ALKALOIDS                                                      [home]   [topic page]

The opiate family of chemicals is a subgroup of the alkaloid family of chemicals.

• Alkaloids are a very diverse group of chemicals produced by vegetables.
• They are highly reactive substances and have an effect on biological systems in low doses.
• They are produced by amino acids within the plant.
• Alkaloids are "true" if formed in plants or "pseudo" if not derived from plants or amino acids.

Certain structures are very common to the alkaloids. Some of these are given below.

The "benzene ring" is particularly important in chemistry and is VERY common in biology.

Some alkaloids originate in animals - the poison-dart frog is an example. This particular group of frogs ( Dendrobates ) from the Amazonian jungle exude an alkaloid used by natives for hunting. Some species are particularly poisonous - even to humans.

The alkaloids' main physical characteristics include

• nitrogen - usually from an amino acid
• bitter tasting, generally white solid ( however nicotine is a brown liquid).
• they are often basic (pH>7)
• they are water soluble.
• Usually they exist as white crystals which form salts with acids. In plants they may be free or as a salt or nitric oxide.

Alkaloids include the nightshade poisons, hemlock, nicotine, codeine, cocaine, curare, strychnine- a large range of dangerous chemicals. If anyone has tasted "green potato" then you have tasted an alkaloid. Potato skin is full of them, tomatoes were considered extremely poisonous by Europeans because of their relationship with the nightshade family in the C19th until shown otherwise. Native Americans knew otherwise of course.

Alkaloids are often potent as medicines because of their high interactivity with the human body chemistry. They have a long history as local medicines known to the native people. It is fairly recently that, with the ability to detail the chemistry of these substances, the pharmaceutical industry is now examining the many plants, and indeed some animals, for their alkaloids.

Curare based medicines are common in anaesthesia. Strychnine is used as an anticlotting agent for stroke victims.