Samenvatting
Summary Herbal Medicine lectures
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- Rijksuniversiteit Groningen (RuG)
Samenvatting Herbal Medicine
[Meer zien]Voorbeeld 4 van de 44 pagina's
Voorbeeld 4 van de 44 pagina's
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Door: jessesmid • 1 jaar geleden
Voorbeeld van de inhoud
Herbal Medicine07/06/2022 – General introduction
Pharmacognosy: science of biogenic or nature-derived pharmaceuticals and poisons (natural
products) > healthcare and therapeutic-oriented
Worldwide around 370.000 plant species, > 50.000 used for medicinal purposes.
About 50% of newly introduced drugs in western countries over past 70 years were of
biogenic origin. Phytomedicines and botanical food supplements (herbal medicinal products
HMPs). Typical natural products are used in labs as probes for many targets to understand
cellular processes (often strongly acting with specific mechanism).
Organic synthesis is the preferred route for many compounds originally obtained from
biogenic sources (relatively simple small organic molecules). Complex structures are still
obtained from biogenic origin. Revival of interest in natural products in both industry and
academia. Ethnobotany and ethnopharmacology important.
Plant-derived drugs:
Pure chemical entities (API, licensed drugs)
- Isolated natural products
- Semi-synthetic derivatives of natural products
- Synthetics based on natural product template
Botanical drugs (from specific medicinal plant parts)
- Herbal medicines (raw materials, extracts, HMPs, phytomedicines)
Isolated natural products:
- Morphine from opium poppy (Papaver somniferum): analgesic
- Digoxin (and other digitalis glycosides) from foxglove (Digitalis species): heart failure
- Quinine from bark of Cinchona species: antimalarial
- Vincristine, vinblastine from Madagaskar periwinkle (Catharanthus roseus):
anticancer
- Atropine from deadly nightshade (Atropa belladonna): anticholinergic
- Paclitaxel from Pacific yew (Taxus brevifolia): anticancer
- Galantamine from Galanthus and Leucojum species: cognitive disorders, Alzheimer
Semi-synthetic derivatives:
- Podophyllotoxin > etoposide (anticancer lung, testicular, lymphoid), rhizome of
Podophyllum peltatum L.
- Artemisinin > arteether (antimalarial), aerial parts of Artemisia annua L.
- Camptothecin > topotecan (anticancer) > bark and stem of Camptotheca acuminate
Template for synthetics:
- Atropine
- Morphine
- Cocaine
- Tubocurarine
Supply problems: sustainability
- Environmental (climate related, political situation)
- Plant related (slow growth, cultivation problems)
- Isolation and purification (low conc, many closely related structures)
Possible solution for supply problems:
- Other plant sources (chemosystematics)
- Selection: high-producing plants (metabolic pattern)
- Use of more abundant precursor (derivatisation)
- Biotechnology: plant cell/tissue cultures, heterologous expression systems (E. Coli)
- Organic synthesis
,Examples:
- Paclitaxel (taxol): pacific yew (Taxus brevifolia) > European yes (Taxus baccata >
Baccatin)
- Podophyllotoxin: may apple (Podophyllum peltatum) > cow parsley (Anthriscus
sylvestris)
Use of herbal medicines:
Strongly culture dependent. Considerable differences between countries in acceptation and
use. The WHO says around 80% of the world population accounts on herbal medicines.
Synthetic drugs may be too expensive or are unavailable. Non-western world like traditional
Chinese medicine (TCM) etc. Western world use of herbal preparation (traditional) and
herbal medicinal products use with (some degree of) scientific proof (phytotherapy).
Early 19th century: awareness that pharmacological properties of plants are due to specific
molecules. Isolation of morphine from poppy by Sertürner.
20th century: enhanced perception of use of plant-derived compounds as medicines. After
WW II knowledge expansion of plant constituents, biosynthesis, pharmacology > paclitaxel,
artemisinin, galanthamine. Large scall screening programmes (marine organisms), but also
OMICS. Interest in science-based herbal medicinal products.
Medicinal plant drug discovery: increased recognition
of plants as source of potential drug leads, starting point
ethnobotanical use. From basis preclinical research to
clinical trials.
Botanical drugs: derived from a plant and transformed
into a drug by drying. Obtained from a plant, but no
longer retains the structure of the plant or its organs (oils,
gum, resin, balm). Isolated pure natural products are not
botanical drugs.
Binomial nomenclature of plant names:
Papaver somniferum L. (opium poppy)
- Genus with species name (italic) plus authority (abbreviated)
- Linnaeus (first description of the species)
(Chemo)taxonomy and (chemo)systematics
Science of naming organisms and correct integration into existing
system of nomenclature. Based of taxa (singular: taxon), hierarchic system, relationship.
