Plants used by South American tribes could provide malaria cure, say Kew scientists

Scientists from Kew Gardens believe that thousands of plants used by Latin American tribes to treat malaria could provide new cures for the deadly disease.

The discovery was made after researchers studied plants used by indigenous communities to treat the disease, which kills tens of thousands of people a year.

It comes as it was announced that Kew Gardens has been officially recognised as home to the largest living plant collection on earth.

The accolade is being added to the 2022 edition of the Guinness World Records book, in recognition of the 16,900 species of plants from all over the world held at Kew’s 320-acre site in west London.

Kew’s researchers, who carried out an exhaustive survey of plant databases and specimens, much of it previously unpublished - along with studying traditional knowledge of medicinal plants - found over 1,000 species which have been used to treat malaria, with some widely used by indigenous peoples in regions such as the Amazon.

They include Aspidosperma excelsum Benth (Apocynaceae), the bark of which is used as traditional medicine for malaria in several Latin American countries, and the bark of Cinchona officinalis, which is collected in Colombia and traditionally used as an antimalarial.

The discovery of plant species whose potential as a treatment for malaria was previously unknown outside indigenous communities, could help develop new treatments for malaria, which in 2019 alone killed 400,000 people.

The new study, led by Dr William Milliken, said: “This could assist with the development of healthcare strategies in the poorest countries in the world. However, this approach relies on continued access to traditional knowledge of how plants are used as medicines.”

It warned that growing industrialisation, deforestation and urbanisation could threaten the knowledge of anti-malarial treatment gathered over the centuries.

“This vital information has been passed down through many generations, mostly by word of mouth, but is now disappearing rapidly as lifestyles change,” the study said. “There is a growing need to document this traditional knowledge and support communities to maintain it, so that this invaluable knowhow, developed and refined over centuries, is available to future generations.”

The methodology used by the research team could be employed in other parts of the world to discover local treatments for fatal diseases.

Dr Milliken’s team said: “This technique could be applied to medicinal plants in other regions of the world, and for other diseases, to predict which plant species might also contain bioactive compounds that could provide potential medicines for the future. This approach may also help identify the most sustainable sources for them.

“This could assist with the development of healthcare strategies in the poorest countries in the world.”

The new Guinness world record is the most significant of several held by the Royal Botanic Gardens at Kew, a Unesco World Heritage site.

These include the world’s largest water lily species, at 3m in diameter; the smelliest plant, the titan arum (Amorphophallus titanum), whose stench - akin to rotting flesh - can be detected up to 0.8km away; and the oldest surviving plant in the world, a prickly cycad (Encephalartos altensteinii) brought from South Africa to the UK in 1775 and dubbed a ‘living fossil’.

Kew also holds the world’s smallest water lily species, which was at one point thought to be extinct.

The nymphaea thermarum, also known as the thermal lily, was successfully propagated by Kew horticulturists and can now be found in the Waterlily House and the Princess of Wales Conservatory at Kew Gardens. Its tiny flower is smaller than a 50p coin and only opens in the morning.

Richard Barley, Director of Horticulture and Learning at RBG Kew, said: “We are absolutely thrilled to hold the record for the largest living plant collection. It is a fantastic accolade, and a credit to the tireless work of our horticulturists and scientists.

“It also re-enforces the importance of botanic gardens around the world, as not only beautiful places to enjoy, but as essential hubs of inspiration and education, increasing awareness of the vital importance of plants to the health of our planet.”