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At least 73 records · Page 4Linked to original sources
PubMed2000

Inhibition of dihydrofolate reductase and cell growth activity by the phenanthroindolizidine alkaloids pergularinine and tylophorinidine: the in vitro cytotoxicity of these plant alkaloids and their potential as antimicrobial and anticancer agents.

The phenanthroindolizidine plant alkaloids pergularinine (PGL) and tylophorinidine (TPD) isolated from the Indian medicinal herb Pergularia pallida have been evaluated for their biological activity and assessed for the first time employing dihydrofolate reductase (DHFR) (5,6,7,8-THF: NADP(+) oxidoreductase, EC 1.5.1.3) as the probe in the present investigations. The enzyme is a key target in cancer chemotherapy and has been purified from Lactobacillus leichmannii. Cytotoxicity studies showed that both PGL and TPD are potently toxic and inhibited the growth of L. leichmannii cells (IC(50)=45 and 40 microM, respectively). Both the alkaloids significantly inhibited DHFR activity (IC(50)=40 and 32 microM for PGL and TPD, respectively). Alkaloid concentrations greater than 75-95 microM resulted in a complete loss of DHFR activity. Our results are suggestive of the alkaloids as potential antimicrobial and antitumour compounds. Alkaloid binding to DHFR is slow and reversible. Inhibition kinetics revealed K(i) values of 9x10(-6) M and 7x10(-6) M for PGL and TPD, respectively for the enzyme and inhibition in both the cases was a simple linear 'non-competitive' type.

Alkaloids↗
PubMed2001

Influence of defoliation on toxic alkaloid concentration and alkaloid pools in tall larkspur.

This study was replicated at two locations in the mountains of central Utah. In 1997, ten uniform plants of tall larkspur (Delphinium barbeyi) in the early bud stage (40 cm in height) were selected at each site and clipped at 5 cm above soil level. In 1998, one stalk from each plant was harvested on a weekly basis; in 1999, one stalk was harvested at four times during its phenological development. Toxic and total alkaloid concentrations were measured and alkaloid pools in the entire stalk were calculated. Clipping reduced stalk height to less than 50 cm in 1998 and 65 cm in 1999, compared to over 100 cm in unclipped control plants. Alkaloid concentration was similar to control plants, but toxic alkaloid pools were 70% lower than control plants, because of the reduction in biomass of the stalks. Clipping reduced subsequent vigor and the amount of toxic and total alkaloids in tall larkspur.

Alkaloids↗
PubMed2002

[Determination of aconitine alkaloids in a pesticide--0.25% aconitine alkaloids mixed with emulsion by high performance liquid chromatography].

The raw root of Aconitum, an important Chinese traditional medicine, contains some very toxic alkaloids such as aconitine, mesaconitine and hypaconitine etc. They are usually processed to lower the alkaloid content before used as a drug. The extract of crude drug (aconite) can be made into a plant pesticide by means of mixing with some emulsion. In order to evaluate the quality of the pesticide, we developed a rapid, specific and precise method using high performance liquid chromatography (HPLC) for the separation and quantitation of the alkaloids in the aconite extract and the mixed products (the aconite extract is mixed with emulsion). Before the determination by HPLC, the sample must be acidified with 2% (mass percentage) HCl at first. Extract the acid liquid with CHCl3. Alkalize the extract with ammonia, and add a little of 0.1 mol/L NaHCO3 and 0.1 mol/L Na2CO3 till pH 9. Extract it with CHCl3. Evaporate the extract and add a certain amount of methanol. Add the internal standard into the sample. Inject the combined sample solution onto a column of chemically bonded octadecylsilane phase and develop the chromatogram with MeOH-H2O-CHCl3-triethylamine (68:32:2:0.1, volume ratio). Aconitine, mesaconitine, hypaconitine and medroxyprogesteroni acetas (internal standard) were on base line separated. Quantify the alkaloids by peak area ratio (aconitine alkaloids vs internal standard). This method has high recovery (> 92%) and good reproducibility (RSD < 3.2%).

Aconitine↗
PubMed2006

Isolation of gelsedine-type indole alkaloids from Gelsemium elegans and evaluation of the cytotoxic activity of gelsemium alkaloids for A431 epidermoid carcinoma cells.

