Chemopreventive effect of Chlorella pyrenoidosa on hepatocarcinogenesis in rats

2478 Epidemiological studies have shown that changes in lifestyle factors, particulary diets, play an important role in the etiology of cancer. We examined the chemopreventive effects of the dietary administration of a dried powder of Chlorella pyrenoidosa ( C. pyrenoidosa ), which is widely available as supplements and health foods worldwide, on diethylnitrosamine (DEN) - 2-amino-3,8-dimethylimidazo[4,5- f ]quinoxaline (MeIQx) induced hepatocarcinogenesis in rats. Male F344 rats were initially given a single dose of DEN (200mg/kg, i.p.) and/or starting 2 weeks later received MeIQx (0.02%) in the diet for a period of 6 weeks. For the DEN and/or MeIQx induced carcinogenesis, C. pyrenoidosa was administered as 10% of the diet during the entire experimental period (beginning 3 days before the initiation of DEN). At 3 weeks after the injection of DEN, all rats were subjected to a two-third partial hepatectomy under etherization. The rats were sacrificed 8 weeks after DEN treatment. The chemopreventive potential of C. pyrenoidosa was evaluated by comparing the number and area per cm 2 of glutathione S-transferase placental form (GST-P) positive foci, which are putative preneoplastic lesions, in the liver with those in the control diet group. Administration of 10% C. pyrenoidosa in the diet significantly (P C. pyrenoidosa possesses chemopreventive effects against hepatocarcinogenesis in rats. Accordingly, C. pyrenoidosa seems to be a promising chemopreventive agent for human liver neoplasia and carcinogenesis induced by heterocyclic amines such as MeIQx.