Concept:
Lignans are natural products formed by coupling of phenylpropanoid units.
Step 1: Podophyllotoxin is a lignan compound.
Step 2: It is obtained from Podophyllum species.
Step 3: It has anticancer importance and is used as a precursor for anticancer drugs.
Step 4: Quinine is an alkaloid, artemisinin is a sesquiterpene lactone, and ergotamine is an ergot alkaloid.
\[
\boxed{\text{Podophyllotoxin}}
\]