Aloeresin H, a new polyketide constituent of Cape aloe

A new constituent, aloeresin H (1), was isolated from Cape aloe, a bittering and laxative agent. Its structure was elucidated by degradation experiments combined with 1D and 2D NMR data. Aloeresin H represents the first C,C-diglucoside discovered in commercial samples of the drug and its polyketide origin can be interpreted in terms of two-chain condensation. Possible conformations of the virtual aglycone were obtained as energy minima by quantum mechanical calculations and were found to be consistent with particular NOE associations observed in the original glucoside. (C) 2003 Elsevier Science Ltd. All rights reserved.