Anthraquinones and b-polysaccharides content and distribution in Aloe plants grown under different light intensities

The curative and therapeutic effects of Aloe plants have mostly been ascribed to anthraquinones such as aloin, and to some characteristic b-polysaccharides. Although the actual concentration of these bioactives in Aloe plants has not yet been fully clarified, it was expected that plant species, age and growth conditions would play an important role. The aim of this work was to investigate the relationship between species, light intensity and the content of bioactives in Aloe arborescens Mill. and Aloe vera (L.) Burm.f.Aloin was determined by liquid chromatography tandem mass spectrometry: Its concentration was higher in the leaves of younger plants and there was more in A. vera than in A. arborescens. The content of b-polysaccharides was determined colorimetrically after binding with Congo Red dye. The results were not affected by plant age, and oncentrations were higher in A. vera than in A. arborescens. Finally, even though the type of tunnel (and therefore light spectrum) under which plants were grown seemed to have no effect on the content of bioactives, the plants grown under reduced light intensities had significantly lower aloin and b-polysaccharides concentrations.