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Oraine reid 18080241
 Should   be able to define Bio-toxins List the bio-toxins present in several  popular Jamaican Botanical Foods Underst...
A naturally produced toxic compound which shows pronounced biological activity and presumably has some adaptive significa...
ƒ  Toxins - metabolic products produced by living organisms for the purpose of repelling or killing Plant   Toxins (Phyt...
AckeeBitter yamPotatoCassavaNutmegCastor oil plant
 Toxic glycoalkaloids are found in the whole  plant of potato Solanum tuberosum, and  also in majority of other species f...
 Glycoalkaloids are termostable, so you cannot  destroy them by cooking, frying or drying. They  bear temperatures higher...
 Glycoalkaloids  are usually found at low levels. They can be higher in certain cases if the vegetable is still: • green ...
They  posses two mechanisms ofaction:   - First: they disturb cellmembranes containing steroidsubstances (an effect simil...
 Acetylcholine is a neurotransmitter (a chemical which transmits nerve impulses or signals) in the brain and the peripher...
   Early signs: of intoxication are colic, diarrhoea with    blood in excrements, apathy, halucinations. Then    follow s...
o   Maturity     • The highest concentrations of glycoalkaloids are usually associated       with areas that are undergoin...
 Storage temperature  • Storage at very low temperatures (0 - 5°C) results    in more bitter-tasting potatoes and thus mo...
   Processing    • Peeling: In normal tubers, potato glycoalkaloids appear to      be concentrated in a small 1.5-mm laye...
AFFECTED   NOT AFFECTED
 There  are approximately ten types of  Jamaican yams known The edible, mature, cultivated yam does  not contain any tox...
    Bitter principles tend to accumulate in immature tuber    tissues.   Wild forms of D. dumetorum do contain bitter   ...
 This compound is a convulsant alkaloid and it  causes central nervous system paralysis in animals. An extract of dihydr...
Toxicity of the plant : The leaves and roots contain free and boundforms of the cyanogenic glycoside linamarin, which is c...
 The   carrier of toxicity is HCN, released from  glucoside in blood It binds to haemoglobin and methaemogobin and  form...
Dissociation of cyanogenic glucosides goes on in two stepsoFirst, β-D-glucopyranose is dissociated due to action of enzyme...
normal plant tissues free HCN doesn’t In occur Described dissociation takes place in mechanically damaged tissues, where...
 Itis a tropical evergreen tree found in East  and West Indes. Contains a number of  methylenedioxy-substituted  compound...
 The  only known mechanism of metabolization of these compounds is the detoxification of safrole to piperonylic acid, a r...
Elemicin undergoes oxidationMyristicin produces MMDA       of its oleficin side chain towhich is metabolised to form   pro...
Traditional use:  • As a spice in foods  • As a traditional medicine for diarrhoeaToxic part of the plant: seeds (nutmeg) ...
Clinical features of poisoning:    symptoms are usually seen within 3-6     hours after ingestion and vary according     ...
   Toxic part of the plant: all parts        Main toxic constituent/s:              all parts of the plant contain spec...
•Upper  picture: a calciumoxalate druse in themesophyll cells of a leaf.•Middle   picture: calciumoxalate needles (raphids...
 Pure  castor oil has been used since  ancient times to loosen the stool and  remove waste products in the intestines  an...
Toxic part of the plant: seeds are the most toxic part (leaves are also poisonous)Lethal dose: 1mg/kg pure ricin in man   ...
 Ricin  is a toxic glycoprotein (with several  minor variants) belonging to the type II  group of ribosome inactivating p...
 Ackee  fruit causes profound hypoglycemia  due to hypoglycin A, a toxic compound  contained in the fruit. Ackee fruit i...
    Metabolism of hypoglycin yields methylenecyclopropylacetyl-CoA (MCPA-CoA).   Acyl-CoA dehydrogenase will accept MCPA...
 MCPA-CoA      exerts its effect by inhibiting  several coenzyme A dehydrogenases  which are essential for gluconeogenesi...
 Between   the years 1880 – 1955, there  evolved an illness that was found  predominantly in Jamaica. In 1955 the causat...
 Jamaican    culture is filled with a diverse  amount of indigenous botanical plants that  are consumed by the population...
Toxins present in caribbean foods
Toxins present in caribbean foods
Toxins present in caribbean foods
Toxins present in caribbean foods
Toxins present in caribbean foods
Toxins present in caribbean foods
Toxins present in caribbean foods
Toxins present in caribbean foods
Toxins present in caribbean foods
Toxins present in caribbean foods
Toxins present in caribbean foods
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Toxins present in caribbean foods

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this presentation was done by a final year biochemistry student at northern Caribbean university in Jamaica. It focuses on several popular Jamaican botanical foods and toxins present and the biochemistry of the effect of these toxins.

