GENERAL NOTES

Botanical names

The herbs are presented under their botanical names and within their botanical families. Using botanical names is necessary to ensure the identity of the herb is understood throughout the world. Common names change from place to place and have on occasion been used to identify different plants altogether e.g. colic root which can signify wild yam—Dioscorea villosa, true unicorn root—Aletris farinosa or pleurisy root—Asclepias tuberosa. Also throughout the scientific literature chemical differences are noted in species with the same genus name so for reasons of both safety and efficacy an exact nomenclature is necessary.

Each herb is set out in the same format and has the botanical and most used common name(s) as well as a simple drawing which can help in the identification, although a more detailed field guide may be required for this purpose.

Description

This covers the general appearance of the plant and its height in flower, or in the case of trees, when mature. It is followed by descriptions of the various parts including fruit and seeds, as well as the flowering or fruiting time of the plant. When two measurements are used together e.g. 5.5 × 2 mm, the first measurement is length/height and the second width. Herbs respond to differences of soil, light and rainfall which make their appearance different in different environments so positive identification should be made from flowers and seeds. Appendix IIIa is a botanical glossary.

Habitat and cultivation

Habitat refers to the country from which the plant originated and the conditions in which it grows wild. Cultivation of that plant is more likely to be successful if the same growing conditions are provided. However many herbs have become successful weeds regardless of their original habitat. Cultivation includes the ways in which each plant may be propagated, and the ideal soil and situation for growing it. The two other factors of drought and frost indicate whether or not the plant will succeed in a particular area on its own or will need special care.

Parts used

This refers to the part of the plant used medicinally. This may involve the whole plant but often only 1 or 2 parts are used and sometimes the part of a herb used differs with tradition. In some cases one part has medicinal value whilst another part of that same plant may be toxic. Whether the part is used fresh or dried can also be significant. In order to make safe medicine attention to these details is essential. Each part of the plant should be harvested at the appropriate time to ensure maximum levels of active constituents.

Wild crafting or gathering non-cultivated plants, particularly roots, should never deplete the habitat of the ability to produce future generations and should not be undertaken at all if the plant is an endangered species.

Plants should be gathered when not wet from dew or rain and processed as quickly as possible after picking so that they do not spoil. If they are to be dried this should be done in a warm, airy place out of direct sunlight. Too much light and/or heat can alter the active constituents and change the herb's therapeutic potential. Once dried, they should be stored, taking into account their particular requirements, some need to be stored before being made into a safe medicine and others may deteriorate if stored for too long. Herbs to be stored should be kept as whole as possible (not crumbled or powdered) because the smaller the pieces of plant material are the greater the level of oxidation that can occur. They are best ground just before processing.

The parts used may include:

• Leaves or Folia (fol.)—generally collected just as the plant comes into flower
• Flowers or Flores (flos.)—usually collected at midday when fully open but before they begin to fade
• Aerial parts or Herba—consists of the whole plant above ground, usually gathered when flowers and/or buds are present as well as leaves and stems
• Fruits or Fructus (fruc.)—consists of the berries collected when just ripe
• Seeds or Semen (sem.)—usually picked as the whole seed head, still on the stalk, when most of the seeds are just ripe
• Bark or Cortex (cort.)—consists of the outer covering or “skin” of the branches, or inner bark as specified. It is usually collected in autumn or early spring before the sap rises so that damage to the plant is minimised. If taken directly from a tree this should be done as longitudinal strips and not as a band (“ring barking” will kill the plant). If inner bark is specified it can easily be separated from the outer cork layer
• Roots or Radix (rad.), rhizomes (rhiz.), bulbs generally collected when the foliage dies back

Active constituents

This knowledge is not as simple to acquire as may be expected. Every plant is made up of many constituents some are considered active; others may become activated in vivo; some may simply assist for example in the absorption of “actives”; and yet others may be nutritional. Not all active constituents have been identified and the importance of some constituents may not be recognised at present.

