Tannins are polyphenolic compounds present in plants which are also found in foods and beverages. They are specially used by pharmaceutical, food, leather and rubber industries, and also for water treatment. Considering the significance of this group of compounds, several of aromatic and medicinal plants cultivated in Northern Rio Grande do Sul State, Brazil, were tested for their total tannin content. Angelica archangelica , Cinnamomun camphora var. linaloolifera fugita , Cymbopogon citratus, Lavandula dentata , Lippia alba, Rosmarinus officinalis and Thymus vulgaris were analysed and compared with Acacia mearnsii (black wattle) which is industrially used for tannin extraction. The extraction procedure was made by macerating the plants in methanol, and the quantification was done using Folin Denis reagent and spectrophotometry. By using a calibration curve (% tannic acid equivalent) the total tannin contents range from 0.01% ( Cymbopogom citratus ) to 18.9% ( Lippia alba ).
medicinal plants; tannins; spectrofotometry; Folin Denis reagent