Integration of ancient and modern medicine towards a sustainable system of animal production and medical care

Jen-Hsou Lin DVM PhD
Phil Rogers MVB MRCVS
Haruki Yamada PhD

Paper to the 24th IVAS Congress, Chitou, Taichung, Taiwan, August 1998

Part 1

Introduction

We use the word "sustainable" to mean a system that puts back, or replenishes, what we take out of the system, with minimal damage to the environment or to the creatures that depend on it. Our current western- and strictly profit- oriented approach to agriculture and food production is not sustainable indefinitely. When we use irreplaceable natural resources at grossly excessive rates, we are stealing them from our neighbours and our descendants. When we pollute our world, we lay the seeds of our own destruction, and we put future generations in danger. If we continue with our present systems, humanity will have a high price to pay. There is no greater human tragedy than the curse of children on the actions, or spirits, of their parents or ancestors.

We live in nature and we depend on nature. If we abuse nature, it will abuse us. Buddhist and many other ancient philosophies, eastern and western, teach that we should show care and compassion for each other, our animals and our environment. The human population is at its highest ever. Because of inequalities of food production and its distribution, famine and malnutrition occur regularly. Thus, the production of wholesome human food, and its distribution to people in need is an ongoing problem that needs international attention.

Apart from animals produced for human food, other species of domesticated animals suffer from many chronic diseases for which western medicine has only partially successful, or very expensive, answers. Examples are cancer and geriatric diseases in pets, and chronic musculoskeletal disorders in sports animals.

Public demand is increasing for a more natural system of animal production, care and welfare. Traditional Chinese medicine (TCM) is one of the most natural and sustainable systems of medicine known. It has very well documented laws and theories. Its laws have been proven by constant use in humans and animals over millennia; its theories have been tested in-vivo and proven or amended by constant criticism and dynamic discussion from within its peers. It uses mainly Chinese Herbal Medicine (CHM), physical medicine (acupuncture, thermotherapy (moxibustion) and mental therapy (Qigong, meditation etc). CHM is the oldest and best-documented system of medicine known. To understand CHM, one must understand the essential concepts of TCM. Its methods of diagnosis are complex and holistic: by a detailed process of pattern recognition, they determine the TCM Syndrome, the nature and location of energy (Qi) disorder in the subject. TCM is used both in prophylaxis and in therapy of humans and animals. This paper suggests some ways to integrate the art, philosophy and science of TCM and modern medicine to develop a more sustainable system of animal production and medical care.

Modern versus ancient philosophy in the prevention and control of animal diseases

Modern science has shown that animal species and genetics are main determinants of the efficiency of feed conversion to meat or milk. As it costs much less to produce a kilo of dry matter (DM) from maize or rice than a kilo of meat DM, one may argue that production of more rice, cereals and protein-rich crops from land used for grazing of ruminants could solve the increasing demand for human food. If we must produce animal-derived human food, one may argue also that governments should encourage the farming of efficient converters [fish, poultry and pigs] and discourage the farming of inefficient converters [ruminants]. However large areas of swamp, mountain, marginal- and arid areas are unsuitable for most farm-uses except grazing. Also, large tracts of grassland are in private ownership. Thus, ruminant farming seems likely to remain to be the main way to convert the earth's supplies of forage and cellulose to human food, unless governments revert to systems of state-control of national resources. Such systems have been discredited on social and economic grounds and are unlikely to be revived in most countries. Even China and Cuba, two of the last bastions of state-control of national resources, are moving slowly towards a market-based economy.

Intensive production of animal-based foods has been the international norm in recent decades. To maximise profits, and minimise costs, the industry depends on high stocking densities - increasing animal numbers in decreasing land or floor areas, and/or increasing numbers in confined air-spaces. This has greatly increased the risk of infectious and parasitic diseases, and the degree of stress to which the animals are exposed. Ignoring considerations of animal welfare, increased stress reduces the efficiency of animal reproduction, lactation and growth. It also reduces their immunocompetence, leaving them more prone to infections and parasitism.

