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Abstract Aloe barbadensis Miller (Aloe vera) has long been used in food, cosmetic and pharmaceutical industries. The solid wastes such as the spikes and the outer green skins are usually separated from the inner gel and discarded during the process of Aloe vera leaves. Three kinds of polysaccharides (designated as ASP-4N, ASP-6N and ASP-8N) were successfully purified from the leaf skin of Aloe vera in our previous work. The present study aimed to analyze the structural and molecular features of ASP-6N and ASP-8N using methylation and GC-MS, NMR, high performance size-exclusion chromatography coupled with multi-angle laser light scattering (HPSEC-MALLS) and scanning electron microscopy (SEM) techniques. Results showed that ASP-6N and ASP-8N were β-(1→4)-glucomannans with acetyl groups, which may attach to O -2, O -3 or O -6 of mannopyranosyl residues in the backbone as mono-, di-, or tri-acetylated forms. HPSEC-MALLS analysis indicated that the polysaccharide fractions from Aloe leaf skin adopted various conformations in the aqueous solution depending on their molecular mass. The polysaccharides had fibrous, ribbon-like and spherical morphology by SEM observation. Graphical abstract Image 1 Highlights • Two polysaccharides from leaf skin of Aloe vera were identified to be O -acetyl-β-(1→4)-glucomannans. • The acetyl groups attached at O -2, O -3 and/or O -6 positions. • HPSEC-MALLS analysis showed that they adopted various conformations in aqueous NaNO 3 solution. [ABSTRACT FROM AUTHOR]

The methanol extracts of leaf skins and flowers of Aloe vera from the Canary Islands were analyzed for their phenolic profiles and screened for their antioxidant and antimycoplasmic activities. The use of reversed phase high performance liquid chromatography (RP-HPLC) allowed the identification of 18 phenolic constituents. Leaf skin extracts were characterized by the abundance of catechin, sinapic acid and quercitrin. Gentisic acid, epicatechin and quercitrin were the most prominent phenolic compounds of the flowers. The in vitro antioxidant activities determined by using the 1,1-diphenyl-2-picrylhydrazyl (DPPH) and ferric antioxidant reducing power (FRAP) assays revealed that both extracts exhibited antioxidant activity, being the leaf skin extract the most active fraction. The leaf skin extract was also found to be active against the microbial strains tested. Therefore, A. vera extracts from leaf skin and flowers can be considered as good natural antioxidant sources.

The methanol extracts of leaf skins and flowers of Aloe vera from the Canary Islands were analyzed for their phenolic profiles and screened for their antioxidant and antimycoplasmic activities. The use of reversed phase high performance liquid chromatography (RP-HPLC) allowed the identification of 18 phenolic constituents. Leaf skin extracts were characterized by the abundance of catechin,sinapic acid and quercitrin. Gentisic acid,epicatechin and quercitrin were the most prominent phenolic compounds of the flowers. The in vitro antioxidant activities determined by using the 1,1-diphenyl-2- picrylhydrazyl (DPPH) and ferric antioxidant reducing power (FRAP) assays revealed that both extracts exhibited antioxidant activity,being the leaf skin extract the most active fraction. The leaf skin extract was also found to be active against the microbial strains tested. Therefore,A. vera extracts from leaf skin and flowers can be considered as good natural antioxidant sources. [ABSTRACT FROM AUTHOR]