Knowledge of active constituents should lead to a better understanding of the herb's pharmacology and possibly to new applications. It is not, however, an exact science. Even with the advantage of sophisticated technology to help separate and identify constituents, extraction procedures are not perfect. Variables that have been identified as contributing to an altered constituent profile include:-

• Geographical location—the origin of the herb and its local environment can alter the quantity and quality of constituents. Cultivated herbs too can vary from those that grow wild e.g. see Tanacetum parthenium
• Genetic variability like polyploidy (e.g. Achillea which may have 2n, 4n or 6n chromosomes) or tendency to hybridisation (e.g. Salix spp.). Genotypes and/or hybrids found in the wild can be hard to distinguish visually and without chemical profiling. These genetic differences may significantly alter the plants’ chemistry. Profiling every plant would render manufacturing uneconomical and certain mixed species, where these are similar enough in actions, have become acceptable pharmaceutically e.g. Barosma
• Time of harvest and growing conditions experienced by plant in year of harvest e.g. water availability, sunshine hours, soil type, insect predator levels (some constituents help repel insect attack)
• Age of herb at time of harvest—constituents can be affected by age e.g. terpene levels are higher in younger gingko leaves
• Incorporation of other plant parts (e.g. leaves may be harvested with or without buds in the case of Cratageus spp.) altering the final preparation
• Conditions in which material is stored prior to extraction (e.g. temperature and light) as well as duration of storage
• Method of extraction and analysis used—the solvent system, temperature, pressure and pH. The procedure and/or solvents used can lead to artefacts or the preferential extraction of some actives at the expense of others. The process used is not necessarily intended to gain a profile of the herb as used by herbalists
• Although an active constituent has been identified in a herb, its lack of bio-availability may mean it does not necessarily have an important role in the herb's activity in vivo e.g. oleuropein in olive leaf
• Dosage forms may alter the bio-availability of active constituents (e.g. a commercial tablet preparation as opposed to a tea or a tincture)

These variables are perhaps academic. Herbalists in times past would not have been concerned about many of these factors, although the difference conditions made to the potency of a herb was sometimes reflected in the instructions surrounding its gathering. Lack of scientific understanding about the herbs did not mean they were any less effective in practice. It is still true, too, that the action of a herb relies on the combination of all, or many, of its constituents acting in synergy, not just the so called “actives”.

For a small number of herbs a great deal of information is available about their constituents, others are only partially determined and for some very little is known. These isolated constituents have again been subjected to a variable degree of pharmacological study. The quantity of information should not indicate the relative worth of any herb.

It should also be noted that with better technology older named constituents may since have been identified and renamed and so no longer appear as listed constituents. This is especially likely to be the case with constituents that were simply identified at one time as a “bitter principle”.

Appendix III lists the more commonly encountered active constituents and their known pharmacology.

Nutritional Constituents

As well as having medicinally active constituents, many herbs contain vitamins and minerals as well as other important nutritional elements such as essential fatty acids and essential amino acids. Herbs like Avena sativa and Urtica dioica may be considered nutritive because of their vitamin and mineral content whilst others like Valeriana have nutritional elements, glutamine in this case, that could be key to the herb's activity. It can help to be aware of the nutritional contribution a herb although this has not generally been well studied. There may be detailed evaluations for some herbs and next to no information on others. As with active constituents, the presence of a nutrient may have variable bio-availability. Any data that exists in the scientific literature has been referenced, otherwise the nutritional information is based on a variety of texts and should act as a qualitative guide to the nutritional potential of the herb.

Actions

Because of their particular mix of constituents, most herbs have a variety of actions. The constituents that occur and their relative proportions interact to give each herb its characteristic main actions. For instance the presence of tannins imparts astringency but the other constituents and/or their mode of metabolism or excretion from the body means that the astringent action is focussed at a particular site—the kidneys (Equisetum arvense) or the upper respiratory mucous membranes (Glechoma hederacea). Knowledge of this sort would have been gleaned anecdotally in the first instance. Early scientific studies relied largely on the use of live animals or their isolated tissues to establish these actions. Modern research has the advantage of being able to use human models to observe them. Definitions of actions may be found in Appendix I.

