Researchers Find High Antioxidant, Antiaging Activity in White Tea
Posted: September 1, 2009
White tea surprised researchers when they found the extract to inhibit collagenase and elastase activity, in addition to having a high phenolic content. Researchers at Kingston University's School of Life Sciences and Neal’s Yard Remedies collaborated to test the antioxidant, anti-elastase and anti-collagenase activities of 23 plant extracts from 21 plant species. The study revealed that approximately 12 of the plants exhibited high or satisfactory anti-collagenase or anti-elastase activities, with nine having inhibitory action against both enzymes.
In terms of anti-elastase activity, white tea was found to inhibit 89%, followed by cleavers at 58%, burdock root at 51%, bladderwrack at 50%, anise at 32% and angelica at 32%. In addition, the highest level of anti-collagenase activity was found in white tea at 87%, followed by green tea with 47%, rose tincture with 41%, and lavender at 31%.
The nine plant extracts with activities against both elastase and collagenase included: white tea, bladderwrack, cleavers, rose tincture, green tea, rose aqueous, angelica, anise and pomegranate, with white tea inhibiting both enzymes the most.
The total phenolic content varied between 0.05-0.26 mg gallic acid equivalents (GAE)/mL, with the exception of white tea at 0.77 mg GAE/mL. For antioxidant assessments, the Trolox equivalent antioxidant capacity (TEAC) assay revealed activity for all extracts. White tea showed the highest activity, equivalent to 21 μM Trolox for a 6.25 μg aliquot. In addition, seven extracts exhibited activities equal to 10 μM Trolox with witch hazel at 6.25 μg = 13 μM Trolox, and rose aqueous at 6.25 μg = 10 μM Trolox.
High levels of activity for white tea were also found via the superoxide dismutase (SOD) assay, in which the material exhibited an 88% inhibition of reduction of nitroblue tetrazolium. Activities were also observed for green tea with an 86.41% inhibition, rose tincture at 82.77%, witch hazel with an 82.05% inhibition, and rose aqueous, 73.86%.