An interesting notion from Corral et al. in the Angewandte: when scouting for new herbicides look at existing antimalarial drugs (DOI). The rationale: malaria and plants share part of their evolution. Where the malaria parasite Plasmodium falciparum has an apicoplast (a kind of organelle used for storage of chemical compounds in a cell), plants and also algea have similar chloroplasts. In fact, organisms such as the malaria parasite possibly have at some point in their evolution gobbled up a red algea and simply kept.
The Corral team (a collaboration between the University of Western Australia and BASF) pitched a collection of known antimalarial 'drug-like' compounds against a well-known weed thaliana on agar resulting in eleven hits. Five of them were promoted to the soil testing competition and the winner was used as a scaffold for selection of another 39 commercially available analogues. Puzzlingly none of these 39 were able to beat the parent: a simple structure featuring a furanyl, an amide , a piperadine, a sulfinyl and a chlorophenyl group. In terms of mechanism another riddle to solve: the mode of action is inhibition of photosynthesis but the scaffold is not a known photosystem inhibitor. The reverse approach, discovery of new antimalarial targets based on known herbicides was not discussed.