Food Toxicology Learning Objectives • Understand the relationship between ecology and the human food chain. • Define ecological biochemistry. Natural in Plants and Fungi: • Explain biochemical adaptation and the roles of The Ecological Biochemistry of Food secondary compounds in plants. • Examine the impacts of plant toxicants in the human food chain. Food Toxicology • Survey examples of plant Instructor: Gregory Möller, Ph.D. toxicants. University of Idaho • Review a range of toxic plant-based supplements. • Review a range of 2 poisonous .

Food Toxicology Food Toxicology Ecology and The Human Food Chain Ecological Biochemistry • Ecology: the scientific study of the distribution and • Coupling of the observational science of ecology with abundance of living organisms and interactions the molecular science of biochemistry. between the organisms and their environment. • Ecological interaction in the food chain. – Derived from the Greek οικος (oikos, "household") and λόγος (logos, "study"); the "study of the household [of nature]". Animals • “Who eats who” and “what eats what” in the human food chain can be described as Plants Fungi “The Ecology of Food.” • Molecular level analysis of this “Ecology of Food” is an Protists Monera 3 aspect of food toxicology. 4

Food Toxicology Food Toxicology Ecological Biochemistry Biochemical Adaptation • Synthesis and transformation of chemicals in the • The metabolic flexibility of a living organism to fit into environment, as the result of biochemical processes a changing environment, improving chances for in an organism, to aid in species survival. survival and reproduction. • Includes: –Evolution 1. Biochemical adaptation. • Many generations. • . – Acclimatization. • Lifetime of an individual. 2. Detoxification. • Biodegradation, • Our challenge: decipher the biomineralization. strategy of the natural world. 3. Bioaccumulation, – Example: Toxic plants biomagnification. 4. Ecological biochemical 5 interaction. 6 Harborne

•1 Food Toxicology Food Toxicology Competitive and Symbiotic Interactions Toxins and Survival Strategy • Plant ↔ Plant ↔ Animal… • Organisms often synthesize or use toxins in their survival strategy. – Secondary plant compounds. – The most conspicuous non-event in the history of •Animal ↔ Animal… the angiosperms is the failure of and other – , toxins. to attack plants on a wide-scale (Feeny, 1975). • Plants dominate the landscape, hence plants must be “broadly repellent” to animals as food and “toxic” in the widest sense. • Overcoming the defense strategy of plants by insects and herbivores Monarch Butterfly and Milkweed is a part of their survival strategy.

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Food Toxicology Food Toxicology Secondary Plant Compounds: Phytochemicals Nitrogen Compounds

• Hypothesis: Number of Physiological activity developed in plants as survival mechanism. structures – Offensive and defensive biosynthesis 6,500 Toxic, bitter – Bio-chemical warfare(?) Amines 100 Repellent, hallucinogenic • • Palatability Amino acids 400 Many toxic • Variable structures, properties, MOA • Concentrations vary Cyanogenic 30 Poisonous (as HCN) - Part of plant glycosides - Stage of maturity - Species Glucosinolates 75 Acrid, bitter - Env. conditions

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Food Toxicology Food Toxicology Terpenoids Phenolics Number of Physiological activity structures Number of Physiological activity structures Monoterpenes 1,000 Pleasant smells Simple phenols 200 Anti-microbial Sesquiterpene 1,500 Some bitter & toxic lactones Flavinoids 4,000 Often colored Diterpenoids 2,000 Some toxic Quinones 800 Colored, sometimes toxic

Liminoids 100 Bitter

Cucurbitacins 50 Bitter & toxic

Cardenolides 150 Toxic & bitter

Carotenoids 500 Color 11 Harborne 12 Harborne

•2 Food Toxicology Food Toxicology Example: The Walnut Tree Example: The Walnut Tree • Allelopathy: “biochemical interactions between all • Leaching causes hydrolysis and types of plant” (Molisch, 1937). oxidation, releasing jugalone, • Since the time of ancient Greece, the walnut tree a powerful quinone herbicide. (Juglans nigra) has been observed to kill nearby OH O Juglans sp. vegetation. – Moderately toxic to some insects, Hydrolysis horses, dogs, humans. Oxidation – 1500s physician’s “Doctrine of Signatures” OHOGlc OH O • Walnut = brain Bound form Jugalone • Produces a bound form of of (5-Hydroxynaphthoquinone) a toxin, which deposits in nearby soil through , nut shells, stems and roots. Harborne 13 14

Food Toxicology Food Toxicology The Human Food Chain What Differentiates Nontoxic from Toxic? •DOSE Virtually all foods and food animal feeds contain – Sufficient concentration? some potential naturally-occurring toxicant. • Dose response curve: Where is NOAEL?

