Demonstrating the relationship between the phytochemical profile of different teas with relative antioxidant and anti-inflammatory capacities
Background: Indigenous or traditional aqueous plant extracts are commonly used by as much as 80% of the world’s population for primary health needs. Teas including Camellia sinensis teas and herbal teas were characterized for phytochemical content and the potential to offer specific bioactivities that could benefit human health by mitigating oxidative stress and inflammation.
Context and purpose of this study: In present study, we compared the phytochemical profiles, antioxidant and anti-inflammatory activities of four Camellia sinensis (white, green, oolong, and black) teas and two herbal (Rooibos and Yerba mate) teas that are produce and consumed by different population worldwide. We also studied the impact of Rooibos tea on the production of inflammatory mediators, including nitric oxide (NO), inducible nitric oxide synthase (iNOS), cyclooxygenase 2 (COX-2) and different cytokines in Raw 264.7 cells, both with or without interferon γ (IFN-γ) and lipopolysaccharide (LPS) stimulation.
Results: White tea had the highest total phenolic content (TPC) and antioxidant activity among these six teas examined, whereas, Rooibos tea has the lowest TPC, antioxidant and anti-inflammatory activities. Yerba mate tea had the greatest potential to inhibit NO production in IFN-γ and LPS-induced Raw 264.7 cells. The anti-inflammatory activity of teas was found to be correlated with antioxidant activity and phytochemical composition. Among the six teas examined, only Rooibos tea was found to induce NO in unstimulated Raw 264.7 cells. Under basal conditions, Rooibos tea induced interleukin (IL)-1α (IL-1α), IL-1β, IL-6, IL-10, granulocyte-colony stimulating factor (G-CSF), granulocyte macrophage colony-stimulating factor (GM-CSF), tumor necrosis factor- alpha (TNF-α), iNOS and COX-2 production. However, Rooibos tea also showed a dose-dependent inhibition of IL-6, IL-10, iNOS and COX-2 expression in stimulated Raw 264.7 cells. Although high concentration Rooibos tea was affective to inhibit induced IL-1α, G-CSF and GM-CSF, low concentration Rooibos tea also can up-regulate the expression of these cytokines. No inhibitory effects of all teas examined were found on mitigation of IL-1β and TNF-α.
Conclusions: Rooibos tea can show dual functions on inflammation, by either promoting an inflammatory response to cytokines induction or, alternatively inhibit inflammation on exposure to cytokine treatment, such as tissue injury or a pathogen infection. Rooibos tea also has marked value in mitigating disease states such as hypertension and cardiovascular diseases where induction of NO production is important.
Keywords: Camellia sinensis, Rooibos tea, herbal tea, inflammation, cytokine, antioxidant
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Copyright (c) 2017 Xiu-Min Chen, David D Kitts, Zhili Ma