Post-initiation modulating effects of allyl sulfides in rat hepatocarcinogenesis

Effects of administration of diallyl sulfide (DAS) and diallyl disulfide (DADS) on the promotion stage of hepatocarcinogenesis were investigated in rats using the Ito model. They were compared with those of phenobarbital (PB), a well-known liver promoter in rats. Initiation was induced by a single dose of N-nitrosodiethylamine (NDEA) and 3 weeks later, a partial hepatectomy was conducted. Two weeks after the NDEA injection, rats received either 0.05% allyl sulfides, PB or both in their diet for 8 weeks. Feeding with DAS increased the number of liver preneoplastic foci by 63% with respect to the untreated group. However, rats fed DAS showed a lower foci development than rats fed PB. The DADS group did not differ from control group for any of the measured morphometric parameters. Simultaneous administration of DADS with PB partially reduced the promotional activity of PB whereas DAS co-treatment did not modify PB properties. These findings confirm that DAS can act as a promoter in rat liver but exerts no co-promoting effect. Conversely, DADS was found to have promotion-inhibiting ability, suggesting that DADS has greater value than DAS as a chemopreventive agent.