Effect of Thiamin Status on the Metabolism of Linamarin in Rats

Umoh, I.B.; Ogunkoya, F.O.; Maduagwu, E. N.; Oke, O. L.

doi:10.1159/000176987

Cited by 13 publications

(12 citation statements)

References 12 publications

(6 reference statements)

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“…Chronic cyanide exposure associated with the consumption of cassava has been associated with a number of cyanide induced disorders including: goiter, dwarfism, and tropical ataxic neuropathy. This is particularly a problem in regions of the world where cassava is the major source of calories (2,22,26,28).Our interest has been to develop strategies for the effective detoxification of cassava food products which would be compatible with the beneficial aspects of cyanogenesis, i.e. protection of the plant against herbivory.…”

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confidence: 99%

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Purification, Characterization, and Localization of Linamarase in Cassava

Mkpong

Hua²,

Chism³

et al. 1990

Plant Physiol.

137

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We have purified cassava (Manihot esculenta) linamarase to apparent homogeneity using a simplified extraction procedure using low pH phosphate buffer. Three isozymes of cassava linamarase were identified in leaves based on differences in isoelectric point. The enzyme is capable of hydrolyzing a number of ,Bglycosides in addition to linamarin. The generation and release ofcyanide (cyanogenesis) occurs in a number of plant species following the rupture ofthe plant tissue and subsequent hydrolysis of cyanogenic glycoside precursors (2, 6, 7). One proposed function of cyanogenesis is to protect the plant against herbivory (1, 2, 18). However, the presence of cyanogenic glycosides in crop plants such as cassava can present health problems for peoples that subsist on these plants (2,8,12,14,17,21).In cassava, the rate limiting step in cyanogenesis is the hydrolysis of linamarin (the predominant cyanogenic glycoside in cassava) to acetone cyanohydrin and glucose by the enzyme linamarase (f3-glucosidase, EC 3.2.1.21) (2, 8, 9).Acetone cyanohydrin dissociates spontaneously at pHs > 5.0 or enzymatically by hydroxynitrile lyase to produce HCN and acetone (6,7,9,21). Generally, over 70% of the linamarin in fresh cassava is removed by enzymatic hydrolysis during processing (12,13,19,20). Significantly, nearly all the cyanide which is generated is removed by volatilization or solubilization (8,12,14). The remaining nonhydrolyzed linamarin present in processed cassava does, however, present health problems. This is due to the fact that linamarin can be ' Financial support from the Colleges of Agriculture and Biological Sciences, Ohio State University. hydrolyzed in the body releasing cyanide (2, 26, 28). Chronic cyanide exposure associated with the consumption of cassava has been associated with a number of cyanide induced disorders including: goiter, dwarfism, and tropical ataxic neuropathy. This is particularly a problem in regions of the world where cassava is the major source of calories (2,22,26,28).Our interest has been to develop strategies for the effective detoxification of cassava food products which would be compatible with the beneficial aspects of cyanogenesis, i.e. protection of the plant against herbivory. Recently, we have demonstrated that infiltration of cassava root tissues with excess linamarase lowers the linamarin content to levels considered safe for human consumption ( 19). This suggests that elevated levels of linamarase in cassava tissues may decrease the cyanide toxicity of the processed food products by driving cyanogenesis to completion. However, before attempts were made to modify the cyanogenic potential of cassava, a more complete understanding of the biochemistry of cyanogenesis in cassava roots and leaves was necessary.In this study we present the results of our investigations on the catalytic properties and stability of cassava linamarase, its localization in leaf cells and the relationship between linamarin content and linamarase activity in low and high cyanogenic (root) varieties...

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confidence: 99%

“…hydrolyzed in the body releasing cyanide (2,26,28). Chronic cyanide exposure associated with the consumption of cassava has been associated with a number of cyanide induced disorders including: goiter, dwarfism, and tropical ataxic neuropathy.…”

mentioning

confidence: 99%

Purification, Characterization, and Localization of Linamarase in Cassava

Mkpong

Hua²,

Chism³

et al. 1990

Plant Physiol.

137

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“…This qualitative difference may be support of the difference in aromatic typical of these foods (Umoh et al, 1985;Onyango et al, 2004;Lasekan and Abbas, 2010).…”

Section: Resultsmentioning

confidence: 71%

Volatile compounds produced in two traditional fermented foods of the Congo: Nsamba (palm wine) and bikedi (retted cassava dough)

Dhellot¹,

Mokemiabeka²,

Moyen³

et al. 2014

Afr. J. Biotechnol.

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“…Thiamine deficiency has also been implicated in the aetiology of TAN. The experimental study of Umoh et al (1985) on the effect of thiamine status on the metabolism of linamarin in rats has also complemented this 34 D.C. MATttANGI AND A. NAMASIVAYAM hypothesis. As we have not included a group with B12 deficiency in this study we are unable to confirm these findings.…”

Section: Role Of Vitamin B12mentioning

confidence: 88%

“…The experimental study of Umoh et al (1985) on the effect of thiamine status on the metabolism of linamarin in rats has shown that thiamine deficiency causes accumulation of unmetabolized linamarin and free cyanide. The studies of Kamalu (1991) on dogs have also shown some changes in the cassava fed animals which did not match the cyanide fed dogs, hence concluded that some factor in cassava other than cyanide, probably intact linamarin, could have caused the observed pathological changes.…”

Section: Role Of Linamarinmentioning

confidence: 99%

Neurochemical and behavioural correlates in cassava-induced neurotoxicity in rats

Mathangi

Ambalavanan

2000

neurotox res

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Chronic cyanide intoxication from cassava has been implicated as the cause for a degenerative neuropathy known widely as tropical ataxic neuropathy. An attempt has been made in this study to identify the specific cause for neuropathy caused by cassava using Wistar strain albino rats as the experimental animal model. The results of cassava fed animals were compared with control animals, animals given cyanide, malnourished animals and malnourished animals fed cyanide, to identify the causative factors. This study revealed that though the behavioural pattern in motor coordination of the cassava fed animals was similar to the other groups studied, the neurochemical basis for the observed behavioural pattern was unique for cassava. Hence the neurotoxicity of cassava could be attributed to unmetabolized linamarin, more than its nutritional status and/or cyanide toxicity.

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Effect of Thiamin Status on the Metabolism of Linamarin in Rats

Cited by 13 publications

References 12 publications

Purification, Characterization, and Localization of Linamarase in Cassava

Purification, Characterization, and Localization of Linamarase in Cassava

Volatile compounds produced in two traditional fermented foods of the Congo: Nsamba (palm wine) and bikedi (retted cassava dough)

Neurochemical and behavioural correlates in cassava-induced neurotoxicity in rats

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