Exposure of chamomile extracts caused minimal growth inhibitory responses in normal cells, whereas a significant decrease in cell viability was observed in various human cancer cell lines. Chamomile exposure resulted in differential apoptosis in cancer cells but not in normal cells at similar doses. HPLC analysis of chamomile extract confirmed apigenin 7-O-glucoside as the major constituent of chamomile; some minor glycoside components were also observed. Apigenin glucosides inhibited cancer cell growth but to a lesser extent than the parent aglycone, apigenin. Ex vivo experiments suggest that deconjugation of glycosides occurs in vivo to produce aglycone, especially in the small intestine. This study represents the first reported demonstration of the anticancer effects of chamomile.
Chamomile tea has long been considered a brew that soothes. But when Blumberg and McKay reviewed scientific literature on the bioactivity of chamomile, they found no human clinical trials that examined this calming effect. They did, however, publish a review article on findings far beyond sedation, describing test-tube evidence that chamomile tea has moderate antimicrobial activity and significant antiplatelet-clumping activity.
The researchers also describe evidence of bioactivity of peppermint tea. In test tubes, peppermint has been found to have significant antimicrobial and antiviral activities, strong antioxidant and antitumor actions, and some antiallergenic potential. Based on a human clinical trial, the team also has reported that drinking hibiscus tea lowered blood pressure in a group of pre-hypertensive and mildly hypertensive adults.
McKay and Blumberg have concluded that the available research on herbal teas in general is compelling enough to suggest further clinical studies.