Abstract
After extracting the thiamine-decomposing thermostable factor (SF) from leaves of sweet potato (I pomoea batatas) with several organic solvents, SF was transferred to ethyl acetate layer, from which it was isolated as yellow needles. The crystals were identified as isoquercitrin by determining melting point, paper chromatogram, absorption spectrum, elementary analysis, and preparing phenylosazone, as well as acetyl and methyl derivatives. Thiamine-decomposing activity of some flavonoids, e.g. isoquercitrin, is accerelated by manganese and the element was detected in the leaves by spectroscopic analysis.
