ESSENTIAL ELEMENTS OF HERBAL PHARMACY
By Ivor Hughes

The use of herbs as healing agents predates recorded history. Investigation of a 60,000 year old paleolithic grave site in Shanidar, Northern Iraq, yielded pollen samples of no less than eight different genera of flowering plants. Many of the species were still official in various pharmacopeias until the mid 1930's. Therefore to say that 'herbs are the mother of all medicine', would not be unreasonable. Herbal therapeutics is a broad term that covers all those systems of medicine in which herbs or their derivatives form an essential part of the therapy, e.g.,

A. Pharmacognosy.  In orthodox medicine Pharmacognosy was an essential branch of Galenic Pharmacy, which in terms of orthodoxy, Galenic Pharmacy, is now all but moribund. It is a descriptive science that requires a good knowledge of botany and biology. This is applicable to the drug plant in its living form, e.g., its wild habitat, its life cycle and collection times. However, when the drug plant arrives in the laboratory or pharmacy it is usually in its dried form and the task of identification becomes more exacting. It will be appreciated that the dried plant, or plant part, will have a very different appearance to that of the fresh plant, therefore, a good knowledge of plant morphology is essential. Morphology is the study of the plants shape or form. e.g., root, leaf, stem, flower, etc. In the event that the material is grossly distorted from the drying process or is shattered, granulated or powdered, then knowledge of plant histology is needed. Histology is the study of minute structures of organic tissue. The material will be compared with a known true sample and examined for foreign material and also for evidence of deliberate adulteration.  

B. Pharmacology. which is the knowledge of the action, the fate and the excretion of drugs when they are introduced to the living system.

C. Toxicology  Literally a knowledge of the toxic effects of poisonous plants on the living system and where known, the antidote and treatment.

D. Posology.  The word is derived from Greek, meaning 'how much' and refers to that branch of medical science that determines the safe functional dose of a substance. It will take into account such variables as age, gender, weight and any acquired or natural tolerance. This must also be balanced against idiosyncrasy or allergic intolerance. It will also take into account the route of administration which has a direct bearing on the speed of action and degree of absorption.

E. Herbal Pharmacy.  The preparation, compounding and the dispensing of plant based drugs.

There are various fragments of materia medica from the ancient Babylonian and Egyptian eras. Examination of the medical recipes show a fine grasp of the knowledge required of a sophisticated system of medicine, that cannot be simply brushed aside as magical mumbo jumbo. Some of the recipes contained animal and insect parts, while others contained faeces from various sources. In the past it has been the trend in orthodox medical circles to dismiss such formulations as gutter or sewer pharmacy, while ignoring the obvious parallel with modern Sera and Vaccines. However, today a more enlightened interpretation of the evidence is steadily gaining ground, e.g.,

So also the ancient idea of urine and other secretions as drugs might easily be written off as primitive superstition if we did not know that it led by rational if quasi-empirical trains of thought combined with the use of chemical techniques originally developed for quite different purposes, to the preparation of the steroid and protein hormones many centuries before the time of experimental endocrinology and biochemistry."

Doctor Joseph Needham
'Science and Civilisation in China'.
Vol. 5 Chapter 15 Cambridge.

The most famous of the Egyptian medical writings, is the so called 'Ebers' papyrus, which has been dated C 1550 BC, i.e., almost 3,500 years old, therefore we must avoid the trap of confusing technology with intelligence, or considering scientific theory to be superior to empirical knowledge, because clearly it is not. 

The Raw Materia Medica. It is not an overstatement to say that herbal therapeutics represents the predominate medical system. The World Health Organization (WHO) estimate that around 80% of the global population are dependant on herbal medicine for their primary health care. The tradition of medicinal herbs is the heritage of all cultures and for many of them a direct lineage can be traced by cross fertilization, e.g.,

Today the rich tapestry has resolved itself into four major strands where natural medicine is practiced as both an art and a science, i.e. 

To this tapestry we must also add the Shaman Practitioners. They are the trunk, of the tree, of all medicine. They are to be found in isolated impoverished communities around the world. And in practicing their Art, they have kept alive, this most ancient of knowledge.  

