Definition • Medical herbalism may be defined as the practice of using products in which all active ingredients are of herbal origin to treat the sick. In practice rather more detail is required.
Definition • According to the World Health Organization (WHO) Guidelines, herbal medicines are considered to be: Plant-derived materials or products with therapeutic or other human health benefits which contain either raw or processed ingredients from one or more plants. • In some traditions materials of inorganic or animal origin may also be present.
Definition • The European Directive defines a herbal medicine thus: A substance or combination of substances of herbal origin presented for treating or preventing disease or with a view to making a medical diagnosis or to restoring, correcting or modifying physiological functions.
History • The exact origins of herbalism are unknown. Probably it was several different groups of prehistoric peoples who discovered that some herbs were good to eat, whereas others had curative powers. • Humans also discovered plants with peculiar, reality altering, stimulating and inebriating effects. In ancient cultures these were considered to be ‘plants of the gods’.
History • The mechanism of action of herbs remained a mystery for centuries – and in some cases still remains a mystery. Only the development of sophisticated techniques of chemical analysis in the last century has begun to provide some of the answers. • The first medical records date from ancient Assyria, China, Egypt and India.
History • William Turner was the first person to study plants scientifically in the sixteenth century. He travelled widely throughout Europe and grew plants in his gardens in south-west London (later the Royal Botanical Gardens, Kew).
History • At this time the Doctrine of Similars determined how plants were used. It was promoted by Paracelsus (1493–1541). According to this paradigm every plant acted in effect as its own definition of its medical application, resembling either the part of the body afflicted or the cause of the affliction. • Nicholas Culpepper (1616–54) was an influential proponent of the Doctrine of Signatures as well as various astrological theories, by which herbs were set under the domination of the sun, moon or one of the five planets then known. His herbal, published in 1652, was extremely successful, being reprinted many times.
History • In America Samuel Thomson (1769–1843) used simple herbs for bodily correction. He was so successful that opposition from the medical profession was strong and uncompromising. His fame spread to England where, thanks to the promotion by a Mr George Lees, the Thomsonian system was embraced byMr Jesse Boot when he opened the first of what was to become the UK’s biggest multiple pharmacy chain, in Goose Gate, Nottingham in 1872. • Renewed interest in ‘natural’ medicines has led to a resurgence of demand for herbal medicines in the last 20 years.
Theory • Traditionally, the herbalist has recognised four clear stages when offering treatment for any particular condition, individualising the prescription according to holistic methodology to take account of their patients’ particular needs: 1. Cleansing the body. 2. Mobilising the circulation. 3. Stimulating digestion. 4. Nourishment and repair.
Theory 1. Cleansing the body: removal of toxins and other noxious influences – real or imagined – that might cause a physical or mental barrier to treatment. Diuretics, expectorants and laxatives are involved here. 2. Mobilising the circulation: traditionally disease was seen as a ‘cold’ influence on the body and before any other treatment the body should be comforted by ‘heating agents’. Hot spices and pungent medicines (e.g. ginger) and more gentle warming medicines are available for this purpose.
Theory 3. Stimulating digestion: inappropriate or too much heat in the body manifests itself as fevers and inflammatory conditions. Thus, the so-called ‘cooling medicines’ are those used to treat these circumstances, leading to improved digestion. Anti-inflammatories, antiallergics and sedatives are examples of therapeutic classes of drugs that fall into this category. 4. Nourishment and repair: in this phase the herbalist deals with the debility arising from disease in the body. The term ‘tonic’ covers a wide range of medicines used to support the body. Examples include hawthorn (Crataegus oxycanthoides), milk thistle (Silybum marianus) and St John’s wort (Hypericum perforatum).
Sources of reference • Materia medica • Repertory • The British Herbal Pharmacopoeia • The American Herbal Pharmacopeia
Sources of reference • Materia medica: a comprehensive list detailing the main characteristics and uses of medicines, e.g. Potter’s Cyclopaedia of Botanic Drugs • Repertory: a comprehensive list of medical conditions with suggested medicines for treatment, e.g. Herbal Medicine by Miller and Murray
Sources of reference • The British Herbal Pharmacopoeia gives identification and usage information as well as providing instructions on how medicines should be prepared and the British Herbal Compendium provides up-to-date summaries of the available scientific knowledge on medicinal plants • The American Herbal Pharmacopeia (www.herbal-ahp.org) began developing qualitative and therapeutic monographs in 1994, and intends to produce 300 monographs on botanicals, including many of the ayurvedic, Chinese and western herbs most frequently used in the USA.
