The editor has retracted this article because a scientific error was made in the identification of the species referred to in the study. The plant studied is not Canscora decussata, as stated in the manuscript, but rather Canscora diffusa. Because of this unintentional error, the scientific content of the article is no longer reliable. All authors agree to this retraction. The online version of this article contains the full text of the retracted article as electronic supplementary material.