Passion-fruit (Passiflora edulis sp.) bagasse extract treatment delays prostate cancer progression in TRAMP mice

The polyphenols present in passion-fruit (Passiflora edulis sp.) bagasse (PFB), as piceatannol, is pointed out as a chemopreventive agent, due to its antitumoral activity. This fact is particularly important in cancers with long latency period, as prostate cancer. This study aims to evaluate the PFB treatment during prostate cancer progression in TRAMP (Transgenic Adenocarcinoma of the Mouse Prostate) mice, considering neoplastic lesions progression and cell proliferation. The PFB extract was prepared using ethanol:water mixture by PLE (Pressurized Liquid Extraction), in order to obtain a high polyphenols yields. Then, the PFB (10mg piceatannol/kg/day) was administered to five TRAMP mice for short-time (4 weeks; PFBE12) or long-time (10 weeks; PFBE18) by gavage. As control, five animals of different ages and tumor progression stage (T8, T12 and T18-weeks old) were used. After the experimental period, the dorsolateral prostate lobe was collected for morphological and PCNA immunolabelling (Proliferating Cell Nuclear Antigen ). The results demonstrated a high polyphenol (153.14 ± 4.16 µg GAE/mg) and piceatannol (31.65 ± 3.31 µg PIC/mg dried extract) content in PFB, as well as a high in vitro antioxidant capacity (ORAC value 3.29 ± 0.15 µmol TE/mg and FRAP 1.37 ± 0.16 µmol TE/mg). Regarding the morphological analysis, the prostatic disease progression was confirmed by the increase of neoplastic and pre-neoplastic lesions frequency in control groups, what was significantly reduced by PFB in both treated groups. To confirm these data, the number of PCNA positive cells reduced in PFB groups (T12 versus PFBE12, -41%; T18 versus PFBE18, -51%), which presented a strong and positive correlation to lesion progression delay (r=0.96; p=0.009), confirming the PFBE antiproliferative effect. In conclusion, the PFBE exerts chemopreventive effects in the prostate cancer, possibly due to its elevated antioxidant capacity, contributing to the maintenance of prostatic morphophysiology.