Poisonous and Medicinal Plants Flashcards
Physiological effects, most from secondary metabolites, are from what?
- Chemical compounds that have a biological effect on another organism
In human use, plants with a biological/physiological effect are usually what categories?
- Poisons
- Medicines
- Hallucinogens
- Stimulants
- Categories do overlap
Why are plants rich in bioactive compounds?
- Production of chemicals have metabolic costs
- Plants are immobile
- Plants produce many chemicals for ecological functions
- Defense
Why do plants contain many toxic chemicals?
- Defense
- Plants are great chemists
- Produce groups of similar compounds, some found in many plants
Many bioactive plant compounds are what?
- Alkaloids
Alkaloids
- contain nitrogen in ring structure
- approx. 6000 known
- Sporadically distributed in flowering plants
Poison
- Substance that causes structural or functional damage by chemical action
Curare arrow poisons
- South America
- Chondodendron tomentosum, Menispermaceae
- Extracted from bark and stem
- Tubocurarine, alkaloid
- Muscle relaxant action
- Applied to use in surgery
Castor Bean
- Ricinus communis, Euphoribiaceae, spurge family
- Common oriental plant
- Has ricin
- Most toxic natural toxin
- Used as laxative
- Used to assassinate Bulgarian dissident Georgi Markova
Georgi Markova
- Bulgarian dissident
- Assassinated in 1978 w/ castor bean oil
- Poison applied from umbrella tip
What is the most toxic natural toxin?
- Castor bean oil
Ricin
Ribosome inactivating protein from ricin seed
- Stops protein synthesis in intestine
- In castor bean oil, act as laxative
Death camas
- Zigadenus venenosus, Lilliacea, Lily Family
- Creamy colour flowers
- Contain alkaloids
- Local, grows in same habitat as common camas
- Deadly to humans and livestock
Common Camas
- Camass quamash
- Purple blue and major food source of local Natives
- Grows in same habitat as poison death camas
Poison oak
- Toxicodendron diversilobum, Anacardiaceae, sumac family
- Leaves w/ distinct sheen
- Common in California, coming here though
- Oily compound urushiol causes dermititis
Urushiol
Oily compound in poison oak that causes dermatitis, sometimes severe
Rhododendrons toxins
- Rhododendron spp., Ericaceae, Heath family
- Abundant ornamental plants
- Grayantoxin found in leaves, flowers, pollen, nectar
- Affects heart, not often fatal
- Mad honey
‘Mad Honey’
- Made from toxic rhododendron pollen
Grayantoxin
- Found in leaves, flowers, pollen, nectar of rhododendron plants
Malaria, quest for cure
- 2012 200million people diseased, 600,000 deaths in sub-saharan africa, mostly young children
- Gates Health foundation spent 2 billion to eradicate by 2040
- Needs pyrethroid insecticides, nets, medication
Malaria
- Debilitating disease caused by Plasmodium parasite transmitted between people in blood carried by mosquitos
History of Malaria Medication
- 1692 Spanish viceroy in Peru treated wife’s malaria w/ Quechua Indian medicine quina quina
- Tree brought to chincon estate in Spain
- Shipped cure to Europe by end of 16th century
- Forests in SA logged for cinchona tree
- Grown in British gardens in India in 1800’s
- Dutch cultivated in Java, gained domination of production
Historical figure known to have died of Malaria
Alexander the Great
Clements Markham
- British plant hunter
- Successfully grew cinchona tree, malaria cure, in India
Quina Quina
- Bark of Cinchona spp. Rubiaceae, coffee family
- Active ingredient, quinine, alkaloid
- Bitter flavour, tonic in gin and tonic
- Malaria treatment when artemisinin not available
WHO in 2006 recommends what as treatment for malaria when what is not available?