Phytohaemagglutinin: a toxic • HAZARD / RISK lectin in uncooked kidney beans – Minimized by crop breeding – Deactivated in cooking/processing – Modified by dietary habits – Genetic factors – Adaptation

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Food Toxicology Food Toxicology Impact: Plant Toxicants on Livestock Impact: Plant Toxicants on Human Health • Estimated $350-400 million loss • Consumption of toxin- annually to livestock producers contaminated meat – direct exposure to plant – Risk low – dilution –Death – Most large-scale events – Illness – clinical recognized and corrected – Loss in body weight – Reproductive failures –Abortions

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•3 Food Toxicology Food Toxicology Impact: Plant Toxicants on Human Health Plant Toxin-Contaminated Milk Wetzlich, 1991 • Consumption of toxin- • Excretion of plant toxicants into milk by lactating contaminated milk animals is minor when compared to other routes of – Risk low – dilution elimination. through bulk handling • Plant toxins have been detected in the milk of animals – Management practices of grazing on toxic plants large dairies • Human health risk is generally small for commercial milk because of diluting in bulk handling and controlled grazing. – Increased risk from animals raised in poisonous plant areas and where these animals are 19 J. Anim. Sci. 1990. 68:892-904 20 a sole source for milk.

Food Toxicology Food Toxicology Plant Toxin-Contaminated Milk Plant Toxin-Contaminated Milk • Milk is an emulsion of lipids in an aqueous solution • Plant toxicants excreted via milk: of . – Tremetol (or tremetone) in white snakeroot (Eupatorium • Virtually any plant toxin or metabolite that is rugosom) and rayless goldenrod (Haplopappus circulating in the body can enter milk. heterophyllus) – Pyrrolizidine alkaloids in Senecio, Crotalaria, – Most toxicants cross the mammary cell membranes by Heliotropium, Echium, Amsinckia, Symphytum (comfrey), simple diffusion, thus chemicals bound to plasma proteins, Cynoglossum (Hounds Tongue), and Festuca (tall fescue) associated with circulating lipids, or free in the plasma can cross through the mammary cells. – Piperidine alkaloids in Conium and tobacco • Lipo-proteineic “Blood-Milk Barrier” – Quinolizidine alkaloids in Lupinus – Basic compounds, such as alkaloids, can become – Glucosinolates in Amoracia (horseradish), Brassica concentrated in milk because milk, with a pH of 6.5, is more (cabbage, broccoli, etc.), Limnanthes (meadowfoam), acidic than plasma. Nasturtium (watercress), Raphanus (radish) and Thlaspi – Lipophilic compounds can also concentrate in milk. (stinkweed). 21 Wetzlich, 1991 22 Wetzlich, 1991

Food Toxicology Food Toxicology Human Health Risk Factors: Milkborne Toxins Impact: Plant Toxicants on Human Health • Susceptibility of infants and very young children • Consumption of toxin- – Dietary loading and immature systems contaminated eggs • Consumption of milk produced by lactating mothers – Risk low – little known who use potentially toxic herbal remedies transfer to egg – Not recognized as a • Availability of toxic plants to vector of toxin exposure grazing dairy animals due to commercial • Long-term health effects from production standards low levels of plant toxicants – Larger problem is • Consumption of milk from infectious individual animals grazing on toxic plants.

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•4 Food Toxicology Food Toxicology Plant Toxins in the Human Food Chain Eupatorium rugosum (white snakeroot) • Perennial herb • Eastern US, Mississippi and Ohio river valleys / Examples moist, shaded uncultivated • ‘Milk sickness’ • Early 1800’s – ¼ to ½ of deaths in IN, OH • Abraham Lincoln’s family

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Food Toxicology Food Toxicology Eupatorium rugosum (white snakeroot) Eupatorium rugosum (white snakeroot) • 1910: identified toxins: tremetol, • Risks tremetone - interferes with TCA – Milk – toxins excreted – cow not cycle and metabolism affected – not destroyed during • Still sporadic problem in rural areas pasteurization • Cumulative problem: fat soluble – Butter – fat soluble

– Meat – long T½ • Clinical signs – Weight loss, listlessness, weakness, tremors, collapse, death within days to weeks – heart, liver

