L. Dao et M. Friedman, COMPARISON OF GLYCOALKALOID CONTENT OF FRESH AND FREEZE-DRIED POTATO LEAVES DETERMINED BY HPLC AND COLORIMETRY, Journal of agricultural and food chemistry, 44(8), 1996, pp. 2287-2291
As part of a program to control the biosynthesis of Solanum glycoalkal
oids in potatoes, we used an HPLC assay to measure the specific alpha-
chaconine and alpha-solanine content of greenhouse-grown potato leaves
at different stages of maturity. Comparative studies were done with t
he bromophenol blue titration assay for total glycoalkaloids. We found
that foliar glycoalkaloids can be extracted with 5% aqueous acetic ac
id, that analysis of glycoalkaloids with freeze-dried leaf powders was
more reproducible than with fresh leaves, and that the bromophenol co
lorimetric method gave higher values than HPLC. As little as one leaf
from a growing plantlet can be analyzed with the HPLC assay. Large var
iations in both alpha-chaconine and alpha-solanine contents of fresh l
eaves suggest that potato foliar glycoalkaloids should be determined b
y HPLC from freeze-dried rather than fresh leaves.