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FDSC 300 > Lecture 16 - Mycotoxins > Flashcards

Lecture 16 - Mycotoxins Flashcards

1
Q

what are mycotoxins?

A

chemical toxins produced by molds

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2
Q

what species are the main producers of mycotoxins?

A

aspergillus, fusarium, penicillin

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3
Q

what percentage of the world’s total crops are affected with unacceptable levels of mycotoxins?

A

25%

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4
Q

what are the 5 major classes of mycotoxins?

A
  • aflatoxins
  • ochratoxins
  • trichothecenes
  • fumonisins
  • zearalenone
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5
Q

name some aflatoxins

A

B1, B2, M1 M2, G1 and G2

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6
Q

name some ochratoxins

A

ochratoxin A, OTA

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7
Q

name some trichothecenes

A
  • deoxynivalenol (DON)
  • T2
  • HT-2
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8
Q

name some fumonisins

A
  • FBs (FB1, FB2, FB3)

- patulin

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9
Q

what’s the abbreviation for zearalenone?

A

ZEN

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10
Q

in what kind of feedstuffs can aflatoxins be present?

A

sorghum, soybeans, corn, wheat, barley

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11
Q

in what kind of feedstuffs can trichothecens be present?

A

barley, oats, sorghum, soybeans, corn, wheat

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12
Q

in what kind of feedstuffs can ZEN be present?

A

wheat, sorghum, corn, barely, silage

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13
Q

describe the solubility of aflatoxins

A
  • soluble in polar organic solvents (chloroform, methanol, ethanol, propyl alcohol)
  • poorly soluble in water
  • insoluble in petroleum ether, ethyl acetate, and hexane
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14
Q

describe aflatoxin stability depending on pH

A
  • stable in neutral solutions
  • resistant to strong acids
  • rapid decomposition in alkaline solutions
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15
Q

what happens to aflatoxins under UV light?

A
  • groups B & G fluoresce

- destructive for low concentration of AFB

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16
Q

describe aflatoxins’ heat stability

A
  • stable in 200C
  • no decomposition until 268C
  • hard to destroy under normal temps
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17
Q

what methods can be used to control and detox?

A 
physical
- grinding & rinsing
- heat treatment
- irradiation
- inorganic absorption
chemical methods
- alkalization
- ozone degradation
biological
- microbial adsorption
- microbial degradation
- biological degradation
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18
Q

solubility of ZEN?

A
  • water insoluble
  • slightly soluble in hexane
    increasingly soluble in benzene, acetonitrile, methylene chloride, methanol, ethanol, and acetone
  • soluble in aqueous alkali
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19
Q

pH stability of ZEN?

A
  • stable when neutral

- ester bond open in alkaline environment

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20
Q

ZEN response to UV light?

A

exhibits blue-green fluorescence (360 nm), but also intense green fluorescence (260 nm)

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21
Q

ZEN heat stability?

A
  • melting point is 161C

- difficult to destroy with normal cooking

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22
Q

expand DON

A

deoxynivalenol

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23
Q

solubility of DON?

A
  • easily soluble in water and polar solvents

- insoluble in hexane and diethyl ether

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24
Q

pH stability of DON?

A
  • stable in neutral AND acid environments

- sensitive to alkaline

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25
Q

DON response to UV light?

A
  • absorption peak under short-wave UV light

- decomposed under high tense UV light

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26
Q

DON heat resistance?

A

resistant

  • stable in 120C for 1 hour
  • decomposed 170C for 14 mins under pH 10
  • hard to destroy by normal cooking
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27
Q

true or false: mycotoxins can be detected from the body

A

false, because they can be transformed

28
Q

health effect of aflatoxin

A

carcinogenic

29
Q

health effect of ctrinin

A

nephrotoxic

30
Q

health effect of fumonisin

A

carcinogenic, hepatotoxic

31
Q

health effect of trichothecenes

A

cytotoxic, immunosuppressive

32
Q

health effect of ochratoxin

A

carcinogenic, nephrotoxic, hepatotoxic, teratogenic

33
Q

health effect of patulin

A

carcinogenic, immunotoxic, genetoxic

34
Q

health effect of zearalenone

A

estrogenic activity, potential carcinogenic and teratogenic

35
Q

what are the general steps for mycotoxin analysis

A
  • sampling
  • pre-treatment/extraction
  • clean-up
  • detection
36
Q

what are some ways mycotoxins can be extracted?