To counter these problems, and enhance profit margins, the agricultural industry has become increasingly dependent on chemical control of these problems in animals. Routine use of vaccines, growth enhancing agents, antibiotics, hormones, pesticides, anthelmintics, herbicides, organophosphates, artificial fertilisers etc is widespread. However, the high cost of modern drugs, hormones and chemicals for routine use in animal husbandry can prove prohibitive for developing countries. Also, due to accidental emissions or low-level exposure to toxic agents used in, or generated by the production process, the manufacture of potent drugs and agrochemicals poses a real threat to the health and welfare of persons working in or living near the factories, and to the animals grazing nearby.

Overuse of western drugs and chemicals has led to adulteration of human food with chemical residues. Though it is not proven conclusively, some medical researchers blame increasing resistance to antibiotics to their abuse in animals. Falling sperm-counts in human males in heavily industrialised nations have been attributed to (amongst other factors) exposure to chronic pollution of air, water and food by substances with estrogenic activity. Exposure of farm workers to agrochemicals has caused acute and chronic toxicity in those workers, including an increase in miscarriage rates and birth deformities in babies of female workers.

In recent years, other issues also have highlighted the importance of consumer perception on the consumption of meat products. They are: the bovine spongiform encephalopathy (BSE) epidemic in Europe and associated fears of contracting new variant CJD from beef, outbreaks of fatal food poisoning by Escherichia coli O157 and Salmonella typhimurium DT104.

The European Union [EU] is trying to eliminate the chemical contamination of human food and raise the standards of food safety. However, it is difficult to enforce the plethora of EU regulations, and consumers are becoming increasingly cynical of government statements as to the safety of food.

Several factors have focussed public awareness on the need for a more natural system of animal production and medical care. These include fear of chemical residues in food, antibiotic resistance and zoonosis, and several other issues, including iatrogenic diseases. These issues have stimulated interest in the Green Movement. Also, public awareness of compromised animal welfare involved in intensive farming has led to rapid growth of the Animal Rights Movement and vegetarianism. Countries whose economies depend heavily on the sale of animal-derived foods must address these issues seriously if they want to protect their public image and market share at home and abroad.

TCM and the farming of domesticated animals in China date far before the birth of Christ. Globally, TCM is the most complete system of traditional medicine. Its documentation is ancient and extensive. Constant use over several millennia has proven TCM and its concepts to be of great clinical value. Several dozen textbooks, based on translations of ancient and modern texts, are devoted to the concepts of TCM. Some of the best (in English) are by Connolly (1979), Turner & Low (1982), Hsu (1982), Kaptchuk (1983), Matsumoto & Birch (1983), Porkert (1983), Wiseman & Ellis (1995), Anon (1993), Xie et al (1994) and Wiseman & Ye (1998).

TCM is a system of Energetics and Correspondences. It sees the body as interacting with and adapting to cosmic, terrestrial-climatic, traumatic and internal forces. It sees disease as a disturbance or disharmony (Full, Empty, Stagnant) of vital energy (Qi), or Blood (Xue), or Fluid (Ye), or as imbalances of the homeostatic dialectic mechanisms (Yin-Yang), or of a more complex Five Phase anabolic-catabolic control system of the body. It also recognises powerful interaction between the soma and the psyche; imbalanced emotions can cause organic disease, and vice-versa.

TCM practitioners use complex methods of pattern recognition, based on subjective and objective symptomatology and phenomenology, to detect which COSs have Qi imbalance and the nature of that imbalance (Qi Full, Empty, Stagnant etc). Therapy that can reestablish the free flow of Qi, or rebalance it, has lasting and beneficial effects on health. Rebalancing (homeostasis) of Qi automatically eliminates all the amenable symptoms and signs of ill health. Not all symptoms and signs are amenable, for example in cases of severe organic damage (advanced cancer, chronic cirrhosis of the liver, severed spinal cord, severe necrosis of the motor neurones etc).

Once a diagnosis is made, CHM uses formulations of 4-10 herbal ingredients, to apply a complex theory of holistic treatment. Treatment aims mainly to obtain and maintain harmony of body function (homeostasis) and to expel pathogens. Many ingredients are to enhance the effects, or to act as antidotes to the unwanted effects, of other ingredients. The formulation may be changed as the subject's Qi patterns change. The history of TCM, its fundamental concepts, Syndrome diagnosis, selection and alteration of remedies are beyond the scope of this paper.

