There is no single active ingredient, only an unresolved mixture
The extract mixes flavonoids, phenolic acids, naphthodianthrones including hypericin and phloroglucinols including hyperforin. It has no molecular formula and no single half-life.
What the study found
There is no active ingredient, only a mixture nobody has resolved
St John's Wort extract is a mixture of flavonoids, phenolic acids, naphthodianthrones including hypericin, and phloroglucinols including hyperforin, with no single constituent identified as the active one. That is why it carries no molecular formula and no single half-life.
The caveat · Summary of others' work, to 2020
This comes from a reference monograph summarising other people's work rather than from primary research, with references last updated in 2020. Which constituent produces the antidepressant effect has never been established, and that is a far less settled question than which one drives the drug interactions.