Alkaloids from flowers of Erythrina corallodendron

Two new Erythrina alkaloids, 10-oxo-erythrinine (1) erythrinine N-oxide (2) together with 23 known ones were obtained from the flowers of Erythrina corallodendron. The structures were determined based on analysis of their spectroscopic data. All compounds were first isolated from plants of Erythrina corallodendron.     

Facile and highly stereoselective synthesis of the tetracyclic erythrinane core

A highly stereoselective synthesis of the tetracyclic core of the Erythrina alkaloids is reported through the application of a Meyers bicyclic lactam template.     

Three Prenylated Isoflavones from Erythrina variegate

Two new prenylated isoflavones (erythrivarones A and B) were isolated from the stem bark of Erythrina variegata Linn, together with the known compound alpinumisoflavone (1). The structures of erythrivarones A and B were characterized as dihydroalpinumisoflavone (2) and 4′-hydroxy-[6″,6″-dimethyldihydropyrano(2″,3″:5,6)]-[6?,6?-dimethyldihydropyrano(2?,3?:7,8)]isoflavone (3), respectively, by means of spectroscopic analysis.     

Erythrinarbine,a Novel nor-A ring Erythrina Alkaloid from Erythrina arborescens

ErythrinaarborescensRoxb.belongstoErythrinagenusofPapilionaceaefamilyplants,andiswidelydistributedintropicalandsubtropicalregionsoftheworld,aswellasinthesouthandsouth-westofChina'.AsaChinesefolkmedicine,itsrootandstemareusedtotreatrheumatismanddysentery'.TheErythrinaalkaloids,normallyaC.,tetracyclicspiroaminesystem,erythrinanel,arethecharacteristicconstituentsinErylhrinagenusandabout100erythrinaalkaloidshavebeensofarreportedfromthisgenusplants'-'.MostoftheseErythrinaalkaloidshaveatetrahydr…     

Erythrinan alkaloids from seeds of Erythrina velutina

Four new Erythrinan alkaloids (1-4) were isolated from the seeds of Erythrina velutina. The structures of these new compounds 1-4 were elucidated by spectroscopic methods including 2D-NMR. Three of four were found to be novel sulfated Erythrinan alkaloids.     

Isolation and characterization of isolectins from Erythrina variegata seeds.

Three isolectins were isolated from seeds of Erythrina variegata (Linn.) var. Orientalis by ion-exchange chromatography, followed by affinity chromatography on lactose-Sepharose 4B and acid-treated Sepharose 4B columns. The purified isolectins (EVLI, EVLII and EVLIII) are all specific for galactopyranosides and N-acetylgalactosamine, and their affinities for simple sugars are EVLIII greater than EVLII greater than EVLI. EVLI and EVLIII are homodimers made up of an A-subunit of molecular mass 36,000 and a B-subunit of molecular mass 33,000, whereas EVLII is a heterodimer composed of the A- and B-subunits. Upon treatment with trifluoromethansulphonic acid, the molecular masses of both subunits decreased to 31,000. Rechromatography of EVLII on the acid-treated Sepharose 4B column again produced the homodimeric lectins (EVLI and EVLIII). It is suggested that the constituent subunits of Erythrina variegata isolectins are eschangeable with each other in vitro.     

Two new prenylflavanones from Erythrina sigmoidea

Two new prenylflavanones named sigmone and sigmotriol have been isolated from the stem bark of Erythrina sigmoidea along with two known constituents 8-(3"-methylbut-2"-enyl)-7,3',4'-trihydroxyflavanone and 7,3',4'-trihydroxyflavanone. Their structures were elucidated by spectroscopic methods.     

Isoflavone glycosides from the root wood of Erythrina latissima

The molecular structures of 3 isoflavone glycosides isolated from the root wood of Erythrina latissima were established as 4'-hydroxyisoflavone-7-O-beta-D-glucopyranoside (compound 1); 4'-hydroxyisoflavone-7-O-alpha-L-rhamnosyl (1-->6)-beta-D-glucopyranoside (compound 2); and a new compound 4', 8-dimethoxy isoflavone-7-O-alpha-L-rhamnosyl (1-->6) glucopyranoside (8-O-methylretusin-7-O-alpha-L-rhamnosyl (1-6)-beta-D-glucopyranoside) (compound 3).     

A short,efficient, synthetic pathway to the 6,7,8,9-tetrahydro-5h-dibenz[d,f]azonine system

The intramolecular, nickel-promoted coupling of a bis[β-(o-iodophenyl)ethyl] amine produces a dibenzazonine of the type exemplified by several naturally occurring compounds and which serve as biosynthetic precursors of the Erythrina alkaloids.     