Scientific information

This section is intended to extend or verify the accepted modern uses of each herb in the practice of herbal medicine.

It begins with a brief historical profile of the herb, official pharmacopoeial uses and also those uses approved by German Commission E. This commission is a governmental regulatory agent established in 1978 and comprised of various scientists including toxicologists, pharmacists and doctors to critically evaluate historical and current data on a range of medicinal herbs and produce guidelines for their use in Germany. They have produced monographs for a number of herbs and these have been translated into English by the American Botanical Society.

Animal based experimental data has deliberately been excluded unless otherwise stated. With the advantage of improved scientific models there is no longer a necessity to rely on these studies which may not only be cruel but also leaves unanswered the question of whether the observed actions can be considered a true reflection of their effects in humans. The history of medicine has many examples of animal models having failed to predict drug activity in humans with serious consequences.

The scientific information used therefore comprises the following three elements:

In vitro

In which isolated human cells or metabolites are subjected to the herb, or its constituents, in a laboratory situation (“test tube”) to evaluate their effects. This research attempts to predict in vivo outcomes. Whilst these models have the advantage of better representing human biochemistry and being more ethical than live animal models they also have some disadvantages which need to be borne in mind. Extracts of herbs, or isolated constituents, bathing human cells is not the same as ingesting them, obvious differences are:-

• in vivo the antimicrobial efficacy may be altered by absorption
• effective concentration around and within the cells is likely to be much higher and experimentally controlled
• absorption through the mucosa may filter out certain constituents e.g. polysaccharides
• the chemistry following ingestion of a herb is likely to be altered as it passes through the gastro-intestinal tract and/or liver and this may or may not alter what eventually reaches individual cells
• the effect the body has to direct where a herb or its constituents may accumulate and/or concentrate for excretion/secretion
• the many complex processes that may intervene to alter the herb or constituent that is ultimately presented to the living cells

There are therefore limitations in these studies and it is difficult to directly extrapolate data gleaned from them to the in vivo situation. However this research may give insights into mechanisms underlying a herb or a constituent's action.

Ex vivo

In which the herb or its constituents are given to live people and then cells or metabolites are isolated in a laboratory, away from the live source, to assess changes made. This method has the advantage of allowing the herb to act in a real live context although end measurements are confined to a single fixed point in time and to the one model for which the experiment was designed.

In vivo

In which the herb or constituent is given to living subjects and the effect on a clinical condition or physiological function is evaluated. This evaluation may be subjective and/or objective, stand alone or be compared to placebo and/or current standard pharmaceuticals. They may be:

• prospective—the outcome of a treatment protocol after a specified period of time (this includes the standard randomised, controlled, double-blind type of study) is assessed
• retrospective—looks back at a lifestyle choice of a sample group and assesses if there is a correlation between it and a particular health outcome
• epidemiological—rates likely causal links between a herb's use in the general population and the development or prevention of diseases or physiological changes for that population

These studies, particularly the epidemiological ones, which link the use of a herb to likely health outcomes can be informative but they are not routinely carried out and can be complicated by the number of confounding variables. Other types of clinical trials are all too often economically driven where a developed health product—this may be a partial extract, one standardised on one or two main constituents or a combination of extracts with or without dietary supplements—is tested and the results are quite specific to that preparation. There is little research relevant to herbalists that establishes a direct benefit for a particular plant extract.

In vivo studies can nonetheless be useful but suffer the following disadvantages:-