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Solanum, Lycopersicon Food Toxicology , Lycopersicon Food Toxicology (nightshades, , , ) (nightshades, potato, eggplant, tomato) • Food / noxious weeds / • Toxins: , ornamentals / herbal anticholinergics, medicines – , tomatidine, • Annual or perennials , , • Over 100 species worldwide , • Poisonings in people – Heat stable – Consumption of berries – Flowers>sprouts>peel and – Consumption of tubers with eyes>shoot>tuber sprouts, leaves, stem – Increase with greening, decrease with maturity

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•5 Solanum, Lycopersicon Food Toxicology Food Toxicology (nightshades, potato, eggplant, tomato) Pyrrolizidine Alkaloids • Digestive and neurological • Genera: Senecio, problems Cynoglossum, Amsinckia, – , , abdominal Symphytum (comfrey) pain, • Hepatotoxic PA – Muscle tremors, staggering, – Meat residues weakness – Milk residues • Consumption of blighted – Honey residues potatoes by pregnant – Herbal teas, dietary women in Ireland – fetal supplements deformities • Risk: typically low – Teratogenic – Home slaughter –Chronic 31 32

Food Toxicology Food Toxicology Pyrrolizidine Alkaloids Pyrrolizidine Metabolism • Hepatotoxicity Mammals – Veno-occlusive disease Ester Retronecine HO H COH • Herbal teas OH2CO HO H2COH 2 • Wound healing – external Hydrolysis -2H use only (astringent) PA megalocytosis N N N • Dietary supplements – of hepatocytes (horse) Pyrrolizidine Alkoloid anticancer, cough remedy General Formula • Contaminant of cereal grains, bread products OH O Bound To Liver (Toxic) 4-Hydroxy-hex-2-enal

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Food Toxicology Food Toxicology Pyrrolizidine Alkaloids Pteridium aquilinum (bracken fern) • Mutagenic • Worldwide distribution • Teratogenic • Rhizomes – flour • Fetotoxic – Europe, New Zealand, Australia • Carcinogenic • Fronds (croziers) – Association between Senecio – Fresh, cooked, preserved and liver neoplasia in – Japan, Hawaii, Brazil populations of South Africa • Meat / milk contamination

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•6 Food Toxicology Food Toxicology Pteridium aquilinum (bracken fern) Herbs and Supplements • Toxin: ptaquiloside • 1994 Dietary Supplement Health – Carcinogenic and Education Act (DSHEA) • Esophagus, stomach, • Drug manufacturers white blood cells – Prove products safe – Esophageal tumors • DSHEA – Makes FDA prove products are • Japan unsafe – Takes years • Individuals searching for “complementary and alternative medicine” – 36% of adults – 19% - use natural products – 1997: $36 to 47 billion on 37 38 CAM therapies

Food Toxicology Food Toxicology Ephedrine Ephedra Replacements • December 2003 • Other stimulants – FDA banned use of ephedra as – Bitter orange (Citrus aurantium) weight loss aid • Synephrine – Steve Bechler, 23 yo MLB pitcher dies – Green tea extract • Previous 5 years • Caffeine + catechins – 14,684 adverse events – 18 heart attacks – 26 strokes – 43 seizures – 5 deaths

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Food Toxicology Food Toxicology St. John’s Wort (Hypericum perforatum) St. John’s Wort (Hypericum perforatum) • Used for centuries – mild to moderate depression • Potential problems • Second most popular herb – “…when using this product, one should avoid – Annual sales: $104 million prolonged excessive contact with sunlight…” • Many active ingredients – Interferes with metabolism of other drugs – Hypericin • Contraceptives – Hyperforin • Heart medication – Induction of the cytochrome P450 metabolic pathway

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•7 Food Toxicology Food Toxicology Plant Supplements to Avoid Plant Supplements to Avoid • Aristolochic acid • Chaparral • Lobelia • Germander (Aristolochia) (Larrea divaricata) (Lobelia inflata) (Teucrium chamaedrys) – Carcinogen, –Liver failure – Respiratory, low bp and HR, – Liver damage diarrhea, dizziness, death

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Food Toxicology Food Toxicology Plant Supplements to Avoid Plant Supplements to Avoid • Skullcap • Yohimbe bark • Kava root • Pennyroyal oil (Scutellaria lateriflora) (Pausinystalia yohimbe) (Piper methysticum) (Hedeoma pulegiodides) – Liver damage – Drop bp, heart arrhythmias, – Liver damage – Liver and kidney damage heart failure

