• Pharmacognosy is the study of medicines from natural sources.

• Derives from the Greek words pharmakon = drug gnosis = knowledge

PHARMACOGNOSY

The term pharmacognosy was used for the first time by the Austrian physician Schmidt in 1811. Originally - during the 19th century and the beginning of the 20th century - "pharmacognosy" was used to define the branch of medicine or commodity sciences ("Warenkunde" in German) which dealt with drugs in their crude, or unprepared, form.

Crude drugs are the dried, unprepared material of plant, animal or mineral origin, used for medicine

•The American Society of Pharmacognosy defines pharmacognosy as "the study of the physical, chemical, biochemical and biological properties of drugs, drug substances or potential drugs or drug substances of natural origin as well as the search for new drugs from natural sources".

Although most pharmacognostic studies focus on plants and medicines derived from plants, other types of organisms are also regarded as pharmacognostically interesting, in particular, various types of microbes (bacteria, fungi, etc.), and, recently, various marine organisms.

• Includes the study of the proper horticulture, harvesting and uses of the raw medicinals found in nature, identification or authentication of crude drugs (using macroscopical, microscopical, radiological or chemical methods), bio-pharmacological and clinical evaluations.

• Interdisciplinary broad spectrum of biological and even socio-scientific subjects:

– Botany– Ethnobotany– Marine biology– Microbiology – Herbal medicine– Chemistry (phytochemistry)– Pharmacology– Pharmaceutics– Clinical pharmacy and pharmacy practice related to the evaluation

and clinical uses of medicines from natural sources, as well as their implications in health care management and public health.

• Academic contexts: study of pure, isolated substances of natural origin, the search for new drugs from natural sources

PHARMACOGNOSY TODAYPHARMACOGNOSY TODAY

From a practical perspective, studies in the field of pharmacognosy includes:

– Quality control identity, purity, consistency– Efficacy therapeutic indication, clinical studies,

pharmacological investigations– Savety Adverse reactions, contraindications,

precautions

Pharmacognosy can be divided into the fields of :

medical ethnobotany: the study of the traditional use of plants for medicinal purposes;

ethnopharmacology: the study of the pharmacological qualities of traditional medicinal substances;

the study of phytotherapy (the medicinal use of plant extracts); and

phytochemistry, the study of chemicals derived from plants (including the identification of new drug candidates derived from plant sources).

Ethnopharmacology

When studying the effectiveness of herbal medicines and other nature-derived remedies, the information of the traditional uses of certain extracts of even extract combinations plays a key role.

Most of the 2000 US companies making herbal or natural products[2] choose to market their products as food supplements that do not require substantial testing

Issues in Phytotherapy

The part of pharmacognosy focusing on use of crude extracts or semi-pure mixtures originating from nature, namely phytotherapy, is probably the best known and also the most debated area in pharmacognosy. Although phytotherapy is sometimes connected to alternative medicine, when critically conducted, it may be considered the scientific study on the effects and clinical use of herbal medicines.

• "active ingredient" phytopharmaceuticals constituent synergy for their activities.

• ginsenosides or hypericin may not correlate with the strength of the herbs.

• poorly characterized or while well-characterized will rely upon the synergy of otherwise weak principles.

• In phytopharmaceutical or herbal medicine the active ingredient may be either unknown or may require cofactors in order to achieve therapeutic goals.

• standardization to a marker compound. • companies use different markers, or different levels of the

same markers, or different methods of testing for marker compounds.

• Many herbalists believe that the active ingredient in a plant is the plant itself

ACTIVE CONSTITUENTS

STANDARDIZATION • Providing processed plant material that meets a specified

concentration of a specific marker constituent. • Plant constituents have synergy and even active constituent

concentrations may be misleading measures of potency if cofactors are not present.

• St. Johnswort is often standardized to the antiviral constituent hypericin hyperforin "active ingredient" for antidepressant use although there may be some 24 known possible constituents.

• A minority of chemicals used as standardization markers are known to be active constituents.

• Different compounds are chosen as "active ingredients" for different herbs, there is a chance that suppliers will get a substandard batch (low on the chemical markers) and mix it with a batch higher

QUALITY• Quality in crude drugs or plant medicines depends upon a variety of

factors: – genetically strong seed– correct species– maturity of the plant at harvest– good soils– air quality– Climate– organoleptic factors (intensity of color, flavor and odor)– storage after collection is a factor worthy of study.

• In modern times certain constituents are identified and measured. HPLC, GC, UV/VIS, AAS are used to identify species, measure bacteriological contamination, assess potency and eventually creating Certificates of Analysis for the material.

• In Germany, the Commission E has produced a book of German legal-medical regulations which includes quality standards

SAFETY"safe" potential dangers to considering the safety of crude drug a dangerous unknown.USDA scientist estimates the dangers of herbal medicine relative to other dangers in the United States as follows:

– Herbs 1 in 1,000,000– Supplements 1 in 1,000,000– Poisonous Mushrooms 1 in 100,000– NSAID's 1 in 10,000– Hospital Surgery 1 in 10,000– Car Accident 1 in 5,000– Improper Use of Medication 1 in 2,000– Angiogram 1 in 1,000– Alcohol 1 in 500– Cigarettes 1 in 500– Properly Prescribed Medications 1 in 333– Medical Mishap 1 in 250– Iatrogenic Hospital Infection 1 in 80– Bypass Surgery 1 in 20

• In a 19 year analysis of poison control in the U.S.:– 44.6% due to pharmaceuticals – 2.4% due to plants (includes exposure to poison ivy,

children eating houseplants and allergic responses). The vast majority did not involve herbal medicines.