• trials do not reflect what happens in our clinics because we treat the whole person not just their “medical condition”
• isolated constituents, standardised extracts or fixed combinations of herbs are more likely to be examined as these can be patented and have commercial potential
• sample groups are usually small (some have been less than 20 people). Financial returns on herbal preparations are not great and there are fewer employed or interested scientists to carry out the research
• herbs may be assessed in the treatment of conditions for which they are not used traditionally. There are medical imperatives for new treatments of epidemic diseases for which no current remedy exists or for which pharmaceutical approaches are no longer effective e.g. antibiotics. The research is therefore driven by the need to treat these diseases, not by the desire to establish the intrinsic value of a herb. Because traditional uses are often not being assessed research may end up distorting the perception of the medicinal benefit of that herb. It may also be that through inappropriate testing, a herb appears not to be effective for its traditional uses even though history tells us otherwise.
• delivery systems may not be relevant to the practice of herbalists e.g. injections
• biochemical processes are being unravelled and illustrate the complexities of living systems, many are still to be elucidated. A herb or constituent may block one or several biochemical processes yet this does not necessarily reflect the full extent of its action, wanted or not, in other metabolic functions. This symptomatic, mechanistic approach is also at odds with the aim of herbal medicine which tries to resolve underlying problems.

Science has come a long way in explaining mechanisms of action for some herbs. Yet it is apparent that their very complex nature means they may remain difficult to understand. Not only are there numerous active constituents for many medicinal herbs but their in vivo interactions are unknown. The multitude of biochemical functions they can influence may remain unknown until technology is much more sophisticated than it is today.

Herbal medicine as practised by phytotherapists is a customised process where the individual's history and needs are established and the whole person treated with tailor-made mixtures not standard formulas, isolated constituents or simples (single herbs). The medical herbalists’ approach to their art is therefore difficult to measure by current standards of clinical research. Because this practice does not conform to the current belief in the overriding value of the randomised, doubleblind controlled study this should not diminish the worth of the materia medica.

On the other hand science can help widen our understanding of herbs.

• It regularly confirms the concept of synergy in the action of herbs, or within a herb, by its constituents
• It has highlighted subspecies differences in herbs that are used in different countries which may explain discrepancies in cultural usage
• New applications may arise from these studies
• Possible dangers and interactions to which we have previously been oblivious are being brought to the fore
• Most importantly science may help persuade a sceptical audience of the medicinal value of herbs.

Medicinal uses

It will be seen that for many herbs the record of their use dates back hundreds if not thousands of years. The current accepted use is often a narrowed or refined version of this list supported by studies undertaken to corroborate them. In many cases they were the accepted uses in pharmacopoeias, even within the last 50 years or so, and they are the accepted uses recorded in standard herbal texts like the BHP and BHC. I have used these latter two as the main guide to modern medicinal uses as well as material provided by members of the National Institute of Medical Herbalists (U.K.). Where research has unequivocally confirmed new uses I have often included them.

Pharmacy

This lists the various preparations which may be made from each herb. These may be for internal or external use. Water-based preparations include infusions and decoctions for internal use, compresses and poultices for external use. Oil-based preparations are infused herb oils and ointments for external use only. Alcohol-water preparations which includes tinctures and fluid extracts are used either as lotions or washes externally or used internally. In addition information is included on standardised extracts which have been used in clinical trials relating to that herb.

A standard infusion is made from leaves and/or flowers or seeds of a single herb or combination of herbs using the dose recommended for each herb. It is made up by adding boiling water to the herb which should then be kept covered with a lid and left to infuse for at least 10 minutes. Some constituents like mucilage are more effectively extracted if left to infuse over night. Once infused the tea should be strained and kept in a cool place if not all used at once. It may be drunk hot or cold and should be made fresh daily.

A standard decoction is used to extract the properties of tougher material such as roots, bark, twigs and some berries. Infusing will not extract well unless these parts are dried and powdered and so a more energetic extraction process is necessary. The same approach to dosage is used as for any infusion, but as some of the water is lost as steam, more water is usually added to start with. Combine water and herb in a saucepan, bring to the boil and simmer for at least 20 minutes. Strain, cool and store as for the infusion. It may be drunk hot or cold.

A compress is made using a soft cotton or linen cloth soaked in a hot or cold herbal extract. This may be made as a standard infusion or decoction or by adding 5–20 ml of tincture to 500 ml of hot or cold water. For a hot compress soak the cloth in the herbal extract until it has absorbed the herb and the heat, wring it out and apply it to the affected area. When it cools or dries repeat the process, reheating the herbal extract. A hot compress is healing for muscle injuries or wounds, spasms, cramps and tension. A cold compress (made with cold preparations rather than hot as above) is helpful for headaches, sprains, sore and tired eyes, burns or rashes.