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Toxins present in caribbean foods

  1. 1. Oraine reid 18080241
  2. 2.  Should be able to define Bio-toxins List the bio-toxins present in several popular Jamaican Botanical Foods Understand the mechanism by which these toxins are able to act on the human body. Give preventative measures that can be taken against the effect of these toxins.
  3. 3. A naturally produced toxic compound which shows pronounced biological activity and presumably has some adaptive significance to the organism which produces it
  4. 4. ƒ Toxins - metabolic products produced by living organisms for the purpose of repelling or killing Plant Toxins (Phytotoxins) • Large array of chemicals, many species of plants. • Toxins include: alkaloids, pyrrolizidine alkaloids, terpenoids, amino acids, others.
  5. 5. AckeeBitter yamPotatoCassavaNutmegCastor oil plant
  6. 6.  Toxic glycoalkaloids are found in the whole plant of potato Solanum tuberosum, and also in majority of other species from family Solanaceae, e.g. tomato or aubergine - Solanum melongena These alkaloids are so called steroid glycoalkaloids (SGA), or pseudoalkaloids, because their precursors are not aminoacids like in genuine alkaloids
  7. 7.  Glycoalkaloids are termostable, so you cannot destroy them by cooking, frying or drying. They bear temperatures higher than 300°C. But during cooking potatoes in water majority of alkaloids pass to water Solanin – in fresh unpeeled tubers there can be concentration of solanin more than 100 mg/kg. The limit for potatoes determined to eat is 200 mg/kg. But at about 150 mg/kg, the taste starts to be bitter and in higher concentration this taste discourages to eat them.
  8. 8.  Glycoalkaloids are usually found at low levels. They can be higher in certain cases if the vegetable is still: • green • damaged • starting to sprout
  9. 9. They posses two mechanisms ofaction: - First: they disturb cellmembranes containing steroidsubstances (an effect similar tothose in saponines) - Second: they inhibit serumcholinesterase too (similar toorganophosphates)
  10. 10.  Acetylcholine is a neurotransmitter (a chemical which transmits nerve impulses or signals) in the brain and the peripheral nervous system. The enzyme cholinesterase functions to break down acetylcholine. When cholinesterase is inhibited, the continued presence of acetylcholine over-stimulates the post-synaptic nerve cell, causing the symptoms of poisoning that characterize the anti-cholinesterases.
  11. 11.  Early signs: of intoxication are colic, diarrhoea with blood in excrements, apathy, halucinations. Then follow seizures, coma and respiration paralysis Toxic dose: is 2-5 mg/kg of body weight and lethal dose between 3-6 mg/kg body weight. Other group of glycoalkaloids in potatoes are leptins. They are natural pesticides and genetics try to put the gene for leptins to other plants to protect them. Tubers also contain so called protease inhibitors, which dissociate trypsine, chymotrypsine, kathepsine D and karboxypeptidases. These inhibitors can be removed and destroyed by exposure to heat
  12. 12. o Maturity • The highest concentrations of glycoalkaloids are usually associated with areas that are undergoing high metabolic activity, such as potato flowers, young leaves, sprouts, peels and the area around the potato eyes. Small immature tubers are normally high in glycoalkaloids since they are still metabolically active.o Exposure to light • Exposure to light has a significant effect on the concentration of both total and individual glycoalkaloids. Potatoes that become sunburned during growth and start to green, owing to lack of soil cover, tend to taste very bitter as a result of their high glycoalkaloid content. In retail outlets, tubers may be displayed under fluorescent lighting and this can increase glycoalkaloid concentration.  Studies have indicated that replacing fluorescent lights with mercury lighting for potatoes on display would significantly reduce glycoalkaloid content and improve food safety.
  13. 13.  Storage temperature • Storage at very low temperatures (0 - 5°C) results in more bitter-tasting potatoes and thus more glycoalkaloids than storage at higher temperatures (up to 20°C. Injury/damage • Any type of injury or damage to the tuber will result in the accumulation of glycoalkaloids. Disease, insect attack or rough handling, during or after harvest, will all initiate glycoalkaloid synthesis (as it is a defence response).
