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The Pathophysiology of Poisonous Plant Intoxication

Bryan L. StegelmeierJanuary 25, 2010

ADVS 5860

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Lecture Outline

Introduction Aristolochia spp. Larkspur

DefinitionsMechanism of ToxicitySpecific Tissue Toxicities

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Aristolochia tomentosa

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Germany 1950’s

Endemic Uropathy 1980’s

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$85 Billion in 2007

Unregulated (Hatch Act)

Unproven efficacy or safety

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Aristolochia fanchi substituted for Stephania tetrandra Chinese herb ‘Mu Tong’

Weight loss herbal product

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20X Incidence

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Recommended it be listed as a known human carcinogen

Dose?Risk of exposure?

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Larkspur (Delphinium spp.)

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5-10% Death loss

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Larkspur Toxins

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Striated Muscle Toxins•Larkspur (MLA block AchR)

•Monkshood (Aconitum inhibits Na channels)

•Botulism (cleaves synaptobrivin, syntaxin and SNAP-25 blocking cholinergic tx)

•Tetnus (tetanospasmin blocks glycine inhibition)

•Cardioglycosides (Inhibits Na/K ATPase enzyme)

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MLA mechanism of action

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Knowing it is poisonous is not enough.

TreatmentSelect resistant animalsMedical applications

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Definitions

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Physiologic Response to Insult

Molecular Response No change Molecular

damage Repairable or

Permanent damage

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Tissue Responses

No ChangeLoss of functionInflammation Rubor Calor Tumor Dolor Loss of Function

NecrosisHyperplasiaNeoplasia

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Animal Responses

No changeSick- diseaseAttitude AppetiteWeightOrgan or system specific changes (Reproduction, Respiration, Cardiac Function, Hematologic Function, Immune Function, Urinary Function, Gastrointestinal Function, Musculoskeletal Function, Endocrine Function, Neurologic Function, etc)Death

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Herd Responses

Stocking RateEconomic, Emotional, and Physical Factors

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Conclusions

There are about 10-20 tissue and animal specific responses and thousands of diseases

Many diseases cause similar responses; few produce specific or pathognomonic lesions.

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Direct vs Indirect toxicity

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Mechanisms of Action

Mechanical Injury: Various grasses- barley,

foxtails etc- foreign body abscesses, stomatitis, and dermatitis

Cocklebur- gastric obstruction

Turkey mullein (Eremocarpus setigerus) phytobezoars and phytoconcretions

Oxalate crystals (Ca oxalate causing cellular damage like nephrosis)

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Local irritant

Contact dermatitis-urushiols, Urtica spp., Stinging treesStomatitis/Gastritis-tannins, phenolic, astringents, saponinsOxalates: Dumb cane (Dieffenbachia sequine)Proteolytics- bromelain and papain, lectins

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Receptor mediated:

AchR- Larkspur alkaloidsNicotinic AchR- Lupine, Tobacco, ConineSteroidal receptors-Veratrum ICA pine needles

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Enzyme inhibition:

Glycosidase inhibitors-swainsonine, calystegins, castanospermineTrypsin and amylase inhibitors- soybeans, peas, potatoes, barley, alfalfaDicumarol- vitamin K antagonistMitosis inhibition- S and prophase arrest of PA’s, metaphase arrest of lupinosisCholinesterase inhibitors-Solanum and green potatoes

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Antinutritional:

Indospecine (arginine analog) Indospecine spicataMimosineSelenium toxicity-Anti-trypsin, anti-amylaseThiaminase

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Direct cytotoxity

DNA/protein alkalation/adduct-denaturingInhibit oxidative phosphoralation-Miserotoxin, Cyanogenic glycosides, fluroacetateAlter membrane permeability-digitalisPhysical cellular damage- oxylatesAlter anion or cation metabolism-Ca++Ca chelation- phytic acid and oxalateCalcinogenic glycosidesCu and Zn storageMg metabolism 3-methy-indoleCholestasis- Lantana, saponinsAll other tissue specific direct toxicity

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Specific Tissue Toxicity

Neurotoxic Plants 1. Locoweed 2. Yellow star thistle and

knapweed 3. Larkspur 4. Hemlocks 5. Death camas 6. Bracken fern 7. Jimsonweed

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Hepatotoxic Plants

Pyrrolizidine alkaloid containing plants

Tetradymia and hepatogenic photosensitization vs primary photosensitization caused by St. Johns wort or spring parsley

Cocklebur

Alsike clover

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Nephrotoxic Plants

Oxalate containing plants- Halogeton and greasewoodOak and other plants causing nephrosis

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Plants with Reproductive Toxins

Pinus ponderosa and broomweedTeratogens such as Veratrum, Lupine etc

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Plants that have Gastrointestinal Toxins

Pineapple (bromelain), papaya (papain) proteolytic enyzymesEnzyme inhibitors (typsin and amylase inhibitors) Dieffenbachia sequine-dumb cane, rhubarb, halogeton, greasewood, oak, phenolics, tannins Grasses/Hay (Nitrate/Nitrite, Saponins)Mustards (Brassica, Raphanus, Descurania)Castor BeanSneezeweed (Helenium)Nightshades

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Plants that are Cardiotoxic or Myotoxic

White snakeroot and rayless golden rodOleander and milkweedsThermopsis

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Sudden Death without many lesions:

Nitrates (sorghum, various grasses, oats, hay, corn, Kochia, pigweed, Russian thistle, nightshades)Cyanide (sorghum, larel cherry, arrow grass, chokecherry)

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Reading Assignment: Cheeke “Natural Toxicants in Feeds,

Forages, and Poisonous Plants” Part 1, pages 3-51