In vitro antibradykinin activity of Aloe barbadensis gel.

When bradykinin-induced contraction of the isolated rat ileum was tested in the presence of Aloe barbadensis Mill. (Liliaceae) gel (fraction F-1) and with the fraction obtained by precipitation of the F-1 with 55% ammonium sulfate (F-55), the maximal responses to bradykinin were reduced by 10 and 22%, respectively. Furthermore, purification of the F-55 by filtration through a column of Sephacryl (S-500-HR) yielded the F-SH fraction, which inhibited the bradykinin effect by 60%. Purification of the F-SH fraction, by filtration through a column of Sephadex G-100, brought about four new fractions: F-GA, F-GB, F-GC, and F-GD. F-GB was the only one that showed the bradykinin inhibition effect (67%). Clearly, Aloe barbadensis gel contains a material that inhibits the bradykinin effect, which might explain the anti-inflammatory properties of Aloe barbadensis.