5th International Meeting:
ADVANCES IN ANTIOXIDANTS
(TRACE ELEMENTS, VITAMINS AND POLYPHENOLS)
Monastir - Sousse (Tunisia); 11-15th October, 2008
Rooibos Tea: A Rich Source of Antioxidant Active Polyphenols with Health Promoting Effects
Gerhard Kroyer
Institute of Chemical Engineering, Division of Natural Products and Food Chemistry
ViennaUniversity of Technology, Vienna, Austria.
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Consumption of a diet rich in polyphenol compounds has been linked with a reduced risk for cardiovascular diseases and certain types of cancer. Polyphenol substances may act as potential antioxidants and radical scavengers and strengthen as dietary natural antioxidants the endogenous antioxidant system by reducing oxidative stress and the risk of toxic diseases by protecting cells from deteriorative effects of free radicals. Their action as anti-inflammatory, anti-bacterial, anti-viral, anti-carcinogenic, anti-allergic and immune system stimulating agents has been documented in numerous studies in literature.In this regard, the content of total polyphenols in rooibos tea, a herbal tea traditionally produced from leaves of the rooibos plant, which grow in the CedarValley in South Africa and the evaluation of their potential antioxidant properties might be of great significance.The objective of this study was to quantify the total polyphenols in water extracts of rooibos tea and to evaluate their respective antioxidant activity in comparison to gunpowder tea, a green tea variety originated from China.
Water extracts of rooibos tea and green tea were prepared and the content of total polyphenols was analyzed by the Folin-Ciocalteu method. The antioxidant and radical scavenging capacity was evaluated by the DPPH radical scavenging method and determined as EC50.
The total polyphenol content (mg/g) of rooibos tea water extracts was remarkable high (315) in comparison to the green tea extract (209). Significant radical scavenging capacity (EC50) was observed in rooibos tea extracts (138), which was more pronounced in the comparatively examined green tea extract (424). The results indicate that rooibos tea produced from leaves of the rooibos plant, which grow in the CedarValley in South Africa, is characterized by its significant high content of polyphenols and remarkable antioxidant and radical scavenging capacity. In comparison, the green tea variety showed elevated radical scavenging properties, which may be due to their higher content of catechin substances.
According to this study African grown rooibos tea consumption would be helpful in maintaining and promoting health particularly in consideration of their beneficial impact to public health especially in respect of cardiovascular disease prevention. Furthermore, rooibos tea extracts could be regarded as effective natural antioxidant additives for food products and as functional dietary food supplements due to their significant content of total polyphenols as bioactive substances.