Metabolism of nanocarbons

Usami et al. (2025) studied the metabolism of nanocarbons by Spodoptera litura larvae. When fed [6]MCPP (methylene-bridged cycloparaphenylene), 4th and 5th instar larvae converted this compound to its oxylene (see figure). Two P450s were particularly induced, CYP6AE70 and CYP6AE47. Usami et al. then showed that these two P450s were responsible for this monooxygenation, as evidenced by RNAi and by expression of CPR-fused P450s in E.coli. Interestingly, these two P450s (that they called X3 and X2) are two of the five alternative splicing isoforms of a CYP6AE gene.The figure below shows the highly unusual insertion of oxygen in a C(phenyl)-C(phenyl) bond. Reactions with [6]MCPP revealed that no other oxygenation is observed, while reactions with [6]CPP also indicated size specificity for the substrate. (adapted from Usami et al.)