Botany Lecture 10: Plants are Chemical Factories

Dr. Z, Tennessee Tech

Secondary plant products

• not essential to plant survival, but have important plant functions (all are defense compounds)

• major categories:

  • alkaloids (most diverse)

  • glycosides

  • phenolic compounds

  • terpenes

Alkaloids

• bitter compounds affecting the nervous system if ingested

• common in herbaceous dicots and fungi

• caffiene, nicotine, cocaine, morphine, ephedrine

Caffeine

• stimulant increasing energy and motor skills

Nicotine

• alkaloid affecting the nervous system, addictive

Cocaine

• alkaloid with stimulant and anesthetic properties

Morphine

• pain-relieving alkaloid derived from opium

Ephedrine

• alkaloid used for respiratory issues

Glycosides

• compounds with sugar attached to active component, used in medicine

• cyanogenic glycoside (cyanide), radioactive glycosides and saponins (steroids)

  • toxic in many cases

  • birth control, heart medication

Cyanogenic glycosides

Release cyanide when metabolized, toxic.

Cardioactive glycosides

Steroids affecting heart function, used in medications.

Saponins

Toxic glycosides with medicinal properties.

Phenolic compounds

• phenolic acid, flavonoids, and tannins

• defense compounds against UV radiation and pathogens, parasites, predators

• widespread in plant foods

• bitterness and astringency

• colors (anthocyanins)

• affect the flavor and color of wines, react with oxygen (tannins oxidize)

Terpenes

• includes both primary and secondary metabolites

• aromatic compounds responsible for fragrance, taste, and pigment in plants

• protects from biotic stress, wards off pathogens and predators

• cannabis often contains medicinal terpene

• tea tree oil, thyme, sage, citrus all have high concentrations

Cannabis

Contains medicinal terpenes for therapeutic use.

Tea tree oil

High terpene concentration with antimicrobial properties.

Caffiene

• alklaloids: substances mainly produced by plants

  • discourage grazing animals

  • stimulates central nervous system

  • increase heartbeat, blood pressure, etc

• benefits:

  • increase in energy, motor skills

  • enhances pain relievers

• drawbacks:

  • insomnia, nervousness, addictive

Possible Benefits of Caffiene

• lower risk for Parkinson’s disease

• may lower risk for type II diabetes

• antioxidant effects of caffiene may help fight cancer, heart disease, and aging

Coffea arabica (Rubiaceae)

• Coffee plant/berries

• native to Ethiopia

• used in religious ceremonies, coffeehouses established, and eventually became focal point for political thought and music

Camelia sinensis (Theaceae)

• Tea plant, a source of various tea types

• tree/shrub from Tibet, India, China, etc

• pruned constantly to encourage shrubby growth

• terminal bud + two leaves are harvested

Black tea

• dried for 12-24 hours

• then fermented

Green tea

• unfermented tea

• health benefits.

Oolong tea

• Semi-fermented tea

• between black and green.

White Tea

• only leaves with buds covered in tiny trichomes

• fancy

Green Tea Drinkers

• have low rates of cancer

• polyphenols interfere with tumor growth

• contains caffeine and theophylline, stimulants

• tannins: staining compounds, anti-herbivory chemicals

“theol”

aroma of tea is due to _____ essential oil

Theobroma cacao (Chocolate)

• Cocoa plant

• central and south America

• Christopher Columbus

• not made into candy until 1847

caffeine; theobromine

chocolate contains both _____ and _______ as stimulants

bitter

theobromine gives the unprocessed cocoa bean a ____ flavor

Chocolate

• cauliflorous: flowers directly on tree

• 4-6 months to mature

• 20-40 seeds (beans)

• surrounded by sweet white pulp (white chocolate), removed before processing

• seeds ferment for 1 week “sweating”

• roasting

• seeds crack, release 2 cotyledons

• ground into oily paste

Cocoa butter

____ _____ (oils) removed to make white chocolate

Spices

• aromatic fruits, flowers, bark, or other plant parts of tropical origin

• used nutritionally insignificant quantities as a food additive and flavor, color, or as a preservative that kills harmful bacteria or prevents their growth

• antibacterial, antimicrobial

Herbs

• aromatic leaves or seeds from plants of temperate origin

• an herb is a plant that is valued for flavor, scent, medicinal or other qualities other than its food value

• used in cooking, as medicines, and for spiritual purposes

Essential oils

• Volatile compounds contributing to plant aroma

• perfumes, medicines, flavoring

• secondary plant product: occurs in plants but is not critical to metabolic function

• terpenes: most essential oils are found in this class of organic compounds

Basil (Ocimum basilicum)

• Lamiaceae: the mint family

• originally native to Iran, India and other tropical regions of Asia, having been cultivated there for more than 5,000 years

Spearmint (Mentha sp.)

