Effects of E/Z isomers of lycopene on experimental prostatic hyperplasia in mice

Lycopene is a member of the carotenoid family and has strong anti-oxidant properties. Lycopene occurs in tomato-based food products primarily as an all-E isomer (80-97%),but its Z-isomers accounts for 79 to 88% of total lycopene in benign or malignant prostate tissues, while the specific biological functions of Z-isomers are still not clarified at present. This study was to examine the bioactive potency of Z-isomers on benign prostatic hyperplasia (BPH) in mice and to make a comparison of effective inhibition between Z-isomers and all-E isomer.

Mice were divided into the Saline group, Vehicle control group and testosterone propionate induced BPH mice group (BPH model group, vehicle BPH model group, lycopene treated (5 mg/kg and 2.5 mg/kg), Z-isomers (57%) treated, Z-isomers (86%) treated, finasteride treated). The drugs were orally administered once a day consecutively for 30 days. The inhibitory effects on BPH of all-E lycopene and Z-isomers were evaluated by prostatic index, prostatic acid phosphatase (PAP), estradiol, testosterone and dihydrotestosterone (DHT) levels in serum and histopathology examination.

Compared with the BPH model group, E/Z isomers exhibited significant differences in prostatic index, PAP, estradiol, testosterone and DHT levels in serum and similar histological aspects observed in the mice of the control group. The present research also shows that Z-isomers may be more potent inhibitors than all-E isomers in BPH treatment.