Chemistry and Life

Medicinal chemistry. Pharmacology. Toxicology. Environmental sciences.

Mayapple and podophyllotoxin

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May apple leafThe woods here in Pennsylvania at this time of year are starting to burst into their summer greenery. One of the plants that is prominent at the moment is the mayapple (Podophyllum peltatum). It is a small herbaceous perennial with an umbrella-like leaf on a single stalk. Underneath this umbrella a single flower blooms which eventually grows into a fruit, the “apple”. The fruit is edible when ripe, but the roots and leaves are quite poisonous.  Even touching the root may cause dermatitis.

The extract of the root (actually a rhizome) is known as podophyllin.  This extract is a complex mixture of chemical compounds including flavonols and lignans.  One of those lignins, podophyllotoxin, is the individual toxin primarily responsible for the poisonous nature of the plant.

Mayapple flowerAs is sometimes the case with poisonous plants, the mayapple has found use medicinally.  Native Americans and early American settlers used it for a variety of ailments.  In modern medicine, both the mixture podophyllin and the purified compound podophyllotoxin have found use in the topical treatment of warts.

Medicinal chemists have also taken note of the properties of podophyllotoxin.  Two semi-synthetic derivatives of podophyllotoxin, teniposide and etoposide, have been developed as pharmaceutical drugs for use in cancer treatment.  These two drugs act as topoisomerase inhibitors.

So it seems we’ve progressed from using the whole plant to using a crude extract, then to using a purified chemical, and finally to using semi-synthetic derivatives designed to hit a specific target enzyme.  What comes next?

 

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