Medicinal Uses of British Plants
The British flora consists of about 1,600 species of which over 400 are documented to have medicinal properties. While documenting the chemistry of these plants it was discovered that in most cases the compounds associated with their medicinal uses had not been characterised. In order to address this lack of knowledge, a study was started on species traditionally used to treat certain conditions such as cancer, skin problems, tuberculosis, memory disorders and diabetes.
In 2004, the Kew Foundation launched the British Medicinal Plants appeal and, as a result of the funds raised, research has been undertaken on over 350 British species. In some cases the compounds associated with their traditional uses have been identified and in others new compounds identified. For example, diterpenoids from bugle (Ajuga reptans) have anti-inflammatory activity and iridoids from figwort (Scrophularia nodosa) have anti-bacterial activity and stimulate fibroblast growth. The biological properties of these compounds could contribute to the traditional use of both these species in the treatment of leg ulcers.
An approach for evaluating the activity of compounds in the plants that is currently yielding results is to look for plant compounds that interact with a specific human protein molecule. In this instance we have selected a protein that is known to be important in stimulating the immune system. With this in mind, extracts of 350 plant species were tested for their ability to interact with the human enzyme calcineurin, which plays an important role in the human immune system.
Compounds that inhibit calcineurin have been shown to have therapeutic potential in treating conditions with an inflammatory component such as eczema. Two species Nepeta cataria and Teucrium chamaedrys were found to contain inhibitor compounds and in both cases the species were used traditionally to treat inflammatory conditions.
This demonstrates the value of a 'target centred approach' when investigating medicinal plants. The advantage being that when active plant compounds are discovered we already have an idea as to how they may interact with human cells at a molecular level and this helps greatly in determining not only what they may be useful for but in explaining their traditional uses.
Another part of the research into British plants involves documenting the diversity of species traditionally used in the 20th century and those currently being used. Emphasis has been placed on tracking down traditional uses of medicinal plants before the start of the National Health Service in 1948. This folklore project is called 'Ethnomedica' or 'Remembered Remedies' and involves a network of volunteers interviewing people throughout the UK. The project is co-ordinated with the help of the National Institute of Medical Herbalists, Chelsea Physic Garden, Natural History Museum, Royal Botanic Garden, Edinburgh, National Botanic Garden, Wales and the Eden Project.
Over 6,000 reports have now been collated with over 250 species being used. The most frequently cited plants are dock, onions, nettle, comprey and elder. The uses made of some of the species do show some regional variation but many have common uses, especially for the treatment of coughs and colds as well as skin conditions.
Project partners and collaborators
- Chelsea Physic Garden
- Eden Project
- Kent University
- Kings College, University of London
- National Institute of Medicinal Herbalists
- National Botanic Garden, Wales
- Natural History Museum
- Nottingham University
- Royal Botanic Garden, Edinburgh
- School of Pharmacy
- Boots the Chemist
- British Medicinal Plant Appeal, Kew Foundation and Friends