Four new gelsedine-type indole alkaloids (1-4) were isolated from the leaves of Gelsemium elegans, together with 11 known alkaloids. The structures were determined as 14-acetoxygelsenicine (1), 14-acetoxy-15-hydroxygelsenicine (2), 14-hydroxy-19-oxogelsenicine (3), and 14-acetoxygelselegine (4), respectively, by spectroscopic analysis. The cytotoxic effects of 14 Gelsemium alkaloids including two new compounds (1, 2) were evaluated using the A431 human epidermoid carcinoma cell line. Of these, the gelsedine-type alkaloids 14-acetoxy15-hydroxygelsenicine (2) [corrected] 14,15-dihydroxygelsenicine (5), gelsedine (7), and gelsemicine (8) showed potent cytotoxic effects.

Alkaloids↗
PubMed2003

Synthesis of 9-N-cinchona alkaloid peptide hybrid derivatives: preparation and conformational study of 9-N-acylamino(9-deoxy)cinchona alkaloids.

The synthesis and conformational analyses of several 9-N-acylamino(9-deoxy)cinchona alkaloids is presented. Peptides were connected to cinchona alkaloids via a 9-amino group. The synthesis of the new cinchona alkaloid derivatives was performed straightforwardly from 9-amino(9-deoxy)dihydroquinidine via coupling with carboxylic acid chlorides and several dipeptides. Both alkaloid derivatives with the configuration of the corresponding natural product as well as its unnatural epimer were studied. The conformations of the prepared derivatives in solution were determined by NMR spectroscopy. It is shown that the conformation is strongly influenced by the configuration at the 9-position.

Cinchona Alkaloids↗
PubMed1988

Tumour therapy with Vinca alkaloids targeted by a hybrid-hybrid monoclonal antibody recognising both CEA and Vinca alkaloids.

The functional properties of a hybrid-hybrid monoclonal antibody (MAb) recognising both CEA and Vinca alkaloids have been explored in vivo in nude mice xenografted with MAWI, a human colorectal tumour. The hybrid-hybrid MAb localises specifically onto CEA-expressing tumour tissue and, furthermore, is able to target Vinca alkaloids to tumour. Under the influence of the hybrid-hybrid MAb a profound change in the bio-distribution patterns of the Vinca alkaloids is observed. Therapeutic data produced in this in vivo model indicates that treatment with Vinca alkaloids in conjunction with hybrid-hybrid MAb is significantly more effective in suppressing tumour growth of established tumour xenografts than the Vincas when given as free drug.

Animals↗
PubMed1998

Acetogenic isoquinoline alkaloids. CXII. Separation and identification of dimeric naphthylisoquinoline alkaloids by liquid chromatography coupled to electrospray ionization mass spectrometry.

The atropodiastereomeric dimeric naphthylisoquinoline alkaloids, michellamines A (1a), B (1b) and C (1c), together with their monomers, korupensamines A (2a) and B (2b), were investigated using electrospray ionization tandem mass spectrometry coupled to liquid chromatography (LC-ESI-MS-MS). From the spectra obtained, characteristic product ions were chosen to monitor the chromatographic separation achieved on an RP-18 column. Under acidic conditions required for chromatographic analysis, the monomeric alkaloids 2a and 2b yielded protonated molecules [M + H]+, while the dimers, the michellamines, exhibited doubly protonated [M + 2H]2+ molecules. In addition, the coeluting alkaloids 1b and 2b were identified unambiguously be means of tandem mass spectrometry. Thus, together with the retention times of the alkaloids, the product ion spectra allowed us the identification of michellamines in the presence of their presumed biogenetic monomeric precursors. Application of the HPLC-MS-MS method successfully proved the enzymatic formation of michellamine C (1c) by in vitro dimerization of korupensamine B (2b).

Alkaloids↗
PubMed2003

The enantiospecific, stereospecific total synthesis of the ring-A oxygenated sarpagine indole alkaloids (+)-majvinine, (+)-10-methoxyaffinisine, and (+)-N(a)-methylsarpagine, as well as the total synthesis of the alstonia bisindole alkaloid macralstonidine.

The first stereospecific, enantiospecific total synthesis of the ring-A oxygenated sarpagine indole alkaloids (+)-N(a)-methylsarpagine (8), (+)-majvinine (14), and (+)-10-methoxyaffinisine (49), as well as the first total synthesis of the Alstonia bisindole alkaloid macralstonidine (9), has been accomplished. This approach employed the Schöllkopf chiral auxiliary for the stereospecific construction of the desired d-(+)-tryptophan unit required for the asymmetric Pictet-Spengler reaction. In addition, the strategy was doubly convergent for the enolate-mediated Pd(0) coupling process and the asymmetric Pictet-Spengler reaction can be employed to synthesize both macroline (2) and N(a)-methylsarpagine (8), the coupling of which provides macralstonidine (9). This approach to ring-A substituted alkoxyindole alkaloids should find wide application for the synthesis of other alkaloids for it is stereospecific and either enantiomer can be prepared with ease.

