Psoralen's shape allows it to fit right in a DNA groove and with sunlight it does this.
When Psoralens intercalates in the DNA it covalently bind to pyrimidines in one or both strands.
The cross-linking is a mutagenic and enhances cancer risk.
Socrates ” I don’t want that its unhealthy.”
Shmowephon “But Socrates Hemlock is all natural?”