Synthesis of Methoxylated Benzoxanthones as Drug Metabolites of Antischistosomal Schistodiones—A Limited Environmental Risk
Abstract
In the search for new antischistosomal 3-benzylmenadiones (benzylMDs), the screening of a library developed in our laboratory led to the identification of two regioisomeric analogues, the 2′,5′- and 3′,5′-dimethoxy-benzylMD—designated schistodiones A2′,5′ and A3′,5′—which were investigated for their activity against the platyhelminth Schistosoma mansoni and various protozoan parasites, bacteria, and fungi. Reported work has shown that benzylMDs act as prodrugs: their bioactivation undergoes a cascade of redox reactions within the parasite, generating multiple drug metabolites, e.g., the main benzoylmenadione (benzoylMD) intermediates, and reactive oxygen species that interfere with key metabolic pathways. Among the secondary metabolites, benzoxanthones have been identified as potential products generated along this oxidative pathway. The aim of the study was to synthetize methoxylated benzoxanthones, as putative metabolites generated from these antischistosomal benzylMDs. During the synthetic work, several difficulties arose, including the absence of starting reagents, the incompatibility of certain reactions with methoxy groups, the possible formation of several isomers, and the easy re-oxidation of sensitive intermediates. To overcome these obstacles, we developed a new retrosynthetic strategy using modified precursors: replacing methoxy groups with O-methylenemethoxy (OMOM) groups that are more stable in basic media, using aldehydes or aromatic esters as precursors, and replacing certain substituents with groups that are easier and less costly to introduce (chlorine or nitro). Selected metabolites (benzoylMDs, benzoxanthones) were then tested in parasite and cellular assays. Furthermore, benzoylMDs were tested as subversive substrates of S. mansoni thioredoxin-glutathione reductase (SmTGR) and selected drug metabolites were investigated in SmTGR modeling experiments. From a One Health perspective, these benzylMD derivatives pose limited environmental risk because their metabolites lack toxicity when encountered externally, as toxicity requires intracellular metabolic activation and localized formation of reactive intermediates in close proximity to their cellular targets inside parasites.
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BibTeX
@article{cesarrodo2026synthesis,
title = {{Synthesis of Methoxylated Benzoxanthones as Drug Metabolites of Antischistosomal Schistodiones—A Limited Environmental Risk}},
author = {Elena Cesar-Rodo and Jeremy Boilevin and Jimmy Richard and Peter D Ziniel and Didier Belorgey and Louis Maes and Francesco Angelucci and David Lee Williams and Elisabeth Davioud-Charvet and Don Antoine Lanfranchi},
journal = {Molecules},
year = {2026},
month = may,
doi = {10.3390/molecules31111839},
url = {https://hal.science/hal-05752442v1},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Synthesis of Methoxylated Benzoxanthones as Drug Metabolites of Antischistosomal Schistodiones—A Limited Environmental Risk
AU - Elena Cesar-Rodo
AU - Jeremy Boilevin
AU - Jimmy Richard
AU - Peter D Ziniel
AU - Didier Belorgey
AU - Louis Maes
AU - Francesco Angelucci
AU - David Lee Williams
AU - Elisabeth Davioud-Charvet
AU - Don Antoine Lanfranchi
PY - 2026
DA - 2026/05/27
JO - Molecules
DO - 10.3390/molecules31111839
UR - https://hal.science/hal-05752442v1
AB - In the search for new antischistosomal 3-benzylmenadiones (benzylMDs), the screening of a library developed in our laboratory led to the identification of two regioisomeric analogues, the 2′,5′- and 3′,5′-dimethoxy-benzylMD—designated schistodiones A2′,5′ and A3′,5′—which were investigated for their activity against the platyhelminth Schistosoma mansoni and various protozoan parasites, bacteria, and fungi. Reported work has shown that benzylMDs act as prodrugs: their bioactivation undergoes a cascade of redox reactions within the parasite, generating multiple drug metabolites, e.g., the main benzoylmenadione (benzoylMD) intermediates, and reactive oxygen species that interfere with key metabolic pathways. Among the secondary metabolites, benzoxanthones have been identified as potential products generated along this oxidative pathway. The aim of the study was to synthetize methoxylated benzoxanthones, as putative metabolites generated from these antischistosomal benzylMDs. During the synthetic work, several difficulties arose, including the absence of starting reagents, the incompatibility of certain reactions with methoxy groups, the possible formation of several isomers, and the easy re-oxidation of sensitive intermediates. To overcome these obstacles, we developed a new retrosynthetic strategy using modified precursors: replacing methoxy groups with O-methylenemethoxy (OMOM) groups that are more stable in basic media, using aldehydes or aromatic esters as precursors, and replacing certain substituents with groups that are easier and less costly to introduce (chlorine or nitro). Selected metabolites (benzoylMDs, benzoxanthones) were then tested in parasite and cellular assays. Furthermore, benzoylMDs were tested as subversive substrates of S. mansoni thioredoxin-glutathione reductase (SmTGR) and selected drug metabolites were investigated in SmTGR modeling experiments. From a One Health perspective, these benzylMD derivatives pose limited environmental risk because their metabolites lack toxicity when encountered externally, as toxicity requires intracellular metabolic activation and localized formation of reactive intermediates in close proximity to their cellular targets inside parasites.
SN - 1420-3049
ER -