Phenolic Constituents in Dried Flowers of <i>Aloe vera</i> (<i>Aloe barbadensis</i>) and their <i>in vitro</i> Antioxidative Capacity

Abstract

The dried flowers from Aloe vera (L.) Burm. f. (Aloe barbadensis Mill.) (Asphodelaceae) were analysed by means of HPLC-DAD and HPLC-MS/MS, verifying chlorogenic, caffeic, 5-P-coumaroylquinic, caffeoylshikimic, 5-feruloylquinic, 5-P-CIS-coumaroylquinic, P-coumaric and ferulic acid as well as luteolin, apigenin, quercetin, kaempferol, isoorientin, isovitexin and their 7-O-glucosides, saponarin and lutonarin. On searching for anthranoids in the flower extract, aloe-emodin as well as the glycosylchromone aloeresin B could be identified. Aloin A and B, the laxative principle of the drug Curaçao-Aloes, are not accumulated in the dried flowers. The polyphenol content of three different batches was 0.73 - 1.01% (+/- 0.05%) and the flavonoid content 0.24 - 0.34% (+/- 0.01%). The hydrophilic antioxidative capacity amounted to 85.7 - 94.9 (+/- 0.5) micromol TEAC/g dried Aloe vera flower and was directly correlated with the polyphenol and flavonoid contents.