The ancient herbalists were right after all: British wild flowers and plants used for centuries in folk medicine have genuine medical properties, scientists at the Royal Botanic Gardens, Kew, have found.
The active ingredients of several herbal remedies recommended by authors such as Nicholas Culpeper in the 17th century have been isolated by Kew researchers systematically investigating the potential medicinal properties of the British flora.
Plants such as common figwort, long used as a poultice to dress wounds and skin diseases, contain chemical compounds that really do stimulate wound healing, the scientists have discovered. Others such as bugle and wild clary contain compounds that may help with inflammatory diseases such as rheumatoid arthritis, or with the uptake of drugs, while bluebells contain compounds that may be used to inhibit the action of viruses.
Led by Professor Monique Simmonds of Kew's Jodrell Laboratory, the researchers have screened more than 60 species of British flowering plants, from stinging nettles to wild basil. Professor Simmonds says they have not yet found a new wonder drug – but with every plant looked at they have found either a new biological use for the plant, a compound not found in that plant before, or an entirely new compound.
It is the search for wonder drugs which has led to an intense scientific scrutiny of wild flowers and plants in recent years, especially those from the rainforest. A spectacular discovery that has caught the world's attention is the rosy periwinkle of Madagascar, which proved to be the source of two compounds, vincristine and vinblastine, which have had enormous success in treating cancers such as Hodgkin's disease and childhood leukaemia. Global sales of these drugs now top $100m a year.
Kew has already had success in finding new drugs from foreign plants; in collaborative projects with other laboratories Professor Simmonds' biological interactions department has identified a potential anti-HIV drug, castanospermine, from an Australian tree, the Moreton Bay chestnut, and a potential anti-cancer compound, tricin, from the bran of a strain of wild rice. Work is continuing on the development of both.
The professor turned her attention to Britain when Kew decided to collect the seeds of all the UK's flowering plants for its £80m Millennium Seed Bank. "We have neglected our own flora over the last few years," she said. "People were looking at the diversity of plants in other countries. There's been recently more emphasis on rushing to the rainforest.
"British plants have been investigated in the past, but in the last 10 or 15 years much has changed and we are approaching them with new methods: we know more about plants at the molecular level, we know more about plant chemistry and we know more about the diseases of people."
The immediate aim, she says, is pure science: to explain how the traditional medicinal properties of plants actually work, rather than to discover new drugs, although if a "magic bullet" were chanced upon Kew she would by no means ignore it. The project, in collaboration with King's College, London, is part-funded by the GlaxoSmithKline foundation, but the giant pharmaceutical multinational has no rights over any discoveries.
Professor Simmonds and her Kew colleagues Elaine Porter and Philip Stevenson began by looking at plants thought to have natural insecticidal properties, such as wild garlic and basil, and did indeed isolate compounds which repelled insects. They then moved on to look at folk remedies, using as a reference point the collection of ancient herbals in Kew's library.
Perhaps their most remarkable finding so far has been with common figwort, whose scientific name Scrophularia nodosa indicates its medicinal history: it was used in the treatment of the tubercular disease scrofula, once known as "the king's evil". It was also used – in the form of a poultice of ground figwort seeds – as a dressing for wounds.
Laboratory analysis of dried figwort seeds pods disclosed a group of compounds called iridoids, which had never been associated with would-healing before. Tests, however, showed that these chemicals stimulated the growth of cells called fibroblasts, which play a part in all the different phases of wound healing. "We were able to explain why figwort worked," Professor Simmonds said.
The team have since been looking at members of the mint family such as bugle – a bright blue spike which is among the Britain's prettiest wild flowers, and was often recommended by herbalists.
They have found that bugle and related plants contain antioxydants, chemicals that protect against heart disease, some cancers and inflammatory diseases such as rheumatoid arthritis. Other members of the mint family such as wild clary, they have discovered, contain alkaloid compounds which may help with the uptake of drugs, while bluebells (in a different family) contain chemicals that may be used to inhibit viruses.
"In the Victorian era a lot more people knew the value of our plants," Professor Simmonds said. "It's only since the National Health Service came in that knowledge about plants has decreased, as there's no longer any need.
"We've lost some of the traditional uses – Granny was told she was old-fashioned in using plants, and modern approaches were best. But there may have been true wisdom in what granny did. Let's go back and look at it in a bit more detail."Reuse content