Site hosted by Build your free website today!

Plant Secondary Compounds

Most information here taken from "Medical Botany - Plants Affecting Man's Health" by Lewis and Elvin-lewis.

See also:

Secondary compounds are complex chemicals made by plants that are not essential to the life of the plant. They are thought to be produced primarily as pesticides and anti-grazing agents, but they also used as pigments, hormones and chemical agents that can attack other plants (alleleopathy).

They are immensely variable, often produced by a long sequence of enzyme-driven steps. The diversity of secondary compounds may reflect a sort of evolutionary arms race between plants and grazers that has led to the rapid evolutionary diversification of some of these substances.

Since toxic or bad tasting secondary compounds have an obvious benefit for the plant, it is hardly surprising that most secondary compounds have neutral or harmful effects for animals.

However, through trial and error, humans and some other species have discovered that under the certain circumstances, the physiological effects of some secondary compounds can have medical benefits or narcotic effects.

The study of how cultures around the world use plants compounds, and how their knowledge of plant biodiversity can be adapted by scientists to make medicines or products with scientifically supported beneficial effects is called ethnobotany.

Ethnobotany was at one time thought to be a good way to help conserve rain forests by emphasizing their importance as sources of biodiversity. Various international treaties tried to protect the intellectual property rights of indigenous peoples as way to encourage "bioprospecting" and generate revenue that could be used for conservation. This approach has not yielded many practical results, partly because scientist's understanding of molecular genetics has grown so quickly that bioprospecting is no longer necessary. It is proving faster cheaper and easier to simply genetically engineer existing plants.


Plant secondary compounds are sometimes grouped into categories:

ALKALOIDS - Generally organic compounds containing ring structure and nitrogen.

                         Many can affect the nervous system.

Glycosides - sugar-based compounds with toxic side groups.

                          Mainly poisonous or medicinal - few are narcotic.

                      CYANOGENIC GLYCOSIDES may contain toxic cyanide

CARDIOACTIVE GLYCOSIDES such as DIGITALIS from foxgloves are known for their specific action on heart muscle


Ergotism - disease caused by fungus Claviceps purpurea

•  fungus infects grain

•  sometimes called St Anthony's fire

•  scourge of middle ages due to village bakeries

•  implicated in Salem witch trials

Cocaine - alkaloid extracted from coca plant Erythroxylum coca

• considered property of Incan royal family

• placed in Incan tombs to give energy to the dead

• used by Spanish to energize enslaved natives

• used to be in Coke - certainly helped you "have a coke and a smile"

• anesthetic - eventually replaced by synthetic Novocain

• powerful natural insecticide.

Caffeine - alkaloid from Coffee arabica

Theobromine - alkaloid from Theobroma cocoa

• stimulant found in chocolate

Nicotine - alkaloid from tobacco with long history in North America. Extremely addictive.

• powerful natural insecticide, and highly toxic to all animals.

• Addictive nature may may be the plant's way of encouraging the animal to eventually receive a lethal dose.

Mescaline - alkaloid from Lophophora williamsii. Called Peyote.

Nutmeg - contains a mixture of hallucinogenic alkaloids

• popular in prison

• long history in medicine and ritual uses along with several other related spices.

Morning glories  - alkaloid D-Lysergic acid amide. Extremely toxic

Tropane alkaloids from the Solanaceae Usually extracted from nightshades. Origin of many myths associated with witchcraft and lycanthrope (changing into a wolf).

Listen carefully to Rob's amazing "origin of witches" story. More info in this book.

Non alkaloids:

Isoxazoles - from fly agaric a fungus that grows on trees. Called SOMA and often worshipped as a god by ancient peoples.

• Bright red skin - resembles and apple or other fruit

• suggestions of soma use feature prominently in world religions, possible biblical significance.

• soma as "God" and the association with "tree of knowledge"

Tetrahydrocannabinol  (THC) from Cannabis sativa

• Used since at least 6000 BC in China.

•Mentioned as a narcotic incense by Herodotus. Mentioned as ingredient in cakes by Galen in 2nd century.

• Prolonged use linked to depression, scizophrenia, especially in women.


• Contains (among other things) compounds that encourage the release of oxytocin - associated with fertility and childbirth (although poisonous to human gastric system).

other articles;

Narcotic honey? ......