Combination effect of lignin F and natural products.

We investigated the effect of lignin F, isolated from the alkaline extract of the cone of Pinus parviflora Sieb. et Zucc, on the cytotoxic activity and radical intensity (measured by ESR spectroscopy) of various natural products. Lignin F slightly inhibited the proliferation of human oral tumor cell lines (human squamous cell carcinoma HSC-2, human salivary gland tumor HSG), but not that of human gingival fibroblast HGF, suggesting its tumor specific cytotoxic action. Lignin F enhanced the cytotoxic activity of vitamin K2, vitamin K3, sodium ascorbate (vitamin C), epigallocatechin gallate (EGCG) (a major component of green tea), gallic acid (structural unit of tannin), chlorogenic acid, and 6 tea extracts (Japanese green tea, Japanese barley tea, black tea, Chinese green tea, Chinese Jasmin tea, Chinese Oolong tea), to various extents. On the other hand, lignin inhibited the cytotoxic activity of curcumin and dopamine. ESR spectroscopy demonstrated that combination of lignin and vitamin K3, EGCG or gallic acid synergistically augmented the radical intensity. Lignin F enhanced the bactericidal activity of EGCG against E. coli. These data suggest the beneficial effect of the combination of lignin F and natural products.