The major schools are eclective, both in system and raw materials, and between them they are able to muster around 5,000 plants of known therapeutic activity. No other system of medicine can command such a flexible and wide ranging materia medica. 

The figure of 5,000 plants must be viewed in context. Of the estimated 250,000 members of the angiospermidae (flowering plants) less than 5% have been screened for medicinal substances. The vast majority of that 5%, have only been screened for a single substance , e.g., an alkaloid; on that basis alone, we can be assured that, the baby has been thrown out with the bath water.  However, the art is still in its infancy and that like an iceberg, much lies hidden.    

All our needs in nature are catered for, if that were not so, we could not have survived as a specie. When a correctly prepared herbal medicine fails to achieve its goal, it is not the efficacy of the herb that is called into question but rather the accuracy of diagnosis and method of treatment. However that is a problem that is common to all systems of medicine. There is no evidence to suggest that high tech diagnostic techniques achieve a greater accuracy than those obtained by a sensitive natural therapist

Crude Vegetable Drugs. For the purpose of this article, the word 'Herb' should be taken to mean 'all of those parts' of the plant kingdom that we utilize for medicinal purposes. All such substances, when in the natural or dried state, are referred to as 'CRUDE' drugs, i.e., drugs that have not been converted to a form that ensures maximum absorbency and effect.

All of the above plant parts are classified as 'ORGANIZED' drugs, in that they have a well defined cellular structure. Another class of crude drugs is the exudations;

Those substances  are said to be "UNORGANIZED', meaning that they do not have a cellular structure.

A further important class of substances are the Bee 'APIS' products;

                               Honey  - Wax  -  Propolis -  Pollen.

The honey, wax and propolis are classed as exudations and have unorganized structures. Pollens, as gathered by bees, are the fertilizing spores of flowering plants and have an organized structure. 

The structure of the crude drug will determine its processing route.

Evaluation of Crude Drugs.  The evaluation of a crude drug is an essential part of Pharmacognosy. The individual drug plant would undergo all or some of the following procedures;

1.  Organoleptic Assessment, which is inclusive of the following;

A. Smell,  e.g. is it characteristic of the material?

B. Sight,  e.g. color, shape, i.e., macroscopic appearance.

C. Taste  e.g. sweet, sour, astringent, spicy, etc.

D. Touch and sound. Usually for assessing roots or tubers.

2. Microscopic Assessment, usually for powdered drugs. Its histological appearance must match that of a known sample, and the % of adullteration with foreign substances noted.

3. Chemical and Physical Testing, physical constants such as melting points (mp), boiling points (bp), specific gravity (SG), solubility; optical rotation, are rarely applied to whole crude drugs but are used extensively with drug constituents, e.g. volatile and fixed oils, alkaloids and glycosides. Chemical methods will also include  thin layer chromatography, ash tests, water and ethanol soluble extractive values, heavy metal tests etc. In these days of increasing specialization, such tasks are no longer performed by the pharmacist. However, they must be able to predict incompatibilities, solubilities and therapeutic dose and advise in such matters.

Herbal Constituents. When utilizing herbs for medicinal purposes, empirically and scientifically, it is the practice to use those parts that contain the greatest amount of 'active constituent', i.e., that chemical entity that elicited a major pharmacological response, e.g. cathartic or analgesic effect. Herbs produce every known pharmacologic response.  

The active constituent levels, in the families of plants that contain them, are a function of known variables and from that a plus/minus % for those levels can be known.

It is now recognized that the overall synergy of a plant is more important than the level of a single constituent. Quite obviously, a plant medicine must be standardized in some way so that a safe functional dose may be prescribed. There are four main methods.    

1. By Chemical Assay. which involves the separation of the known constituents. The concentration is determined and adjusted to a specific potency based on the original concentration.

2. By Biological Standardization. This method is usually reserved for potent drugs where a chemical assay is not possible or unreliable, for example Digitalis, (Foxglove). The assay carried out by the LD. 50 test (Lethal Dose: 50%). A number of experimental animals are used to determine the minimum dose required to kill 50% of the creatures, within a defined period of time. Such tests are not precise, due to the differing metabolism of humans and the animals, and also the human idiosyncrasy as may be observed by the high rate of toxic effects of digitoxin when administered to patients of the same size and weight.

