Yangambin and Epi-yangambin Isomers: New Purification Method from Ocotea fasciculata and First Cytotoxic Aspects Focusing on In Vivo Safety.

Ocotea fasciculata presents yangambin (YAN) and its isomer epi-yangambin (EPI-YAN) as major lignans, which are employed as the plant markers for quality control purposes and as potential pharmacological compounds. However, a gap between the pure isomers and safety and efficacy protocols is faced by the scientific community. In this context, this work aimed to report (i) a new and advantageous purifying process in a semi-preparative scale for YAN and EPI-YAN isolation from Ocotea fasciculata, and (ii) an in vitro cytotoxicity study to estimate, for the first time, the LD₅₀ values of the isolated epimers, as well as the influence of albumin concentration in cell culture medium. The best condition for epimers isolation was achieved in normal-phase liquid chromatography. The lignan fraction (LF), previously obtained from the plant ethanolic extract, was purified yielding 17% and 29% of YAN and EPI-YAN, respectively. The in vitro study demonstrated that YAN and EPI-YAN were safe, and only at the highest concentration studied, a decrease on cell viability was observed. The estimated LD₅₀ value was higher than 1612 mg/kg for both epimers. The LF, on the other hand, demonstrated an estimated LD₅₀ of 422 mg/kg. Lignan cytotoxicity studies also evidenced that the higher cell viability was related to the higher concentration of fetal bovine serum as a source of albumin in medium. This is the first time the LD₅₀ and safety of the isolated epimers were estimated, opening up great perspectives of success in in vivo studies.