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Recebido em 25/2/03; aceito em 5/1/04; publicado na web em 27/05/04 POLAR CONSTITUENTS OF THE LEAVES OF Machaonia brasiliensis (RUBIACEAE). Chemical investigation of the MeOH extract of the leaves of Machaonia brasiliensis (Rubiaceae) resulted in the isolation and identification of 3β-O-β-glucopyranosyl stigmasterol, 3β-O-β-glucopyranosyl sitosterol, secologanoside, 7-O-β-glucopyranosyl quercetagetin, 4,5-O-dicaffeoylquinic acid and 5-O-caffeoylquinic acid. The structures of these compounds were established by spectroscopic analysis, including 2D NMR experiments. The chemotaxonomic relevance of the isolation of secologanoside is discussed.

Artigo mio/metanol 1:1, como um sólido castanho amorfo. O espectro na região do infravermelho (IV) de 1 apresentou bandas de absorção típicas de grupos hidroxila (3361 cm-1) e carboxila de éster (1729 cm-1) além de uma lactona α,β insaturada (1713 e 1659 cm-1). Os dados espectroscópicos de RMN desta substância, evidenciaram a presença de um esqueleto iridoidal caracterizado pelos sinais δ H /δ C em 7,30 (d,

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Chemical investigation of the leaves of Solanum sordidum Sendtn., Solanaceae, resulted in the isolation and identifi cation of sitosterol, stigmasterol, 3β- and N-trans-feruloyltyramine.The structures of these compounds were established by analysis of 1D and 2D NMR spectrometric data and comparison with data in the literature. The evaluation of antioxidant activity showed an IC50 of 159.5 ppm for the chloroformic fraction and IC50 of 77.5 ppm for the hydromethanolic fraction.

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