Antioxidant and anti-glycation properties of Thai herbal teas in comparison with conventional teas Pawinee Deetae a,⇑ , Prangthip Parichanon a , Paweena Trakunleewatthana a , Charturong Chanseetis b , Sittiwat Lertsiri c a Food Technology Program, Mahidol University, Kanchanaburi Campus, Saiyok, Kanchanaburi 71150, Thailand b Agricultural Science Program, Mahidol University, Kanchanaburi Campus, Saiyok, Kanchanaburi 71150, Thailand c Department of Biotechnology, Faculty of Science, Mahidol University, Bangkok 10400, Thailand article info Article history: Received 10 August 2011 Received in revised form 22 December 2011 Accepted 2 February 2012 Available online 11 February 2012 Keywords: Herbal tea Tea Antioxidant capacity Anti-glycation capacity ABTS FRAP FIC abstract 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 proper- ties 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. Ó 2012 Elsevier Ltd. All rights reserved. 1. Introduction Free radicals are generated in the human body from endoge- nous (e.g. respiratory chain, oxidative enzymes) and exogenous (e.g. air pollution, smoking) sources. The occurrence of such free radicals is balanced by endogenous defense systems such as anti- oxidative enzymes and metal binding proteins (Young & Woodside, 2001). Overproduction of such free radicals leads to oxidative stress that damage cell matrices such as lipids, proteins and nucleic acids, resulting in the development of various diseases, e.g. cancers, diabetes, cardiovascular diseases and Alzheimer’s diseases (Barnham, Masters, & Bush, 2004; Rahimi, Nikfar, Larijani, & Abdollahi, 2005; Young & Woodside, 2001). Hence, the normal biological system can be maintained by exclusion of excessive amounts of free radicals by antioxidants. Oxidative stress also plays a role in glycation. The glycation pro- cess starts with chemical reaction between available amino groups of amino acid residues in proteins and reducing sugars, resulting in the formation of Amadori products. Over time, these products are transformed through glycoxidative process and further modifica- tions, and result in the formation of advanced glycation end prod- ucts (AGEs) (Rojas & Morales, 2004; Wu & Yen, 2005). The glycation process occurs to higher extent under ageing and hyper- glycemia such as diabetics in comparison to healthy persons (Baral et al., 2000). AGEs formation is also enhanced with oxidative stress (Parija, Bobby, Vinod, & Saradha, 2005; Selvaraj, Bobby, Das, Ramesh, & Koner, 2002; Wu & Yen, 2005). In terms of pathogenesis, accumulation of AGEs is toxic to cells and can accelerate diabetic complications including retinopathy, neuropathy, cataract and ath- erosclerosis (Ahmed, 2005). The investigation of food with both antioxidative and anti-AGEs formation properties offers a potential prevention of such illness. Teas brewed from Camellia sinensis and herbal tea brewed from the leaves, flowers, seeds, fruits and roots of plant species other than C. sinensis are some of the most consumed beverages world- wide. Beside the attractive flavours, their popularities come from their primary and secondary antioxidant properties (Aoshima, Hirata, & Ayabe, 2007; Horz ˇic ´ et al., 2009; Kome, Horz ˇic ´, Belšc ˇak, Ganic ´, & Vulic ´, 2010). Primary antioxidants directly scavenge free radicals, while secondary antioxidants indirectly prevent the for- mation of free radicals through Fenton’s reaction (Chan, Lim, Chong, Tan, & Wong, 2010). Teas of C. sinensis generally exhibit both primary and secondary antioxidant capacities higher than 0308-8146/$ - see front matter Ó 2012 Elsevier Ltd. All rights reserved. doi:10.1016/j.foodchem.2012.02.012 ⇑ Corresponding author. Tel.: +66 034585060x2506; fax: +66 034585071. E-mail addresses: pawinee_deetae@hotmail.com, kapawinee@mahidol.ac.th (P. Deetae). Food Chemistry 133 (2012) 953–959 Contents lists available at SciVerse ScienceDirect Food Chemistry journal homepage: www.elsevier.com/locate/foodchem