3. By Physical Standardization, this method is usually combined with the chemical method and takes account of boiling point, melting point and specific gravity. Once again the level of 1 or 2 known constituents are adjusted to a specified level of activity.

4. Arbitrary Standardization is carried out by adjusting a liquid extract to volume, whereby 1 milli-litre of the extract is equal to 1 gram of the air dried herb. Obviously the quality of the herb is the only variable when that method is used.

Ethical considerations, to one side, and from the standpoint of holistic therapy, methods 1, 2, and 3 are not acceptable because the natural synergy of the herb has been destroyed. It is well known among Galenic Pharmacists that extracts and tinctures prepared by arbitrary standardization usually display a higher level of activity than would be expected from the known concentrations of the so called active principle. In clinical practice they also display a more acceptable pharmacological response than assayed products.  

Brief Description of Herbal Constituents, and Solubilities in Alcohol and Water. Before proceeding to a description of the carriers and solvents employed in herbal pharmacy, it will be helpful to review the major compound constituents of herbal drugs and their solubilities in alcohol and water.

Alkaloids. The alkaloids represent the largest class of drugs to be found in the plant kingdom. The majority of alkaloids so far discovered have been isolated from the ANGIOSPERMAE or flowering plants. Commercially, the alkaloids, because of their medical and toxic properties, are extremely important. They are naturally occurring nitrogenous bases and are combined with acids as salts. They may be solids or liquids. The majority of the known alkaloids are solids and in addition to nitrogen, they contain carbon, hydrogen and oxygen. Generally the alkaloids are freely soluble in alcohol or diluted alcohol but only feebly so in water.  However, if the alkaloid has been precipitated as a salt, they become freely soluble. Most of the alkaloids are sensitive to heat. (Thermolabile) The alkaloid containing drugs should not be exposed to temperatures exceeding 60�C. Therefore, the practice of preparing infusions or decoctions from alkaloidal herbs is a dubious procedure because the resulting changes may render the alkaloid liable to hydrolysis (decomposition) or it may be converted to an isomeride, i.e., a compound which has the same kind of atoms, in the same proportions, but are arranged differently. This changes the chemical and physical properties of the original compound. In some cases both reactions may occur together, thus the synergy is irretrievably destroyed.

Anthraquinone Derivatives, (Emodins)  Emodins are found in the anthracene group of the vegetable purgatives or cathartics. Members of this group display widely differing modes of activity. While there is no doubt that Emodins have a laxative effect, it is generally considered that the differences are due to other more complex substances, such as glycosides which yield emodin. This view may be supported by the fact that Emodins are widely distributed throughout the vegetable kingdom in plants that exhibit no noticeable laxative effect. Anthraquinone derivatives are soluble in both water and alcohol. Some are stable to temperatures of up to 100�C, while others will decompose at temperatures in excess of 60�C. In view of that fact, it would be prudent to treat the anthraquinones as thermolabile.   

Albumins and Globulins. The albumins and globulins belong to a class of substances known as proteins. The proteins are the primary component of all living matter. From a medicinal view, they are considered to be ballast or inert substances. Invariably they are subject to putrefaction, the breakdown products render preparations containing them unstable and unfit for human consumption. Their exclusion from medicinal substances is desirable. Generally the albumins are insoluble in alcohol and soluble in water. The globulins are insoluble in both, therefore they may be precipitated from an alcoholic solution and removed by filtration, rendering a herbal preparation stable.

Chlorophyll. Chlorophyll is a green pigment that is to be found in the leaves and stems of plants. It traps the sunlight for the photo synthetic process, this enables the plant to produce starch, without which we could not exist. Medicinally it is claimed that chlorophyll is a mild bactericide with deodorant properties. For the natural therapist it is a natural chelation compound of extraordinary efficiency that assists the body to excrete heavy metals and also to dissolve kidney stones, therefore, its presence in medicinal preparations is to be encouraged as a detoxifier. Chlorophyll is insoluble in water but soluble in alcohol.

