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Whirlwind around stevia could also include DNA protection

By Stephen Daniells , 30-Nov-2007

Stevia, the natural sweetener causing a whirlwind of interest around the globe, could also be a rich source of antioxidants and may protect against DNA damage and cancer, says a study from India published yesterday.

An extract from Stevia rebaudiana leaves was found to contain an abundance of antioxidant polyphenols, including quercitrin, apigenin, and kaempferol. Subsequent tests showed that the extract could protect against DNA strand scission by hydroxide radicals, states the report in the Journal of Agricultural and Food Chemistry. "These results indicate that Stevia rebaudiana may be useful as a potential source of natural antioxidants," wrote lead author Srijani Ghanta from the Indian Institute of Chemical Biology in Kolkata. Derived from the South American plant stevia rebaudiana, stevia is said to have up to 300 times the sweetness of sugar. Its taste has a slower onset and longer duration than that of sugar, and developments in processing methods have already claimed to have solved the problem of the ingredient's liquorice-like aftertaste. If it is ultimately as easy to use in food and beverage formulations as it claims to be, stevia's 'natural' label could see it take prime spot as the holy grail of sweeteners, as manufacturers increasingly try to adapt their formulations to the demands of the more health conscious consumer. Extracts were obtained using methanol and ethyl acetate, and the antioxidant activity measure using the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging assay. For the methanol extract, 47.66 micrograms per millilitre were required to scavenge half the radicals, while 9.26 micrograms per millilitre were needed for the ethyl acetate extract. Moreover, in a test for scavenging hydroxide radicals, only 3.08 micrograms per millilitre of the ethyl acetate extract were needed for 50 per cent inhibition. Hydroxide radicals were used to promote DNA strand damage, but in the presence of 0.1 milligrams per litre of the ethyl acetate extract all DNA strand damage was inhibited. DNA damage from oxidative stress has been linked to an increased risk of various diseases, particularly cancer. The total polyphenols content was measured at 0.86 mg of gallic acid equivalents per milligram, and the researchers report that the main flavonoids in this ethyl acetate extract were quercetin-3-O-arabinoside, quercitrin, apigenin, apigenin-4-O-glucoside, luteolin, and kaempferol-3-O-rhamnoside. More research is necessary to further explore the potential health benefits of the ingredient, but the study comes at time of increased interest and excitement around stevia. The ingredient is not even approved for use in food yet. In Europe, EFSA is reported to have started a new scientific evaluation of the ingredient. The agency in May received a mandate from the European Commission to carry out a safety assessment of stevia. In the US, FDA said it is also soon expecting to be petitioned to approve stevia, which will set the wheels of approval into motion on the other side of the Atlantic. Source: Journal of Agricultural and Food Chemistry Published online ahead of print, ASAP Article, doi: 10.1021/jf071892q "Oxidative DNA Damage Preventive Activity and Antioxidant Potential of Stevia rebaudiana (Bertoni) Bertoni, a Natural Sweetener" Authors: S. Ghanta, A. Banerjee, A. Poddar, and S. Chattopadhyay

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