– ± 8% of all hospital admissions are due to adverse reactions to synthetic drugs.

– Deaths or hospitalizations due to herbs are so rare that they're hard to find.

– The U.S. National Poison Control Centers does not even have a category in their database for adverse reactions to herbs.

• Hepatoxicity– where perhaps the strongest case against some herbs lies– the statistic show that over 80% of cases of fulminant

hepatic failure were due to poisoning by freely available non-prescription NSAID's.

– Not one case was due to ingestion of medicinal herbs.

• Poisonous plants :– Which have limited medicinal use are available only to

trained practitioners (Aconite, Arnica, Belladonna, Bryonia, Datura, Gelsemium, Henbane, Male Fern, Phytolacca, Podophyllum, and Veratrum)

– Secondly, are herbs with powerful actions, often causing nausea, sweating vomiting,

– Third are plants with specific toxicity like hepatotoxic pyrrolizidine alkaloids like Comfrey or Petasites.

– There are other plant medicines which require caution or can interact with medications including St. Johnswort or grapefruit.

HERB AND DRUG INTERACTIONS• Herbs and drugs have been combined for centuries

in Asia and Europe• The disrupted relationship between traditional herbal

medicine and pharmaceutical allopathic medicine in the United States

• Herbal safety show cases that may lack the appropriate pharmacokinetics to produce the adverse results inferred.

• A study of herb drug interactions indicated that the vast majority of drug interactions occurred in four classes of drugs with narrow therapeutic windows, the chief class being blood thinners, but also including protease inhibitors, cardiac glycosides and certain antibiotics like cyclosporin. Antioxidants interfere with chemotherapy

• St. Johnswort counteracts immunosupressive drugs and interfere with digoxin and protease inhibitors.

• Ginkgo biloba may have anti-platelet effects, although the results are not clear as it also contains flavanoids that improve blood function.

• Constituents of garlic, peppermint and milk thistle have been shown to have effects on the CYP3A4 enzymes in vitro.

• Many herbs that are listed as "potentiating" merely have an additive effect, and including laxative herbs as antagonistic to anti-diarrheal medications is tautological.

CONFUSION OF CONSTITUENTS WITH WHOLE PRODUCTS

• Crude drug constituents may have an opposite, moderating or enhancing effect.

• When any constituent is isolated it does not follow that its actions represent the whole herb.

• Ephedra has constituents that increase the heart rate and constituents that decrease it.

• The drug ephedrine only used the constituents that increased the heart rate and had side effects absent from the traditional preparation of the herb.

Natural products chemistry

Instead of studying compound mixtures (crude extract or partially purified, eg. by fractionation), this aspect of pharmacognosy concentrates on

isolated, pure compounds originating from nature. Most bioactive compounds of natural origin are secondary metabolites, i.e. species-

specific chemical agents that can be grouped into various categories . A typical protocol to isolate a pure chemical agent from natural origin is

bioassay-guided fractionation, meaning step-by-step separation of extracted components based on differences in their physicochemical

properties, and assessing the biological activity, followed by next round of separation and assaying.

The most common means for separation is high-performance liquid chromatography (HPLC), but other chromatographical methods, such as

thin-layer chromatography (TLC) are also used for these preparative purposes.

After isolation of a pure substance, the task of elucidating its chemical structure can be addressed. For this purpose, the most powerful

methodologies available are nuclear magnetic resonance spectroscopy (NMR) and mass spectroscopy (MS)

Loss of Species

• One major source of species loss is the rate of habitat destruction.

• Plant, animal and microbial species are themselves the sources for some of today's most important medicines and make up a significant proportion of the total pharmacopoeia.

• Scientists have analysed the chemistry of less than 1% of known rainforest plants for biologically active substances even smaller percentages of known animals, fungi and microbes.

• A high proportion of nonnative species seen as invasive (kudzu, Japanese knotweed, mimosa, lonicera, St. Johnswort and purple loosestrife) be harvested for the domestic herbal medicine market.

• Traditional Chinese Medicine crude drugs of plant and animal origin are used with increasing demand.

Sustainable Sources of Plant and Animal Drugs

• As species face loss of habitat or overharvesting, there have been new issues to deal with in sourcing crude drugs. These include changes to the herb from farming practices, substitution of species or other plants altogether, adulteration and cross-pollination issues.

• Pills and capsules are the preferred method of ingesting medication as they are cheaper and more available than traditional

The farming of medicinal species has difficulties :– One solution is to farm medicinal animals and plants as a

way of guaranteeing supplies as well as protecting endangered species.

– Farming alone can never resolve conservation concerns, as government authorities and those who use Chinese medicine realise.

– One alternative to farming involves replacing medical ingredients from threatened species with manufactured chemical compounds. Most TCM uses compounds which may act synergistically.

– Tauro ursodeoxycholic acid, the active ingredient of bear bile, can be synthesised and is used by some Western doctors to treat gallstones, but many TCM consumers reject it as being inferior to the natural substance from wild animals.