General types of medicinal herbs used • Practitioners use medicinal plants with: • powerful actions, e.g. liquid extracts of foxglove and belladonna, with substantial toxic risk • intermediate actions, e.g. tinctures of arnica and khella, with some adverse drug reactions (ADRs) • gentle actions, e.g. infusions of German camomile and peppermint with less risk of ADRs. • In many instances conditions can be treated by drugs in each of the three groups, e.g. cardiac disease responds to foxglove in the powerful group, arnica in the intermediate group and hawthorn in the gentle group.
Active constituents in herbal medicines • Bitters • The ‘hot’ medicines • Resins • Saponins • Tannins • Volatile oils
Active constituents in herbal medicinesBitters • Traditionally these were used extensively to stimulate appetite (i.e. in the final fourth stage of the healing process outlined above). • It is now thought that they will be effective only if a malnourished state exists. • The bitter constituents simulate the bitter receptors in the taste buds at the back of the mouth and give rise to an increase in the psychic secretion of gastric juice. • The most effective chemicals are the monoterpene secoiridoid glycosides of gentian. Other extracts that have been used as bitters include quassia, quinine (Cinchona) and strychnine (Nux vomica).
The ‘hot’ medicines • The three most commonly used ‘hot’ medicines include black pepper (Piper nigrum), cayenne pepper (Capsicum) and ginger (Zingiber). • They are used as metabolic stimulants, more specifically as a ‘facilitating agent’ to accompany other herbs whose stimulatory activity may be augmented.
Resins • The term ‘resin’ is applied to the sticky water-insoluble substance of complex chemical nature often exuded by the plant, soon hardening to protect an injury. Resins are usually produced by the plant in ducts or cavities, but may also be found in special cells elsewhere, e.g. in elements of the heartwood of guaiacum and the internal cells of the male fern.
Resins • The term may also be applied to that part of a plant that is soluble in ether or alcohol (e.g. guaiacum resin and kava resin). Resins are used as astringents and antiseptics of the mouth and throat and have also been applied to inflammatory conditions of the upper digestive tract.
Resins • Propolis, a product collected by bees from resinous plants, is used in herbal medicine, although it is not strictly herbal in nature. The product is also used in homeopathy. • A ‘balsam’ (e.g. balsam of Peru and balsam of Tolu) is an oleoresin containing a high proportion of aromatic balsamic acid.
Saponins • Saponins are glycosides that produce frothy aqueous solutions. Plants containing these compounds (e.g. Quillaia saponaria) have been used for centuries as gentle detergents. • Decoctions of soapwort (Saponaria) have been used to wash and restore ancient fabrics. They also have haemolytic properties and when injected into the bloodstream are highly toxic. When taken by mouth saponins appear to be comparatively harmless. • Sarsaparilla is rich in saponins but is widely used in the preparation of non-alcoholic drinks.
Saponins • Two distinct types of saponins may be recognised. • The steroidal saponins are of great pharmaceutical importance because of their relationship to compounds such as the sex hormones, cortisone and the cardiac glycosides. • Some species of the yam (Dioscorea spp.) and potato (Solanum spp.) contain steroidal saponins.
Saponins • The second group of saponins is known as the pentacyclic triterpenoid saponins. This includes quillaia bark and liquorice root (Glycyrrhiza). The former is used as an emulsifying agent, the latter as a flavouring agent, demulcent and mild expectorant.
Tannins • This is not a specific phytochemical group but a name for a group of chemicals that have a particular characteristic. • The term ‘tannin’ was first applied by Seguin in 1796 to denote substances present in plant extracts that were able to combine with animal proteins in the hides, preventing putrefaction and converting them to leather. Most tannins have molecular masses (Mr) of about 1000–5000 and many are glycosides.
Tannins • Tannin-producing drugs will precipitate protein and have been used traditionally externally as styptics, and for burns and weeping eczema, and internally for the protection of inflamed surfaces of the mouth and throat. • They are also claimed to be antioxidants.Witch-hazel (Hamamelis virginiana) is a tannin-containing drug used principally for its astringent properties.
Volatile oils • Volatile oils are volatile in steam. They differ widely in both chemical and physical properties from fixed oils. • They are secreted in oil cells, in secretion ducts or cavities, or in glandular hairs, and are frequently associated with gums and resins. With the exception of oils derived from glycosides (e.g. bitter almonds and mustard oil), volatile oils are generally mixtures of hydrocarbons and oxygenated derivatives mainly responsible for odour and taste.
Volatile oils • In some oils (e.g. oil of turpentine) the hydrocarbon portion dominates whereas in others (e.g. oil of cloves) the opposite is true. Volatile oils are used in perfumery and cosmetics (e.g. oil of rose, oil of bergamot), in food flavourings (e.g. oil of lemon) as well as in medicine. • Many oils with a high phenolic content (e.g. clove and thyme) have antiseptic properties, whereas others are used as carminatives. • Oils showing antispasmodic activity include peppermint (Mentha piperita) and camomile (Matricaria chamomilla).
