Antiplasmodial in vivo activity of Carica papaya leaf decoction

Within the framework of a larger research project [1] aiming at evaluating a variety of widespread natural products for their possible plasmodicidal activities we now report the in vivo evaluation of a decoction of papaya leaf. The antimalarial activity of papaya is mostly anecdotal but we have recently reported the in vitro antiplasmodial properties of a dried decoction of papaya leaf. In the present study the antiplasmodial activity was investigated in the murine malaria model of P. berghei. BALB/c female mice weighing about 20g, maintained in cages and kept in standard conditions at the ISS animal facilities, were used for experimental infections with P. berghei NK 65 strain, stored in liquid nitrogen in our laboratory. By analyzing the reduction of parasitemia, it was found that the papaya extracts at the two higher doses tested had low plasmodicidal activity until the seventh day but the plasmodicidal activity became markedly positive in the following days. In particular, in the D10 the reduction of parasitemia was 76.7% in the papaya 500 group and 100% in the papaya 750 group; the reduction of parasitemia by D13 was 100% for both doses. These preliminary results obtained so far in our laboratory are definitely encouraging and suggest us to plan a new series of experiments to provide further evidences and eventually confirm the antiplasmodial activity of Carica papaya leaf extracts.

Acknowledgements: The Ente Cassa di Risparmio di Firenze and Toscana Life sciences are gratefully acknowleged for generous financial supports.

References: 1. Sannella, AR. et al. (2007) Biochem Biophys Res Commun 353: 177–181.

2. Berkelar, D. (2002) Echo Tech Notes 71:1–4.