Isolation, structure elucidation, antioxidative and immunomodulatory properties of two novel dihydrocoumarins from Aloe vera

Two new dihydrocoumarin derivatives, compounds 1 and 2, were isolated from Aloe vera. Their structures were determined by X-ray crystallographic diffraction analysis and extensive 1D, 2D NMR spectroscopic data. Both of them evidently sit owed antioxidant activity against superoxide and hydroxyl radicals. Only I obviously exhibited immunomodulatory activity in relation to increasing the phagocytic activity and stimulating the production of superoxide anions in the oxygen respiratory burst of rat peritoneal macrophages. (c) 2005 Elsevier Ltd. All rights reserved.