Phytochemical groups of constituents • Alkaloids • Coumarins • Flavonoids • Glycosides • Polysaccharides
Phytochemical groups of constituents • Alkaloids Typical alkaloids are basic, contain one or more nitrogen atoms, and have a marked physiological action on humans and animals. • Coumarins Coumarins are benzo-a-pyrones generally with a hydroxyl or methoxy group in position 7. • Flavonoids Flavonoids consist of a single benzene ring joined to a benzo-c-pyrone structure.
Phytochemical groups of constituents • Glycosides Glycoside is a term that covers many different combinations comprising a monosaccharide part (e.g. fructose or glucose) and a non-sugar part, which may be a simple phenol, flavonoid, anthraquinone, triterpenoid or other structure, known as ‘aglycone’. • Polysaccharides Polysaccharides are polymers based on sugars and uronic acid.
The preparation and presentation of herbal medicines • The medicines are made according to standards quoted in the appropriate pharmacopoeias, e.g. British Herbal Pharmacopoeia.
The preparation and presentation of herbal medicines • Herbal medicines may be administered as crude drugs or extracts. • The latter include infusions, decoctions and cold aqueous macerates that can be freshly prepared by the consumer. • There are also liquid extracts, tinctures and solid and dry extracts that are industrially produced. • Solid dose forms and topical preparations in which herbal ingredients have been incorporated are also available.
Crude drugs • Crude drugs are extracted by the consumer as an infusion if the herbs are of a light fleshy nature or as a decoction if fibrous and woody (roots and barks). The advantages are that the extraction is freshly prepared and is particularly appropriate for herbs with active constituents that need to be given hot.
Infusions • This is the preferred method of extracting fresh active ingredients from light leafy herbs. • The drug may be extracted alone or in the form of a herbal tea, of which there are simple (e.g. camomile, peppermint) and more complex varieties with more than one active principle and a number of excipients. • They are convenient when the active constituents are water soluble.
The herbal tea • Commercially available medicinal teas are ready formulated for the consumer and are usually prepared freshly as an infusion before taking. • They contain the following constituents: • The remedium cardinale • The adjuvans • The constituens, corrigens and colorants
The herbal tea • The remedium cardinale: one or more basic medicinal agents, e.g. a laxative tea may contain senna leaves and frangula bark. • The adjuvans: one or more auxiliary medicines that enhance the action of the basic medicine or reduce undesirable side effects. Thus, drugs with carminative (anise, caraway or fennel) and/or spasmolytic properties (camomile flowers, silverweed) may reduce unwanted side effects of senna.
The herbal tea • The constituens, corrigens and colorants: fillers and aesthetic agents to improve aroma, appearance, colour or texture. Up to 20% of the tea may be a filler (e.g. raspberry leaves) which prevents it from separating into its components. To ensure concordance, herbal teas must be reasonably palatable; this is especially important for children. Widely used excipients include bitter orange peel, orange blossom, hibiscus flowers and peppermint leaves. Colorants such as cornflower, mallow and marigold are also used.
Decoctions • Roots and barks may be extracted using a decoction method.
Liquid extracts • Liquid preparations weaker than 1:2 are usually called ‘tinctures’, whereas 1:1 and 1:2 preparations are called ‘extracts’. • Tinctures are usually made by maceration and extracts by percolation.
Applications of herbalism • Generalised conditions • Autoimmune conditions • Acute inflammation of muscles, joints and connective tissues • Psoriasis and other skin conditions
Applications of herbalism • Debility • Chronic fatigue syndrome • Fatigue and debility after illness • Fatigue linked to depression • Support during terminal illness • Fevers • Fevers resulting from infectious causes • Febrile symptoms of non-infectious origin
Applications of herbalism • Infectious disease • Acute gastrointestinal, respiratory, and urinary infections • Topical bacterial infections • Minor-to-moderate febrile infections • Minor-to-moderate chronic bacterial, fungal and viral infections • Malignant diseases • Cancers of varying types • Symptoms resulting from cancer • Problems with body systems
Applications of herbalism • Cardiovascular system • Hypertension • Angina • Ongoing symptoms of cardiac disease Patients with heart disease are reported to benefit from treatment with herbal medicine with fewer side effects
Applications of herbalism • Gastrointestinal (GI) system • Dyspepsia • GI reflux • Food intolerance and allergies • Constipation and diarrhoea • Genitourinary system • Urinary tract infections • Benign prostate hypertrophy Impaired lactation
Applications of herbalism • Menopausal problems • Premenopausal syndrome (PMS) • Nervous system • Anxiety states • Insomnia • Nervous exhaustion • Pain control • Stress symptoms
Applications of herbalism • Respiratory system • Upper respiratory tract infections • Allergic rhinitis • Bronchitis • Asthma • Skin diseases • Acne • Allergic reactions • Eczema.