From Azithromycin to Nafithromycin
Three real, independently-derived macrolide antibiotics in generational sequence. Key atoms and structural motifs are identified programmatically (RDKit ring perception + maximum-common-substructure mapping) and highlighted directly on each 3D structure, then carried forward — or dropped — as the scaffold evolves into a ketolide.
Structures generated from each compound's canonical isomeric SMILES (PubChem CIDs: Azithromycin 447043, Clarithromycin 84029, Nafithromycin 117587595); 3D coordinates from ETKDG embedding + MMFF94 optimization (RDKit). Highlighted atoms are not manually placed — the azalide nitrogen, C-methoxy and ketolide 3-keto sites are located by ring-perception + substituent-typing rules, and the conserved-vs-novel split between clarithromycin and nafithromycin comes from an RDKit maximum-common-substructure atom mapping. These three compounds are each independently synthesized from erythromycin — this shows generational lineage and the real structural change at each step, not a literal reaction pathway.