EFFECTIVENESS OF COMBINED LIMONENE AND 4-HYDROXYANDROSTENEDIONE IN THE TREATMENT OF NMU-INDUCED RAT MAMMARY-TUMORS

Limonene, a monocyclic monoterpene, occurs naturally in orange peel oi l. It has been shown to exhibit both chemopreventive and chemotherapeu tic activity without toxicity in rodent models. In this study we exami ned the effect of limonene both al maximally optimal and suboptimal do ses and in combination with suboptimal doses of 4-hydroxyandrostrenedi one on nitrosmethylurea-induced rat mammary tumours. A 10% limonene do se mixed in the diet caused tumour regression in all animals. A 5% lim onene dose was only able to cause regression in 50% of the rats (P<0.0 5). A suboptimal dose of 4-hydroxyandrostrenedione (12.5 mg kg(-1)) re sulted in tumour regression in 75% of rats. A combination of 5% limone ne with 4-hydroxyandrostrenedione (12.5 mg kg(-1)) resulted in a great er tumour regression (83.3%) than either agent given individually (P<0 .001 and 0.006 for limonene/4-hydroxyandrostrenedione vs limonene alon e and 4-hydroxyandrostrenedione alone respectively).