Peroxynitrite-induced apoptosis in epithelial (T84) and macrophage (RAW 264.7) cell lines: effect of legume-derived polyphenols (phytolens)

Peroxynitrite (ONOO-) has been proposed as a mediator of gut inflammation and as an inducer of cell death by apoptosis. Phytolens (PHY), a water-soluble extract of polyphenolic antioxidants from nonsoy legumes (Biotics Research Corp, patent pending), was evaluated as a cytoprotective agent in human colonic (T84) and murine macrophage (RAW 264.7) cell lines. In the antioxidant testing, PHY showed a significant free radical scavenging ability against 1,1-diphenyl-2-picrylhydrazyl radical (DPPH) and superoxide (O2.) radicals with an IC50 of 4.44 and 5.87 microg/ml against DPPH and O2., respectively. Apoptosis (DNA fragmentation) was measured by an ELISA technique. Cells were exposed to oxidative stress by treating them with peroxynitrite (100-300 microM) for 4 h in the presence and absence of PHY. Peroxynitrite elicited a dose-dependent increase in DNA fragmentation in both cell lines compared to the control group receiving decomposed ONOO-. PHY (10, 30, or 50 microg/ml) significantly attenuated the degree of apoptosis in T84 cells induced by ONOO- (P < 0.05). PHY (10-100 microg/ml) did not directly affect T84 cell viability or induce apoptosis after 4 h or overnight exposure. RAW 264.7 cells exposed to PHY alone (>30 microg/ml) for 4 h displayed decreased cell viability (P < 0.05) and increased apoptosis (P < 0.05). Phytolens may have beneficial effects on inflammation by attenuating peroxynitrite-induced apoptosis. The sparing of epithelial cells while compromising the viability of macrophages suggests that PHY may be beneficial in autoimmune disorders.