A
  • liquid-liquid extraction
  • supercritical fluid extraction
  • solid phase extraction
  • solid phase micro-extraction
37
Q

what are some ways mycotoxins can be detected?

A
  • TLC
  • GC
  • HPLC
38
Q

a mycotoxin-sampling plan is defined by a mycotoxin test procedure and a(n) _____/_____ limit

A

accept/reject

39
Q

true or false: traditional methods of sampling an be applied to mycotoxins

A

false, because population can be heterogeneous

40
Q

how do you determine sample number for mycotoxins in large and small lots?

A
  • square root of total number of containers for large lots

- one fourth of the containers for small

41
Q

liquid-liquid extraction makes use of partitioned liquid phases to separate analytes with different affinities. what solvents can be used to extract mycotoxins?

A

polar solvents

  • methanol
  • acetone
  • acetonitrile
  • ethyl acetate
  • diethyl ether
  • toluene
  • chloroform
42
Q

what does water do to mycotoxins?

A

breaks up complexes along with acid

43
Q

solid phase extraction is based on _____

A

molecularly imprinted polymers (MIP)

44
Q

what are MIPs?

A
  • molecularly imprinted polymers
  • synthetic receptors for mycotoxins
  • used for extraction, cleanup, and concentration
45
Q

what kinds of solid phases are out there?

A
  • C-18
  • silica gel
  • anionic and cationic exchange
  • immunosorbents
  • molecularly imprinted polymers
46
Q

what’s an immunoaffinity column?

A
  • analyte (mycotoxins) are bound selectively to antibodies

- used for solid phase concentration

47
Q

how do immunoaffinity columns concentrate mycotoxins?

A
  • mycotoxins bind to antibodies
  • rinsing step removes most possible interferences
  • toxin eluted by antibody denaturation
48
Q

true or false: immunoaffinity columns are highly selective

A

true

49
Q

why do we bother doing sample clean-up?

A
  • remove interference

- concentrate analyte for better detection

50
Q

describe TLC

A
  • clean, smooth glass plate has a thin layer of silica gel applied
  • sample is applied as a spot just above the solvent level
  • solvent rises by capillary action
  • compounds separate out based on affinity for solvent and silica
51
Q

what is TLC used for?

A
  • qualitative analysis (characterization)

- semi-quantitative measurement using fluorescence and comparing it with a standard

52
Q

how is detection achieved using gas chromatography?

A
  • linking system to MS, flame ionization, or fourier transform infrared spec
53
Q

true or false: mycotoxins are often volatile so they are suitable for analysis using GC

A

false - they’re not volatile and need to be derivatized. GC isn’t really used for commercial purposes

54
Q

what kind of reactions can derivatize mycotoxins?

A
  • silylation

- polyfluoroacylation

55
Q

how is detection accomplished using HPLC?

A

by linking the system to often one of the following detectors

  • UV
  • fluorescence
  • amperometric
  • spectrofluorimetric
56
Q

since mycotoxins have natural fluorescence, they can be directly detected with what?

A

HPLC-fluorescence (HPLC-FD)

57
Q

which detectors have greater sensitivity than HPLC-FD?

A

MS with electrospray or pressure chemical ionization

58
Q

the LOD for HPLC-MS can be between _____ and _____ ug/kg

A

0.1 and 1

59
Q

advantages of HPLC?

A
  • high resolution
  • improved limit of detection
  • possibility of being coupled to multiple detection automated
60
Q

which method of detection is widely accepted as an official method for the determination of mycotoxins?

A

HPLC

61
Q

limitations of chromatographic assays

A
  • $$$ equipment
  • time-consuming
  • requires clean-up procedures
62
Q

expand ELISA

A

enzyme linked immunosorbent assay

63
Q

describe the principle of ELISA

A

based on the ability of a specific antibody to distinguish the 3-D structure of a specific mycotoxin

64
Q

what kind of ELISA is commonly used in mycotoxin analysis?

A

direct competitive

65
Q

what’s a competitive assay for ELISA like?

A

we got mycotoxin. and we got enzyme-toxin conjugate. we let those fight to bind for antibodies
the enzyme conjugate makes a colored, fluorescent or chemiluminescent product (so more mycotoxin = less color)

FDSC 300 (9 decks)

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