Antioxidant and anti-glycation properties of Thai herbal teas in comparison with conventional teas
Highlights
► Thai herbal teas had antioxidants and anti-glycation capacities. ► Significance differences were observed among 18 teas studied. ► Only stevia, sappan primary antioxidants, anti-glycation comparable to Camellia sinensis. ► Purple velvet, mulberry, false mallow metal chelations higher than C. sinensis. ► Cluster analysis showed stevia, sappan properties similarly to C. sinensis.
Introduction
Free radicals are generated in the human body from endogenous (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 antioxidative 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 et al., 2004, Rahimi et al., 2005, Young and 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 process 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 modifications, and result in the formation of advanced glycation end products (AGEs) (Rojas and Morales, 2004, Wu and Yen, 2005). The glycation process occurs to higher extent under ageing and hyperglycemia such as diabetics in comparison to healthy persons (Baral et al., 2000). AGEs formation is also enhanced with oxidative stress (Parija et al., 2005, Selvaraj et al., 2002, Wu and Yen, 2005). In terms of pathogenesis, accumulation of AGEs is toxic to cells and can accelerate diabetic complications including retinopathy, neuropathy, cataract and atherosclerosis (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 worldwide. Beside the attractive flavours, their popularities come from their primary and secondary antioxidant properties (Aoshima et al., 2007, Horžić et al., 2009, Kome et al., 2010). Primary antioxidants directly scavenge free radicals, while secondary antioxidants indirectly prevent the formation 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 herbal teas such as lemon grass (Cymbopogon citratus), chamomile (Matricaria recutita) and rosemary (Rosmarinus officinalis). Herbal tea of mint (Mentha spicata) and peppermint (Mentha spicata) have exceptionally higher secondary antioxidant capacities than all teas of C. sinensis (Chan et al., 2010). Recent studies have shown that some teas possess not only antioxidant capacity but also anti-AGEs formation properties (Ho et al., 2010, Lunceford and Gugliucci, 2005). Black tea, balm (Melissa officinalis), sage (Salvia officinalis), mate (Ilex paraguariensis) and common verbena (Verbena officinalis) herbal teas exhibited anti-AGEs formation properties comparable to green tea (Ho et al., 2010, Lunceford and Gugliucci, 2005).
Hence, tea and herbal tea beverages are potential dietary sources for both antioxidant and anti-AGEs formation properties. However, the role of anti-AGEs formation capacity of various herbal teas is still not well investigated. Among those herbals, various Thai herbs such as mulberry (Morus alba), safflower (Carthamus tinctorius) are often consumed as herbal tea and are commercially available. However their health promoting properties, especially antioxidant and anti-AGEs formation properties have rarely been studied. The objective of this work was to study the antioxidants and anti-AGEs formation properties in correlation with phenolic, flavonoid and non-flavonoid contents of 15 Thai herbal teas comparing to conventional green, black and oolong teas for the first time.
Section snippets
Chemicals
Folin–Ciocalteu’s phenol reagent and gallic acid monohydrate were purchased from Sigma–Aldrich Chemie (Steinheim, Germany). l-Ascorbic acid was purchased from Riedel-deHaën®. Ferric chloride hexahydrate, ferric sulphate, d-glucose, sodium azide, potassium persulfate were obtained from Ajax Finechem (New South Wales, Australia). 2,4,6-Tri-(2-pyridil)-S-triazine (TPTZ), ferrozine (3-(2-pyridyl)-5,6-diphenyl-1,2,4-triazine), 2,2′-azino-bis 3-ethylbenzothiazoline-6-sulfonic acid diammonium salt
Total phenolic, flavonoid and non-flavonoid contents
Total phenolic (TPC), flavonoid (TFC) and non-flavonoid (TNFC) contents were found in the tea infusions as shown in Fig. 1. Comparing to teas of C. sinensis, Thai herbal teas generally had lower TPC and TFC. Exceptions were stevia (SV) and sappan (S) herbal teas with total phenolic and flavonoid contents higher than oolong tea (OT). Among 18 infusions studied, green tea (GT) was recognized as the richest source of both total phenols and flavonoids, 132 and 125 mg GAE/100 ml respectively. Most of
Conclusion
We investigated antioxidants and anti-glycation capacities of 15 Thai herbal teas in comparison with green, black and oolong tea for the first time. Thai herbal teas generally had lower antioxidants and anti-glycation activities than teas of C. sinensis. Stevia and sappan herbal teas were the exceptions for their primary antioxidants and anti-glycation capacities. Among the properties tested, metal ion chelating efficiency of mulberry, purple velvet and false mallow herbal teas were outstanding
Acknowledgements
This work was financed from the Mahidol University research grant. The authors thank to the instrument center of Mahidol University Kanchanaburi Campus. Dr. Duangkamol Poltem, Division of Science and Liberal Arts, Mahidol University Kanchanaburi campus, is gratefully acknowledged for the statistical analysis technique.
References (31)
Advanced glycation endproducts-role in pathology of diabetic complications
Diabetes Research and Clinical Practice
(2005)- et al.
Iron-chelation properties of phenolic acids bearing catechol and galloyl groups
Food Chemistry
(2006) - et al.
Antioxidative and anti-hydrogen peroxide activities of various herbal teas
Food Chemistry
(2007) - et al.
The role of iron in ascorbate-dependent deoxyribose degradation. Evidence consistent with a site-specific hydroxyl radical generation caused by iron ions bound to the deoxyribose molecule
Journal of Inorganic Biochemistry
(1987) - et al.
Antioxidant activity of Camallia sinensis leaves and teas from a lowland plantation in Malaysia
Food Chemistry
(2007) - et al.
Antioxidant properties of tropical and temperate herbal teas
Journal of Food Composition and Analysis
(2010) - et al.
Iron-catalyzed hydroxyl radical formation. Stringent requirement for free iron coordination site
The Journal of Biological Chemistry
(1984) - et al.
Comparison of anti-glycation capacities of several herbal infusions with that of green tea
Food Chemistry
(2010) - et al.
The composition of polyphenols and methylxanthines in teas and herbal infusions
Food Chemistry
(2009) - et al.
Antioxidant properties of several tropical fruits: a comparative study
Food Chemistry
(2007)
Ilex paraguariensis extracts inhibit AGE formation more efficiently than green tea
Fitoterapia
Extraction of active ingredients from green tea (Camellia sinensis): Extraction efficiency of major catechins and caffeine
Food Chemistry
A review on the role of antioxidants in the management of diabetes and its complications
Biomedicine & Pharmacotherapy
Antioxidant activity applying an improved ABTS radical cation decolorization assay
Free Radical Biological & Medicine
Advanced glycation and endothelial function: A link toward vascular complications in diabetes
Life Sciences
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