Evaluation of in vitro antitumoral activity and neurotoxicity of a Hibiscus Sabdariffa ethyl acetate fraction against human multiple myeloma cells

Background: Hibiscus Sabdariffa is a plant of the Malvacee family commonly used in Asian and African folk medicine and for Karkadè preparation. In our laboratory, we previously demonstrated that Hibiscus Sabdariffa total extract (HSE) exerted against human multiple myeloma cells a reversible cytostatic effect and reduced cell motility/invasiveness. In order to identify the molecule/s involved in HSE effects, in this study we evaluated the antitumoral activity of a fraction of HSE obtained after ethyl acetate separation (HEF). Material and methods: Human multiple myelomacell s RPMI8226 were treated with different HEF concentrations and cell viability was evaluated by MTT and Trypan blue vital count assays. Apoptosis cell death was evaluated by AnnexinV assay and Caspase3 western blot. Cells migration/invasion was assessed using Boyden Chamber assay. Rat embryo dorsal root ganglia cultures were used to assess HEF neurotoxicity in vitro. HEF and HSE activity was compared. Results: HEF was effective in reducing RPMI8226 cell viability in a dose and time dependent manner. HEF enhanced cell mortality, AnnexinV positive cells and Caspase3 activation. Moreover, HEF was effective in reducing cells migration/invasion and it was not neurotoxic in vitro. Conclusions: In this study we evaluated the in vitro effects of HEF against human multiple myeloma cells RPMI8226. Our results demonstrated that HEF treatment showed an increased effectiveness and Caspase3-dependent apoptosis, but not an increased neurotoxicity, compared to HSE. Considering evident anticancer properties of HEF, it can provide the basis for a further fractionation in order to isolate molecules responsible for Hibiscus sabdariffa effects.