Phytochemistry and antiglycation activity of Aloe sinkatana Reynolds

A new anthraquinone along with 10 known compounds were isolated from the leaves of Aloe sinkatana Reynolds (Aloaceae), and their structures were elucidated as the new compound 2,8-dihydroxy-6-(hydroxymethyl)-1-methoxyanthracene-9,10-dione (1) and the known compounds Aloe-emodin (2), feralolide (3), 1-hydroxy-5-methoxy-3-methyl-9,10 dihydroanthracene 9,10-dione (4), β-sitosterol (5), β-sitosterol with glycosidic bond (6), microdontin (7), homoaloins A (8) and B (9) and aloins A (10) and B (11). Characterization of compounds 1–9 was based on spectral analyses and comparison with reported data, particularly the new compound 1 was identified by 1D- and 2D NMR, mass spectroscopic and X-ray crystallography analyses. Antiglycation activity of the extracts and isolated compounds were carried out using the hemoglobin-δ-gluconolactone and glucose–bovine serum albumin assays. The results obtained showed that MeOH and EtOAc extracts as well as compound 1 showed an inhibitory effect on early stage protein glycation. Compound 1 also showed significant inhibitory effects against glucose-induced advanced glycation end-products.