Alstonia↗
PubMed2005

ent-Dioncophylleine A and related dehydrogenated naphthylisoquinoline alkaloids, the first Asian dioncophyllaceae-type alkaloids, from the "new"plant species Ancistrocladus benomensis.

Three new fully dehydrogenated naphthylisoquinoline alkaloids, the 7,1'-coupled ent-dioncophylleine A (3a), the likewise 7,1'-coupled 5'-O-demethyl-ent-dioncophylleine A (4), and the 7,8'-linked dioncophylleine D (5), have been isolated from the leaves of the recently described Malaysian highland liana Ancistrocladusbenomensis. All of them lack an oxygen function at C-6; this so-called Dioncophyllaceae-type structural subclass had previously been found only in naphthylisoquinoline alkaloids from West and Central African plants. Moreover, compounds 3a and 4 are the first fully dehydrogenated, i.e., only axially chiral, naphthylisoquinoline alkaloids of this type that are optically active; compound 5, by contrast, is fully racemic, due to its configurationally unstable biaryl axis. The structural elucidation was achieved by spectroscopic and chiroptical methods. Biological activities of these alkaloids against different protozoan parasites are described.

Alkaloids↗
PubMed2000

Convenient synthesis of 2,3,9,10-tetraoxygenated protoberberine alkaloids and their 13-methyl alkaloids.

New and convenient synthesis of 2,3,9,10-tetraoxygenated protoberberine alkaloids and their 13-methyl alkaloids through the same intermediates was developed. Acylation of the brominated benzylphenethylamine (13) with alpha-chloro-alpha-(methylthio)acetyl chloride, followed by cyclization with stannic chloride, furnished the key intermediates 4-methylthio-3-phenethylisoquinolin-3-ones (14), which were methylated to provide their methyl derivatives (17). Both isoquinolin-3-ones (14, 17) were easily transformed into protoberberine alkaloids (16) and their 13-methyl alkaloids (21) in good yield.

Alkaloids↗
PubMedDate not supplied

Alkaloids of papaver genus IX. Alkaloids of Glaucium vitellinum Boiss and Buhse, population Seerjan and Glaucium pulchrum Stapf, population Elika.

Glaucium vitellinum Boiss and Buhse. population Seerjan was shown to contain three major alkaloids, isocorydine (0.44%), protopine (0.42%), dicentrine (0.24%), and four minor alkaloids, tetrahydropalmatine (0.13%), muramine (0.12%), bulbocapnine (0.06%) and glaucine (0.01%). Glaucium pulchrum Stapf popllation Elika was shown to contain two major alkaloids, corydine (0.3%) and bulbocapnine (0.18%) and three minor alkaloids N-methylindcarpine (0.1%), isocorydine (0.03%) and protopine (0.01%). N-methyllindcarpine was found for the first time in the Papaveraceae and tetrahydropalmatine was detected for the first time in Glaucium.

Alkaloids↗
PubMedDate not supplied

Alkaloids of thalictrum. XX. Isolation, identification and structural elucidation of the alkaloids of the root of Thalictrum longistylum.

A study of the alkaloids of the roots of Thalictrum longistylum DC. resulted in the isolation of 12 alkaloids plus an artifact, 8-trichloromethyldihydroberberine. The 12 alkaloids were berberine, columbamine, jatrorrhizine, magnoflorine, methothalistyline, N-desmethylthalistyline, oxyberberine, palmatine, thalibrine, thalifendine, thaliglucinone, and thalistyline. Of these alkaloids, methothalistyline, N-desmethylthalistyline, and thalistyline are new compounds and with thaliglucinone possess hypotensive activity in dogs and rabbits. Methothalistyline, N-demethylthalistyline, thalistyline, and thalibrine were found to be active against Staphylococcus aureus and Mycobacterium smegmatis with with thalistyline being most active (50 microgram/ml).

Alkaloids↗
PubMed2003

General approach for the synthesis of sarpagine indole alkaloids. Enantiospecific total synthesis of (+)-vellosimine, (+)-normacusine B, (-)-alkaloid Q3, (-)-panarine, (+)-Na-methylvellosimine, and (+)-Na-methyl-16-epipericyclivine.

