Which plants help relieve medical conditions? What compounds from natural sources make effective medicines? A gathering of Friends of Te Papa found out about the processes of medical conditions from Botanical Commentator Reg Harris and how plant-based drugs treat conditions ranging from high cholesterol to cancer.

  • High cholesterol—seeds and shoots of alfalfa have high levels of plant sterols which block cholesterol from being absorbed into the bloodstream and remove more from the body. Reg posed the question “Do statins, a commonly prescribed cholesterol-lowering medicine, conflict with an alfalfa strategy?” He explained there is no conflict as the mechanisms of the drug actions are different.
  • Thrombosis (a blood clot)—an extract from the maidenhair tree Ginkgo biloba inhibits platelet aggregation.
  • Nociceptive pain (where nerve fibres are triggered by inflammation, chemicals, or physical events such as stubbing a toe)—white willow Salix alba is highly effective in reducing pain. Around 400 BC, Hippocrates knew willow leaf tea could relieve pain and inflammation. White willow contains the natural compound Salicin from which aspirin (Salicylic acid) is derived.
  • Oxidative stress (caused by free radicals which break down cells resulting in premature aging and disease)—the flowers and fruit of common hawthorn Crataegus monogyna contain antioxidants, which neutralise the actions of free radicals. It is best to inject the fresh compounds to get the maximum benefit.
  • High blood pressure—yew Taxus leaves are a key source of calcium channel blockers, drugs that are used to lower blood pressure by preventing the release of internal calcium stores into cell cytosol (the liquid found inside cells).
  • Nerve gas poisoning—deadly nightshade Atropa belladonna contains atropine, an antidote to nerve gas poisoning, for example, from sarin.
  • Cancer (where cells divide and don’t stop replicating)—Paclitaxel from the bark of Pacific yew Taxus brevifolia thwarts cell division and the cell remains frozen in metaphase, that is, the cell doesn’t divide into two cells and cancer growth is prevented. In 2017, the global Paclitaxel injection market was valued at NZ$ 3,052m.

Reg emphasised that along with the good, there is the bad. While yew is a source of calcium channel blockers and helps to fight cancer through the chemotherapy drug Paclitaxel, the plant contains a major toxin called taxine. Found mainly in the needles, taxine can cause death through yew poisoning when ingested.

This informative session from Reg was part of the Friends of Te Papa’s insightful Science for Lunch series. Finding out how plant therapies alleviate a range of medical conditions extended my understanding of the power of plants. I now look at plants in quite a different way. There are more Friends of Te Papa events coming, see them here.

Loralee Hyde
Member, Friends of Te Papa

Feature image: Reg Harris shows how white willow relieves pain and inflammation. Photograph by Loralee Hyde.