Antioxidant and anti-glycation properties of Thai herbal teas in comparison with conventional teas

Fifteen Thai herbal teas in comparison with teas of Camellia sinensis, were studied for their antioxidants and anti-glycation properties in correlation with their total phenolics, flavonoids, and non-flavonoids contents. Significant differences were observed among the tea infusions. Only stevia and sappan herbal teas had primary antioxidants and anti-glycation capacities comparable to C sinensis. However, purple velvet, mulberry and false mallow herbal teas were exceptionally stronger in metal chelating capacity than the C. sinensis teas. Principal component analysis showed that total phenolics, particularly flavonoids highly correlated with primary antioxidants and anti-glycation. Cluster analysis showed that the properties of stevia and sappan herbal teas were similar to green, black and oolong teas. Some common, but rarely mentioned, Thai herbal teas could be choices of interest for healthy beverages and could be new dietary sources for bioactive compounds. (C) 2012 Elsevier Ltd. All rights reserved.