Gametocytogenesis induction by Berenil in cultured Plasmodium falciparum

Berenil, which is known to inhibit synthesis of nucleic acid, DNA and RNA, and polyamine, induced gametocytogenesis in cultured Plasmodium falciparum, although the mechanism by which Berenil induces gametocytogenesis is unknown. Asexual parasites of a strain of P. falciparum that seldom produce gametocytes in in vitro culture began gametocytogenesis after 2-24 hr treatment with RPMI 1640 medium containing Berenil (final concentration, 0.1-10.0 micrograms/ml) with horse serum. Gametocytogenesis was consistently observed from 3 days after the addition of Berenil to culture. After parasites were cultivated in RPMI 1640 medium containing Berenil (final concentration, 3.0-10.0 micrograms/ml) and concanavalin A with horse serum for 2 hr, Berenil and concanavalin A were removed from culture medium by centrifugation. Nevertheless, induction of gametocytogenesis was observed. The addition of concanavalin A (final concentration, 10 micrograms/ml) to RPMI 1640 medium containing Berenil enhanced the induction of gametocytogenesis by Berenil. However, when RPMI 1640 medium with concanavalin A was used without the addition of Berenil, no gametocytogenesis was observed as in RPMI 1640 medium alone.