The first total synthesis of (+)-Na-methyl-16-epipericyclivine (9) was completed [from d-(+)-tryptophan methyl ester] in an overall yield of 42% (eight reaction vessels). The optical rotation [[alpha]D +22.8 (c 0.50, CHCl3)] obtained on this material confirmed that the reported optical rotation [[alpha]D 0 (c 0.50, CHCl3)]47 was biogenetically unreasonable. The total syntheses of (+)-vellosimine, (+)-normacusine B, (-)-alkaloid Q3, (-)-panarine, and (+)-Na-methylvellosimine are also described. Moreover, a mixed sample (1:1) of synthetic (-)-panarine and natural (-)-panarine yielded only one set of signals in the 13C NMR; this indicated that the two compounds are identical and further confirmed the correct configuration of (+)-vellosimine, (+)-normacusine B, and (-)-alkaloid Q3. In this approach, the key templates, (-)-Na-H,Nb-benzyltetracyclic ketone 15a and (-)-Na-methyl,Nb-benzyltetracyclic ketone 43 were synthesized on multihundred gram scale by the asymmetric Pictet-Spengler reaction and a stereocontrolled Dieckmann cyclization via improved sequences. An intramolecular palladium (enolate-mediated) coupling reaction was employed to introduce the C(19)-C(20) E-ethylidene function in the sarpagine alkaloids for the first time in stereospecific fashion.

Alkaloids↗
PubMed1994

Marine alkaloids, 15. Two alkaloids, flustramine E and debromoflustramine B, from the marine bryozoan Flustra foliacea.

A new alkaloid, flustramine E [1], with inhibitory activity towards Rhizotonia solani and Botrytis cinerea was isolated by gas-phase extraction from the marine bryozoan Flustra foliacea. The structure was determined as 3a,8a-cis-1-methyl-3a-(3-methyl-2- butenyl)-6-bromo-1,2,3,3a,8,8a-hexahydropyrrolo[2,3-b]indole, based on spectroscopic investigations. Another alkaloid, debromoflustramine B [2a], was detected in trace amounts and identified by comparison of the mass spectrum with that of a synthetic sample. The extract also contained the previously reported alkaloids flustramine A and B in the ratio 1:7.

Alkaloids↗
PubMed2002

Isolation and structure elucidation of a new indole alkaloid from Rauvolfia serpentina hairy root culture: the first naturally occurring alkaloid of the raumacline group.

A new monoterpenoid indole alkaloid, 10-hydroxy- N(alpha)-demethyl-19,20-dehydroraumacline ( 1), was isolated as a mixture of E- and Z-isomers from hairy root culture of Rauvolfia serpentina Benth. ex Kurz (Apocynaceae) and the structure was determined by 1D and 2D NMR analyses. The new indole alkaloid represents the first naturally occurring alkaloid of the raumacline group and its putative biosynthetical pathway is discussed.

Carbon Isotopes↗
PubMedDate not supplied

[Ergot alkaloids and alkaloids from other endophytes, responsible for causing toxic syndrome in cattle after eating contaminated grass].

Different signs of ergotism in livestock associated with animals consuming feed grains and pasture grasses infected by Clavicipitaceae (e.g. Balansia spp. and Acremonium spp.) have been considered. Endophyte-infected tall fescue causes the damage to livestock, and its toxicity and ryegrass in livestock are associated with ergopeptide alkaloid ergovaline and indole-isoprenoid lolitrems produced by A. coenophialum and A. lolii. The role of another compound attendant to endophyte-infected fescue such as peramine and loline alkaloid is discussed. Concentration of alkaloids depends upon the season and the period of growing plant-host. The advantages and the problems of endophyte-grass mutualistic symbiosis in pasture conditions are considered. The perspective of genetic manipulation of grass and fungus to produce endophyte-infected grasses with stress and insect deterences without affecting ruminant health.

Alkaloids↗
PubMed1975

Alkaloids of Vinca species V: structure elucidation of herbadine, an alkaloid isolated from Vinca libanotica.

Herbadine, a novel dihydroindole alkaloid, was isolated from the arterial parts of Vinca libanotica Zucc. (Apocynaceae). The physical and spectral data (UV, IR, NMR, and mass spectroscopy) indicated the alkaloid to be a derivative of aimaline. Comparative high-resolution NMR studies with quebrachidine and high-resolution mass spectral studies established the structure of the alkaloid to be 2-epi-3-hydroxyquebrachidine. Herbadine was previously isolated from another species by Russian workers and a structure was postulated. The current paper gives evidence for a corrected structure of herbadine.

Ajmaline↗