Intestinal absorption and tissue distribution of immunoactive and antiviral water-soluble (14C) lignins in rats.

Intestinal absorption and tissue distribution of water-soluble lignins which had both immunomodulating and antiviral activities were investigated using the isotope tracer techniques. Three types of water-soluble lignins with different molecular weights, i.e., EP3 (av. mol. wt., 3.2 × 105D) and SB1000 (mol. wt., 103—104D), both of which were fractionated from LEM (an extract of culture medium of Lentinus edodes mycelia), and PLS(purified lignosulfonate, av. mol. wt., 2 × 104D) were used after being labeled with 14C-HCHO.After p. o. administration, every [14C] lignin was absorbed and reached maximum levels in the tissues, especially, kidney cortex, lymph node, liver and vertebra within 6 hr. 14C-EP3, the sample of the highest molecular weight, showed the lowest absorption, whereas it remained in cortex for a longer period. By summing up the isotope amount in urine and tissues, the absorption extents of 14C-EP3, 14C-PLS and 14C-SB1000 were estimated to be approximately 0.8%, 5.9% and 8.0% of radioactivity, respectively. Absorption and prolonged remain of 14C-EP3 in the lymph node and vertebra suggest that the in vitro immunological activities of this lignin would be linked to those in vivo.