Inhibition of Cyanogenesis by tannins
1Department of Ecology and Evolutionary Biology, University of California, Irvine, 92717, Irvine, CA.
Abstract:
During isolation of two biosynthetic types of cyanogenic glycosides fromCarica papaya, weak cyanide tests were obtained from initial fractions. Upon final purification, strongly positive cyanide tests were obtained. Pretreatment of extracts to remove polyphenolics alleviated inhibition of cyanogenesis, which led us to suspect that tannins were inhibitory agents. Qualitative and quantitative measures of inhibition were made using standard cyanogenic glycosides and polyphenolics. Cyanogenesis was inhibited quantitatively when condensed tannins (quebracho, wattle, and chestnut), or hydrolyzable tannin (tannic acid) were added. When tannins were precipitated from the reaction mixture, cyanide tests proceeded optimally. These results stress the need to interpret negative cyanide tests with care and indicate possible ecological synergisms between plant defensive chemicals.
Related Concept Videos
Phase II Reactions: Miscellaneous Conjugation Reactions
A key example involves the conjugation of cyanide ions, which impair cellular respiration and alter hemoglobin into non-oxygen-carrying cyanmethemoglobin. To neutralize this threat, a sulfur atom from thiosulphate is transferred to the cyanide ion, catalyzed by the enzyme rhodanese, resulting in an inactive compound called thiocyanate. The production of...
Aldehydes and Ketones with HCN: Cyanohydrin Formation Overview
Feedback Inhibition
Oral Hypoglycemic Agents: α-Glucosidase Inhibitors
Acarbose and miglitol are...
Enzyme Inhibition
Aldehydes and Ketones with HCN: Cyanohydrin Formation Mechanism


