Introduction Of Herbal Medicine Part 1

As with food, the earliest human beings collected plants to be used as medicine. Although it is not clear why certain species were chosen, no doubt trial and error played an important part. At the beginning, and still today, plants for herbal medicine were and may be collected locally; however, the development of trade and migrations between countries and continents has led to a utilization of foreign material.

Some of the earliest writings on medicinal plants were produced in China, Egypt, and India hundreds of years BC. In the first century AD, the Greek physician Dioscorides wrote the first European herbal, listing about 600 herbs.

This work influenced Western medicine for a very long time. In the nineteenth century conventional medicine started to outstrip herbalism, at least in Western culture.

Nevertheless, in Europe, North America, and some other countries there is still a strong interest in plant medicines indeed, there is an increasing appreciation, because of a desire on the part of consumers to return to a more natural life-style and because, rightly or wrongly, modern synthetic medicines are often considered too expensive,and give rise to unwanted side-effects. In some parts of the world (e.g. India, China, Africa) herbalism still over shadows conventional medicine; about 80% of the population of developing countries depend on herbal medicine....

The laws concerning the practice of herbal medicine vary according to the country in some the practice must be carried out by qualified physicians. World-wide, the trade in herbal medicines runs into billions of dollars. The herbal medicine practitioner will start with the plant or parts of the plant (seeds, roots, etc.) and then prepare the herbal medicine. For this activity to be successful certain precautions are necessary. Exact identification of the material is required.

The vast majority of medicinal plants are angiosperms (flowering plants), and are classified into family/genus/ species. A well-known herb is Roman chamomile. This belongs to the family Compositae (term normally used in Europe)/Asteraceae (term normally used in North America). Some other families, too, have alternative names, which, if they exist, are also used in this book.

The genus of Roman chamomile is Chamaemelum, the species is nobile. This is the so-called ‘binomial nomenclature’. Latin, rather than common names are given to enable communication at an international level. In some cases alternative Latin names called synonyms have been used commonly for herbs. Botanists recognize a preferred or correct name for a plant, on the basis of first publication and other criteria.

Medicinal herbs were used for centuries without people knowing the reasons for their activity. It was at about the beginning of the nineteenth century that chemical investigations led to the identification of constituents, some of which were supposed to be ‘active principles’ chemical constituents that have a healing or therapeutic effect.

Plants contain thousands of chemical substances, and the claims that some are active principles have not always been supported by scientific investigation. Because of improving methods of analysis, many types of substances have been identified in plants. As stated earlier, the present book is meant for the general reader, and therefore a simplified list of presumed active principles is presented below.

1. Alkaloids. These include some of the first active principles isolated from plants, e.g. morphine from opium(about 1800). They contain nitrogen. Plants that pos-
sess alkaloids tend to be toxic but, nevertheless, some are used in herbal medicine and are available, e.g. lobelia, comfrey, and borage. Some alkaloids can affect
the liver; consequently, herbal products containing these substances should be treated with great caution, and indeed are by professional herbalists.

2. Phenols. A number of different types of phenolic substances are regarded as active principles:
(a) Simple phenols: e.g. salicylic acid in willow the forerunner of aspirin.
(b) Tannins: very widespread in herbal plants and used commercially to convert hides into leather. Tannins are ‘astringent’, i.e. they harden and tighten skin and internal delicate (mucous) membranes. They are claimed to be antiseptic, to reduce bleeding, and to control diarrhoea. Tannins are said to function as antioxidants. The ‘French paradox’ refers to the lower than expected rate of heart disease in France, despite a relatively high-fat diet. This has been correlated with the high consumption of red wine, which is rich in tannins. Grapeseed products, also
rich in tannins, have been developed in France as a health food.
(c) Coumarins: responsible for the smell of new mown hay. Scopoletin, found in cramp bark and black haw, shows antispasmodic (controls spasms and cramps) activity; it has also been claimed,from animal studies, that this particular coumarin exhibits anti-inflammatory and analgesic (pain reducing) properties. Dicoumarol, formed from
coumarin in spoiled sweet clover hay, is a potent blood anti-clotting drug and its discovery led to the development of modern anticoagulants.
(d) Anthraquinones: active principles in well known laxative drugs, e.g. cascara, senna, and aloe.
(e) Flavonoids: very widely distributed in plants, and some constitute the white, yellow, red, purple, and blue flower and fruit pigments. Numerous
properties have been attributed to flavonoids, such as being antibacterial, anticancer, antiviral, anti-inflammatory, and that they bring about a reduction in blood capillary fragility, thus improving microcirculation. Flavonoids are claimed to be antioxidants.

3. Essential (volatile) oils and resins.
(a) Essential oils contain terpenoids (monoterpenes and sesquiterpenes). In food, they are well known flavourings, e.g. cinnamon, clove, and mint. As regards herbal medicine: some (e.g. fennel and peppermint) are used as carminatives (they relieve digestive gas or wind and indigestion); some stimulate the gastric
juices (e.g. sweet flag); and others (e.g. chamomile) are said to be antispasmodic and anti-inflammatory.

The essential oil produced by mustard is used as a rubefacient (it brings blood to the skin and causes reddening and warming) and a counter-irritant (irritant to the skin, supposed to relieve deep-seated problem). Garlic essential oil has many herbal uses.Steam distillation is employed to isolate essential oils from the plant, and consequently great care must be taken with some ‘neat’ oils: e.g. thus jone in wormwood and sage oil (notorious in the liqueur absinthe), while safrole in sassafras oil is carcinogenic.
(b) Resins: sticky, solid substances, and a mixture of chemicals. A well known example is propolis (bee glue).

4.Saponins and cardioactive chemicals.
(a) Saponins produce frothing in water. Steroidal saponins (e.g. in yam) can be used to make sex and other hormones.
(b) Cardioactive drugs are steroids that strengthen a weakened heart. Digoxin is extracted from a fox glove species (Digitalis lanata) but, because of the powerful action and legal restrictions, herbalists are very cautious about using Digitalis. Hawthorn is a cardioactive herbal.

5. Cyanogenetic glycosides, iridoids, and bitter principles.
(a) A cyanogenetic glycoside yields toxic prussic acid on hydrolysis. Cassava is a well known food plant that contains a cyanogenetic glycoside, but processing
removes the prussic acid. Apricot seed kernels possess amygdalin, a cyanogenetic glycoside, once claimed as a treatment for cancer but now disproved.
(b) Iridoids are said to be the active principles of valerian and devil’s claw, and possess sedative properties.
(c) Bitter principles are a range of chemical compounds. Plants containing (e.g. bitter quassia) are used for their appetite-stimulating properties,
which may lead to better health.

6. Mucilage. Mucilage contains carbohydrates, and in herbal medicine is used for its demulcent (soothing) action on inflamed conditions of the digestive tract. It can also function as a laxative. Marshmallow and ispaghula are examples of mucilage-containing plants.

7. Phytoestrogens. These affect reproductive and sex hormone activity. Examples are the isoflavonoids found in soya and red clover, which may have potential as
cancer-treating chemicals.

8. Inorganic elements. Plants possess a very wide range of inorganic elements, some of which are claimed to play an important part in herbal medicine; e.g. iodine in
seaweeds.