Diferuloylputrescine and p-coumaroyl-feruloylputrescine, abundant polyamine conjugates in lipid extracts of maize kernels

Extraction of corn bran or corn fiber with polar solvents such as methylene chloride, ethanol or chloroform/methanol yielded common lipids and two unknown high-performance liquid chromatography (HPLC) peaks, each with an ultraviolet absorbance maximum at 320 nm. HPLC-mass spectrometry revealed that the unknowns were diferuloylputrescine (DFP) and p-coumaroyl-feruloylputrescine (CFP). When compared to extracts of corn fiber (a pericarp-enriched fraction from the wet milling of corn), comparable extracts of corn bran (a pericarp- enriched fraction from the dry milling of corn) yielded three- to eightfold higher levels of DFP and CFP. Extraction of corn bran or fiber with an accelerated solvent extractor revealed that elevated temperatures greatly enhanced the extraction of DFP and CFP by methylene chloride and ethanol. “Corn bran oil,” prepared by extraction of corn bran with hot methylene chloride, contained 14 wt% DFP and 3 wt% CFP. However, when hexane was used as a solvent, accelerated solvent extraction of the corn bran or fiber did not extract any DFP or CFP. Extraction of wheat bran or psyllium hulls with hot methylene chloride did not yield any detectable DFP or CFP. Because it has been suggested that polyamine conjugates such as DFP and CFP may function as natural pesticides, a rapid method was developed to purify them so that their biological activity could be evaluated.