Biochemical basis of the toxicity of manipueira (liquid extract of cassava roots) to nematodes and insects

✍ Scribed by Claúdio P. Magalhães; J. Xavier-Filho; Francisco A. P. Campos

• Book ID: 101285432
• Publisher: John Wiley and Sons
• Year: 2000
• Tongue: English
• Weight: 124 KB
• Volume: 11
• Category: Article
• ISSN: 0958-0344
• DOI: 10.1002/(sici)1099-1565(200001/02)11:1<57::aid-pca489>3.0.co;2-e

✦ Synopsis

The presence of defence-related proteins and the concentration of cyanogens in the cell-sap solution of cassava roots (termed manipueira) have been investigated. It is demonstrated that manipueira is devoid of lectins, serine proteinase inhibitors and chitinase activity, although very low levels of a-amylase inhibitory activity were detected. Within 6 h of storage, all of the major cyanogenic glycoside of cassava, linamarin, had disappeared, while the concentration of acetone cyanohydrin, the breakdown product of the hydrolysis of linamarin, had dropped to 40% of the initial value at zero time and remained unchanged until 72 h of storage. This stabilization of the acetone cyanohydrin during storage seems to be caused both by a drop in pH due to lactic fermentation, which prevents its spontaneous breakdown, and by the absence of ahydroxynitrile lyase in cassava roots. It is concluded that the well-known toxicity of manipueira may be causally related to the stabilization of the acetone cyanohydrin.