HM is a valid science, with great potential for integration with WM to the benefit of human and animal health and welfare. As the pharmacological basis becomes better understood, it will be easier to integrate HM into conventional WM. However, HM needs more research, development, goodwill and education before it can reach its full potential. Problems of supply of raw ingredients, the protection of endangered species, quality control, registration of proven formulations and access to expert information need to be addressed urgently.

The science behind TCM

The World Health Organisation (WHO 1993) supports the use of effective and safe remedies and accepts Traditional Medicine (TM) as a valuable and readily available resource for primary health care.

Many of the world's cultures developed their own forms of HMs over centuries. Today, 75-80% of the world's population still relies on HM (plants, plant extracts etc) and other tools of TM in basic health care (Abelson 1990; Chan et al 1993; Cox & Balick 1994; Schwartz 1994; Yamada 1994a; Chaudhury 1995). In Asia, especially in China, Japan, Korea, Taiwan, Vietnam etc, medical practitioners are trained to prescribe TMs together with Western Medicines (WMs) (Chan et al 1993). WMs often are expensive. To research, develop, register and market a new pharmaceutical drug in the USA takes about 10 years and costs about 200 million dollars (Abelson 1990; Cox & Balick 1994). Also WMs have sometimes limited results in many chronic conditions and their use may cause development of drug resistance and iatrogenic disease, especially if they must be used for long periods.

Because of these factors, demand for TMs, especially CHM, is increasing and traditional HM therapy is used widely in the United States and Europe (Otsuka 1988; Yamada 1994a). Although many individual ingredients used in CHM are highly toxic if used wrongly, carefully prescribed CHMs can be used for relatively long periods with minimal or no adverse effects (Hsu 1982; Hosoya & Yamamura 1988; Dharmananda 1991; Chan et al 1993; Schwartz 1994; Yamada 1994a). However, most TM systems (including HM and AP) need more scientific research on aspects of safety and efficacy (Dharmananda 1991; Chaudhury 1995; Lin et al 1995a).

CHM uses a complex combination of medicinal plant- and other- natural products (Luo & Shi 1986; Ou 1989). Plant products include specifically selected parts (leaves, branches, stems, roots, tubers or bark etc) harvested from herbs, flowers or trees etc. The other natural products include parts of living or dead tissue (animal, insect, reptiles, venoms, shell, coral etc) and minerals (mineral salts, certain types of pulverised rocks and soils etc).

CHM formulas or remedies are carefully balanced mixtures of many ingredients. They are taken as decoctions, or as extracts in water or alcohol, or as dried extracts (as pills etc). Some are used externally. Other presentations of HMs are being developed: pills, tablets, powders, capsules, tinctures, syrups, suppositories, ointments and injections etc.

CHM uses TCM theory and a TCM diagnosis of the pathological condition of the patient. When the TCM Syndrome is established, suitable HMs are prescribed. Treatment aims mainly to maintain harmony of body function, including the psyche and to expel pathogens. Many ingredients are to enhance the effects, or to act as antidotes to the unwanted effects, of other ingredients. The overall aim, and the effect when successful, is to help the body to help itself to attain homeostasis between its own natural functions and the external environment.

History of scientific research into CHM

The ancient history of TCM and CHM is documented by Ou (1989), Schwartz (1994) and Xie et al (1994).

From the 19th century up to the beginning of this century, the influx of western ideas demolished much traditional Chinese culture and science. TCM nearly became extinct. In the past 40 years, shortage of WMs has renewed Chinese interest in the techniques of TCM. In 1990, Hong-Cheng Fong published two books on veterinary herbology, which contain more than 10000 formulas, probably the biggest collection of TCVM since antiquity. Today, there is a nation-wide TCVM Society in China, with thousands of members who practice TCVM daily. Foreign (non-Chinese) graduates may attend courses on TCVM and VAP in China (Lin & Panzer 1994). Development and research into TCM in humans and animals have become popular again throughout China, Japan, Korea and Taiwan (Hsu 1982; Hosoya & Yamamura 1988; Yamada 1994a; Lin et al 1995a). Traditional Oriental Medicine (TOM) and Kampo Medicine (KM) are forms of TM from east Asia and Japan respectively. Both came mainly from CHM, or were influenced strongly by it.