Cellulose and Lignin. Cellulose stiffens the cell walls of plants and provides support. As a substance it is classified as a polysaccharide and forms an expandable primary wall for the cell. Lignin forms the secondary cell wall which grows when the cell has matured. The primary function of lignin is for stiffening and support and is present in all shrubs and trees. Cellulose and lignin are insoluble in alcohol and water. Medicinally they are considered to be inert and are discarded on completion of the extraction process. However the Spagyric School considers that view to be incorrect, and further recover the salts from the cellulose and lignin, which is then added to the final extract.

Fixed Oils. Fixed oils are only slightly soluble in alcohol and insoluble in water. Generally, fixed oil, when present in material which is being extracted, interferes with the process, e.g., strophanthus seeds which are defatted prior to extraction.

Flavonoids. The therapeutic status of flavonoids has still not been settled. In older medical literature they have been classed as vitamin 'P' (P for permeability) however, studies have shown that little or no flavonoid is absorbed by the intestinal tract which does not support the vitamin theory. They are bio-active and are biologically classed as co-enzymes, many of which are known to catalyze the hydrolysis of glycosides, unless they are rendered inactive. Flavonoids are thermolabile and destroyed by temperatures exceeding 60�C. They are inactivated and soluble in aqueous solutions of alcohol.

Glycosides. The glycosides are widely distributed in nature and display a diverse range of physiological action. As a class of compound they are notorious for their susceptibility to hydrolysis. The breakdown products are either inactive or medicinally less active. As a general rule they are heat sensitive and soluble in alcohol and water. The saponins, as with the other glycosides, are prone to breakdown. They are unstable in water based preparations while the alcoholic based solutions are stable and less prone to hydrolysis.

Gum Mucilage. The natural gums are a class of vegetable products that are insoluble in alcohol and soluble in water. Medicinally they are considered to be inert. They provide a good growth medium for mould spores, e.g., Agar-ager, so it is desirable that they be removed from medicinal preparations, if decomposition is to be avoided.

Resins. The resins may be divided into three main groups;

1. The true resins are usually solids and non volatile, e.g., Colophony, Copal. They are soluble in alcohol and volatile oils but insoluble in water.

2.  Oleo-resins and Balsams. The oleo-resins are a mixture of resin and volatile oils. Those products, which also contain benzoic and cinnamic acids, in addition to the resin, are usually designated as balsams, e.g. copaiba and Balsam of Tolu. They are soluble in alcohol but not in water.

3. The Gum resins form an important group of medicinals, e.g. Asafoetida, Galbanum, Gamboge, Myrrh, Olibanum and Scammony. Many of the gum resins also contain volatile oils. The gums are usually completely soluble in water but insoluble in alcohol. The resins and volatile oils are soluble in alcohol (90%) and insoluble in water. The gums are precipitated from solution by the alcohol.  

Starch. Starch is a white proto-substance found throughout the vegetable kingdom. It is classed as a nutrient but medicinally inert. It is to be found in barks, roots, rhizomes and seeds. Starch is insoluble in alcohol but soluble in boiling water. When present in an alcoholic menstruum, it forms a precipitate that may be removed by filtration. Aqueous solutions are prone to spoiling and growth of micro-organisms.

Tannins. The vegetable tannins are widely distributed in the plant kingdom. Chemically they have been divided into three groups. Medicinally only the group known as Pholobatannins' is important. Tannins are a major cause of incompatibility in herbal preparations. They can form insoluble complexes with the heavy metals, alkaloids and glycosides, therefore it is not advisable to combine a tannin containing herb with others of a different type. Tannins are soluble in alcohol, water and glycerine.

Volatile Oils.  The essential or volatile oils are a further class of product which are extensively distributed. They are obtained from barks, flowers, fruits, grasses, leaves, roots and wood. They consist of complex mixtures of organic chemical compounds and are freely soluble in alcohol 90%. They are slightly soluble in water and insoluble in glycerine. The volatile oils themselves also have solvent powers particularly of organic fats and waxes.

Waxes. The waxes, are esters of fatty acids, as are the fixed oils and fats, the major difference is that the alcohol represented in the waxes is not glycerol. A number of plants waxes also contain paraffin hydrocarbons. They are insoluble in water and glycerine, sparingly soluble in alcohol and soluble in chloroform and ether.   

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