Teas and herbal infusions as sources of melatonin and other bioactive non-nutrient components

The consumption of teas and herbal infusions has increased in Europe and the USA in recent years. The goal of this work was to provide new knowledge on the contents of melatonin and other bioactive non-nutrient compounds of nineteen highly consumed herbal infusions. Melatonin was previously assessed in some medicinal plants alcoholic extracts but not described in herbal aqueous infusions as we reported for the first time. Noticeable melatonin contents were found in most of herbal infusions, showing chamomile and green tea the highest values. These studied herbal infusions could be considered as potential dietary sources of this antioxidant compound, and they also exhibited high levels of total phenolic compounds and total flavonoids (lemon balm revealed the highest contents). From results, the total phenolic compounds and total flavonoids were associated with the inhibition of lipase and α-glucosidase, as well as to the in vitro antioxidant capacity measured through five different methods (DPPH, ABTS, FRAP, ORAC, and deoxyribose assays). Thus, the studied teas and herbal infusions could be consided as suitable drinks herein validated for their bioactive compounds that may act as antioxidants and non-protein inhibitors of digestive enzymes, promoting health-promoting properties.