Protective effect of phlorotannin components phloroglucinol and eckol on radiation-induced intestinal injury in mice.

Components of phlorotannin, which were extracted from Ecklonia species, have been reported to have in vitro radioprotective and antioxidative effects. The radioprotective effects of two of the components of phlorotannin, phloroglucinol and eckol, in intestinal stem cells were examined by evaluating their effects on jejunal crypt survival and apoptosis in gamma-irradiated mice. Pretreating the mice (i.p. 20 mg/kg of body weight at 12 and 36 h before irradiation) prior to irradiation with either phloroglucinol or eckol significantly improved the survival of the jejunal crypt (p < 0.001 and p < 0.01 vs irradiation controls at 3.5 days after 8 Gy irradiation, respectively). The administration of phloroglucinol and eckol prior to irradiation protected the intestinal crypts from radiation-induced apoptosis (p < 0.05 vs irradiation controls at 12 h after 1 Gy irradiation). Although the mechanism for this inhibitory effect remains unknown, these results showed that phloroglucinol and eckol might be useful radioprotectors that can defend intestinal stem cells against the oxidative damage caused by gamma-irradiation.