In vitro radical scavenging and anti-yeast activity of extracts from leaves of Aloe species growing in Congo

Extracts obtained from leaves of Aloe barbadensis and A. congolensis, growing in Congo, were analyzed for their in vitro antiradical and anti-yeast activity. Different leaf tissues (tegument and gel) were analyzed separately. Their phenolic fractions showed the presence of chromones and anthrones (aloesin, aloin B, aloin A, and isoaloeresin), flavonoids (apigenin and kaempferol derivatives), and hydroxycinnamic acids. A differential quantitative composition was observed between leaf tegument and gel: in the first, higher concentrations of the four classes of compounds were observed. The extracts from the tegument exhibited higher in vitro antiradical and antimycotic activity than gel extracts. In a few cases, extracts from teguments were active against amphotericin B-insensitive yeasts. Due to the lack of radical scavenging and yeast inhibition observed when aloin was used, it was possible to postulate that the in vitro activities of the teguments could be related to their high concentration of flavonoids and hydroxycinnamic acids