Plant Alkaloids in Cancer Treatment

The word alkaloid goes back to the 1800s and refers to chemical compounds derived from plants that contain at least one nitrogen atom in their molecules and that produce an observable physiological effect on humans.  The word seems archaic in modern chemistry, but it finds some use. Some alkaloids are effective as medicines. Others (e.g. nicotine) are used by humans but for other purposes.

Alkaloids used for cancer treatment are a major part of the chemotherapy arsenal.  In addition to compounds taken directly from plants, hemisynthesized congeners inspired by natural materials have also found use.

Mechanism

Alkaloids tend to be cell-cycle specific, although their mechanism at the biochemical level differs from medicine to medicine.

Classifications

See our page on vinca alkaloids for more on these medicines derived from the Madagascar periwinkle.

Podophyllotoxins

These drugs are derived from Podophyllum peltatum, also called the Mayapple and are also called Epipodophyllotoxins.  Podophyllotoxin is a plant product incorporated into a cream medication called podofilox and used for viral skin infections.   It is used in topical applications for illnesses such as warts.  The cancer drugs Etoposide and Tenisopide are derived from podophyllotoxin.  These are called antimitotic or antimocrotubule agents, or just mitotic inhibitors.

Podophyllotoxin itself (sometimes called podofilox) is not approved for cancer treatment but there has been research interest in it.

Taxanes

The taxanes are drugs with origins in the yew genus of trees.  Paclitaxel and Docetaxel.

Camptothecan analogs

Camptotheca is a genus of tree found in China.  It is sometimes called the Happy Tree.   Camptothecin was first found in this tree.  Follow-on research has produced similar compounds also used in cancer treatment.

Irinotecan

Topotecan

Epipodophyllotoxins

Epipodophyllotoxins are alkaloids that came from the American Mayapple plant.  In the body they act as topoisomerase (type II) inhibitors. Etoposide and teniposide are in this class.

Others

Other alkaloids of some interest but not approved are

Rohitukine

Harringtonine 

Cephalotaxine

Acronycin

Thalicarpine

Ellipticine

Isoreserpiline

Usambarensine

Matrine

So-called nutraceuticals have less science behind them but are of some tangential interest to serious investigators.  These include

Berberine

Evodiamine

Piperine

Sanguinarine

Tetrandrine

Some people believe plants have chemoprotective properties and the medical industry generally recommends people eat plants as a major part of their diet.  However, attempts to prove compounds derived from plants can prevent cancer has not been successful.

Ixabepilone

Brand/Trade Names: Ixempra

Formula: C27H42N2O5S

Mechanism: Microtubule Inhibitor

Class: plant alkaloid

Administration: Intravenous

Notes:  First approved by the FDA in 2007.

Teniposide

Brand/Trade Names: Vumon

Formula: C32H32O13S

Mechanism: topoisomerase II inhibitor

Class: plant alkaloid

Administration: Intravenous

Notes:  Approved by the FDA in 1992.

Omacetaxine

Brand/Trade Names: Synribo

Formula: C29H39NO9

Mechanism: protein translation inhibitor

Class: plant alkaloid

Administration: Intravenous

Notes: Approved for cancers that have not responded to tyrosine kinase inhibitors.  Approved by the FDA in 2012.