  14. 14.  Processing • Peeling: In normal tubers, potato glycoalkaloids appear to be concentrated in a small 1.5-mm layer immediately under the skin, therefore, with normal tubers, peeling will remove between 60% - 95% of the glycoalkaloids present. • Unfortunately, peeling or slicing also elicits a stress response in the tubers and causes a slow rise in glycoalkaloid levels. If long delays occur before subsequent processing, glycoalkaloids can accumulate. Cooking • The heat stability of glycoalkaloids means that only high temperature processing, such as deep frying, has any significant effect on levels in potatoes.
  15. 15. AFFECTED NOT AFFECTED
  16. 16.  There are approximately ten types of Jamaican yams known The edible, mature, cultivated yam does not contain any toxic principles. The Jamaican yam tuber has a brown or black skin which resembles the bark of a tree and off-white, purple, white, yellow and sometimes red flesh, depending on the variety.
  17. 17.  Bitter principles tend to accumulate in immature tuber tissues. Wild forms of D. dumetorum do contain bitter principles, and hence are referred to as bitter yam. The bitter principle has been identified as the alkaloid dihydrodioscorine. These are water-soluble alkaloids,
  18. 18.  This compound is a convulsant alkaloid and it causes central nervous system paralysis in animals. An extract of dihydrodioscorine produces a long lasting hypotension and contraction of the smooth muscle fibers of the intestine both in vivo and in vitro when administered to animals (Oliver-Bever, 1989). This explains the use of Dioscorea species for the preparation of poison bit for fishing, hunting and preparation of insecticide
  19. 19. Toxicity of the plant : The leaves and roots contain free and boundforms of the cyanogenic glycoside linamarin, which is converted tocyanide in the presence of linamarinase, a naturally occurring enzymein cassava or via exposure to the atmosphere.Two varietiesSweet - contains as little as 20 milligrams of cyanide (CN) per kilogramof fresh rootsBitter - may produce more than 50 times as much (1 g/kg)Lethal dose : One dose of pure cassava cyanogenic glucoside(40mg) is sufficient to kill even a cow. Hence about 300 grams of freshroot is enough to kill an adult human and about 125 grams of fresh rootwould be enough to kill a child
  20. 20.  The carrier of toxicity is HCN, released from glucoside in blood It binds to haemoglobin and methaemogobin and forms cyanhaemoglobin and cyanmethaemoglobin respectively Cyanides and cyanic acid act as neurotoxins and they also bind to several proteins damaging enzyme systems. They decrease tissue breathing, block cytochromoxidase (HCN binds to Fe and Cu), cause tissue suffocation, because oxygen is not passed on to tissues, blood is oversaturated by oxygen and is of bright brick red colour
  21. 21. Dissociation of cyanogenic glucosides goes on in two stepsoFirst, β-D-glucopyranose is dissociated due to action of enzyme called β-D-glucosidase and α hydroxynitrile is formedoThis substance is dissociated to HCN and aldehyde or ketone due toenzyme hydroxynitrillyaseDissociation of cyanogenic glucosides:R1 O- β-glucopyranose R1 OH C C + glucoseR2 C= N + H2O R2 C = Ncyanogenic glucoside α-hydroxynitrile β –glucosidaseR1 OH R1 C C = O + HCNR2 C= N + H2O R2 Aldehyde and ketoneα-hydroxynitrile α-hydroxynitrillyase
  22. 22. normal plant tissues free HCN doesn’t In occur Described dissociation takes place in mechanically damaged tissues, where glucosides and enzyme, normally stored separately, come into touch and start to react together Released HCN must be detoxified in plant or in animal somehow - product of detoxification is thiocyanate SCN- Theenzyme sulphurtransferases is used to detoxify HCN released in plants or animals.
  23. 23.  Itis a tropical evergreen tree found in East and West Indes. Contains a number of methylenedioxy-substituted compounds, including myristicin, elemicin, and safrole It also contains elemycin, eugenol, and methyleugenol. {Weil, Andrew. Nutmeg as a Narcotic. 1965. 19(3), 194-217
  24. 24.  The only known mechanism of metabolization of these compounds is the detoxification of safrole to piperonylic acid, a reaction which also shows the capability of oxidizing olefinic side chains. If this same degenerative process will act on myristicin, or elemicin, then a possible intermediate (a vinyl alcohol) could undergo transamination.