A poultice is similar to a compress but is made from the actual herbs rather than an extract of herbs. Boil sufficient chopped herb to cover the area, squeeze out the moisture and spread the herb directly on the skin or on a piece of gauze. Cover with a cotton or gauze bandage to hold it in place. May be used hot or cold. Replace the poultice every 2–4 hours or as necessary. If applying the herb directly to the skin rub a little oil on first to protect it and keep the herb from sticking.

A succus is the juice of a fresh herb expressed using a press or juicer. It can be done with succulent herbs only and is a way of accessing the herb's constituents without the need for additional water or alcohol and without the application of heat.

Infused herb oil is made by covering the herb with vegetable oil in a container and indirectly heating it, as in a double boiler, for several hours. Strained oil can be stored for later use or combined with beeswax to give an ointment.

Tinctures are made by adding alcohol to the water in the extraction process and not using heat as in infusions/decoctions. Water is a good solvent and can dissolve out many of the chemical constituents. But water does not extract some constituents like resin, for example, and so herbs in which this is an important active constituent are not usually infused. In these cases tinctures are made by chopping or powdering the fresh or dried herb and adding a water- alcohol mixture to it. The amount of herb to water-alcohol (menstruum) gives the extraction ratio quoted as e.g. 1:10. This means one unit by weight of herb has been extracted by 10 units by volume of menstruum. The menstruum is given as a percentage which refers to the alcohol strength of the water/alcohol mixture. So that a 25% mixture would be made by diluting 25 ml of pure alcohol with water to give a final volume of 100 ml of menstruum. The alcohol content is varied according to which constituents are being extracted and how soluble they are in water and alcohol. Water extracts will not keep, so the use of alcohol is also a means of preserving the herbal extract.

Commercially produced tinctures in some countries are required to have chemical profile checks run to ensure the correct actives are present and contaminants are not.

Fluid Extracts. Strictly speaking this represents a tincture with the extraction ratio of 1:1 in other words 100 g of herb is extracted into 100 ml of water-alcohol. This represents the strongest tincture usually encountered although with new research and more sophisticated procedures tinctures that are standardised for a particular constituent may be stronger than this.

Dosages given are according to the BHP and BHC where available. Where these do not exist guidelines are offered based on other sources as indicated.

Contraindications

Contraindications should not be ignored. They indicate in which conditions it is not safe to use a particular herb. Pregnancy is an obvious case where extreme care should be taken and it is best to avoid treatment of any sort in the first trimester because at this stage the developing foetus is most vulnerable. This principle applies to any type of medication. Herbs rarely have side-effects but they do have contraindications and the safest standards of practice must be observed.

A table of conditions and the herbs that are contraindicated for them appears in Appendix IV. Note not all standard texts are in agreement over contraindications.

Pharmacokinetics

This section contains any relevant data on the study of the fate of pharmacologically significant chemicals derived from the herb. It may cover the absorption, distribution, metabolism and excretion of one or a few constituents. This information is usually only available for the most commonly used herbs and may serve as a guide to the time frame for dosing, expected effectiveness or potential toxicity.

Precautions and/or safety

These cover any safety checks that have been carried out in vitro or such as genotoxicity or mutagenicity tests or in vivo effects on particular groups of people e.g. pregnant women. It also lists reported side-effects for the herb that are either anecdotal or part of the information gathered during clinical trials. They may of course be specific for the particular preparation being tested. In general they tend to be minor, occurring at about the same rate and of the same severity as those recorded for placebos. However there have been more serious side effects reported for some herbs. They are for the most part anecdotal in nature, are limited in numbers and a direct causal link is not often established. Validation of anecdotal reports requires that scientists have access to the offending preparation for proper identification and characterisation. If the herb has been wild harvested by the person admitted for emergency treatment it is unlikely to be readily available for analysis. It may be that the wrong plant has been used or that the right herb was harvested but contained toxic contaminants. Unless verified it cannot be categorically accepted that the herb was to blame but the doubt of its safety becomes a matter of record. If the preparation is a commercial one it is possible to do the requisite analysis but this does not always seem to have been carried out and many cases of reported serious events do not report that positive identification of the herbal preparation was made, that the preparation only contained the ingredients specified and that other contaminants (toxic plants, pesticides, heavy metals) were not present. It may therefore be difficult to interpret the reality of the danger of any herb it may have purported to contain. Mixtures of herbs have their own problems in that it may be difficult to identify which is the likely culprit or if a particular constituent is to blame. However there are certainly instances of herbs having caused serious health problems and idiosyncratic reactions can and do occur.

