Tuberaria lignosa preparations: influence of drying methods and oral dosage forms on antioxidant properties and phytochemical composition

Many herbal beverages used in folk medicine have pharmacological properties connected with the presence of antioxidants such as phenolic compounds. Tuberaria lignosa (Sweet) Samp. (Cistaceae) is one of the most popular medicinal plants in several regions of the Iberian Peninsula used to prepare herbal infusions or decoctions. In the present work, the effects of drying (freeze or shade-drying) and preparation methods (water infusion or decoction) on the antioxidant activity and phytochemical composition of wild and commercial samples of Tuberaria lignosa were evaluated. Infusion of the freeze-dried wild sample led to the highest levels of sugars, while infusion of shade-dried wild sample and decoction of the freeze-dried sample retained the highest ascorbic acid and phenolic compounds levels These two samples revealed the highest antioxidant activity, even higher, in some cases, than trolox Decoctions had lower amounts of disaccharides than infusions, which seemed to be hydrolyzed increasing the content in monosaccharides. Commercial samples showed much lower contents in phenolic compounds, mainly in ellagitanins and flavonoids, as also the lowest antioxidant activity. Data give scientific evidence to folk medicinal uses of Tuberaria lignosa. highlighting the interest of its decoctions and infusions as sources of bioactive compounds (e.g. phenolic compounds and ascorbic acid).