Microdiffusion method with solid state detection of cyanogenic glycosides from cassava in human urine

Area of Science:

• Biochemistry
• Analytical Chemistry
• Toxicology

Background:

• Cyanogenic glycosides are toxic compounds found in various plants, including cassava.
• Human exposure to cyanogenic glycosides can occur through diet, posing potential health risks.
• Accurate methods for quantifying these compounds in biological samples are crucial for health assessments.

Purpose of the Study:

• To develop and validate a novel method for the quantitative determination of cyanogenic glycosides in human urine.
• To assess urinary linamarin levels in populations consuming inadequately processed cassava.
• To investigate the absorption and excretion of cassava-derived cyanogenic glycosides in humans.

Main Methods:

• Enzymatic cleavage of cyanogenic glycosides to release hydrogen cyanide.
• Microdiffusion of hydrogen cyanide followed by solid-state detection using a picrate-impregnated sheet.
• Quantification via thin-layer (TLC) densitometry measuring light absorption at 540 nm.
• Method validation with normal and pathological urine samples.

Main Results:

• The developed method allows quantification of urinary linamarin at levels above 70 µmol/litre using only 40 µL of urine.
• Tested with various urine matrices including glucose, protein, leucocytes, blood, and bacteria.
• Mean urinary linamarin levels of 211 µmol/litre were observed in Mozambican subjects consuming insufficiently processed cassava.
• This is the first evidence of substantial absorption and intact urinary excretion of cassava's main cyanogenic glycoside.

Conclusions:

• A sensitive and reliable method for urinary cyanogenic glycoside determination has been established.
• Dietary cyanogenic glycosides from cassava are significantly absorbed and excreted unchanged in human urine.
• Findings highlight the public health importance of processing cassava to reduce cyanogen toxicity.