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11.
Shaza M. Al-Massarani Ali A. El-Gamal Adnan J. Al-Rehaily Ebtesam S. Al-Sheddi Mai M. Al-Oqail Nida N. Farshori Alden S. Estep Nurhayat Tabanca James J. Becnel 《Molecules (Basel, Switzerland)》2021,26(4)
Chromatographic purification of the alcoholic extract from the aerial parts of the Saudi plant Nuxia oppositifolia (Hochst.), Benth., resulted in five isolated phenolic compounds. Two flavones, hispidulin (1) and jaceosidin (2), and the phenylethanoid glycosides, verbascoside (3), isoverbascoside (4), and conandroside (5), were identified and their chemical structures were determined by spectroscopic analyses. The insecticidal activity of compounds 1 and 2, in addition to 11 compounds isolated in a previous research (6–16), was evaluated against the Yellow Fever mosquito, Aedes aegypti. Four compounds displayed adulticidal activity with LD50 values of 2–2.3 μg/mosquito. Free radical scavenging properties of the plant extracts and compounds (1–5) were evaluated by measuring the 1,1-diphenyl-2-picrylhydrazyl radical (DPPH) and 2,2′-azino-bis (3-ethylbenzothiazoline-6-sulfonate radical cation (ABTS•+) scavenging activity. All compounds exhibited notable activity, compared with the positive control, l-Ascorbic acid. This study suggests that N. oppositifolia could be a promising source of secondary metabolites, some with lethal adulticidal effect against Ae. aegypti. 相似文献
12.
H.-J. Mai S. Wocadlo H.-C. Kang W. Massa K. Dehnicke C. Maichle-Mssmer J. Strhle D. Fenske 《无机化学与普通化学杂志》1995,621(5):705-712
Phosphanimine and Phosphoraneiminato Complexes of Iron. The Crystal Structures of [FeCl3(Me3SiNPEt3)], [FeCl2(Me3SiNPEt3)]2, [FeCl2(NPEt3)]2, and [Fe(O2C? CH3)2(NPEt3)]2 The phosphanimine complexes [FeCl3(Me3SiNPEt3)] (red-orange) and [FeCl2(Me3SiNPEt3)]2 (colourless) have been prepared by reactions of Me3SiNPEt3 with FeCl3 and FeCl2, respectively, in CH2Cl2 suspensions. Thermal decomposition of these donor-acceptor complexes in boiling toluene leads to the phosphoraneiminato complex [FeCl2(NPEt3)]2 (black), whereas [Fe(O2C? CH3)2(NPEt3)]2 (brown) is formed from iron(II) acetate and Me3SiNPEt3 in boiling acetonitrile. The complexes are characterized by IR spectroscopy and by crystal structure determinations. [FeCl3(Me3SiNPEt3)] (1) : Space group P21/c, Z = 8, structure determination with 4 673 unique reflections, R = 0.033. Lattice dimensions at ?15°C: a = 1 607.8, b = 1 602.0, c = 1 417.2 pm, β = 106.56°. 1 forms monomeric molecules with tetrahedrally coordinated iron atoms. Bond lengths in average: Fe? N = 196.9 pm, Fe? Cl = 219.7 pm. [FeCl2(Me3SiNPEt3)]2 (2) : Space group P21/c, Z = 4, structure determination with 4 992 unique reflections, R = 0.048. Lattice dimensions at 20°C: a = 1 457.9, b = 1 685.4, c = 1 507.3 pm, β = 116.74°. 2 forms dimeric molecules, which are associated by chloro bridges. The iron atoms are tetrahedrally coordinated with trans positions of the phosphanimine ligands. Both lengths in average: Fe? N = 202.2 pm, Fe? Clterminal = 224.7 pm, Fe? Cl bridge = 241.0 pm. [FeCl2(NPEt3)]2 (3): Space group P21/n, Z = 2, structure determination with 2763 unique reflections, R = 0.039. Lattice dimensions at ?70°C: a = 799.1, b = 1009.0, c = 1441.9 pm, β = 93.45°. 3 forms centrosymmetric dimeric molecules, in which the tetrahedrally coordinated iron atoms are associated by the nitrogen atoms of the phosphoraneiminato ligands. Bond lengths in average: Fe? N = 191.4 pm, Fe? Cl = 222.7 pm. [Fe(O2C? CH3)2(NPEt3]2 (4): Space group P21/n, Z = 2, structure determination with 3005 observed unique reflections, R = 0.034. Lattice dimensions at -65°C: a = 886.4, b = 1444.6 pm, β = 90.60°. 4 forms centrosymmetric dimeric molecules, in which the octahedrally coordinated iron atoms are associated by the nitrogen atoms of the phosphoraneiminato ligands with bond lengths Fe? N of 191.9 and 195.0 pm. The acetate groups are coordinated in a chelating fashion. 相似文献
13.
Chiral quaternary ammonium salts derived from cinchonidine have been applied to catalyze the stereoselective iodolactonizations of trans-5-aryl-4-pentenoic acids leading to a mixture of two regioselectively iodolactonized products with fair to excellent yield (37-98%) and moderate enantioselectivity (exo = 42.0% ee, endo = 31.0% ee) under mild conditions. This work is the first example of asymmetric iodolactonization reaction in the presence of less than a stoichiometric amount of chiral reagent. 相似文献
14.
On Mg-containing Y zeolites toluene undergoes disproportionation and demethylation. The relative importance of the two processes is discussed.
Mg- Y . .相似文献
15.
Mai Thanh Thi Nguyen 《Tetrahedron letters》2004,45(46):8519-8522
A novel dimeric methanodibenzoxocinone, named neosappanone A (1), possessing a unique unprecedented novel carbon framework, has been isolated from the heartwood of Caesalpinia sappan L. of Vietnam, and its structure was elucidated on the basis of spectroscopic analysis. Neosappanone A (1) competitively inhibited xanthine oxidase in a concentration-dependent manner (IC50, 29.7 μM; Ki, 16.3 μM). 相似文献
16.
o-Xylene conversions has been investigated in the presence of MgNaY zeolites with different Si/Al ratios and degrees of exchange. Disproportionation proceeds to a higher degree than does isomerization. The distribution of reaction products is attributed to geometric factors. The results are in agreement with a monomolecular mechanism of isomerization.
- MgNaY Si/Al . , , . . .相似文献
17.
18.
用电感耦合等离子体发射光谱法(ICP-AES),测定了海口市266例正常儿童头发中锌、铁、阵、铜四种微量元素的含量,计算出海口市儿童四各微量元素的正常范围。并与其它地区文献报道值进行了比较。 相似文献
19.
S V Dzyadevych T Mai Anh A P Soldatkin N Duc Chien N Jaffrezic-Renault J-M Chovelon 《Bioelectrochemistry (Amsterdam, Netherlands)》2002,55(1-2):79-81
This article describes a biosensor based on pH-sensitive field-effect transistors (pH-FETs) as transducer, and immobilised enzyme tyrosinase as biorecognition element, which was used for the determination of phenolic compounds in water solutions. The biologically active membrane was formed by cross-linking of tyrosinase with bovine serum albumin (BSA) in saturated glutaraldehyde (GA) vapours on the sensitive transducer surface. The main analytical characteristics were studied under different conditions as well as the possibility to optimise these working parameters. Different factors such as the pH of immobilisation, the enzyme loading, the time of exposition to glutaraldehyde vapours were investigated in regards to the influence on sensitivity, limit of detection, dynamic range, and operational and storage stability. 相似文献
20.