Total phenolic content and antioxidant activity of plants used in traditional Romanian herbal medicine

A number of herbal plants from Romania widely used as natural food additives or for health promotion in traditional medicine were investigated for their antioxidant activity. Methanol extracts were obtained from plants belonging to the Lamiaceae family (lavender Lavandula angustifolia L.; lemon balm Melissa officinalis; sage Salvia officinalis; oregano Origanum vulgare L.; rosemary Rosmarinus officinalis L.; thyme Thymus vulgaris L.; mullein Verbascum phlomoides; mint Mentha longifolia), Clusiaceae family (St John’s wort Hypericum perforatum L.), and Compositae family (elecampane Inula helenium). Total phenolic concentration was determined using the Folin-Ciocalteu phenol reagent method, while total flavonoids were measured using the aluminium chloride colorimetric method. Relationships between total antioxidant activity and composition of plant extracts were evaluated. Origanum vulgare extract showed the highest antioxidant activity and total phenolic content compared to the other plants extracts. A positive correlation was observed between total antioxidant activity and total phenolic content of the analyzed extracts.