The formation and bioactivities of green substances in Chrysanthemum morifolium tea

One interesting phenomenon of Chrysanthemum morifolium tea is its formation of green or dark green color after hours of brewing. We investigated the greening reaction and its bioactivities, including an analysis of the green compounds. Results showed that the green color was due to a decrease in the L* (lightness), b* (yellowness/blueness), chroma values and an increase in hue angle. The green substances were found to be substances with similar polarities and unstable in acidic conditions. There was no significant difference (p 0.01) in antioxidant activity between non-green and green samples. The green substances did not lead to cytotoxicity in PC12 cells at low concentrations, but at high concentrations, they caused a significant (p 0.01) decrease in cell viability. The saccharide percentage and FT-IR results showed that the greening reaction was affected by the glycosides or groups attached to the saccharides, which might suggest a new mechanism for color-forming reactions.