Anticancer tomatoes: UV reveals details of lycopene extract

Chemical cancer prevention

Tomato cancer protection

UV-Vis spectroscopy and several other techniques have been used to characterise a lycopene extract from tomatoes. The extract has also been evaluated for its anticancer properties in laboratory mice.

Biophysicists Prachi Gupta, Mohinder Pal Bansal and Ashwani Koul of Panjab University, in Chandigarh, India, report that liver cancer incidence is on the rise, it being the fifth most common malignancy worldwide and the second leading cause of cancer deaths. Unfortunately, given the liver's central role in metabolising ingested, or indeed injected, compounds, chemotherapy only has limited effects in this disease and so new strategies are required to address the issue of liver cancer.

One such strategy might include modifying one's diet to incorporate large amounts of natural compounds thought to have a chemoprotective effect against cancer or to ingest a dietary supplement containing an efficacious quantity of such a compound. The Panjab team has focused on lycopene extract (LycT) from tomatoes, Lycopersicum esculentum. Lycopene is a red carotenoid pigment, actually a polyunsaturated hydrocarbon, an alkene, with the succinct chemical name (6E,8E,10E,12E,14E,16E,18E,20E,22E,24E,26E)-2,6,10,14,19,23,27,31-octamethyldotriaconta-2,6,8,10,12,14,16,18,20,22,24,26,30-tridecaene. It is found in tomatoes, red carrots, watermelon and papaya, but not cherries or strawberries.

The antioxidant properties of lycopene have given it somewhat privileged status in natural product research especially as several small-scale studies of the last few years have hinted at it having a protective effect against certain forms of cancer, most notably prostate cancer. There is some evidence that it may be useful in that regard and it is marketed in supplement form, although the US Food & Drug Administration has been hesitant in raising the compound's official status to allow companies to market products containing lycopene as having cancer protective properties.

Gupta and colleagues have set out to determine whether lycopene might have demonstrable chemopreventive effects against liver cancer caused by the widespread hepatocarcinogen N-diethylnitrosamine (NDEA). They have now tested the effects of lycopene extract on susceptibility to this disease in female Balb/c mice in terms of hepatic tumour incidence, multiplicity, burden, hepatosomatic index and animal survival rate.

The extraction itself was carried out using hexane-acetone-ethanol and UV-Vis, NMR and Fourier transform infrared spectroscopy were used to characterise the extract. The team reports that the average lycopene content of tomatoes was between 11.6 and 14 milligrams per kilogram of tomato mass. The spectral data confirmed that lycopene was indeed extracted from the fruit.

Prophylactic pretreatment

Pre-treatment of the mice reduced tumour incidence in mice exposed to NDEA by more than 40% as well as lowering the other markers of tumour burden and multiplicity compared with control animals not given lycopene. "Histopathological analysis revealed that the increased survival rate in LycT + NDEA-treated animals was due to the delay in the formation of aggressive tumour nodules," the team says. "These observations indicate that lycopene seems to be an able candidate for chemoprevention in hepatocarcinogenesis resulting from NDEA insults."

"Spectroscopic Characterization of Lycopene Extract from Lycopersicum esculentum (tomato) and Its Evaluation as a Chemopreventive Agent Against Experimental Hepatocarcinogenesis in Mice", Phytother Res,2012; DOI: 10.1002/ptr.4741