Evaluation of the in vitro and in vivo anticancer properties of Moroccan propolis extracts

This investigation aimed to evaluate the in vitro and in vivo antitumor potential of a Moroccan propolis extracts. For in vitro assays, three mammalian tumor cell lines were used: BSR (hamster renal adenocarcinoma), Hep-2 (human laryngeal carcinoma) and P815 (murin mastocytoma). The propolis ethanolic extract as well as the ethyl acetate extract, exert an in vitro cytotoxic activity in dose-dependent manner. The IC50 values were ranging from 15 µg/mL to 38 µg/mL. This activity depends not only on the extract's chemical composition (analysed by HPLC/ESI-MS), but also on the target tumor cells. Interestingly, the cytotoxic effect of these extracts on the normal human peripheral blood mononuclear cells (PBMC) was weak when compared to that induced on tumor cells. On the other hand, oral route treatment of P815 tumor-bearing mice (DBA2/P815) with propolis ethanolic extract (5 mg per mouse every fourth day, five times for group A, and 2.5 mg per mouse every fourth day, five times for group B) significantly reduced the tumor volume (1.2 cm3 for group A and 2.7 cm3 for group B at the 22nd day after tumor graft). These effects are statistically significant as compared to those obtained with the control untreated mice (tumor volume 3.5 cm3 at day 22).