Chemosystematics: closely related plants contain similar constituents
Focus in pharmacy on evolutionary higher plants; the seed-bearing plants (angiosperms and
gymnosperms).
Photosynthesis: pyruvate and acetyl coenzyme A are key intermediates between primary
and secondary metabolism.
Plant metabolites:
- Primary: essential to the functioning of the plant, involved in
growth/development/reproduction, carbohydrates/AA/proteins/lipids/nucleosides
- Secondary: ecological role (toxins), e.g. flavonoids, lignins, aromatic alkaloids,
terpenoids, alkaloids, polyalkalides, fatty acids.
Pyruvate and acetylcoenzyme A are key intermediates between primary and secondary
metabolism.
,Typical plant constituents (pharma and food):
Isoprenoids (terpenoids), phenolic compounds, essential oils, glycosides, alkaloids,
carbohydrates (mono-, oligo-, polysaccharides), fats.
Ethnobotany, ethnopharmacology:
Traditional medicine used for novel drug development.
Ethnobotany: study of relationship between humans and plants in all its complexity
Ethnopharmacology: interdisciplinary research field focusing on traditional medical systems
and other empirical knowledge throughout the world
Bioprospecting: focus on development of new drugs for huge markets in northern
hemisphere
Convention of Rio:
Who benefits from the exploration and exploitation of natural sources? Provider (state,
people) are often lower income countries, researchers are often from richer countries, no
colonialism! Ethnopharmacological research using the biological resources of a country is
based on international and bilateral agreements and permits. Countries that provide
resources have well-defined rights, mutual responsibilities made clear, sharing benefits.
Story of curare: early explorers documented use of curare (tube-curare from bamboo, pot-
curare from calabash) as arrow poison by South American tribes.
Tubocurarine and peripheral muscle relaxants:
- Neuromuscular blocking drugs (anticholinergics)
- Peripheral muscle relaxants
- Quaternary ammonium compounds (only active when administered parenterally)
Oriental (Asian) forms of traditional medicine:
- Traditional Chinese medicine (TCM)
- Ayurveda, Unani – India
- Kampo – Japan
- Jamu – Indonesia
TCM:
Stretches back over 5000 years. Philosophically based, holistic approach (looking at the
whole body, balance and harmony very important). Food and medicine became interrelated.
In the 20th century TCM came under attack from Western influences, however TCM
reinstalled.
Current TCM: herbal medicine, acupuncture, cupping,
moxibustion, tui na massage, food.
Qi I the essential life force, vital body energy. Balance
between yin and yang. Five elements theory; fire (heart),
wood (liver), earth (spleen), metal (lungs), water
(kidneys).
Methods of diagnosis: examination of the tongue, pulse
diagnosis, palpitation of internal organs, massage, and
interviewing.
, Treatment examples:
TCM recipes: rectify harmony, restore qi and yin-yang balance. Mixture of mild and strongly
acting plants, often contain many different plants and plant parts. Processing of some raw
material, also raw materials and animal and mineral origin.
Around 100 monographs of TCM plants in Ph. Eur.
Concerns about TCM: mixture of many plants (may cause interactions), contamination
reported (with heavy metals, synthetics, designer drugs, toxic plants, microorganisms,
radionuclides), may contain (parts of) protected animals (rhinoceros, tiger penis, bear bile,
seahorse).
Vietnamese Traditional Medicine (VTM):
Acupuncture, coin rubbing, massage. Integrated healthcare. Based on TCM with âm and
du’o’ung, and khí. Mostly used in rural areas. Government stimulates use and further
development of VTM.
Kampo – Japan:
Acupuncture, acupressure. Typical kampo formula contains 5-9 herbs. Integrated in
healthcare system, 75% of Japanese medical doctors prescribe Kampo. Regulation of
traditional herbal medicine products in Japan.
Ayurveda – India:
Holistic, life force, five elements, opposing forces of ‘humors’ (tridosha).
Prana: life energy
Bhutas: five elements
Tridosha: vatta, pitta, kapha
Life style, food, and herbs. Medicinal plants for oral, massage, steam baths, enemas, and
nasal lavages. Popularity in Western countries is growing. E.g. Azadirachta indica (neem).
Jamu – Indonesia (Malaysia, Singapore):
Originally from Java. Illness is imbalance of the body. Jamu preparations are essential
supplements and are preventive and curative. Jamu medicine, freshener, and cosmetic.
From jamu gendong > obat herbal terstandar > fitofarmaka. Safety problems, poor quality,
aflatoxins, and microbial contamination.
Complementary and Alternative Medicine (CAM):
Therapies, medicines and diagnostic treatments without generally accepted scientific proof of
efficacy and safety. This includes acupuncture, chiropractic, osteopathy, hypnotherapy,
reflexology, but also anthroposophy, aromatherapy, homeopathy.
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