Menaquinone and Ubiquinone levels change in response to Ro 48-8071 treatment. (A) Ro 48-8071 inhibited parasite growth in a concentration-dependent manner (IC50 = 4.5 ± 0.3 μM; mean ± S.D., n = 3 experiments), calculated according to Moneriz et al. [23]. (B) Decrease of MQ-4 contents in the schizont stages after the treatment with 4.5 μM of Ro 48-8071. The effect of Ro 48-8071 on MQ biosynthesis was analyzed (by RP-HPLC, Protocol II, with the extraction methodology described by Bekker et al. [18]) as the relationship between control and Ro 48-8071 treated parasites (2.7 × 109) metabolically labelled with [1-(n)-3H]GGPP (mean ± S.D., n = 3 experiments). Significant differences comparing control parasites and parasites treated with Ro 48-8071 (One-way ANOVA, P values indicated). UQ: Ubiquinone; MQ-4: menaquinone.