Cycasin

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Cycasin
Chemical structure of cycasin
Names
IUPAC name
(Z)-1-[(β-D-Glucopyranosyloxy)methyl]-2-methyldiazene 2-oxide
Systematic IUPAC name
(Z)-1-Methyl-2-({[(2S,3R,4S,5S,6R)-3,4,5-trihydroxy-6-(hydroxymethyl)oxan-2-yl]oxy}methyl)diazene 1-oxide
Other names
β-D-Glucosyloxyazoxymethane; Methylazoxymethanol β-D-glucoside; Cycas revoluta glucoside; [(Z)-Methyl-ONN-azoxy]methyl β-D-glucopyranoside[1]
Identifiers
3D model (
JSmol
)
ChEBI
ChemSpider
KEGG
MeSH D003492
UNII
  • InChI=1S/C8H16N2O7/c1-10(15)9-3-16-8-7(14)6(13)5(12)4(2-11)17-8/h4-8,11-14H,2-3H2,1H3/b10-9-/t4-,5-,6+,7-,8-/m1/s1
    Key: YHLRMABUJXBLCK-LBCXAKKBSA-N
  • InChI=1/C8H16N2O7/c1-10(15)9-3-16-8-7(14)6(13)5(12)4(2-11)17-8/h4-8,11-14H,2-3H2,1H3/b10-9-/t4-,5-,6+,7-,8-/m1/s1
    Key: YHLRMABUJXBLCK-LBCXAKKBSA
  • [O-]/[N+](=N/CO[C@@H]1O[C@@H]([C@@H](O)[C@H](O)[C@H]1O)CO)C
Properties
C8H16N2O7
Molar mass 252.223 g·mol−1
56.6 g/L[2]
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).

Cycasin is a

neurotoxic glucoside found in cycads such as Cycas revoluta and Zamia pumila. Symptoms of poisoning include vomiting, diarrhea, weakness, seizures, and hepatotoxicity. In metabolic conditions, cycasin is hydrolyzed into glucose and methylazoxymethanol (MAM), the latter of which dissociates into formaldehyde and diazomethane.[3]

It induces hepatotoxicity and Zamia staggers, a fatal nervous disease affecting cattle resulting from browsing on the leaves or other parts of cycads.[4]

Sources

Cycasin is found in all known

BMAA. The origin and biological role of these toxins is unknown, as there does not appear to be a statistically significant correlation between the concentration of toxic material and the types of herbivory observed in animals consuming the plants.[5][6]

The enzyme

methyl-ONN-azoxymethanol to produce UDP and cycasin.[7]

Ecological significance

The butterfly Eumaeus atala, whose larvae feed on Z. pumila, contain the poison as a consequence of their diet.[8]

Presence in sago

In order to produce sago, cycasin and other cycad toxins must be removed from the flesh of the plants. The flesh, seeds, and roots of the cycad are first dried and ground into a fine powder, before being submerged in boiling water. The water is then allowed to drain, leaching out the toxic material while leaving the starch behind. The extracted starch is then alternately dried and pounded until a fine powder is obtained. This repeated pounding and leaching process ensures that there is as little cycasin as possible left behind.[9]

Structure

Cycasin is a glucose-derived glycoside with a methylazoxymethanol substitution at the beta position.

Stereochemistry at the azoxy group is (Z) (or trans (E) when oxygen removed formally to form azo- group).[10]

Toxicity

Cycasin has an oral

β-glucosidase enzymes found in the gut. Treatment with β-glucosidase causes cycasin to release methylazoxymethanol (MAM), which spontaneously decomposes to form formaldehyde and methyl-diazonium. The amount of formaldehyde released is too small to induce toxicity, but methyl-diazonium is a potent methylating agent. The presence of this molecule methylates DNA, causing long-term damage and potentially giving rise to cancers.[3]

Methylazoxymethanol (MAM)

Symptoms

Early symptoms of cycasin poisoning are vomiting, nausea, abdominal pain, and diarrhea. Later stages of poisoning manifest as liver dysfunctions. [13]

Zamia staggers

Livestock that consume raw leaves, nuts, and flour of cycads develop a neurologic syndrome known as

dorsal root ganglia.[4]

Suspected association with Lytico-bodig disease

The

amyotrophic lateral sclerosis (ALS) and parkinsonism. It is characterized by muscle atrophy, maxillofacial paralysis, inability to speak or swallow, and dementia. The disease is fatal in all cases, with the diaphragm and respiratory accessory muscles becoming paralyzed in the later stages of the disease.[14]

Observation of the diets of the native Chamorro people led to the creation of the so-called "Cycad hypothesis." Starches prepared from the seeds of a native cycad species,

BMAA in their fat by consuming cycad seeds, resulting a in a high concentration of the neurotoxin.[15]

Cycas micronesica, one of the cycad species consumed by the Chamorro

See also

References

  1. ^ b-D-Glucosyloxyazoxymethane, ChemSpider
  2. ^ "Showing Compound Cycasin (FDB018287) - FooDB".
  3. ^
    PMID 4881504
    .
  4. ^
    PMID 8373871
    .
  5. doi:10.1016/S0031-9422(00)80069-2
    .
  6. JSTOR 3557555
    .
  7. doi:10.1271/bbb1961.49.2827
    .
  8. doi:10.1016/S0031-9422(00)81161-9
    .
  9. S2CID 31799259
    .
  10. doi:10.1107/S0567740881007887
    .
  11. ISBN 0442283040
    .
  12. S2CID 31799259
    .
  13. ^ "Symptoms of Plant toxin-induced liver damage -- Cycasin - RightDiagnosis.com". www.rightdiagnosis.com. Healthgrades.
  14. ^
    S2CID 41622254
    .
  15. PMID 14612559
    .
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