Antioxidative activity of animal and vegetable dietary fibers

Some dietary fibers originated from insects such as silkworm (Sericin) and others along with constituents of several representative seaweeds such as wakame Undaria pinnatifida; hijiki Hizikiafusifome; and kombu Laminaria japonica, were found to have fairly large reaction rates determined by quenching experiments of emission spectra in the near-infrared region lambda(max) 1270 nm for singlet oxygen O-1(2), Cypridina luminescence method for superoxide, and peroxide value (POV) for autoxidation. The determined reaction rates are between 10(3) 10(5) (g/L)(-1) s(-1) for the insect and the plant dietary fibers; the larger ones are as large as that of ascorbic acid, 1.93 x 10(4) (g/L)(-1) s(-1) for singlet oxygen. Most of these seaweed constituents also showed antioxidative activity against autoxidation and superoxide as well as their immunological enhancing activity. These results suggest a possibility that dietary fibers that are supposed to prevent the large-intestine cancer by their physical properties may prevent the cancer, at least in parts, by their chemical, antioxidative activity.