Your head is affected most pleasantly. Thoughts come cleanly. You feel friendly...never cross...You cannot hate with kava in you." -Tom Harrison, Savage Civilization, 1937 45 46

Food Toxicology Food Toxicology Toxins Occurrence • Mushroom poisoning is caused by the consumption of • Occurs most commonly when hunters of wild raw or cooked fruiting bodies (mushrooms, mushrooms (especially novices) misidentify and toadstools) of a number of species of higher fungi. consume a toxic species. – The term toadstool is commonly given to poisonous mushrooms. • When recent immigrants collect and consume a • German Todesstuhl, death's stool poisonous American species that closely resembles • No general rule for distinguishing edible mushrooms an edible wild mushroom from and poisonous toadstools. their native land. – Most mushrooms that cause human • When mushrooms that contain poisoning cannot be made nontoxic by cooking, canning, freezing, or psychoactive compounds are any other means of processing. intentionally consumed by – Only way to avoid poisoning is to persons who desire these avoid consumption of toxic species. effects.

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•8 Food Toxicology Food Toxicology Physiological Effects of Mushroom Toxins Protoplasmic : ex. Cyclic Peptides USFDA/CFSAN • Protoplasmic poisons • Amanita, Galerina – Result in generalized destruction of cells, followed by organ • Conocybe, Pholiotina, Lepiota failure • Many associated with roots of trees • • and phallotoxins – inhibit Amanita phalloides – Cause neurological symptoms such as profuse sweating, (death cap) nuclear RNA polymerase – coma, convulsions, , excitement, depression, spastic colon synthesis • Gastrointestinal irritants • Delayed onset – Produce rapid, transient nausea, • Targets: GIT, kidney, liver vomiting, abdominal cramping, • 50-90% death rate for large dose and diarrhea • Disulfiram-like toxins 49 – Interact with alcohol 50

Food Toxicology Food Toxicology Poisoning by the Amanitins Neurotoxins: ex. and • Long latent period (range 6-48 hours, average 6-15 hours) during which the • Amanita, Tricholoma patient shows no symptoms. • Symptoms appear at the end of the latent period in the form of sudden, •Toxins: neurotransmitters severe seizures of abdominal pain, persistent vomiting and watery diarrhea, – Ibotenic acid (GABA derivative) extreme thirst, and lack of urine production. • If this early phase is survived, the patient may appear to recover for a short – Muscimol (false neurotransmitter) time, but this period will generally be followed by a rapid and severe loss of – Affects serotonin, noradrenalin, Amanita muscaria strength, prostration, and pain-caused restlessness. dopamine: similar to LSD (fly ) • Death in 50-90% of the cases from progressive and irreversible liver, kidney, cardiac, and skeletal muscle damage may follow within 48 hours • Onset: 30-90 min; Peaks: 2-3 hrs (large dose), but the disease more typically lasts 6 to 8 days in adults and 4 • Initial abdominal discomfort to 6 days in children. • Two or three days after the onset of the later phase, , cyanosis, and • Chief symptoms are drowsiness coldness of the skin occur. and dizziness, followed by a period • Death usually follows a period of coma and occasionally convulsions. If of hyperactivity, excitability, illusions, recovery occurs, it generally requires at least a month and is accompanied by enlargement of the liver. Autopsy will usually reveal fatty degeneration and delirium. and necrosis of the liver and kidney. • Fatalities rarely occur in adults 51 USFDA/CFSAN 52

Food Toxicology Food Toxicology Gastrointestinal Irritants Disulfiram-Like Toxins Coprinus atramentarius • GI Irritants: Many types • No illness results when eaten Inky Cap – Green Gill (Chlorophyllum molybdites), in the absence of alcoholic Gray Pinkgill (Entoloma lividum), Tigertop beverages (like Antabuse®) (Tricholoma pardinum), Jack O'Lantern (Omphalotus illudens), Naked Brimcap • Produces an unusual amino ( involutus), Sickener (Russula Omphalotus illudens acid, coprine (Jack o’lantern) emetica), Early False Morel (Verpa – Converted to cyclopropanone bohemica), Horse mushroom (Agaricus hydrate in the human body arvensis) and Pepper (Boletus piperatus), – Interferes with the breakdown of alcohol • Rapid onset – Consumption of alcoholic • Signs: vomiting, beverages within 72 hours after diarrhea – short lived eating it will cause , nausea and vomiting, flushing, • Rare fatalities: and cardiovascular disturbances 53 54 that last for 2 - 3 hours.

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