- Recommends Quina Quina
- When Artemisinins not available
Artemisinins
- Isolated from Artemesia annua, Asteraceae, sunflower family
- Sesquiterpene lactone, not an alkaloid
- Sweet wormwood, herb used in Chinese medicine
- Best action against plasmodium/malaria parasite
Who discovered and developed Artimisinins?
- Chinese chemist, Youyou Tu in 1967
Youyou Tu
- Discovered Artimisninins
- Sent to coast to look for malaria cure in 1967
- Screened 2000 plus chinese medicinal recipes
- Nobel Prize in Physiology or Medicine, 2015
Development of Artemisinins
- Youyou Tu found effective Chinese medicine recipe from 17th century
- Human trials in 1972
What percentage of medicinal compounds currently used are derived from plant origin and how many of these contain ingredients still obtained from plants?
- 75% derived from plant origin
- 25% of those still use plant ingredients today
What cultures use plants as medicines?
- All cultures
What are the basic categories of plants for medicines?
- 352, 000 angiosperms, gymnosperms, non-vascular plants, fungi
What are the oldest written evidence in existence of plants as medicine?
- Sumerian clay tablet, 4000 years old, 12 recipes and 250 plus plants
- Chinese herbal text Pun-tsao, attributed to Sheng Nung, 4500 years ago
- Ebers papyrus of Egypt, 3500 years old, 700 plus plants
- Holy Hindu Veda epics in India
- Bandanius manuscripts, Aztec, recorded in 1592
- Greek and Roman, De Materia Medica by Dioscorides, 1st century
How many herbs are still commonly used?
- 250 herbs
Role of plants in medicines
- Used as herbal medicines
- Based on ethnobotanical knowledge
- More extensive in developing countries
- Need for new drugs, source of pharmaceutical chemicals
Features of the most useful medicinal plants
- Contain unique compounds
- Rich in a particular compound
How drugs from plants are discovered?
- Define a target biological activity against an illness/parasite/disease
- Select plants to test
- Collect plant samples
- Bioassay plant extract for activity
- Isolate active component
- Further screen with testing chemical analogs
Pharmacocnosy
- Selecting plants to test for drugs
- Search cultural knowledge
- obeserve animal use (pregnant elephant eating particular leaves)
Isolating active component from plant extract
- Separate into fractions by chemical properties
- Screen fractions for activity with bioassay
- Identify active compound by instrumental analysis
Attributes of good drug chemical?
- highly specific to target
- low toxicity
What is the rate of success in finding new drug from natural sources?
- 60% of cancer drugs have natural origins
For a specific target, how many samples yield a commercial drug?
- 1 in 250,000
For a specific target, how many samples are promising, continue to trials, and are tested to become a drug? Time frame/
- 1:10,000 shows promising activity
- 1:10 continue to clinical trials
- 1:10 tested to become drug
- Time frame 8-15 years
Improvement in instrumentation and technical automation in screening has not resulted in dramatic increase in finding drugs, True or False?
True
Willow Bark
- Salix alba, Salicaceae, willow family
- Salicin, phenolic glycoside, also occurs in other plants
- Makes aspirin
Aspirin
- From acetylsalicylic acid, willow bark
- less stomach irritation
- Reduces pain and inflammation
- other medicinal applications
- Plant signal compound
Pacific Yew Tree
- Taxus brevifolia, Taxaceae
- Taxol from bark, complex terpene
- Used against ovarian, breast and other cancers
- Acts on dividing cells
Snakeroot
- Rauwolfia serpentina, Apocynaceae, dogbane family
- From India, used by mongoose?
- Reserpine, and other alkaloids
- Reduces blood pressure
- Calming effect
- Treats schizophrenia
St. John’s Wort
- Hypericum perforatum, Guttiferae
- Hypericin, complex phenolic
- Photosensitizer and antiviral effect
- Popular as natural anti-depressant
Periwinkle
- Catharanthus roseus, Apocynaceae
- Alkaloids vinblastin and vincristin
- Used against childhood leukemia
