Francisco de A.M. Reis

Composition and Biological Activity of Essential Oils from Lippia origanoides H.B.K.

Abstract Analyses of the leaf oils from three colletions of Lippia origanoides H.B.K. by GC/MS and 1H- and 13C-NMR showed a similar chemical composition. Carvacrol (33.5–42.9%) was identified as the major component together with γ-terpinene (8.0–10.5%), thymol (5.1–8.4%), methyl thymol (6.1–8.7%) and p-cymene (11.9–15.8%). In vitro evaluation of the oils showed significant antimicrobial activity against Escherichia coli, Staphylococus aureus, Staphylococus aureus MRSA, Candida albicans and Candida tropicalis.

Naphthenic acids from crude oils of Campos Basin

Abstract Previous work based on chemical evidence and information from the hydrocarbon fractions of Marlim and Albacora, giant oil fields of Campos Basin (offshore Brazil), in connection with other geochemical parameters, led to conclusions on the oil accumulation, migration and biodegradation. The acidic components, as carboxylic acids of Marlim and Albacora were never investigated before and this work revealed a significant correlation between both fractions (neutral and acidic) therefore opening new horizons for the use of these naphthenic acids as additional geochemical parameters to enrich and enlarge previous geological conclusions on Marlim and Albacora. A naphthenic acid of 16 carbon atoms was detected and based on its mass spectrum and that of its corresponding deuterated hydrocarbon an 8-carboxy-9-ethyl-drimane structure was proposed.

13C NMR analysis of aporphine alkaloids

Abstract The 13 C NMR spectra of some tertiary and quaternary aporphine alkaloids are recorded and the signals assigned. The substituent shielding effects together with the effects of N - and O -methylation, and the twisting of the biphenyl system, are analysed and utilized in the spectral interpretation.

13C NMR spectral analysis of some isoquinoline alkaloids

Abstract The 13C NMR spectra of some isoquinoline and tetrahydroisoquinoline alkaloids and their corresponding N-methosalts and of the bisbenzylisoquinoline alkaloid isochondodendrine were recorded and the signals assigned. The substituent shielding effects and the 13C1H long range couplings were analysed and utilized in the spectral interpretation.

Structure-drift time relationships in ion mobility mass spectrometry

Ion mobility spectrometry (IMS) separates ions while they travel through a buffer gas under the influence of an electrical field. The separation is affected by mass and charge but most particularly by shape (collision cross section). When coupled to MS, IMS-MS offers therefore a powerful tool for structural elucidation and isomer separation. Systematic studies aimed to compare and quantitate the effects of structural changes on drift time such as length and ramification of carbon chain, unsaturation, geometrical isomerism (cis/trans isomers for instance), cyclization and ring size are, however, scarce. Herein we used traveling wave ion mobility mass spectrometry (TWIM-MS) to systematically evaluate the relationship between structure and drift time. For that, a series of deprotonated carboxylic acids were used as model ions with a carboxylate “charge tag” for gas phase MS manipulation. Carboxylic acids showed a near linear correlation between the increase of carbon number and the increase of collision cross section (CCS). The number of double bonds changes slightly the CCS of unsaturated acids. No differences in drift time and no significant differences in CCS of cis- and trans-double bond of oleic and elaidic acids were observed. Cyclization considerably reduces the CCS. In cyclic carboxylic acids, the increase of double bonds and aromatization significantly reduces the CCS and the drift times. The use of a more polarizable drift gas, CO2, improved in some cases the separation, as for biomarker isomers of steranoic acids. The β-isomer (cis-decaline) has smaller CCS and therefore displayed lower drift time compared to the α-isomer (trans-decaline). Structural changes revealed by calculations were correlated with trends in drift times.

3-Alkyl and 3-carboxyalkyl steranes in marine evaporitic oils of the Potiguar Basin, Brazil

Abstract The geochemical characterization of marine evaporitic oils from the Fazenda Belem oil field, Potiguar Basin, Brazil showed good correlation between both acidic and neutral fractions, and led to the identification of several biomarkers including the homologous series of 3-alkyl- and 3-carboxyalkyl-5α(H) steranes and also the new series of 3-alkyl- and 3-carboxyalkyl-5β(H) steranes. These compounds were identified using GC/MS and their structures were confirmed by coinjection with synthetic standards. A minor series of 4-carboxyalkyl steranes was also detected. The analysis of the acidic biomarkers allowed a more accurate evaluation of maturation, biodegradation and migration of the studied oils.

Peptide alkaloids of Scutia buxifolia

Abstract From the bark extract of S. buxifolia , the known alkaloids scutianines B, C, D and E, and the new one, scutianine H, have been isolated. The structure of scutianine H, based mainly on its MS fragmentation and on the MIKES (mass-analysed ion kinetic energy spectrum) of the base ion peak, is suggested. From the 13 C NMR spectral analysis of the diastereoisomeric scutianines D and E, information for the assignment of the stereochemistry of the β-hydroxyleucine unit in related alkaloids was also obtained.

Callus culture of Aspidosperma ramiflorum Muell. Arg.: growth and alkaloid production

Callus culture of Aspidosperma ramiflorum was established in Murashige and Skoog medium. Callus were supplemented with 1 mg.L 2,4-dichlorophenoxyacetic acid, 1.5 mg.L benzylaminopurine, 30 g L sucrose and 10 g L agar. Cultures accumulated the same major alkaloids, ramiflorine A and ramiflorine B, present in the stem bark of the parent plant. The alkaloid contents of 10-methoxy-geissoschizol, ramiflorine A and ramiflorine B, of bark and callus cultures were quantitatively compared by HPLC.

Quaternary alkaloids from Peschiera fuchsiaefolia

Abstract From an ethanolic extract of Peschiera fuchsiaefolia three quaternary alkaloids have been isolated and their structures determined from their spectral data as 12-methoxy-4-methylvoachalotine, 12-methoxy-4-methylvoachalotine ethyl ester and fuchsiaefoline. Analyses of the 13 C NMR spectra of some sarpagine alkaloids were carried out to confirm the structures of these compounds.

MONOTERPENES, SESQUITERPENES AND FATTY ACIDS FROM JULOCROTON TRIQUETER (EUPHORBIACEAE) FROM CEARA - BRAZIL

ABSTRACT In this study the volatile constituents from leaves and fruits of Julocroton triqueter (Lam.) Didr. (Euphorbiaceae), a medicinal plant from northwest Brazil, were investigated by GC/MS. Twenty one compounds, which represent about 96% of the total constituents of the essential oil, were identified. Caryophyllene oxide, humulene epoxide II, trans -caryophyllene, occidentalol, α-humulene in the fruit and cis -carvyl acetate, spathulenol, cis -carveol, trans -caryophyllene, trans -carvyl acetate and α-humulene in the leaves were the principal components. From one fraction of the hexane extract of the fruits a mixture of fatty acids were identified as: dodecanoic, tetradecanoic, hexadecanoic, 9-octadecenoic, eicosanoic, trieicosanoic and tetracosanoic acids. The partial analysis of the non-volatile constituents (hexanic fraction) from fruit allowed the isolation and characterization of tetracosan-1-ol (identify by 1 H and 13 C NMR, FTIR). Keywords : Julocroton triqueter , volatile constituents, Euphorbiaceae, fatty acid