Density functional theory study on the coupling and reactions of diferuloylputrescine as a lignin monomer.

Diferuloylputrescine has been found in a variety of plant species, and recent work has provided evidence of its covalent bonding into lignin. Results from nuclear magnetic resonance spectroscopy revealed the presence of bonding patterns consistent with homo-coupling of diferuloylputrescine and the possibility of cross-coupling with lignin. In the present work, density functional theory calculations have been applied to assess the energetics associated with radical coupling, rearomatization, and dehydrogenation for possible homo-coupled dimers of diferuloylputrescine and cross-coupled dimers of diferuloylputrescine and coniferyl alcohol. The values obtained for these reaction energetics are consistent with those reported for monolignols and other novel lignin monomers. As such, this study shows that there would be no thermodynamic impediment to the incorporation of diferuloylputrescine into the lignin polymer and its addition to the growing list of non-canonical lignin monomers.

Diferuloylputrescine, a predominant phenolic amide in corn bran, potently induces apoptosis in human leukemia U937 cells.

The purpose of this study was to investigate how proliferation and apoptosis in human leukemia U937 cells are affected by four hydroxycinnamic acid derivatives (HCADs) in corn (Zea mays L.) bran: p-coumaric (CA), ferulic acids (FA), dicoumaroylputrescine (DCP), and diferuloylputrescine (DFP). Of the four HCADs, DFP dose dependently exerted the strongest cytotoxic effect and induction of apoptosis in the U937 cells. In addition, DFP induced distinct morphological changes characteristic of cellular apoptosis, such as chromatin condensation, apoptotic bodies, and DNA fragmentations. The DFP-induced apoptosis was also associated with released cytochrome c in the cytosol with activation of caspase 3, together with the downregulation of anti-apoptotic proteins, including XIAP and cIAP2, Bcl-2, and Mcl-1. Finally, the DFP-induced apoptosis was a cell-specific response in leukemia cells, as compared with those of other cancer cells, such as Caki, HT29, SK-Hep1, and MDA-MB231. Thus, these results suggest that DFP may be useful as a potential source of natural antileukemic agents.