Tetrahydrofuran (THF) has commonly been used to deliver carotenoids to cells but the use of THF is associated with cytotoxicity and low uptake efficiency of carotenoids. Here, we used fetal bovine serum (FBS) as the delivery vehicle for lycopene in comparison with THF, THF containing 0·0025 % butylated hydroxytoluene (THF/BHT), methyl-β-cyclodextrin (M-β-CD) and micelles in two human prostate cancer cell lines, DU145 and PC-3. Lycopene (10 mm) solubilized in THF/BHT and then diluted in FBS at ratios of 5 and 10 gave the highest lycopene uptake in DU145 cells. Using a dilution factor of 10, we found that lycopene (10 μm) carried in FBS in a cell-free system led to significantly less loss of lycopene than in THF, THF/BHT and M-β-CD within 24 h of incubation. Lycopene solubilized in micelles was more stable than that in FBS within 24 h, but the micelle itself led to marked cytotoxicity to DU145 cells. Lycopene at 10 μm in FBS led to significantly higher uptake of lycopene in both cell lines than that in THF, THF/BHT or M-β-CD within 24 h of incubation. When FBS was replaced with lipoprotein-deficient serum, the uptake of lycopene by DU145 cells was markedly decreased and was not significantly different from that of THF or THF/BHT. These results demonstrate that FBS is superior to THF, THF/BHT, M-β-CD and micelles as a delivery vehicle for lycopene in prostate cell lines and that the lipoprotein of FBS is likely responsible for the improved stability and cellular uptake of lycopene.
