David the origin of drugs and how they were detected is fascinating.
Take cisplatin, that was totally accidental. It was found that bacteria were killed near platin electrodes. This was followed up and the rest is history. Or take saccharin, the chemist was working on tar products! He did not look for sweeteners and must have ingested some by accident (it is about 300 times more sweet than sugar) so it did not take much.

M