Kampo literally means Han's formulas. Most formulas of KM are from two texts, both written by Zhang Zhong-jing (Zhang Ji), about 210 AD and arranged some years later by Wang Shu-He (Wang Xi) (Hsu 1982; Xie et al 1994; Otsuka 1988). These are the Shang Han Lun (Treatise on Cold-induced (Febrile) Disorders and the Jin Kui Yao Lue Fang Lun (Essentials of the Golden Cabinet). Since 1976, the Japanese Ministry of Health and Welfare has approved 146 formulations of KM. National health insurance in Japan covers the use of the herb components of such approved KMs.

WHO has issued guidelines for evaluating the safety and efficacy of HMs. National and international conferences, such as those run by the World Veterinary Association, the Japanese Pharmaceutical Society and the Medical and Pharmaceutical Society for Wakan-Yaku (Japan) also discuss these topics. Appendix 1 lists Journals that publish research on the chemistry and pharmacology of HMs and phytotherapy.

Pharmacological research in HM

Pharmacognosy is the study of compounds sought out by humans or animals and ingested, or otherwise used, as supposed medicines; zoopharmacognosy is the study of the actions of these materials in animals (Robles et al 1995). These disciplines have led to the identification of many useful medicines. Phytotherapeutics is the therapeutic use of these compounds.

In 1985, worldwide, 3500 new chemical structures were discovered and 2619 of these were isolated from higher plants. In 1987, Japan captured 56% of patented natural products summarised in Phytotherapy Research. Germany also has been more active than the United States in this field (Abelson 1990).

Research in phytotherapy can be classified under many different headings. Research on pharmacological effects of HMs will be discussed under three headings:

a. individual herbs or extracts;

b. individual active compounds of individual herbs;

c. complex HM formulas.

The boundaries between these headings are not easy to maintain; thus there is some overlap between them.

a. Research on individual herbs or extracts

Documentation of TCM is more than 3000 years old. Thus there are extensive data and cumulative experience on the use of CHM, including recent textbooks (Hsu 1982; Xie et al 1994; Bensky et al 1986; Luo & Shi 1986; Tsung 1987; Hosoya & Yamamura 1988; Ou 1989; Dharmananda 1991 and Chaudhury 1995).

Bensky et al (1986), summarises the actions of some potent herbal ingredients. Ginseng radix (ren shen = Man Root, Man Essence) is sometimes man-shaped (like mandrake). The medicinal use of ginseng in China dates to before 100 BC. There are many varieties, Appalacian, Korean, Japanese, Chinese etc. Ginseng is attributed with great therapeutic and mystical potency. Much sought-after, it is very expensive. It is one of the most often cited herbs in TCM. Experimentally, it has potent effects on the CNS and peripheral nerves. Centrally, it improves nervous responses in a homeostatic way, enhancing both stimulatory and inhibitory processes, depending on their initial state of receptivity. In this way, it resembles the homeostatic effect of AP, in which stimulation of the same AP points can have diametrically opposed effects, depending on the state of the subject. Normally ginseng is a central stimulant like caffeine but, in large doses it is a sedative. It counteracts the stimulant effects of some other stimulants and the inhibitory effect of opiates. It enhances the acute hypnotic effect of pentobarbital. Small doses of ginseng have muscarinic effects on peripheral nerve; large doses have nicotinic effects. It shortens the latency of nerve reflexes, accelerates nerve transmission and strengthens conditioned reflexes. Over long periods, it tends to the middle (neither stimulatory nor inhibitory). Experimentally, it has cardiotonic effects, similar to cardiac glycosides; it is clinically useful in cardiac arrythmia.

