2) qualifying above screening parameters were further subjected to molecular dynamics simulation. Conducting these studies, here we confirmed that 6-chloro-3-[3-(3-hydroxy-2-piperidyl)-2-oxo-propyl]-7-(4-pyridyl) quinazolin-4-one can be potential drug candidate to fight against Leishmania donovani parasites.  相似文献   

18.

Objective:

Hemorphin peptides exhibit biological activities that interfere with the endorphin system, the inflammatory response, and blood‐pressure control. VV‐hemorphin‐7 and LVV‐hemorphin‐7 peptides exert a hypotensive effect, in particular, by inhibiting the renin–angiotensin system. Furthermore, levels of circulating hemorphin‐7 peptides have been found to be decreased in diseases such as type 1 and type 2 diabetes.

Design and Methods:

Because type 2 diabetes and obesity share common features, such as insulin resistance, microinflammation, high glomerular‐filtration rate (GFR), and cardiovascular risk, we evaluated serum VV‐hemorphin‐7 like immunoreactivity (VVH7‐i.r.) levels, using an enzyme‐linked immunosorbent assay method, on a group of 54 obese subjects without diabetes or hypertension, compared with a group of 33 healthy normal‐weight subjects.

Results:

Circulating VVH7‐i.r. levels were significantly decreased in the obese group compared with the control group (1.98 ± 0.19 vs. 4.86 ± 0.54 µmol/l, respectively, P < 0.01), and a significant negative correlation between VVH7‐i.r. and diastolic blood pressure (DBP) was found in obese patients (r = ?0.35, P = 0.011). There was no significant correlation between VVH7‐i.r. level and insulin resistance, metabolic syndrome, or GFR.

Conclusions:

The decreased serum hemorphin‐7 found in obese subjects, as in diabetes, may contribute to the development of hypertension and to the cardiovascular risk associated with these metabolic diseases.
  相似文献   

19.
The degradation of a lignin substructure model compound, 5-formyl-3-hydroxymethyl-2-(4-hydroxy-3,5-dimethoxyphenyl)-7-methoxycoumaran (I), in ligninolytic culture of a white-rot wood decay fungus,Phanerochaete chrysosporium, was investigated. It was found that I was hydroxylated or dehydrogenated in its coumaran ring to give 2-(5-formyl-2-hydroxy-3-methoxyphenyl)-3-hydroxypropiosyringone (II) and two coumarones, 5-formyl-3-hydroxymethyl-2-(4-hydroxy-3,5-dimethyoxyphenyl)-7-methoxycoumarone (V) and 3,5-diformyl-2-(4-hydroxy-3,5-dimethoxyphenyl)-7-methoxycoumarone (VI), II was further converted to 2,6-dimethoxy-p-benzoquinone (IV), syringic acid (III), and 5-carboxyvanillic acid (VIII). These metabolic products were identified by mass spectrometric comparison with the authentic compounds. A proposed pathway for the degradation of I is presented on the basis of these metabolic products. The degradation could be catalyzed mainly by phenol-oxidizing enzymes.Non-Standard Abbreviations TLC thin layer chromatography  相似文献   

20.
Abstract

A short and simple synthesis of 5-amino-3-β-D-ribofuranosylpyrazolo[4,3-d]pyrimidin-7(6H)-one, (7) was achieved from 7-amino-5-chloro-3-β-D-ribofuranosylpyrazolo[4,3-d]pyrimidine (5), in two steps, first deamination of 5 with NOCI, followed by amination of 6 with MeOH/NH3. Also, an efficient synthesis of 5-amino-1(or 2)-methyl-3-β-D-ribofuranosylpyrazolo[4,3-d]pyrimidin-7(6H)-one was accomplished from the corresponding 1 (or 2)-methyloxoformycin B in four steps by a sequence consisting of (i) 2′,3′,5′ acetylation with AC2O, (ii) 5,7-chlorination with PhP(O)Cl2, (iii) selective hydrolysis of the 7-chloro group with aqueous Na2CO3, (iv) followed by amination of the 5-chloro group with MeOH/NH3. Single crystal X-ray analysis off 11 confirmed position 7 as the site of selective hydrolysis with Na2CO3. The three guanosine C-nucleosides prepared were evaluated for their ability to inhibit certain RNA and DNA viral replication in vitro and Semliki Forest virus infection in vivo. Only 5-amino-1-methyl-3-β-D-ribofuranosylpyrazolo[4,3-d]pyrimidin-7(6H)-one (13) provided protection (67% survivors, compared to 0% for placebo controls) against a lethal dose of Semliki Forest virus infection in mice. The antiviral effect of 13 is believed to be due to the enhancement of the host immune function.  相似文献   

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