Constituents from Polygonum cuspidatum

Two lignan sulfates, a stilbene derivative and a phenol sulfate, together with 10 known compounds, were isolated from an aqueous extract of the root of Polygonum cuspidatum. The new compounds were elucidated based on chemical evidence and spectroscopic techniques including two-dimensional NMR methods. They exhibited no inhibition of lipid peroxidation and no cytotoxic and DNA cleavage activities.     

A new naphthoquinone from Polygonum aviculare

A new naphthoquinone, 6-methoxyplumbagin was isolated from the acetone extracts of Polygonum aviculare. Its structure was elucidated by various spectroscopic methods. The known compounds sitosterol, oleanolic acid and 5,6,7,4'-tetramethoxyflavanone were also obtained from this natural source.     

Three New Anthraquinones from Polygonum cillinerve

Three new anthraquinones, emodin-8-β-D-（2＂-O-coumarate）glucoside 1, emodin-8-β-D-（6＇-O-acetyl）glucoside 2 and physicon-8-β-D-（6＇-O-acetyl）glucoside 3, were isolated from the roots of Polygonum cillinerve and their structures were established by spectroscopic methods. The biological activity indicated that compound 1 had the scavenging activity on 1,1-diphenyl-2-picrylhydrazyl （DPPH） radicals （the IC50 = 8.5 μmol/L）, and compound 1-3 showed no activities against HL-60 and BCJC-823 cells by MTT method in vitro.     

Bioactive phenolic amides from Celtis africana

Nine compounds have been isolated for the first time from Celtis africana, namely trans-N-coumaroyltyramine (1), trans-N-feruloyltyramine (2), trans-N-caffeoyltyramine (3), lauric acid (4), oleic acid (5), palmitic acid (6), lupeol (7), β-sitosterol (8) and oleanolic acid (9), respectively. Their structures have been elucidated by different spectroscopic techniques. The isolated compounds were screened for their antioxidant, anti-inflammatory and acetylcholinestrease enzyme inhibitory activities. Compounds 1-3 showed significant antioxidant and anti-inflammatory activities and weak to moderate acetylcholinestrease enzyme inhibition activity.     

2-Acetylpyridine- and 2-benzoylpyridine-derived thiosemicarbazones and their antimony(III) complexes exhibit high anti-trypanosomal activity

Complexes [Sb(2Ac4oClPh)Cl₂] (1), [Sb(2Ac4oFPh)Cl₂] (2), [Sb(2Ac4oNO₂Ph)Cl₂] (3), [Sb(2Bz4oClPh)Cl₂] (4), [Sb(2Bz4oFPh)Cl₂] (5) and [Sb(2Bz4oNO₂Ph)Cl₂] (6) were obtained with 2-acetylpyridine-N(4)-ortho-chlorophenyl thiosemicarbazone (H2Ac4oClPh) and its N(4)-ortho-fluor (H2Ac4oFPh) and N(4)-ortho-nitro (H2Ac4oNO₂Ph) analogues, and with the corresponding 2-benzoylpyridine-derived thiosemicarbazones (H2Bz4oClPh, H2Bz4oFPh, H2Bz4oNO₂Ph). The studied compounds are excellent inhibitors of Trypanosoma cruzi growth. H2Bz4oClPh and complexes (4) and (1) were the most trypanosomicidal.Upon coordination of H2Ac4oClPh to antimony(III) in 1, the therapeutic index (TI) goes from 10.58 to 14.35. However, the best values of TI were found for H2Bz4oClPh (TI = 1240) and H2Ac4oNO₂Ph (TI = 773). Structure-activity relationship (SAR) studies did not allow the establishment of correlations between the anti-trypanosomal activity and physico-chemical parameters, but correlations were found between the cytotoxicities and physico-chemical properties.     

