RESUMO
Abstract Morinda lucida leaves are largely used by Congolese traditional healers for the treatment of uncomplicated malaria. The antimalarial activity of their ethanolic extract has been confirmed both in vitro and in vivo. However, the development of relevant formulations for potential clinical application is hampered since the active ingredients contained in this extract exhibit poor water solubility and low oral bioavailability. Hence, this work aims not only to develop self-nanoemulsifying drug delivery systems (SNEDDSs) for oral delivery of the ethanolic extract of Morinda lucida (ML) but also to evaluate its oral antimalarial activity alone and in combination with other Congolese ethanolic plant extracts (Alstonia congensis, Garcinia kola, Lantana camara, Morinda morindoides or Newbouldia laevis). Based on the solubility of these different extracts in various excipients, SNEDDS preconcentrates were prepared, and 200 mg/g of each plant extract were suspended in these formulations. The 4-day suppressive Peter's test revealed a significant parasite growth inhibiting effect for all the extract-based SNEDDS (from 55.0 to 82.4 %) at 200 mg/kg. These activities were higher than those of their corresponding ethanolic suspensions given orally at the same dose (p<0.05). The combination therapy of MLSNEDDS with other extract-based SNEDDS exhibited remarkable chemosuppression, ranging from 74.3 % to 95.8 % (for 100 + 100 mg/kg) and 86.7 % to 95.5 % (for 200 + 200 mg/kg/day). In regard to these findings, SNEDDS suspension may constitute a promising approach for oral delivery of ML alone or in combination with other antimalarial plants.