  25. 25. Elemicin undergoes oxidationMyristicin produces MMDA of its oleficin side chain towhich is metabolised to form produce TMA (3,4,5-TMA. MMDA has a higher trimethoxyamphetamine), apotency than TMA psychotropic drug agent
  26. 26. Traditional use: • As a spice in foods • As a traditional medicine for diarrhoeaToxic part of the plant: seeds (nutmeg) and, to a lesser extent, the aril (mace)Lethal dose: Humans: 1-3 nutmegs (5-15g) for adults, 2 nutmegs for children Animals: oral dose of 24mg nutmeg oil per kg body weight
  27. 27. Clinical features of poisoning:  symptoms are usually seen within 3-6 hours after ingestion and vary according to the dose taken and the variability between different samples of nutmegs  intoxication resembles anti-cholinergic intoxication i.e profuse sweating, flushed face, dry mouth, burning epigastric pain, tachycardia, restlessness, giddine ss, hallucinations.
  28. 28.  Toxic part of the plant: all parts  Main toxic constituent/s:  all parts of the plant contain specialized cells containing bundles of needle-like calcium oxalate crystals and toxic proteins  Mode of action:  When the plant is chewed the sharp crystals injure the mucous membrane allowing toxic proteins to penetrate  Lethal dose:  The extreme oropharyngeal response generally limits the amount of plant ingested and oxalate absorbed through the oral mucosa is unlikely to cause systemic poisoning.  Symptoms:  Eating parts of the plant causes a severe burning in mouth and throat. Other symptoms may include:  Redness, swelling, pain, burning pain of the tongue and mucous membranes, profuse salivation, dysphagia  Swelling can rarely cause obstruction and respiratory compromise  Loss of speech may last several days and swelling more than a week  Treatment of poisoning:  wipe out the mouth with a cold, wet cloth and give milk to drink  antihistamines, mouthwashes, antiseptics and steroids may be usedReferences: http://en.wikipedia.org/wiki/Alocasia [3 July 2008]; Jayaweera DMA. Medicinal plants used in Ceylon.Part 1. Colombo: The National Science Foundation, 2006; Lucas GN, De Silva TUN. Poisonous plants of SriLanka. Colombo: Sri Lankan College of Paediatricians, 2006
  29. 29. •Upper picture: a calciumoxalate druse in themesophyll cells of a leaf.•Middle picture: calciumoxalate needles (raphids) incells of a root tuber.•Lower picture: silicatebodies of silicate cells in theepidermis.
  30. 30.  Pure castor oil has been used since ancient times to loosen the stool and remove waste products in the intestines and colon. This thick liquid is rich in fatty acids, thereby making it a natural emollient perfect for moisturizing. It has been applied internally and externally as a remedy for various kinds of medical conditions and ailment
  31. 31. Toxic part of the plant: seeds are the most toxic part (leaves are also poisonous)Lethal dose: 1mg/kg pure ricin in man  Ingestion of a single well chewed bean has caused death  1-3 seeds can be fatal to a child  2-4 seeds cause severe poisoning in an adult  poisoning is unlikely if seeds are swallowed without chewing
  32. 32.  Ricin is a toxic glycoprotein (with several minor variants) belonging to the type II group of ribosome inactivating proteins (type II RIP) found in the seeds (beans) of the castor oil plant. It is composed of two polypeptide chains of approximately 30 kDa joined by a disulfide bond.
  33. 33.  Ackee fruit causes profound hypoglycemia due to hypoglycin A, a toxic compound contained in the fruit. Ackee fruit is produced biannually by the tropical evergreen tree,Blighia sapida Unripe fruit and the water used to cook it are toxic and cause Jamaican vomiting sickness when ingested
  34. 34.  Metabolism of hypoglycin yields methylenecyclopropylacetyl-CoA (MCPA-CoA). Acyl-CoA dehydrogenase will accept MCPA-CoA as a substrate. This causes a removal of a proton from the a-carbon to yield an intermediate that irreversibly inactivates acyl-CoA dehydrogenase by reacting covalently with FAD on the enzyme.
  35. 35.  MCPA-CoA exerts its effect by inhibiting several coenzyme A dehydrogenases which are essential for gluconeogenesis Depletion of glucose reserves and the inability of cells to regenerate glucose leads to hypoglycemia.
  36. 36.  Between the years 1880 – 1955, there evolved an illness that was found predominantly in Jamaica. In 1955 the causative factor of JVS was isolated, a non proteinogenic amino acid, hypoglycin A, so named due to its ability to induce severe hypoglycemia. Concentrations within the arilli ranges from over 1000 ppm in the immature fruit to less than 0.1 ppm in the fully mature fruit
  37. 37.  Jamaican culture is filled with a diverse amount of indigenous botanical plants that are consumed by the population. The consumption of these plants and their derivatives have caused and have the potential to cause several chronic illnesses. It is important that the contents of these foods are known and necessary precautionary measures be taken to reduce the effects by toxins.

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