Plants That Kill: Aconite alkaloids

From hemlock and deadly nightshade to poppies and tobacco, poisonous plants have long been used in medicine, rituals, and even warfare. For the next few months, Princeton Nature will be taking a closer look at the evolution, survival strategies, physiology, and biochemistry of the most toxic plants on Earth. Pulling from Elizabeth A. Dauncey & Sonny Larsson’s new book, Plants That Kill, we hope to provide you with just a sample of the deadly and intriguing plants that can be found in this gorgeously illustrated book.

Adapted from page 48-49 of Plants That Kill:

Aconite alkaloids are mostly restricted to a small number of genera in the buttercup family, particularly the aconites (Aconitum spp.) and their close relatives the larkspurs (Delphinium spp.). The presence of the compounds seems to give these plants a strong evolutionary advantage, as the group constitutes about a third of all species within the family. Aconites and larkspurs produce these highly toxic compounds from a substance called geranylgeranyl diphosphate, which is an essential part of the chlorophyll needed for photosynthesis. They can be grouped into three different ‘flavors’, called veatchine, atisine and aconitine alkaloids. The compounds in the last of these groups are the most toxic, which is thought to be due to their ability to pass through fat-containing barriers such as cell membranes and also the skin. This explains why gardeners and florists who, with bare hands, handle the cut stems or crushed material of aconite and larkspur plants in large amounts or for extended periods of time may experience mild symptoms of tingling or numbness.

There are around 250 species of aconite (Aconitum spp.) found in the wild in the northern hemisphere, but they are also widely grown in temperate gardens and sold as cut flowers.                              Photo credit: Alex Polo, Shutterstock

Species of aconite are used to treat joint pain in traditional Chinese herbal medicine in the form of bath additives, rubs and ointments. Their alkaloids can be absorbed through the skin, where they act as local anaesthetics. They may also be taken orally to treat asthma, gastroenteritis and various tumours, or as a supportive and revitalizing tonic. How is this possible, when these plants are very poisonous and small amounts can cause dangerous, or even lethal, effects on the heart and respiratory muscles? 

Before use, the raw material must be subjected to pao zhi (a detoxifying measure), which might include heating and/or soaking with the intention of ensuring maximal therapeutic efficacy with minimal adverse effects. During such processes, the toxic alkaloids are transformed into less harmful compounds, explaining why aconite use has persisted in spite of its high risk of poisoning. However, even though pao zhi is usually performed, a number of patients who take traditional Chinese aconite medicines are hospitalized each year due to poisoning. 

Plants That Kill: A Natural History of the World’s Most Poisonous Plants
By Elizabeth A. Dauncey & Sonny Larsson

This richly illustrated book provides an in-depth natural history of the most poisonous plants on earth, covering everything from the lethal effects of hemlock and deadly nightshade to the uses of such plants in medicine, ritual, and chemical warfare.

Featuring hundreds of color photos and diagrams throughout, Plants That Kill explains how certain plants evolved toxicity to deter herbivores and other threats and sheds light on their physiology and the biochemistry involved in the production of their toxins. It discusses the interactions of poisonous plants with other organisms–particularly humans—and explores the various ways plant toxins can target the normal functioning of bodily systems in mammals, from the effects of wolfsbane on the heart to toxins that cause a skin reaction when combined with the sun’s rays. This intriguing book also looks at plants that can harm you only if your exposure to them is prolonged, the ethnobotany of poisons throughout human history, and much more.

A must for experts and armchair botanists alike, Plants That Kill is the essential illustrated compendium to these deadly and intriguing plants.

  • Provides an authoritative natural history of the most poisonous plants on earth
  • Features hundreds of color illustrations throughout
  • Looks at how and why plants produce toxins
  • Describes the effects of numerous poisonous plants, from hemlock and deadly nightshade to poppies and tobacco
  • Explains poisonous plants’ evolution, survival strategies, physiology, and biochemistry
  • Discusses the uses of poisonous plants in medicine, rituals, warfare, and more

 

This post is part of a series, explore additional posts here<< Plants That Kill: Apocynaceae