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%.
The researchers concluded that white tea reduces the risk of inflammation, which is characteristic of rheumatoid arthritis and some cancers, as well as wrinkles. Neal's Yard plans to use the information gained via this study to select efficacious antiaging ingredients for its natural skin care lines.
This study was published in the August 2009 issue of BMC Complementary and Alternative Medicine in the article, Anti-collagenase, anti-elastase and anti-oxidant activities of extracts from 21 plants.