Lannea acida A. Rich. (Anacardiaceae) is a west African plant used in traditional medicine. In a course of an activity screening in Multiple Myeloma Cancer Stem Cells, the dichloromethane extract of the plant's root bark inhibited the cell growth at 20 μg/mL (<30% of cell growth). A bioassay-guided fractionation was performed to isolate and identify active molecules that inhibits the cell proliferation, using analytical techniques such as High Performance Liquid Chromatography, Mass Spectrometry, Nuclear Magnetic Resonance, Infrared, Ultraviolet-visible and Circular Dichroism spectroscopies, Specific rotation and MTT-proliferation assay. Using these techniques, four new and active molecules with similar structures were isolated. They have comparable inhibition concentrations (IC50), surrounding 10-15 μM, in MM-CSCs which are drug resistant cells, responsible of some cancer relapses.