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 showed antioxidant activity against superoxide and hydroxyl radicals. Only 1 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.