Fukiinsäure und 3′-O-Methyl-fukiinsäure,zwei phenolische Hydroxycarbonsäuren aus Piscidia Erythrina

Purification of crude piscidic acid from ‘Cortex Piscidiae Erythrinae’, the root bark of Piscidia Erythrina L. (Papilionaceae), led to the isolation of fukiic acid (5) and 3′-O-methyl-fukiic acid (8). Since partition chromatography with alcoholic solvents produced the corresponding half-esters as artefacts, the acids were transformed to their methyl esters before separation. Spectroscopic methods and comparison with authentic samples from Petasites japonicus F. SCHMIDT (Compositae) confirmed the structures 5 and 8 .     

New palladium-catalyzed reaction pathway to the Erythrina skeleton

Palladium-catalyzed arylation of alpha,beta-unsaturated gamma-lactam, which could be prepared by condensation of amines and keto-esters, has been carried out to make the core structure of Erythrina alkaloids.     

Phenolic constituents in Erythrina x bidwilli and their activity against oral microbial organisms.

Five flavonoid compounds, including two new isoflavanones, were isolated from the root bark of Erythrina x bidwilli. Their structures were determined to be 2,10-di(gamma,gamma-dimethylallyl)-3,9-dihydroxypterocarpan (erythrabyssin II), 6,8-di(gamma,gamma-dimethylallyl)-7,2',4'-trihydroxyisoflavanone (bidwillon A), 8-gamma,gamma-dimethylallyl-2',4'-dihydroxy-[6",6"-di-methylpyrano - (2",3":7,6)]isoflavanone (bidwillon B), 8-gamma,gamma-dimethylallyl-7,4'-dihydroxyisoflavone (8-gamma,gamma-dimethyl-allyldaidzein), and 8-gamma,gamma-dimethylallyl-5,2',4'-trihydroxy-[6",6"-dimethylpyrano+ ++- (2",3":7,6)]isoflavone (auriculatin), by means of spectroscopic analysis. Some potent activities against oral microbial organisms (Fusobacterium nucleatum and Prevotella intermedia) were shown in these flavonoid compounds.     

Antifeedants from Chinese medicinal herb, Erythrina variegata var. orientalis, against maize weevil Sitophilus zeamais

The screening for insecticidal principles from several Chinese medicinal herbs showed that the stem bark of Erythrina variegata var. orientalis possessed significant feeding deterrence against maize weevils, Sitophilus zeamais. Bioassay-directed fractionation of the stem bark extract of E. variegata var. orientalis resulted in the isolation of two alkaloids, identified as erysopine and erysovine from their spectroscopic data. Erysopine and erysovine possessed antifeedant activity against S. zeamais adults with EC50 values of 108.5 and 89.7 ppm, respectively.     

Unprecedented new nonadecyl para-hydroperoxycinnamate isolated from Erythrina excelsa and its cytotoxic activity

A new unprecedented cinnamate derivative (1) was obtained from Erythrina excelsa (Leguminosae) and identified as nonadecyl para-hydroperoxycinnamate. This compound was isolated together with three known compounds, namely lupeol (2), mixture of sitosterol and stigmasterol (3), and isoneorautenol (4). Their structures were established on the basis of NMR and mass spectroscopic data in conjunction with those reported in the literature. Compound 1 was evaluated for its capability of inhibiting cancer cell lines and growth of a panel of microbial strains. It turned out that 1 is moderately to significantly cytotoxic against six cancer cell lines and shows weak to no antimicrobial activity.     

Erythrina alkaloids from leaves of Erythrina arborescens

Continued interest in Erythrina alkaloids resulted in the isolation of 38 alkaloids including 7 undescribed ones from the leaves of Erythrina arborescens Roxburgh. Among the new compounds, erythrivarines H-I were two dimeric alkaloids, while others were Erythrina alkaloid glucosides. Dimeric Erythrina alkaloids and monomers, turcomanidine and isoboldine, showed medium xanthine oxidase inhibition.     

