Eduardo Guerreiro

Acute and chronic antiinflammatory effects of plant flavonoids

The antiinflammatory activities of 30 flavonoids isolated from several plants of the Compositae family were investigated using carrageenan-induced mouse paw edema and cotton pellet-induced rat granuloma. Compounds were administered with a unique dose of 75 mg/kg i.p. in the acute test with carrageenan and 25 mg/kg/day in the chronic granuloma test. Flavonoids inhibit the development of the induced granuloma, mostly when a catechol or guaiacol-like B ring is contained in the compound structure, jaceosidin being the most active flavonoid screened. Flavonoids significantly inhibited the maximum edema response in the acute test. We conclude that several of the isolated flavonoids tested here showed antiinflammatory effects, depending on the experimental model used.

The sesquiterpene lactone dehydroleucodine (DhL) affects the growth of cultured epimastigotes of Trypanosoma cruzi

Here,we report an inhibitory effect of a sesquiterpene lactone dehydroleucodine (DhL) on the growth of Trypanosoma cruzi in culture. At concentrations of the drug between 5 and 10 µg/ml in the medium,the parasites remained alive for at least 4 days. Higher concentrations of DhL were lethal for the parasites within a few hours. The effect of DhL is irreversible. Morphological changes induced by DhL were also observed in the parasites. The effect of DhL was blocked by the presence of reducing substrates such as glutathione or dithiothreitol, but these agents were not able to reverse the effect of DhL if added 2 days after the start of drug exposure.

ENHANCEMENT OF TESSARIC ACID PRODUCTION IN TESSARIA ABSINTHIOIDES CELL SUSPENSION CULTURES

Abstract The total production of the sesquiterpene tessaric acid (TA) by cell cultures of Tessaria absinthioides at day 25 of the culture period reached 0.086 mg g−1 DW, with intracellular accumulation accounting for 0.059 mg g−1 DW. Dimethylsulfoxide-induced permeabilization of the cells effected both total production and extracellular accumulation of the sesquiterpene to reach levels of 148% and 271%, respectively. Cultures treated with elicitor preparations of Verticillum sp., Monodyctis cataneae, Acremonium sp., and Aspergillus niger produced TA at levels of 281%, 197%, 149%, and 139%, respectively. Treatment of cell suspension cultures with cis-(-)-jasmonic acid (5 μM) increased production to 267%, whereas jasmonic acid pretreatment and subsequent elicitation raised external tessaric acid to 702%.

Sesquiterpenes and flavonoids from Tessaria species

Abstract The investigation of aerial parts of Tessaria ambigua afforded two known flavonoids. The aerial parts of T. integrifolia gave two known flavonoids and the aerial parts of T. fastigiata afforded three new and three previously reported eudesname derivatives.

5,8-Dihydroxy-3,6,7-trimethoxyflavone from Gnaphalium gaudichaudianum

Abstract 5,8-Dihydroxy-3,6,7-trimethoxyflavone and 5,8-dihydroxy-6,7-dimethoxyflavone were isolated from aerial parts of Gnaphalium gaudichaudianum and identified by spectral data.

Sesquiterpenes from Tessaria absinthioides

Abstract The sesquiterpenes tessaric acid, 2-deoxytessaric acid, ilicic acid, 3-oxo-4,11(13)-eudesmadien-12-oic acid and 3β,5α-dihydroxycostic acid have been isolated from the aerial parts of Tessaria absinthioides . The structure of a new eudesmane, 3β,5β-dihydroxicostic acid, was established by spectroscopic data.

Deoxyelephantopin and 2-epideoxyelephantopin analogues from Gochnatia palosanto.

Reexamination of the aerial parts of Gochnatia palosanto gave five new ester analogues of deoxyelephantopin and five new ester analogues of 2-epideoxyelephantopin in addition to the previously isolated 2-methylbutyrate analogues.

Sesquiterpene lactones from Gochnatia palosanto and coumarins from G. argentina

Abstract Two sesquiterpene lactones were isolated from the aerial parts of Gochnatia palosanto . Their structures were established as desacyldeoxyelephantopin 2-methylbutyrate and desacylisodeoxyelephantopin 2-methylbutyrate. Three coumarins and two flavonoids were isolated from the aerial parts of Gochnatia argentina . Their structures were established as capensin, fraxidin, fraxetin and luteolin 7-methyl ether and hispidulin, respectively.

Chemotaxonomy of the Argentinian species of Gaillardia

The biosystematic study of the Argentinian entities of the genus Gaillardia Foug. have confirmed the differentiation of three species, Gaillardia cabrerae, G. tontalensis and G. megapotamica, and the three varieties of the latter (var. megapotamica, var. scabiosoides and var. radiata). The chemotaxonomic study carried out on the above species and varieties has confirmed the morphological findings and resulted in the isolation of the biogenetic precursor, the pseudoguaianolide 2β-hydroxy-2,3-dihydrohelenalin from G. megapotamica var. radiata.

Hydroxylation of sodic grindelate by Cunninghamella echinulata

Abstract A new grindelane derivative: 2β-hydroxygrindelic acid and the known grindelanes 3β-hydroxygrindelic acid and 6,8(17)-dehydrogrindelic acid were obtained by microbial transformation of sodic grindelate using cultures of Cunninghamella echinulata .