Talk of medicinal plants might sound rather folksy and out of date, but that perception could not be more wrong. Traditional herbal remedies are now being investigated to discover innovative new treatments and pharmaceuticals. Professor Monique Simmonds explains how it’s now possible to identify the plant compounds responsible for therapeutic properties of traditional cures – paving the way for the creation of new drugs.
Wild medicine is a vast and vital resource for us all. Yet as pressures on the planet intensify, plants with the power to heal are disappearing, as is the knowledge of how to use them.
To try to stem that erosion of expertise –and to learn more about the healing powers of the world’s wild plants – Professor Monique Simmonds co-ordinates a team of researchers in the Jodrell Laboratory at Kew. Here, scientists investigate the chemical and therapeutic properties of wild medicinal plants (of which there are estimated to be 50,000) and look for global patterns in their use and distribution, building on Kew’s expertise in plant taxonomy, ecology and conservation.
'For the treatment of Alzheimer’s disease, Elaine Porter and Melanie Howes have been studying alkaloids from species in the lily family, as well as other compounds such as diterpenoids, which are found in some common herbs in the sage family and can increase blood flow, perhaps enhancing memory processes.'
‘In a few cases we can already explain a plant’s traditional medicinal uses,’ says Monique – and indeed, ancient remedies using willow bark inspired the development of that workhorse painkiller, aspirin. But in most cases, up to now, no one has really investigated the detailed chemistry of medicinal herbs traditionally used to treat particular complaints. Monique and her colleagues are trying to fill that gap, in part by looking for commonalities in the plant chemistry of our very own native flora. Down the line it is hoped that this cutting-edge research could inspire new therapeutic breakthroughs for the pharmaceutical industry.
To pinpoint which plants to investigate, Monique’s team has delved into old herbals and tapped into recent folklore. In one arm of the project, called Remembered Remedies, people from all over Britain answered an appeal to record their memories of traditional uses of medicinal plants – knowledge that was commonplace before the NHS arrived in 1948. Now such folklore – better regarded as ethnobotanical knowledge – is helping to point to native wild plants with medicinal potential.
In one focus of current research, members of the team are analysing the plants once used to treat rheumatism. Folklore suggests that a range of plants were found useful, including yarrow (Achillea millefolium), wild angelica (Angelica sylvestris), white bryony (Bryonia dioica), goosegrass (Galium aparine), and species of willow (Salix), Rumex and ash (Fraxinus excelsior). ‘Ash has a particularly rich folklore,’ says Monique. ‘Many uses are linked to superstitions associated with the tree, but there are reports of the leaves being used to treat rheumatism and fevers.’ In fact, it was commonly used to combat fever before the arrival of quinine made from Cinchona bark.
Although these plants linked to rheumatism in folklore aren’t closely related, Monique suspects they might share similar compounds that could explain their medicinal uses. Or it could be that every species contains an array of different compounds that together create a similar medicinal effect. ‘To find the answers to such questions, we’re putting the plants through an array of biological tests associated with rheumatism and also profiling the compounds they contain,’ she explains. Plants that are traditionally used to treat coughs, sore throats and colds, as well as tuberculosis, are also being investigated by Kew scientists.
Since 2006, Monique’s team has been investigating some 300 British native plants that each have an enduring reputation as effective herbal remedies. ‘Over the past 20 or 30 years, there has been very little research into British medicinal plants,’ points out Monique. ‘Today we have better analytical equipment to study plants and screen them for novel chemistry.’ Already, the research has been scientifically very rewarding. ‘We continue to find new information about every species that we study,’ she reveals.
Plants: From Roots to Riches
Prof Kathy Willis examines the legacy of early encounters with alkaloids from plants.
Tests have included species of geranium that have been used to treat warts and extracts from crab apples reputedly used to treat colon and stomach cancer. The team is also investigating the anti-diabetic properties of a range of species, including bugle (Ajuga reptans). For the treatment of Alzheimer’s disease, Elaine Porter and Melanie Howes have been studying alkaloids from species in the lily family, as well as other compounds such as diterpenoids, which are found in some common herbs in the sage family and can increase blood flow, perhaps enhancing memory processes.
‘Sage means wisdom – the name says it all. It’s perplexing why it’s only being evaluated now,’ Monique comments. But at the same time she stresses the complexities of plant chemistry – each leaf is packed with hundreds of compounds, which are likely to have subtle and interacting effects. This makes such research exceedingly difficult to pin down. ‘What we do is put little bits of the jigsaw together,’ explains Monique, ‘and try to convince specialist researchers in universities or pharmaceutical laboratories to take the work further.’Wound healing is another focus of intensive research. Monique and her colleague Phil Stevenson have been concentrating on isolating and identifying compounds in figwort (Scrophularia nodosa) and goosegrass (Galium asparine), to understand why these species can be used effectively to treat wounds. ‘We’ve shown that these species contain a range of phenolic compounds,’ says Monique – some have anti-bacterial activity that would keep a wound clean, while others have antioxidant and anti-inflammatory activity. And figwort also contains compounds called iridoids that stimulate the production of fibroblasts, which are cells that play an important role in the repair of skin and connective tissue. So the combination of iridoids and phenolics could explain why figwort really is an effective treatment for cuts and ulcers.
‘We’re taking folklore, paying attention to it, and taking it further, looking for the science behind it.’
Professor Monique Simmonds
Now the team, which comprises more than a dozen researchers working on different aspects of medicinal plant chemistry, is also investigating relatives of figworts, including heart’s ease (Viola tricolor). They’re also looking at species from other plant families that are likely to contain an array of different compounds, including elder (Sambucus nigra), primroses (Primula vulgaris), cowslips (Primula veris), bird’sfoot trefoil (Lotus corniculatus), brooklime (Veronica beccabunga), ivy (Hedera helix) and marsh mallow (Althaea officinalis). ‘Throughout the world, various different species seem to be used to promote wound healing,’ Monique explains. ‘We’re taking folklore, paying attention to it, and taking it further, looking for the science behind it.’
This article originally appeared in Kew Magazine. Gail Vines is a freelance science writer.