Huang (1993, pp21-45) devotes a full chapter to the medicinal uses and pharmacology of the root of ginseng. In summary, it contains volatile oils, saponins (glycosides, panaxosides, ginsenosides), antioxidants, peptides, polysaccharides, fatty acids and vitamins and other active ingredients, many of whose chemical structures are known. It is known as the "Elixir of Life", as it has potent antiaging effects and antiirradiation effects, probably due to its antioxidants and immunostimulating properties. Experimentally, it increases endurance in animals and has potent antistress effects against many environmental stressors (Huang 1993). It has antidiabetic/hypoglycaemic effects and alpha-2-adrenergic and antihypertensive effects (blocked by yohimibin). It has -adrenergic blocker effects in oxygen starvation. It has antiinflammatory effects and activates the reticuloendothelial system, dilates cerebral and coronary vessels, stimulates haematopoiesis in the bone marrow, lowers serum cholesterol levels and has antiatherosclerotic effects, which protect against cardiac ischaemia. It has potent effects on the CNS, increases concentration and awareness, increases night-adaptation of the eyes, and has sedative/calming effects. It has antipyretic effects and increases the release of corticotropin releasing factor (CRF) from the hypothalamus. It activates the thyroid, testis and ovary and has clinical uses in male and female infertility and male potency via the hypothalamic-gonadal axis. Ginseng also activates the posterior pituitary, exerting an antidiuretic action. A most important use of ginseng is its ability to activate the immune system in clinical and experimental cancer, experimental radiation sickness and after exposure to cytotoxic agents. Symptomatically, it stimulates appetite, the sense of wellbeing and the will to live in convalescence from chronic diseases. Ginseng is non-toxic At normal dosage, but may be toxic at high doses; the LD50 in mice was 5 g ginseng powder/kg LW in mice. Clinically, ginseng is used in a myriad of conditions. Indications include: shock and emergencies (cardiac, haemorrhagic, septic and toxic); heart failure, acute myocarditis, angina, arteriosclerosis, cough, fevers, hormonal disorders (infertility, diabetes mellitus, diabetes insipidus, thyroid disorders), hypotension, hypertension, stress, insomnia, headaches, anaemia, neurasthenia, muscle atrophy, chronic debility, impotence, poor concentration, gastrointestinal disorders (inappetance, indigestion etc), cancer therapy, immunosuppression and senility (Huang 1993).

Huang (1993) categorised herbs under the following headings in a systematic study of the pharmacology of CHM: those acting on the cardiovascular system (multiple action-, cardiac-, antiarrythmic-, antihypertensive-, antianginal-, antihypercholesterolemic- and antishock- herbs); nervous system (anaesthetic- and muscle-relaxing- herbs; sedative- and hypnotic- herbs; anticonvulsive-, analgesic-, antipyretic-, antirheumatic- and central stimulating- herbs); alimentary system (stomachic- and "Wind"-dispelling herbs; herbs promoting digestion; antacid/antiulcer-, laxative-, antidiarrhoeal-, emetic-, antiemetic-, choleretic-, antihepatitis-, tonic- and supporting- herbs); respiratory system (antitussive-, expectorant- and antiasthmatic- herbs); genitourinary system (diuretic-, uterine-active- herbs); haematopoietic system (promoters of blood formation; haemostatic- and antistatic- herbs); endocrine system (herbs affecting the thyroid, adrenal cortex and pancreas); and chemotherapeutics (antibacterial-, antiviral-, antifungal-, antitubercular-, antiseptic-, disinfectant-, anthelmintic-, antiamoebic-, antitrichomonial-, antimalarial- and anticancer- herbs).

These and other modern texts and reviews show that medical compounds in HMs include immunomodulators, such as antiallergic, antiasthmatic, antiinflammatory, antiinfectious, antihepatotoxic, antineoplastic, antioxidant and antitoxic compounds. HMs also include antistress compounds (hypotensives, muscle relaxants, sedatives, vasodilators), hypoglycemics, and insect repellents (antifeedants).

The role of individual herbs or formulas (herb-combinations) in therapy are discussed under two headings: allergies and the immune system (including antiviral effects). Most of the data for these sections are from the review by Dharmananda (1991).

Antiallergic Herbs

(summarised from Tsung 1987): Important antiallergic herbs include: achyranthes, alisma, alpinia, apricot seed, arctium, asarum, astragalus, atractylodes, bezoar, bupleurum, cardamom, ching pi, cinnamon, citrus, cluster, cornus, ephedra (ma huang), galanga, ganoderma, gentian, ginger, ginseng, hoelen, licorice, magnolia, moutan, pinnelia, polyporus, pueraria, rehmannia, scute, stephania, tang-kuei, zedoaria, zizyphus (jujube).

