Bioactivity and toxicity evaluation of infusions from selected Greek herbs

Abstract

Plants used in water infusions, as aromatic or refreshing hot beverages, are the most consumed drinkable forms of herbs worldwide; used for centuries due to their perceived medicinal and preventive properties. The aim of this study was to assess the bioactivity and toxicity of 9 herbal infusions originating from Greek flora. To measure the total phenolic content, antioxidant activity and potential toxicity of each species, spectrophotometric assays, in vitro bioluminescence inhibition of Vibrio fischeri and mammalian renal cells viability assays were used. Significant total phenolic content (0.11–2.90 mg caffeic acid equivalents/mL) and antioxidant activity (0.103–11.7 μug Trolox equivalents/mL) were obtained and were positively correlated in most of the herbal infusions. Species-specific inhibition was observed using both bioassays. Tarragon and chamomile infusions showed the highest inhibition of Vibrio fischeri. Yarrow and sage showed the highest toxicity towards renal cells, while chamomile, linden and valerian infusions showed no signs of toxicity. A direct correlation between sage extract dosage and renal toxicity was observed. The results suggested that herbal infusions may be potential natural antioxidants with supplementary bioactivity, but also may have some potential toxicity.