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Evaluation of alkaloid contents, acute toxicity and antitussive activity of the bracts of two varieties of Bougainvillea glabra Choisy

Abstract:

The Bougainvillea glabra Choisy plant, used for the treatment of various diseases, occurs in varieties due to the color of its bracts, which show different chemical compositions, which gives the possibility of presenting various therapeutic activities and potentially different toxic effects. Hence the importance of evaluating both the pharmacological activity and the toxicity of the bracts with different colors of B. glabra. In this investigation, the antitussive activity and acute toxicity of orange and purple bracts of B. glabra, respectively, were evaluated. For preclinical acute toxicity tests, a dose of 2,000 mg·kg-1 of the extract of the purple and orange bracts of B. glabra, respectively, was applied to CD1 mice, which was non-toxic when ingested orally. For the antitussive activity, CD1 mice were used and were divided into 6 groups, a control group and five groups that were administered the doses of 250 mg·kg-1 (T1 and T2) and 500 mg.kg-1 (T3 y T4) of the dry extract of the purple bracts, oranges, and codeine (30 mg·kg-1) (T5) as positive control, respectively. Antitussive activity occurred in all treatments, but the 250 mg·kg-1 treatment of the orange bracts (T2) provided significantly (P<0.05) the highest antitussive activity, compared to the 500 mg·kg-1 treatment of the same color (T4) and the other treatments (T1, T3 and T5). The orange bracts had higher concentrations (0.24 ± 0.02) mg·g-1 of alkaloids than the purple ones (0.16 ± 0.02) mg·g-1. Apparently, the orange bracts of B. glabra decrease the effectiveness of the antitussive activity when the concentration of the extract increases due to the high content of alkaloids. This study provides evidence that the purple and orange bracts of B. glabra have antitussive activity, at the doses used and without acute toxicity effects.