Secondary metabolites are compounds produced by plants that are important for the survival and propagation of the plants that produce them. Secondary metabolites serve as chemical signals enabling the plant to respond to environmental cues or functioning in the defense of the producer against herbivores, pathogens, or competitors. Other secondary metabolites provide protection from radiation from the Sun or assist in pollen and seed dispersal. They are produced at various sites within the cell and stored primarily within the vacuole. The three major classes of secondary plant compounds are alkaloids, terpenoids, and phenolics.
Compound Source Observation
Alkaloids
Morphine Papaver somniferum Analgesic (painkiller) (opium poppy)
Cocaine Erythroxylum coca (coca) Anesthetic in eye surgery and dentistry; often abused as an illegal substance
Caffeine Coffea arabica (coffee), Stimulant found in many Cannellia sinensis (tea), beverages and Theobroma cacao (cocoa)
Nicotine Nicotiana tabacum Stimulant; highly toxic, causing (tobacco plant leaves) harmful effects from cigarette smoking
Conine Conium maculatum Nerve toxin; killer of Socrates (poison hemlock)
Compound Source Observation
Strychnine Strychnine tree Potent nerve stimulant and convulsant
Tubocurarine Curare tree Used as a muscle relaxant during surgery; component of arrow poisons
Codeine Papaver somniferum Cough suppressant (opium poppy)
Atropine Hyoscyamus muticus Used in eye exams to dilate pupils (Egyptian henbane) and as an antidote to nerve gas and Atropa belladonna (belladonna nightshade)
Vincristine Catharanthus roseus Main treatment for certain (Madagascar periwinkle) kinds of leukemia
Quinine Cinchona officinalis Bitter flavor of gin and tonic; (quinine tree) used to prevent malaria
Terpenoids
Menthol Mints and eucalyptus tree Strong aroma; used in cough medicines
Camphor Cinnamomum camphora Component of disinfectants (camphor tree) and plasticizers
Compound Source Observation
Nepetalactone Nepeta catoria (catnip) Very attractive to cats
Digitalin Digitalis purpurea Cardiotonic used to stimulate (purple foxglove) heart action
Oleandrin Nerium oleander (oleander) Heart poison (similar to digitalin)
Hycopene Lycopersicon esculentum Red/orange pigment (tomatoes)
Rubber Hevea brasiliensis Component of rubber tires (rubber tree)
Taxol Taxus brevifolia Drug that inhibits cancerous (Pacific yew) tumors, especially of ovarian cancer
Phenolics
Salican Salix spp. (willow tree) Folk medicine against headaches and fever; precursor of aspirin
Salic acid Juglans (walnut husks) Main component of some tannins
Myristicin Manodora myristica Main flavor of the spice (nutmeg)
Rutin Fagopyrum esculentum Common
"bioflavonoid" sold (buckwheat) in
nutrition stores
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