• Lamiaceae: the mint family

• some invasive

• spread via stolons

• many uses, many flavors

Rosemary (Rosmarinus officinalis)

• Lamiaceae

• woody, perennial herb with fragrant evergreen needle-like leaves

• native to the mediterranean region

Dill (Anethum graveolens)

• apiaceae: carrot family

• dill originated in Eastern Europe

• finely dissected leaves used as flavoring

Coriander (Coriandrum sativum)

• annual herb in the Apiaceae

• native to southern Europe and North Africa to southwestern Asia

• cilantro

Fennel (Foeniculum vulgare)

• Apiaceae

• hardy, perennial herb

• considered indigenous to Mediterranean

• widely naturalized in many parts of the world

Chammomile (Matricaria recutita)

• asteraceae: daisy family

• best known for their ability to be made into a tea

• commonly used to help with sleep and stomach ailments

• finely dissected leaves

• fruity scented

Cinnamon (Cinnamomum zeylanicum)

• fragrant bark

• Lauraceae

• Native to India and Sri Lanka

Spices: Black Pepper (Piper nigrum)

• Piperaceae

• India and East Indies

• tropical vine

• white pepper is harvested from mature fruits on the vine

• black pepper is harvested early, dried, turn black

• volatile oils escape quickly upon grinding

Spices: Nutmeg (Myristica fragrans)

• Myristicaceae

• red aril around the “pit” used for mace

• pit contains a seed that is used as nutmeg flavoring

• mace

Ginger (Zingiber officionale)

• grown in Jamaica

Turmeric (Curcuma longa)

• used for its yellow dye

• flavor

• yellow mustard, curry powder

• curcumin: powerful antioxidant

Capsicum sp. (Solanaceae)

• hot chilies

• originated in the New World

• 7 different alkaloids make peppers spicy

• contains capsaicinoids: most common in peppers

Scoville Heat Units

• used to judge pepper spiciness

• dilution of pepper until panel of testers can detect the spiciness

• amount of dilution: Scoville Unit

Capsaicin

• triggers heat-sensitive nerve fibers in our mouths to create “hotness”

Pepper X

World's hottest pepper as of 2023.

Age of Herbals

• Renaissance Period

• Herbalism: use of plants as medicine

Hippocrates

• Father of medicine

• promoted natural remedies/rest because diseases have natural causees

Dioscorides

• military physician

• Author of 'De Materia Medica', a key herbal text still used as reference

Modern Prescription Drugs

• herbalism declined in the 18th and 19th centuries

• pharmaceutical sciences isolated compounds

  • opium from poppy

  • aspirin from willow

• 25% of medicines today contain plant compounds

• herbal remedies sold as a dietary supplement

Herbal Medicine Today

• 75-90% of world relies on herbal remedies as their only healthcare

• China leads the world in use of herbal medicine in modern healthcare

• ex: India’s Ayurvedic medicine

• Native American medicine men (and women)

• Amazonian Shaman

Foxglove (Digitalis purpurea)

• treats heart conditions with glycosides

• decrease edema, increase kidney function

Willow (Salix sp.)

• aspirin

• salicylic acid produces salicin (glycoside)

• anti-inflammatory, antipyretic, analgesic

Ephedra sp.

• ephidrine

• mormon tea

• alkaloid stimulates central nervous system, increases heart rate, blood flow

• overdoses dangerous, FDA banned

Madagascar periwinkle

• Catharanthus roseus

• tropical herb

• Vinblastine and vincristine alkaloids used to treat leukemia and lymphoma

Yew

• Taxus sp.