Type 1 allergies (IgE- and chemically- mediated immediate disorders) are due to circulating IgE attached to mast cells, which releases chemical mediators (including histamine). They include: drug allergies, hay fever, hives and allergic asthma. Herbs that suppress IgE activity in stage 1 allergic response are: alisma, apricot seed, bupleurum, cardamom, gentian, ginseng (Japanese), licorice, tang-kuei, Zizyphi fructus (jujube). Herbs which suppress release of chemical mediators (such as histamine) following IgE binding to mast cells in stage 2 allergic response are: achyranthes, asarum, bezoar, ching pi, cinnamon bark, Ephedra (ma huang), ganoderma, magnolia flowers, moutan, scute, sinomenium. Those herbs have antiinflammatory and antimediator release action. Some of them have -adrenergic and/or antihistaminic effects: they suppress the reaction of the target organs (capillary permeability, smooth muscle contraction in nasal membranes, lungs, gut, skin; hypothyroidism etc) after release of chemical mediators in stage 3 allergic response. Asarum (contains methyleugenol and higenamine); atractylodes and sinomenium also have antihistaminic activity.

Formulas in Type 1 allergy:

Antiallergic (Stage 1): Bupleurum and Hoelen Formula; Minor Bupleurum Formula.

Antiallergic (Stage 2): Minor Bupleurum Formula; Minor Blue Dragon Formula; Ma Huang and Apricot Seed Formula.

Antiallergic (Stage 3): Minor Blue Dragon Formula; Pueraria and Magnolia Formula; Tang-kuei and Arctium Formula.

Antiinflammatory, detoxifying, anti chest-distention: Bupleurum + Scute.

Antiemetic, antinausea, digestive: Pinnelia + Ginger.

Stomachic and antiheartburn: ginseng + jujube + licorice.

Diuretic, antiascitic, antioedematous: Alisma + Polyporus + Hoelen + Atractylodes.

Type 2 allergies (complement-mediated disorders) are due to activation of complement by complement-fixing antibodies against cell-surface antigens. They include: anaphylactic shock (side effects of incompatible blood), haemolytic anaemia in autoimmune or drug reactions, decreased platelet numbers. Herbs with anticomplement activity include: cinnamon bark, ganoderma and licorice. Formulas for type 2 allergies have these as major ingredients.

Type 3 allergies (immune-complex disorders) are due to activation of complement after formation of antigen-antibody complexes. They include: bacterial glomerular nephritis, chronic hepatitis-B, atopic bronchial asthma, erythromatosis, chronic rheumatoid arthritis, thyroiditis. Therapy for type 3 allergies uses anticomplement or antiinflammatory drugs.

Herbs used in type 3 allergy include ganoderma, bupleurum, cinnamon, citrus, cornus, ginseng, licorice, ma huang, moutan and tang-kuei.

Formulas used in Type 3 allergy (and those used in kidney disorders) include: Atractylodes Formula, Bupleurum and Hoelen Formula, Bupleurum and Dragon Bone Formula, Ginseng and Astragalus Formula, Stephania and Astragalus Formula, Rehmannia Eight Formula. These formulas use various combinations of herbs listed in the previous paragraph; they have antiallergic and antiinflammatory effects, and anticomplement activity.

Type 4 allergies (no antibody involvement) are mediated by T-lymphocytes. They include: contact dermatitis, tubercular lesions, chronic hepatitis, bacterial glomerular nephritis, erythromatosis, rheumatoid arthritis, Hashimoto's thyroiditis and intestinal ulcers.

Herbs used in type 4 allergy include ganoderma, ginseng, hoelen, licorice, magnolia bark, pinellia and zizyphus.

Formulas used in Type 4 allergy include: Minor Bupleurum Formula, Bupleurum and Hoelen Formula, Bupleurum and Schizonpeta Formula, Cinnamon and Atractylodes Formula, Tang-kuei and Gardenia Formula, Minor Blue Dragon Formula and Pueraria Formula.

In WM, steroids are used widely in controlling allergies. Combination of HMs (which often contain plant steroids themselves) with WM steroids reduce the doses of the latter to 33-50%. This reduces the risk of steroidal side-effects.

Herbs with immunostimulatory, antiinflammatory, antitoxic, antiviral and antioxidant effects include: akebia, albizzia, alisma, astragalus, centella, cimicifuga, cistanche, codonopsis, dianthus, dioscorea, ginseng, lycium fruit, melia, mushrooms (coriolus, ganoderma, hoelen, lentinus, polyporus, tremella), platycodon, polygala, rehmannia, sambucus, zizyphus etc. They have been used for centuries to treat inflammation, fevers, intoxications, infectious and neoplastic diseases.

b. Research on individual active compounds

WM uses many drugs extracted from natural products: aspirin, atropine, cocaine, curare, digitalis, ephedrine, hyoscine (scopolamine), opiates (codeine, morphine), pilocarpine, primrose oil, quinine, reserpine, steroids, taxol, warfarin etc. Other WMs from natural materials include kaolin, bentonite (in preparations of mineral matter); antibiotics, ergotamine, ergometrine, mescaline (from fungi); allergens for desensitisation, antitoxins and antivenoms, heparin, hormones (steroids, HCG, PMSG, insulin etc), vaccines and venoms, etc (from animal tissue).

