RESUMO
Various hydroxycinnamoyl ß-d-xylopyranosides were efficiently prepared from 2,3,4-tri-O-acetyl-α-d-xylopyranosyl bromide (TAXB) with amine by amine-promoted glycosylation. The resulted acetylated hydroxycinnamoyl ß-d-xylopyranosides with acetoxy groups at C-2, C-3, and C-4 were regioselectively deacetylated at C-4 position with Novozym 435. Antioxidant activities of free hydroxycinnamic acids and the respective ß-d-xylopyranosides were evaluated by DPPH radical scavenging activity as well as their inhibitory effect on autoxidation of bulk methyl linoleate. The radical scavenging activity on 1,1-diphenyl-2-picrylhydrazyl (DPPH) decreased in the order ferulic acid>caffeic acid≈caffeoyl ß-d-xylopyranosides≈sinapinic acid>sinapoyl ß-d-xylopyranosides≈feruloyl ß-d-xylopyranosides>p-coumaric acid>p-coumaroyl ß-d-xylopyranosides. In bulk methyl linoleate, the antioxidant activity order against autoxidation was almost consistent with the scavenging activity order. The results showed that caffeoyl ß-d-xylopyranosides and sinapoyl ß-d-xylopyranosides were as effective as free caffeic acid, sinapinic acid, and ferulic acid.
Assuntos
Ácidos Cumáricos/síntese química , Sequestradores de Radicais Livres/síntese química , Glicosídeos/síntese química , Xilose/síntese química , Acetilação , Compostos de Bifenilo/antagonistas & inibidores , Ácidos Cafeicos/química , Ácidos Cumáricos/química , Enzimas Imobilizadas , Sequestradores de Radicais Livres/química , Proteínas Fúngicas , Glicosídeos/química , Glicosilação , Ácidos Linoleicos/química , Lipase/química , Oxirredução , Picratos/antagonistas & inibidores , Estereoisomerismo , Xilose/análogos & derivados , Xilose/químicaRESUMO
Various glycosyl ferulates were efficiently synthesized from 2,4,6-tetra-O-acetyl-α-D-glucopyranosyl bromide (TAGB) with amine by amine-promoted glycosylation without using heavy metal. The resulted acetylated glycosyl ferulates with acetoxyl groups at C-2, C-3 and C-4 were regioselectively deacetylated at C-4 and C-6 positions with Novozym 435. Antioxidant abilities of free ferulic acids and its synthetic glycosyl ferulates were evaluated by inhibitory effect on autoxidation of bulk methyl linoleate as well as their radical scavenging activity. The radical scavenging activity on 1,1-diphenyl-2-picrylhydrazyl (DPPH·) decreased in the order ferulic acid>sinapinic acid ≈ glycosyl sinapinates ≈ glycosyl ferulates>p-coumaric acid>glycosyl p-coumarates. In bulk methyl linoleate, the antioxidant activity order against autoxidation was very consistent with the scavenging activity order. The results showed that glycosyl ferulates and sinapinates were effective as well as free carboxylic acid forms.
