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

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.