Positive Health Online

Abstract

ZHAO and colleagues, Center for Cancer Causation and Prevention, AMC Cancer Research Center, Denver, CO 80214 USA write that procyanidins in grape seeds are known to exert anti-inflammatory, anti-arthritic and anti-allergic activities, prevent skin ageing, scavenge oxygen free radicals and inhibit UV radiation induced peroxidation activity. Because many of these events are associated with tumour promotion stages of carcinogenesis, the authors suggest that grape seed polyphenols and procyanidins could be anticarcinogenic and/or anti-tumour promoting agents. The authors assessed the anti-tumour promoting effect of a polyphenolic fraction isolated from grape seeds (GSP).

Background

Methodology

The authors used the 7,12-dimethylbenz(a)anthracene (DMBA)-initiated and 12-O-tetradecanoylphorbol 13-acetate (TPA)-promoted SENCAR mouse skin two stage carcinogenesis protocol as a model system.

Results

Following tumour initiation with DMBA, topical application of GSP at doses of 0.5 and 1.5 mg/mouse/application resulted in a highly significant inhibition of TPA tumour promotion. The anti-tumour promoting effects of GSP were dose dependent and reduced tumour incidence (35 and 60% inhibition), tumour multiplicity (60 and 83% inhibition) and tumour volume (67 and 87% inhibition) at both 0.5 and 1.5 mg GSP, respectively. Based upon these results, the authors attempted to isolate and identify the individual polyphenols present in GSP and to assess their antioxidant activity. Nine individual polyphenols were identified as catechin, epicatechin, procyanidins B1-B5 and C1 and procyanidin B5-3-gallate. Five of these individual polyphenols, assessed for antioxidant activity significantly inhibited epidermal lipid peroxidation. Procyanidin B5-3-gallate showed the most potent antioxidant activity .

Conclusion

These results for the first time show that grape seed polyphenols possess high anti-tumour promoting activity due to the strong antioxidant effect of procyanidins. Grape seed polyphenols in general and procyanidin B5-3-gallate in particular should be studied in more detail to be developed as cancer chemopreventive and/or anticarcinogenic agents.

References

Zhao J et al. Anti-tumor-promoting activity of a polyphenolic fraction isolated from grape seeds in the mouse skin two-stage initiation-promotion protocol and identification of procyanidin B5-3-gallate as the most effective antioxidant constituent. Carcinogenesis 20(9): 1737-45. Sep 1999.

Comment

Great research study! Not only have the authors demonstrated that grape seeds possess potent anti-tumour and anti-carcinogenic activity, but they have also separated, analysed and identified the procyanidin fractions with the anti-cancer activity. For what more can one ask? The more cynical among us might ask, that assuming that naturally-occurring procyanidins from grape seeds are probably not patentable, will any profit-seeking pharmaceutical company develop this as a drug? Please email me with your comments sandra@positivehealth.com.