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. Alkaloids tend to be cell-cycle specific, although their mechanism at the biochemical level differs from medicine to medicine.  In addition to compounds taken directly from plants, hemisynthesized congeners inspired by natural materials have also found use.

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.

Camptothecin 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 profession 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.

Pharmacognosy

There’s even a word for the pursuit of medicines from plants: Pharmacognosy.  It’s all very romantic, but the notion that there are a bevy of easily obtained cancer drugs in the forests overlooked because myopic researchers won’t get out of the laboratory is false.  People have always tried to find medicines in nature and modern pharmaceutical companies are no exception.  New drugs continue to come from plants.  But we can’t expect miracles from this source.

Ixabepilone

Brand/Trade Names: Ixempra

Manufacturers: Tecoland Corporation, Concord Biotech, Formosa Laboratories, Hubei Honch Pharmaceutical Co.

Formula: C₂₇H₄₂N₂O₅S

Mechanism: Microtubule Inhibitor

Class: Plant alkaloid

Administration: Intravenous

Notes:  Approved by the FDA in 2007.  Used for treatment of breast cancer.

Omacetaxine

Brand/Trade Names: Synribo

Formula: C₂₉H₃₉NO₉

Manufacturers: AMRI, MINSHENG GROUP SHAOXING PHARMACEUTICAL CO., Stragen Pharma, SA TAIHUA NATURAL PLANT PHARMACEUTICAL CO.

Mechanism: protein translation inhibitor

Class: Plant alkaloid

Administration: Intravenous

Notes:  Approved by the FDA in 2012.  Used for treatment of chronic myelogenous leukemia.