Este trabalho descreve a síntese de neoglicoconjugados diméricos, triméricos e tetraméricos derivados de D-galactose. O ligante monossacarídico foi preparado em cinco etapas utilizando-se a modificação de Doebner da reação de Knoevenagel na etapa de extensão da cadeia lateral. O ligante foi acoplado a 1,4-butanodiamina, tris-(2-etilamino)amina, pentaeritritiltetramina e dendrímeros PAMAM (núcleo 1,4-butanodiamina G0 e núcleo 1,12-dodecanodiamina G0). Os glicodendrímeros desprotegidos foram purificados por cromatografia por exclusão de tamanho (SEC). Esta foi a única etapa em que um método cromatográfico foi empregado em toda rota sintética. Essa é uma estratégia nova e eficiente para a preparação de neoglicoconjugados.

In this work, the synthesis of dimeric, trimeric and tetrameric D-galactose-based neoglycoconjugates is reported. The monosaccharide ligand was prepared in 5 straightforward steps from D-galactose using the Doebner modification of the Knoevenagel reaction for chain elongation. The ligand was coupled to 1,4-butanediamine, tris-(2-ethylamino)amine, pentaerythrityltetramine and PAMAM dendrimers (1,4-butanodiamine core G0 and 1,12-dodecanediamine core G0). The unprotected glycodendrimers were purified by size-exclusion chromatography (SEC). This was the only step in which a chromatographic method was employed throughout the synthetic route. This is a new and efficient strategy for the preparation of neoglycoconjugates.

Six pentacyclic triterpenes were isolated from hexane extract of stems of Maytenus salicifolia Reissek, Celastraceae: 30-hydroxyfriedelan-3-one (1), 3,16-dioxofriedelane (2), friedeline (3), lupeol (4), betuline (5) and lup-20(29)-en-3,30-diol (6). The structure each one was established on the basis of detailed ¹H and 13C NMR spectral investigation and by comparison with the respective literature values. For compound 1, the complete 2D NMR (HMBC, HMQC and NOESY) spectral data were herein reported for the first time. Compounds 1, 2, 5 and 6 were isolated for the first time from this plant. Antioxidant activity is described for some extracts from species of the Celastraceae family, then, the extracts from aerial parts of M. salicifolia were evaluated in relation to antioxidant potential using the DPPH method. Compared to quecertin, the AcEt extract (EAF) from leaves, AcEt (EAPF) and MeOH (EMPF) from pulp fruit and AcEt (EAT) and MeOH (EMT) from stems showed significant antioxidant property.