It remains possible also that although herbs used properly are safe there is scope for individual levels of tolerance to differ just as happens with pharmaceuticals. This is accounted for by the current state of health, immune status, liver function and genetic make-up of that individual. We must therefore remain open to the possibility that side-effects exist. The precautions will indicate if there have been any earlier reported problems with the use of this herb. If encountered in practice side effects should always be reported to relevant professional bodies of herbalists for evaluation and to enable a data base of adverse reactions to be established for future reference.

Interactions

This is an area of knowledge that is growing with the choice by the public to use both herbs and pharmaceutical medicines together for their health care. There are again the two types of scientific enquiry that have been undertaken to assess the possible interactions of herbs and drugs.

In vitro—Using isolated drug metabolising enzymes or drug transport carriers which represents potential or theoretical interactions. These potential interactions are not always borne out in vivo but indicate caution may be necessary.

In vivo—Real live studies are limited except for the most popular herbs e.g. Hypericum and Ginkgo and may be represented by anecdotal events which often have a number of variables for consideration e.g. pharmaceuticals being used concurrently, whether the product contained what was claimed or contained constituents not disclosed on the label.

Studies have also been conducted using herbs in:

• healthy volunteers simultaneously given probe drugs, known to be metabolised by a particular route, or
• clinical trials of populations who require the use of pharmaceuticals as well. The latter are more likely to accurately reflect interactions of significance. Established interactions are indicated by bold type face of named drugs under the given herb.

Given that popular herbs are reaching many people across all ages and in varying states of health there are remarkably few actual herb/drug interactions reported. This may reflect the true state of affairs or it may be a case of under-reported events. Also those herbs that are used less frequently may be associated with interactions not recognised and/or properly reported. Knowledge of the actions of pharmaceuticals and herbs being used concurrently may help in assessing if an interaction has occurred. Again any such possibility should be reported so that proper databases can be established.

A table of clinically relevant cytochrome P450 isozymes, their substrates, inhibitors, inducers and herbs with potential to affect them has been included for reference purposes in Appendix VI.

Historical uses

The long history attached to our materia medica has gone through and continues, to some extent, to go through fashions. Under this heading is given abbreviated lists of past usage of each herb, where known, and which may point to applications that are worth revisiting in the future.

Therapeutic index

Lists medical conditions for which whole herb or essential oil (if this is generally available) may be beneficial and in the main is based on traditional use or scientific evidence (in vivo).

Isolated constituents and in vitro uses are not generally included in the therapeutic index as their relevance to the practice of herbal medicine is uncertain. Exceptions have been made in two areas which are major problems today and for which new treatment strategies are constantly being sought, namely cancer and drug-resistant pathogens. A single asterisk (*) besides an entry denotes data for the whole herb, whilst a double asterisk (**) denotes information on isolated constituents of a herb, all based on in vitro research. The reason this has been done is to suggest possible treatment strategies for conditions for which current medication is inadequate. Herbs or their constituents that have shown the ability to effect cancer cell or pathogen survival, but for which clinical trials are lacking, may still have a supportive role to play in the overall treatment strategy as indicated by these studies.

Some applications for disease conditions suggested by in vitro studies on a herb has also been indexed to indicate a potential benefit and should not be taken as an accepted therapeutic effect of the herb without further evidence.

Actions listed for within each monograph appear in the index in bold.