Plants That Kill: Ephedera

Adapted from page 214 of Plants That Kill:

The drug ma huang has been one of the most important in the Chinese materia medica for millennia, having been first recorded in Shen-nung Pen-ts’ao Ching (Divine Husbandman’s Materia Medica), the earliest extant Chinese pharmacopoeia (c. ad 25–200). Today, it is sourced from four species of ephedra (Ephedra spp.), including E. sinica, which is native to northeast China, Mongolia and parts of Russia. In fact, at least two-thirds of Ephedra species from across the globe are used medicinally, and are the source of useful compounds in the fight against cold and flu symptoms. Unfortunately, however, they are also subject to abuse.

Chinese ephedra (Ephedra sinica) is a gymnosperm and close relative of conifers, including yews (Taxus spp.). The stems are photosynthetic and the fruit are fleshy cone bracts. Photo credit: WILDLIFE, Alamy Stock Photos

The small genus of Ephedra contains around 54 species within its own family, Ephedraceae, distributed in northern temperate regions of the world as well as in western South America. There is evidence that ephedra may be one of the first plants that was used medicinally, as pollen of medicinal plants, including high-climbing jointfir (E. altissima), was found in the grave of a male Neanderthal buried in Shanidar Cave, Iraq, in around 60,000 bc. Some scientists dispute the interpretation that flowers had been placed deliberately in the grave, however, as the pollen may have been introduced by burrowing rodents. 

Indisputable recorded uses of ephedra in traditional medicine systems include the treatment of asthma, hay fever and other allergies, as well as respiratory diseases such as bronchitis, emphysema, and colds and influenza. The effectiveness of ephedra in treating many of these conditions is not in doubt, but abuse of the active compounds has required their use today to be controlled. 

Ephedra species contain several alkaloids: ephedrine, pseudoephedrine, norephedrine, norpseudoephedrine (cathine), methylephedrine and methylpseudoephedrine. Levels vary tremendously between the species (the North American species Nevada ephedra (E. nevadensis) is apparently devoid of them) and also between plant parts, with the alkaloids concentrated in green stems and leaves, while fruits and roots have virtually none. 

Ephedrine and related alkaloids stimulate the nervous system by mimicking the effects of compounds naturally produced by the body that bind to and activate receptors (endogenous agonists). They are potent stimulators of receptors that are targets for adrenaline (epinephrine) and noradrenaline (norepinephine), and responsible for the ‘fight or flight’ response. The effects of these drugs include constriction of blood vessels (vasoconstriction), raised blood pressure, increased heart rate, expansion of bronchial tubes (bronchodilation), which makes breathing easier, and increase in energy expenditure (thermogenesis). 

The two major alkaloids found in Ephedra species, ephedrine and pseudoephedrine, have been used in decongestant medicines to treat coughs, colds and sinusitis. However, these alkaloids are structurally similar to synthetic amphetamines, with ephedrine differing from methamphetamine only in a hydroxyl group, leading to the use of these medicines in the illicit manufacture of amphetamines. In response, restrictions are generally in place on the sale of products containing the alkaloids. In the United Kingdom, for example, they can legally be sold only at pharmacies, by or under the supervision of a pharmacist, with permitted levels of the alkaloids kept to a minimum if sold without a prescription. 

Restrictions also apply to the sale of the herbal ephedra drug ma huang and others, which have been marketed as ‘herbal ecstasy’. Despite these legal restrictions, the raw herb and products containing ephedra and its alkaloids are still openly sold over the Internet, posing a potential risk to consumers who are unaware of the extremely dangerous side effects.

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: Cycads