Neucirio Ricardo de Azevedo

Chemical variability in the essential oil of Hyptis suaveolens

The essential oils of Hyptis suaveolens plants collected from 11 localities of the Brazilian Cerrado region were investigated by GC-MS. Sabinene, limonene, biclyclogermacrene, beta-phellandrene and 1,8-cineole were the principal constituents. The results were submitted to principal component and chemometric cluster analysis which allowed three groups of essential oils to be distinguished with respect to the content of p-mentha-2,4(8)-diene, limonene/beta-phellandrene/gamma-terpinene and germacrene D/bicyclogermacrene. In patterns of geographic variation in essential oil composition indicated that the sesquiterpenes are mainly produced in the samples grown at lower latitudes.

Essential oil chemotypes in Hyptis suaveolens from Brazilian Cerrado

The composition of nine samples of essential oil of individual plants in fruiting stage of Hyptis suaveolens from Brazilian Cerrado was investigated by GC–MS. Spathulenol, 1,8-cineole and (E)-caryophyllene were the principal constituents. The results were submitted to Principal Component and Chemometric Cluster Analysis which allowed three groups of essential oils to be distinguished with respect to the content of 1,8-cineole/sabinene, β-bourbonene and α -bulnesene. Latitude seems to be the most important environmental factor influencing the oil contents. Pattern of geographic-variation in essential oil composition indicated that sesquiterpenes are mainly produced in the samples grown at lower latitudes and altitudes.  2002 Elsevier Science Ltd. All rights reserved.

The Michael Reaction of Enaminones with N-(p-tolyl)-maleimide: Synthesis and Structural Analysis of Succinimide-enaminones

Succinimido enaminonas foram sintetizadas atraves da reacao de enaminonas e a N-(p-toluil)-maleimida em rendimento moderado a bom. A acao antibacteriana destes compostos contra E. coli e S. aureus foi avaliada, mas a atividade antibacteriana nao foi significativa. A regioquimica das succinimido enaminonas foi racionalizada empregando-se a teoria dos orbitais moleculares de fronteira. A estrutura cristalina de um dos compostos foi determinada e foram observadas varias pontes de hidrogenio inter- e intramolecular do tipo NH...O e CH...O.

A 2-acylcyclohexane-1,3-dione from Virola oleifera

A novel arylalkanone derivative, oleiferinone, has been isolated from the chlorophyll-free hexane fraction of the 95% ethanol extract from leaves of Virola oleifera. Its structure was deduced as 3,6β-dihydroxy-2-(13-phenyltridecanoyl)-2-cyclohexen-1-one, on the basis of the NMR techniques.

A Method to Separate Lignoids fromVirolaLeaves

The genus Virola (Myristicaceae) comprises approximately 35 species which are distributed in neotropical countries (Rodrigues, 1980). Their geographical and taxonomic distribution has been used in studies of chemical ecology (Paulino Filho, 1985), especially of the Amazon forest. The bark resin, derived from various Virola species, provides hallucinogenic snuff and an arrow poison, and the species has thus attracted phytochemical examination (Holmstedt et al., 1980). The genus is well known to be an abundant source of lignans and neolignans, and its important physiological actions have been reported (MacRae and Towers, 1985). A particularly striking finding is the observed high levels of lignoids found in human urine (enterolignans), following dietary intake of vegetable fibre and grain (Bannwart et al., 1989), which have been suggested to have cancer-protective effects (Adlercreutz et al., 1991). Investigations of lignoids in plants were mainly carried out with trunk wood (Fernandes, J. B. et al., 1980), bark, fruit (Lemus and Castro, 1989), fruit pericarp, aril, seed coat and kernel (Kato et al., 1990), while little is known of the distribution of these compounds in the leaves (Martinez et al., 1985). The apparent lack of phytochemical data may be due in part to the nature of the crude extracts of Virola leaves, which generally yield a sticky residue composed of chlorophylls and other colouring matters which are difficult to resolve by chromatographic methods. The general procedure for the removal of colouring matter from plant leaves includes the treatment of green extracts with freshly activated charcoal or by passing through a charcoal column (Nair et al., 1990), as well as by lead acetate adsorption. There are, however, disadvantages to these procedures: metabolite losses can occur through occlusion in the precipitate and a residuum of lead acetate remains in solution and can cause problems in subsequent stages. As part of our continuous research work on the Virola, we have examined the lignoid constituents of the leaves of V. surinamensis (Rol.) Warb. (Barata et al., 1978; Queiroz Paulo, 1982; Santos and Barata, 1990) of V. oleifera (Schott) A. C. Smith (Fernandes, A. M. A. P. et al., 1993, 1994) and of V. pavonis (A. DC.) A. C. Smith (Ferri and Barata, 1991, 1992). The crude extracts of the leaves were systematically submitted to chlorophyll elimination yielding purified fractions free of colouring matter and rich in lignoid mixtures. This resulted in the isolation of seventeen lignoids, including nine new compounds. The present work describes the use of this simplified methodology for an efficient separation of the lignans and neolignans from apolar and polar crude extracts of the leaves of V. oleifera and V. pavonis.