ABSTRACT
RESUMO A espécie Mikania glomerata Sprengel, popularmente conhecida no Brasil como guaco, é amplamente utilizada como expectorante para tratar doenças respiratórias e tem a sua atividade farmacológica atribuída principalmente a cumarina. Os resultados mostraram que o método apresenta linearidade de 0,05 a 0,8 mg mL-1. Ele foi considerado seletivo, exato e preciso. A proposta de um método rápido para determinação de cumarina em extratos de guaco torna-se interessante para a rotina de controle de qualidade industrial, visando à obtenção de medicamentos fitoterápicos padronizados.
ABSTRACT The species Mikania glomerata Sprengel, popularly known in Brazil as “guaco”, is widely used as an expectorant to treat respiratory diseases. Its pharmacological activity is mainly attributed to coumarin. The results showed that the method for determining coumarin presented linearity from 0.05 to 0.8 mg mL-1. It was considered selective, accurate, and precise according to the specific resolution from ANVISA, the Brazilian regulatory agency. The proposal of a rapid method for the determining coumarin in extracts of guaco is interesting for routine industrial quality control in order to obtain standardized, efficient, and safe phytotherapic medicines.
Subject(s)
Mass Spectrometry/methods , Coumarins/analysis , Validation Study , Mikania/classification , Plants, Medicinal , PhytotherapyABSTRACT
Natural products produced by microorganisms have been an important source of new substances and lead compounds for the pharmaceutical industry. Chromobacterium violaceum is a Gram-negative β-proteobacterium, abundant in water and soil in tropical and subtropical regions and it produces violacein, a pigment that has shown great pharmaceutical potential. Crude extracts of five Brazilian isolates of Chromobacterium sp (0.25, 2.5, 25, and 250 µg/mL) were evaluated in an in vitro antitumor activity assay with nine human tumor cells. Secondary metabolic profiles were analyzed by liquid chromatography and electrospray ionization mass spectrometry resulting in the identification of violacein in all extracts, whereas FK228 was detected only in EtCE 308 and EtCE 592 extracts. AcCE and EtCE 310 extracts showed selectivity for NCI/ADR-RES cells in the in vitro assay and were evaluated in vivo in the solid Ehrlich tumor model, resulting in 50.3 and 54.6% growth inhibition, respectively. The crude extracts of Chromobacterium sp isolates showed potential and selective antitumor activities for certain human tumor cells, making them a potential source of lead compounds. Furthermore, the results suggest that other compounds, in addition to violacein, deoxyviolacein and FK228, may be involved in the antitumor effect observed.
Subject(s)
Animals , Humans , Male , Mice , Antineoplastic Agents/pharmacology , Chromobacterium/metabolism , Indoles/pharmacology , Neoplasms, Experimental/drug therapy , Antineoplastic Agents/isolation & purification , Antineoplastic Agents/therapeutic use , Cell Line, Tumor , Complex Mixtures , Indoles/isolation & purification , Indoles/therapeutic use , Spectrometry, Mass, Electrospray IonizationABSTRACT
Three gaseous acyclic distonic acylium ions: *CH2-CH2-C+=O, *CH2-CH2-CH2-C+=O, and *CH2=C(CH2)-C+=O, are found to display dual free radical and acylium ion reactivity; with appropriate neutrals, they react selectively either as free radicals with inert charge sites, or (and more pronouncedly) as acylium ions with inert radical sites. The free radical reactivity of the ions is demonstrated via the Kenttamaa reaction: CH3S* abstraction with the spin trap dimethyl disulfide; their ion reactivity by two reactions most characteristic of acylium ions: transacetalization with 2-methyl-1,3-dioxolane and the gas-phase Meerwein reaction, that is, expansion of the three-membered epoxide ring of epichlorohydrin to the five-membered 1,3-dioxolanylium ion ring. In "one-pot" reactions with gaseous mixtures of epichlorohydrin and dimethyl disulfide, the ions react selectively at either site, but more readily at the acylium charge site, to form the two mono-derivatized ions. Further reaction at either the remaining free radical or acylium charge site forms a single bi-derivatized ion as the final product. Becke3LYP/6-31G(d) calculations predict the reactions at the acylium charge sites of the three distonic ions to be highly exothermic, and both the "hot" transacetalization and epoxide ring expansion products of *CH2-CH2-CH2-C+=O to dissociate rapidly by H2C=CH2 loss in overall exothermic processes. The calculations also predict highly spatially separate odd spin and charge sites for the novel cyclic distonic ketal ions formed by the reactions at the acylium charge sites.
ABSTRACT
Reactions of gaseous SF(3)(+) ions with furan, thiophene, pyrrole, and several of their alkyl derivatives were performed via MS(2) experiments and found to occur readily both by electron abstraction and F(+) transfer. Then, by performing MS(3) experiments, the F(+) transfer products-the protonated monofluorinated molecules-were mass-selected and deprotonated by a second reaction with a stronger base. F(+) transfer from gaseous SF(3)(+) followed by deprotonation promotes therefore C-H by C-F replacement in five-membered heteroaromatic compounds and the efficient gas-phase synthesis of their neutral monofluorinated derivatives.
ABSTRACT
A systematic investigation of a novel epoxide and thioepoxide ring expansion reaction promoted by gaseous acylium and thioacylium ions is reported. As ab initio calculations predict, and 18O-labeling and MS3 pentaquadrupole experiments demonstrate, the reaction proceeds by initial O(S)-acylation of the (thio)epoxides followed by rapid intramolecular nucleophilic attack that results in three-to-five-membered ring expansion, and forms cyclic 1,3-dioxolanylium, 1,3-oxathiolanylium, or 1,3-dithiolanylium ions. This gas-phase reaction is analogous to a condensed-phase reaction long since described by H. Meerwein (Chem. Ber. 1955, 67, 374), and is termed as "the gas-phase Meerwein reaction"; it occurs often to great extents or even exclusively, but in some cases, particularly for the most basic (thio)epoxides and the most acidic (thio)acylium ions, proton transfer (eventually hydride abstraction) competes efficiently, or even dominates. When (thio)epoxides react with (thio)-acylium ions, the reaction promotes O(S)-scrambling; when epoxides react with thioacylium ions and the adducts are dissociated, it promotes S/O replacement. An analogous four-to-six-membered ring expansion also occurs predominantly in reactions of trimethylene oxide with acylium and thioacylium ions.
ABSTRACT
A new MIMS-derived technique, headspace membrane introduction mass spectrometry (HS-MIMS), is described for direct trace level analysis of volatile organic compounds (VOCs) in soil and other dry or wet solid matrixes. A silicone membrane interface is placed about 15 cm from the ion source, and a closed airspace (headspace) is created by connecting a toggle valve to the 1/4 in. tubing that connects the membrane interface to the ion source. For the VOC analysis, the headspace is evacuated and the solid sample vessel is heated to 90 degrees C. The VOCs are rapidly desorbed from the sample, pervaporated through the membrane, and preconcentrated for 4 min in the evacuated headspace. Then, the toggle valve is opened and the trapped VOCs are released into the ion source region of a quadrupole mass spectrometer. By electron ionization and selected-ion monitoring, a relatively sharp and intense peak is obtained and used for quantification. The HS-MIMS analysis shows excellent linearity and reproducibility and detection limits for many VOCs typically of 50-100 ng/kg (ppt).