β-elimination from transition metal amides

Ruthenium, rhodium, and palladium phosphine complexes are found to produce metal hydrides in high yields by a β-elimination reaction from the corresponding metal amides. Evidence is presented to support the formation of an imine as the organic product. The isotope effect for the reaction is 6 ± 1 indicative of the importance of CH bond breaking in the transition state.     

a-Hydroxy amides from carbamoylsilane and aldehydes

1. Download : Download full-size image

     

A New Steroid from Polygonum nodosum Pers

A new steroid named as Zhonghualiaoine1(1) was isolated from Polygonum nodosun pers(Chinese name “Zhonghualiao“,Berberidaceae).Its structure was deduced on the basis of its spectral data.     

Two new anthraquinone malonylglucosides from Polygonum cuspidatum

Two new anthraquinone malonylglucosides polygonins A and B were isolated from Polygonum cuspidatum along with seven known compounds. The structures of 1 and 2 were elucidated based on their spectroscopic data.     

Synthesis of enamides from aldehydes and amides

A range of double unsaturated amides (15, 19, and 21), obtained by cross-coupling reactions was reacted with aldehydes to hemiaminals. Heating the hemiaminals in the presence of Ac₂O and pyridine affected clean conversion to the corresponding enamides, such as 42, 45, and 47. Alternatively, N,S-acetals were prepared which were oxidized to the sulfones. Treatment with base also gave the enamides, favoring the cis-isomer. However, this method is less general. Application of these methods led to the natural products lansiumamide-A (30_cis), lansiumamide-I (31) and lansiumamide-B (32).     

A new ellagic acid derivative from Polygonum runcinatum

A new ellagic acid derivative, 3,3′-dimethylellagic acid-4′-O-(6″-galloyl)-β-d-glucoside, named runcinatside (5), together with four known compounds 3,3′-dimethylellagic acid (1), 3,3′,4′-trimethylellagic acid (2), 3,3′-dimethylellagic acid-4′-O-β-d-glucoside (3) and 3-methylellagic acid-4′-O-α-l-rhamno-pyranoside (4), was isolated from the roots of Polygonum runcinatum Buch.-Ham. ex D.Don Var. sinense Hemsl and the structures of these compounds were established by spectroscopic methods and comparison with previously reported data. All compounds showed antioxidant activities in vitro and compound 5 possessed the highest activity.     

A novel dimeric procyanidin glucoside from Polygonum aviculare

A novel dimeric procyanidin glucoside,catechin 3-O-acetate-(4 α→8)-catechin 3-O-acetate-3’-O- β-D-glucopyranoside(1), along with five flavonoids and one lignan were isolated from the aerial parts of Polygonum aviculare.Their structures were elucidated by spectroscopic analyses including 1D,2D NMR,MS and CD methods.     

Further sesquiterpenes from Polygonum viscosum (Polygonaceae)

Two new sesquiterpenes, 4-methoxycarbonyl-7-(1-methylethyl)-6-oxo-3,3a,7,8,8a-pentahydroazulene-1-carboxylic acid (viscoazusone) and 1,4-dimethoxy-carbonyl-7-(1-methylethyl)-6-oxo-3,3a,7,8,8a-pentahydroazulene (viscoazulone), were isolated from the whole plant of Polygonum viscosum. The structures of these compounds were determined by spectroscopic means.     

A purified 124-kDa oat phytochrome does not possess a protein kinase activity

The presence of protein kinase activity in the purified phytochrome preparations [Wong, et al. (1986) J. Biol. Chem. 261, 12089-12097] has been re-examined. The phytochrome preparations having SAR (specific absorbance ratio, A668/A280 for the Pr form as a measure of phytochrome purity) values of greater than 0.95 were homogeneous on SDS gel, but could be further purified to a SAR value of 1.07 by repeated gel filtrations on a Bio-Gel A-0.5 m column. The protein kinase activity remained in the phytochrome preparations having SAR values less than 1.05, but it became undetectable in the phytochrome preparation with a SAR value of 1.07. Two dimensional gel electrophoresis of the phytochrome preparation (SAR, 0.89) showed that a phytochrome band with pl 5.8 had no kinase activity. Phosphorylating activity of the protein kinase was enhanced to some extent by polycations, polylysine and histone. Phytochrome served as a good substrate for this enzyme. The present data indicate that phytochrome has no intrinsic protein kinase activity, but a protein kinase is present in highly purified phytochrome preparations.