Differential staining of western blots of avian egg white glycoproteins using diverse lectins

Avian egg white glycoproteins which differ in structure and carbohydrate composition, vary in their interactions with diverse lectins. Generally, wheat germ agglutinin (WGA) and concanavalin A (Con A) are used for the identification and separation of those of the chicken. In the present study, interactions of a battery of lectins, including: the above two, several galactophilic lectins (from Aplysia gonad (AGL), Erythrina corallodendron (ECorL), peanut (PNA) and Pseudomonas aeruginosa (PA-IL)), and fucose-binding lectins (from Ulex europaeus (UEA-I), Ulva lactuca (ULL) and P. aeruginosa (PA-IlL), which also binds mannose) with chicken, quail and pigeon egg white glycoproteins, were examined using both hemagglutination inhibition and Western blot analyses. The chicken egg white glycoproteins interacted most strongly with WGA, followed by Con A > AGL = PA-IlL. The quail glycoprotein order of affinities was: Con A > WGA = AGL = PA-IlL, while that of the pigeon was: AGL > PA-IL > WGA > Con A = PA-IlL. The blocking of the other lectins by the egg whites were insignificant. The results demonstrated the selectivity and efficiency of the five most reactive lectins for differential tagging of avian egg white glycoproteins and unveiled the profound heterogeneity of the latter, as well as the possible potential lectin usage for improving purification and quality control of the desired glycoproteins.     

Differential staining of Western blots of human secreted glycoproteins from serum, milk, saliva, and seminal fluid using lectins displaying diverse sugar specificities

Human milk, serum, saliva, and seminal fluid glycoproteins (gps) nourish and protect newborn and adult tissues. Their saccharides, which resemble cell membrane components, may block pathogen adhesion and infection. In the present study, they were examined by a battery of lectins from plants, animals, and bacteria, using hemagglutination inhibition and Western blot analyses. The lectins included galactophilic ones from Aplysia gonad, Erythrina corallodendron, Maclura pomifera (MPL), peanut, and Pseudomonas aeruginosa (PA-IL); fucose-binding lectins from Pseudomonas aeruginosa (PA-IIL), Ralstonia solanacearum (RSL), and Ulex europaeus (UEA-I), and mannose/glucose-binding Con A. The results demonstrated the chosen lectin efficiency for differential analysis of human secreted gps as compared to CBB staining. They unveiled the diversity of these body fluid gp glycans (those of the milk and seminal fluid being highest): the milk gps interacted most strongly with PA-IIL, followed by RSL; the saliva gps with RSL, followed by PA-IIL and MPL; the serum gps with Con A and MPL, followed by PA-IIL and RSL, and the seminal plasma gps with RSL and MPL, followed by UEA-I and PA-IIL. The potential usage of these lectins as probes for scientific, industrial, and medical purposes, and for quality control of the desired gps is clearly indicated.     

Studies on metal — protein interactions: Inter-comparison among various approaches

Binding ability of mercury, thallium, lead and bismuth with Erythrina variegata seed protein have been investigated using tracer packet technique. Due to the lack of standard methods, inter-comparisons have been made among three different approaches, like trichloroacetic acid (TCA) precipitation, isoelectric precipitation and dialysis of protein after incubation with the metals. Good agreement was observed for all the cases except that of lead.     

Fluorous-based carbohydrate microarrays

The success of microarrays, such as DNA chips, for biosample screening with minimal sample usage has led to a variety of technologies for assays on glass slides. Unfortunately, for small molecules, such as carbohydrates, these methods usually rely on covalent bond formation, which requires unique functional handles and multiple chemical steps. A new simpler concept in microarray formation is based on noncovalent fluorous-based interactions. A fluorous tail is designed not only to aid in saccharide purification but also to allow direct formation of carbohydrate microarrays on fluorous-derivatized glass slides for biological screening with lectins, such as concanavalin A. The noncovalent interactions in the fluorous-based array are even strong enough to withstand the detergents used in assays with the Erythrina crystagalli lectin. Additionally, the utility of benzyl carbonate protecting groups on fucose building blocks for the formation of alpha-linkages is demonstrated.     

Pd‐Catalyzed Asymmetric Intramolecular Arylative Dearomatization of para‐Aminophenols†

Asymmetric arylative dearomatization reactions of para‐aminophenols are realized by a Pd‐catalyst consisting of a TADDOL (α,α,α',α'‐tetraaryl‐2,2‐disubstituted 1,3‐dioxolane‐4,5‐dimethanol)‐derived chiral phosphoramidite ligand. The tetracyclic products bearing the key skeleton of Erythrina alkaloids are afforded in reasonable yields (up to 73%) with good to excellent enantioselectivity (up to 97% ee). Concise total synthesis of (–)‐3‐demethoxyerythratidinone is achieved by employing this method as the key step.