- Attenuation of capsaicin-induced acute and visceral nociceptive pain by alpha- and beta-amyrin, a triterpene mixture isolated from Protium heptaphyllum resin in mice. Oliveira, F.A., Costa, C.L., Chaves, M.H., Almeida, F.R., Cavalcante, I.J., Lima, A.F., Lima, R.C., Silva, R.M., Campos, A.R., Santos, F.A., Rao, V.S. Life Sci. (2005)