Search results for "Native"
showing 10 items of 1727 documents
Cocaine addiction and personality: a mathematical model.
2010
The existence of a close relation between personality and drug consumption is recognized, but the corresponding causal connection is not well known. Neither is it well known whether personality exercises an influence predominantly at the beginning and development of addiction, nor whether drug consumption produces changes in personality. This paper presents a dynamic mathematical model of personality and addiction based on the unique personality trait theory (UPTT) and the general modelling methodology. This model attempts to integrate personality, the acute effect of drugs, and addiction. The UPTT states the existence of a unique trait of personality called extraversion, understood as a di…
Basing the Analysis of Comparative Bioavailability Trials on an Individualized Statistical Definition of Equivalence
1993
The conventional definition of bioequivalence in terms of population means only, is criticized for lacking relevance to the individual subject. Both approaches to bioequivalence assessment proposed here for avoiding this shortcoming, focus on the probability of an event induced by the response of a randomly selected subject to two formulations of a given active agent. The first approach leads to converting the basic idea underlying the well-known 75-rule into an exact statistical procedure. The second approach is of a parametric nature. It reduces bioequivalence assessment to testing against the alternative hypothesis that the standardized expected value of a Gaussian distribution is contai…
Phytoelectrochemical analysis ofZanthoxylum chiloperone
2016
Introduction An innovative application of the voltammetry of microparticles methodology to characterize the phytochemical composition of extracts of different parts of Zanthoxylum chiloperone var. angustifolium Engl. is described. Objective Characterize the phytochemical composition of extracts of different parts of plants by electrochemical methodologies. Methods The voltammetry of microparticles methodology was applied to alcoholic extracts from leaves, seeds, fruits, roots and stem bark of Zanthoxylum chiloperone. Results In contact with aqueous phosphate buffer, characteristic cathodic signals of its main natural products (canthin-6-one, 5-methoxycanthin-6-one and trans-avicennol) were …
Styryl-lactones from the stem bark of Goniothalamus arvensis
1999
The fractionation of the methanolic extract of Goniothalamus arvensis (Annonaceae) stem bark led to the isolation of two novel styryl-lactones, arvensin and (+)-2-epi-altholactone. The structures of these compounds, which belong to the furano-pyrone group, were established on the basis of mass spectrometry, one- and two-dimensional nuclear magnetic resonance experiments, as well as simple chemical derivatization. The relative and absolute configurations of the compounds are discussed. Copyright © 1999 John Wiley & Sons, Ltd.
Novel Acylated Triterpene Glycosides from Muraltia heisteria
2002
Four new acylated triterpene glycosides (1-4) have been isolated as two inseparable mixtures of the trans- and cis-3,4,5-trimethoxycinnamoyl derivatives (1,2 and 3,4) from the roots of Muraltia heisteria. The structures of these compounds were elucidated by various 1D and 2D NMR techniques, including (1)H and (13)C, COSY, NOESY, HSQC, TOCSY, and HMBC experiments and FABMS. Compounds 3 and 4 were shown to be cytotoxic in a human colon cancer cell line but did not show any ability to potentiate in vitro cisplatin cytotoxicity.
Acylated Preatroxigenin Glycosides from Atroxima congolana
2003
Six new acylated bisdesmosidic preatroxigenin saponins named atroximasaponins E1, E2 (1, 2), F1, F2 (3, 4), and G1, G2 (5, 6) were isolated as three inseparable mixtures of the trans- and cis-p-methoxycinnamoyl derivatives, from the roots of Atroxima congolana. Their structures were established through extensive NMR spectroscopic analysis as 3-O-beta-D-glucopyranosylpreatroxigenin-28-O-beta-D-xylopyranosyl-(1--4)-alpha-L-rhamnopyranosyl-(1--2)-[beta-D-glucopyranosyl-(1--3)]-[4-O-trans-p-methoxycinnamoyl]-beta-D-fucopyranoside (atroximasaponin E1, 1), and its cis-isomer, atroximasaponin E2 (2), 3-O-beta-D-glucopyranosylpreatroxigenin-28-O-beta-D-xylopyranosyl-(1--4)-alpha-L-rhamnopyranosyl-(…
Epoxy-Acetogenins and other Polyketide Epoxy Derivatives as Inhibitors of the Mitochondrial Respiratory Chain Complex I
2000
Annonaceous acetogenins (ACG), an extensive group of cytotoxic natural products, are antitumor agents whose main mode of action is inhibition of the mammalian mitochondrial complex I. Herein we describe the importance of the different chemical groups along the alkyl chain for optimal inhibitory potency, discussing the structurally relevant factors present in these compounds. For this purpose, a series of epoxide derivatives from alpha-linolenic acid were prepared and their activity compared with that of epoxy-acetogenins and tetrahydrofuranic (THF) acetogenins isolated from Rollinia membranacea.
Tucumanin, a β-hydroxy-γ-lactone bistetrahydrofuranic acetogenin from Annona cherimolia, is a potent inhibitor of mitochondrial complex I
2004
A new β-hydroxy-γ-methyl-γ-lactone bistetrahydrofuranic acetogenin, tucumanin, with the infrequent symmetrical threo/trans/threo/trans/ threo relative configuration at the tetrahydrofuran rings was isolated from Annona cherimolia (Annonaceae) seeds. The inhibitory potency on the mitochondrial complex I of acetogenins with this relative configuration (tucumanin and asimicin) was compared with that shown by the corresponding pairs with an asymmetrical threo/trans/threo/trans/erythro relative configuration (laherradurin/rolliniastatin-2, and itrabin/molvizarin). All these compounds act as selective inhibitors of mitochondrial complex 1 in the 0.18 - 1.55 nM range. Fil: Barrachina, Isabel. Univ…
Steroidal saponins from two species of Dracaena.
2010
Four new steroidal saponins (1-4) were isolated from the stem and bark of two species of Dracaena: deistelianosides A and B (1 and 2) from D. deisteliana and arboreasaponins A and B (3 and 4) from D. arborea. Six known saponins and one known sapogenin were also isolated. The structures of 1-4 were established as diosgenin 3-O-[3-O-sulfate-alpha-l-rhamnopyranosyl-(1-->4)]-beta-d-glucopyranoside (1), 1-O-beta-d-xylopyranosyl-(1-->2)-[alpha-l-rhamnopyranosyl-(1-->3)]-beta-d-fucopyranosyl(23S,24S)-spirosta-5,25(27)-diene-1beta,3beta,23alpha,24alpha-tetrol 24-O-alpha-l-arabinopyranoside (2), pennogenin-3-O-alpha-l-rhamnopyranosyl-(1-->2)-[alpha-l-rhamnopyranosyl-(1-->3)]-[6-O-acetyl]-beta-d-gluc…
Cytotoxic activity of diterpenoids isolated from the aerial parts of Elaeoselinum asclepium subsp. meoides.
2008
The phytochemical investigation of the acetone extract of the aerial parts of Elaeoselinum asclepium (L.) Bertol. subsp. meoides (Desf.) Fiori afforded several known diterpenoids as well as meoidic acid ( 5), new in the literature. The cytotoxic activities of elasclepic acid ( 1), ENT-atis-16-en-19-oic acid ( 2), ent-beyer-15-en-19-oic acid ( 3), ent-kaur-16-en-19-oic acid ( 4) and meoidic acid ( 5) were investigated on rat glioma C6 cells by evaluation of cell growth inhibition.