Jatropha seed: Testing for toxic compounds
Since seeds of the jatropha plant (Jatropha curcas) are mildly poisonous (making them inedible), an ongoing concern is whether toxic compounds exist in the smoke when these seeds are burned in our Jiko Safi stove. Board member David Covert – a professor of Atmospheric Chemistry at the University of Washington (UW) - is assessing this concern by reviewing the scientific literature on jatropha seed composition and using an analytical method to measure the several chemical compounds of concern in jatropha seed – a class of molecules called phorbol esters.
One compound among these, TPA(1), is a known co-carcinogen or tumor promoter; other molecular forms are less active promoters. Previous studies have detected several phorbol esters in jatropha seeds, but have not detected TPA nor have concentrations of these compounds been well quantified. Even if present in the seed, it is highly likely that phorbol esters break down to harmless forms when the seeds are burned. No study to date has examined this possibility!
In summary, there is a great need for basic chemical measurements to address the question of potential toxicity of smoke from burning of Jatropha curcas seed.
To date a method has been developed(2) and validated in collaboration with the analytical chemistry lab in the Department of Environmental Health at UW using oils pressed from both croton and jatropha seeds. Croton oil serves as a reference material because it is known to contain TPA as well as six other forms of phorbol ester. All seven forms were clearly identified and quantified in the croton samples, with good reproducibility.
Analysis of oil pressed from jatropha seed samples from Tanzania and Uganda showed no detectable TPA, and only small amounts of two other, less toxic, phorbol esters. Developing these procedures involved a significant outlay of time and money; however, we are now in a position to make the first-ever assessment of jatropha oil and Jiko Safi smoke composition with respect to phorbol esters. Stay tuned for more results in 2014.
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(1) TPA: 10-0-Tetradecanoylphorbol-13-acetate
(2) Basic features of this procedure are extraction in methanol and quantification using liquid chromatography and mass spectrometry in conjunction with a commercial grade TPA standard. The method yields a detection limit of 2 ng/ml, which is as good as or better than reports in the literature for similar analyses of phorbol esters in croton and jatropha seed oils.
One compound among these, TPA(1), is a known co-carcinogen or tumor promoter; other molecular forms are less active promoters. Previous studies have detected several phorbol esters in jatropha seeds, but have not detected TPA nor have concentrations of these compounds been well quantified. Even if present in the seed, it is highly likely that phorbol esters break down to harmless forms when the seeds are burned. No study to date has examined this possibility!
In summary, there is a great need for basic chemical measurements to address the question of potential toxicity of smoke from burning of Jatropha curcas seed.
To date a method has been developed(2) and validated in collaboration with the analytical chemistry lab in the Department of Environmental Health at UW using oils pressed from both croton and jatropha seeds. Croton oil serves as a reference material because it is known to contain TPA as well as six other forms of phorbol ester. All seven forms were clearly identified and quantified in the croton samples, with good reproducibility.
Analysis of oil pressed from jatropha seed samples from Tanzania and Uganda showed no detectable TPA, and only small amounts of two other, less toxic, phorbol esters. Developing these procedures involved a significant outlay of time and money; however, we are now in a position to make the first-ever assessment of jatropha oil and Jiko Safi smoke composition with respect to phorbol esters. Stay tuned for more results in 2014.
______________________________________________________________________________________________________________________________________
(1) TPA: 10-0-Tetradecanoylphorbol-13-acetate
(2) Basic features of this procedure are extraction in methanol and quantification using liquid chromatography and mass spectrometry in conjunction with a commercial grade TPA standard. The method yields a detection limit of 2 ng/ml, which is as good as or better than reports in the literature for similar analyses of phorbol esters in croton and jatropha seed oils.