Most of these medicines have been discovered on the basis of information derived from traditional medicine and ethnopharmacognostics (Table 1). For instance, ephedrine was isolated from Ephedra sinica in 1885. Ephedra sinica and Ephedra distachia were used medicinally for centuries in Asia to treat asthma, hay fever, nasal congestion and hypotension. Ephedrine is closely related to epinephrine (adrenaline) and the amphetamines. It is still used widely today, as the first successful product of the modern pharmaceutical industry (Otsuka 1988), to relax the bronchioles in asthma and bronchitis, as a nasal decongestant in some allergies and as a mydriatic. It stimulates the CNS and is used to treat hypotension, cardiac failure and narcotic poisoning. Digitalis purpurea was used to treat ascites and oedema in congestive heart failure and its alkaloids are still used for that purpose. Cinchona bark is the source of several alkaloids, especially quinine and quinidine. Both have antimalarial, antifebrile and analgesic effects. Quinidine also is a cardiotonic, used in cardiac arrhythmia, fibrillation and heart block.

TABLE 1. Some important drugs isolated from plants

DRUG

MEDICAL USE

PLANT SOURCE

Aspirin

Analgesic, antiinflammatory, reduces platelet stickiness

Filipendula ulmaria

Codeine

Analgesic and antitussive

Papaver somniferum

Digoxin, Digitoxin

Cardiac stimulant

Digitalis spp.

Ephedrine

Bronchodilator

Ephedra sinica

Forskolin

Cardiac stimulant

Coleus forskolin

Ipecacuanha

Emetic

Psychotria ipecacuanha

Pilocarpine

Antiglaucomic

Pilocarpus jaborandi

Quinine

Antimalarial

Cinchona pubescens

Reserpine

Antihypertensive

Rauwolfia serpentina

Scopolamine

Eases motion sickness

Datura stramonium

Taxol

Treats ovarian cancer

Taxus brevifolia

Theophylline

Bronchodilator

Camellia sinensis

Vinblastine, Vincristine

Treats Hodgkin's disease

Catharanthus roseus

Raw ingredients used in HMs contain pharmacologically active compounds of low- and/or high- molecular weight. Low molecular-weight compounds include primary metabolites (sugars, fatty acids, peptides etc) and secondary metabolites (alkaloids, terpenoids, saponins, flavonoids etc). High molecular-weight compounds include proteins, tannins and polysaccharides. The therapeutic activity of HMs derives from these compounds (Yamada 1994a, b). Clarification of the active principle(s) of HMs helps us to understand the modes of action at a molecular level, to evaluate efficacy and to maintain herbal quality. It also helps us to develop novel drugs by extraction from plants, biotechnology, or by synthetic methods. This may provide remedies for diseases incurable or poorly controlled by modern chemotherapeutics.

The following is summarised from the review by Dharmananda (1991). In WM and pharmacognosy, active compounds are classified in many different ways: by their physiological effects, by their clinical indications or by their chemical-pharmacological nature. The latter method groups medicines into 8 classes:

1. carbohydrates (sugars, polysaccharides (gums, mucilages, pectins));

2. steroids (steroid hormones, sterols, bile acids)

3. glycosides (antraquinones, flavonoids, lactones, phenols);

4. alkaloids (tropanes, quinolines, indoles)

5. tannins (catechols, pyrogallols);

6. lipids (fixed oils, waxes, fatty acids);

7. volatile oils (alcohols, aldehydes, ketones, phenols);

8. resins (oleo-resins, gum-resins, balsams);

HMs used to treat various disorders of the immune system, including allergies, inflammations, infections, cancer and AIDS contain one or more of these active compounds. Some HMs contain mixtures of these compounds, for example ginseng and hoelen contain potent polysaccharides and steroids.

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