Monoclonal Antibodies That Recognize the Alkylation Signature of Antimalarial Ozonides OZ277 (Arterolane) and OZ439 (Artefenomel).

The singular structure of artemisinin, with its embedded 1,2,4-trioxaneheterocycle, has inspired the discovery of numerous semisynthetic artemisininand structurally diverse synthetic peroxideantimalarials, including ozonidesOZ277 ( arterolane) and OZ439 (artefenomel). Despite the critical importance of artemisinincombination therapies (ACTs), the precise modeof actionof peroxidicantimalarials is not fully understood. However, it has long been proposed that the peroxidebond in artemisininand other antimalarial peroxidesundergoes reductive activation by ferrous hemereleased during hemoglobin digestion to produce carbon-centered radicals that alkylate hemeand parasite proteins. To probe the modeof actionof OZ277 and OZ439, this paper now describes initial studies with monoclonal antibodies that recognize the alkylation signature (sum of hemeand protein alkylation) of these synthetic peroxides. Immunofluorescence experiments conducted with ozonide-treated parasite cultures showed that ozonidea...