• Taxol, a terpene, obtained from bark of tree

• interferes with cell division, antitumor properties

Psychoactive Drugs

• affect the central nervous system

  • influence neurotransmitters

  • mimic neurotransmitters

  • may be inhibitory or excitatory

• stimulants, hallucinogens, or depressants

  • medicinal dose

  • psychoactive dose

  • toxic dose

Stimulants

• excite, enhance mental alertness and activity

• reduce fatigue and suppress hunger

• ex: cocaine, caffeine

Hallucinogens

• changes in perception, thought or mood

• induce “dream-like” state

• ex: peyote, marijuana, LSD

Depressants

• dull mental awareness, reduce physical performance, induce sleep or trance-like state

• ex: morphine, heroin

Narcotics

• Traditional: drug that induces central nervous system depression, induces numbness, lethargy, and sleep

• Contemporary: any drug that is dangerously addictive

  • psychological dependence, physiological dependence, and tolerance

• affect mesolimbic dopamine system (the brain’s reward circuit) over time = tolerance

alkaloids

• psychoactive plants usually have _____ as the active compounds

Poppy (Papaver somniferum)

• opium

• annual herb, capsule sap, milky latex

• pain reliever, dissolved in alcohol

• 20 alkaloids: source of morphine and codeine

Cocaine (Erythroxylum coca)

• naturally has same stimulant level as caffeine

• shrub

• alkaloid

• leaves chewed with lime (ash)

• used by Spanish explorers to increase slave productivity

Peyote (Lophophora williamsii)

• Hallucinogenic cactus used in Native American rituals

• 30 alkaloid compounds

• mimics a neurotransmitter

Kava (Piper methysticum)

• depressant beverage made from roots

• Piperaceae family

• lactones active component

• liver toxicity, hepatitis due to mode of preparation

Mad Honey

• Eriaceae

• grayanotoxins in pollen end up in honey

• used hallucinogen and in traditional medicine

Poisonous Plants Overview

• many plants can adversely affect the health of humans and other animals

• plants are “sitting ducks”

• some plants fatal depending on dose

• used as medicines, insecticides, hunting

• alkaloids and glycosides most common

Strychnine

• alkaloid from Asian tree

  • Strychnos nux-vomica

    • stimulates central nervous system

    • induces muscle spasms, convulsions

    • used in rodent poison today

Curare

• used in hunting game, poison arrows

• Strychnos toxifera

  • 70 different species used, bark of 2 trees most common

  • induces paralysis quickly: tubocurarine

  • relaxes muscles by blocking nerve impulses

Apiaceae

• carrot family

• Conium maculatum: poison hemlock

• Cicuta sp: water hemlock

• 2 of the most poisonous plants!

• Socrates killed with conium

• Alkaloid

• kills by causing paralysis

Milkweeds (Asclepias sp.)

• milky sap, opposite or whorled leaves

• umbles of flowers, fruit a capsule

• Galitoxin: resinous toxin

• Cardioactive glycosides

• livestock and humans easily poisoned

• monarch butterfly caterpillars feed exclusively on milkweed

Nerium Oleander

• one of deadliest shrubs

• all parts of the plant are poisonous

• 50 toxic compounds

• Cardioactive glycosides, oleandroside, nerioside

• burning branches releases toxic smoke

• people died from roasting hotdogs on green oleander sticks

Yew (Taxus sp.)

• hedges, shrubs

• chemotheraputic

• taxine arils found in all parts of plant except for red aril

• dizziness, dry mouth, heart pumps erractically

• seeds can be fatal to a small child

Lily (Liliaceae family)

• contain deadly poisons

  • glycosides and saponins

  • vomiting, diarrhea, burning sensation

  • cardiac glycosides slow heartbeat

Poinsettia (Euphorbiaceae)

• milky latex, sap

• irritation to skin and mucus membranes

• castor bean: seeds can be highly toxic

• ricin: most deadly plant poison, due to kidney failure

Plants that cause Mechanical Injury

• plants can puncture skin via spines, thorns, prickles, burrs, or hairs

• Cactaceae

  • spines: modified leaves

  • minute hairs: glochids

• Urticaceae: stinging hairs

  • inject toxins under skin

  • contains histimine-complex causing allergic reaction

Plants that cause Mechanical Injury: Photosensitivity

• UV light exposure causes burns

• St. John’s Wort: hypericin

• swelling, irritation

• Euphorbiaceae: latex can burn the skin

• used to brand cattle

Insecticides from Plants

• plants produce many secondary compounds

• reduce palatability of plant to insects

• 2 most important:

  • Pyrethrum

    • powder made from Chrysanthemum flower heads

    • nerve poison, paralyze household insects

  • Rotenone

    • derived from roots of legumes

    • used to stun fish

    • widely used garden insecticide

Contact Dermatitis

• hypersensitivity triggered by the immune system responding to harmless substance

• Toxicodendron radicans

• T. quercifolium: oak

• T. vernix: sumac

• Urushiol: oily resin that bonds to proteins in skin

  • one drop causes dermatitis in 500 people

  • long-lasting 100 years!