Our ancient knowledge of the healing properties of plants, contained in remedies written down by herbalists over the centuries, is being given new relevance by the ability of molecular technology to unlock their secrets.
Both the old and new understanding of the UK's wild flowers and herbs are being brought together in a remarkable scientific programme at London's Kew Gardens.
A clinical trial is about to begin into the active compound contained in one plant, figwort, after scientists started to investigate how it had been used in the past to help diabetics. But there is concern that some old remedies widely used across the UK before the Second World War may be lost forever because they have not been documented.
The search for medicines from plants is nothing new. For years, pharmaceutical investigators have searched forests and swamps around the world looking for a cure for cancer or heart disease. Aspirin came from the willow tree, and the cancer drug taxol was found in the Pacific yew tree.
But the search is now being conducted among the 1,600 species of plants native to the UK. At Kew's Jodrell laboratory, scientists carry out molecular tests, looking for the active compounds in different plants to see whether there is any kind of scientific basis for the claims made by herbalists about particular plants. One of the first to show promise is figwort, a dark-leaved plant found in Northern Ireland and Norfolk, where it grows in shady woods and meadows.
Nicholas Culpeper, the famous apothecary described it in his famous book, Herbal, of 1628. 'The decoction of the herb, taken inwardly, and the bruised herb applied outwardly, dissolves clotted and congealed blood within the body, comping by any wounds, bruis or fall (sic).' He added that a distilled water made from the whole plant would dry up 'hollow or corroding ulcers'.
Professor Monique Simmonds, chief plant scientist at Kew, explained that records show that down the ages this has been used for treating leg wounds. 'We think that it might be particularly promising for diabetes. Many of these patients suffer from leg ulcers, and sadly these sometimes result in an amputation because there is not that much which works by way of treatment.'
The names of plants often give away their uses. The herb lovage, for example, won its name because of its reputation as an aphrodisiac. 'Sage is a herb that has been connected with wisdom down the ages, and now for the first time we can see whether it really helps with cognitive ability, or memory,' said Simmonds.
Around the world, it is used by many communities to help the memory. Researchers at King's College London and Newcastle University have worked with Kew to identify that it does affect receptors in the brain, and work is still continuing into exactly what it does. One discovery was that people taking sage oil extract showed a marked improvement in their memory.
Plants of the same species can produce chemicals of very different potency, so it is important that scientists distinguish between the varieties. Another problem is that a freshly picked plant can act very differently from one which has dried out over a few days, as key components may decompose in that time.
After the introduction of the NHS in 1948, plant-based remedies fell into neglect, as herbal remedies became discouraged by the medical community and the knowledge of plants was lost. Some sections of the medical profession are still sceptical about the use of herbal remedies, but they are increasingly popular with the public. If scientists can use the recent advances in molecular biology and chemistry to investigate the active compounds of plants, then they may end up playing a bigger role in our health.
'We decided to look at the biodiversity within our own country, and we began to realise that very, very little was known about our own British plants,' said Simmonds.
In order to find out more about such remedies, some records have already been collected by Kew. They set up a 'field hospital' in their gardens two years ago in which visitors were encouraged to write down their recollections of popular remedies. They collected more than 1,000 remedies from that event.
'We were able to identify the most frequently used plants, and then we pulled together a number of plants whose properties we couldn't really explain by the chemistry we knew about. For figwort we knew that people would make a fresh poultice for these leg wounds.'
The team started to break down the different compounds found in figwort and another plant, goosegrass, and worked with King's College London to see if their compounds would 'kick-start' a healing process in cell cultures. It worked, but only if the plant was fresh. Simmonds now hopes that a clinical trial involving patients with leg ulcers may be given the go-ahead in Oxford.
She is optimistic about the future, although funding for the research is tight. 'As we understand more about the molecular processes involved in diseases we can understand how the compounds derived from plants can work,' she said. 'It's a question of old traditional knowledge and new technology coming together and giving us new answers.'
Other plants with medicinal powers
Sweet Flag (Acorus calamus). Used to treat fevers and malaria.
Yellow Iris (Iris pseudacorus). Used to treat colds, toothache and sores in the mouth.
Black Bryony (Tamus communis). For gout and chilblains.
Lovage (Ligusticum scoticum). As the name suggests, an aphrodisiac.
Mistletoe (Viscum album). Used to treat many conditions - hysteria, heart palpitations, fevers, etc - as it has a calming action on the nervous system.
Marsh mallow, or althaea officinalis Herbalists have used it for centuries to cure inflammations and irritations of the bowel.
Figwort, or scrophularia Grows in shady woods and is described by Culpeper as useful for healing wounds, piles and ulcers.
Goosegrass, or gallium aparine Also known as Grip Grass, Catchweed, Cleavers or Bedstraw, is seen by herbalists as one of the best tonics available for the lymphatic system.
Sage, or salvia There are many varieties of sage, some of them toxic, but it is a highly common garden herb. Culpeper said three teaspoons of it with sugar would help patients with tuberculosis. Now being investigated by UK researchers for its memory-boosting powers.
Any remedies?
If you know of any traditional remedies which can be used for healing purposes, scientists at Kew would like to hear about them.
Please email the details to m.simmonds@kew.org
