Antioxidant activity and phenolic content of herbal infusions from medicinal plants used in Argentina

Abstract

Currently, teas and herbal infusions represent an important part of the human diet. Most contain phenolic compounds with high antioxidant activity, usually associated with human health protective functions. This attribute defnes teas and infusions as nutraceutical foods. In Argentina, several native species are traditionally used for medical purposes. Some of those species are Larrea cuneifolia, Larrea nitida, Grindelia chiloensis, Pteromonnina dictyocarpa, Mandevilla laxa, and Monttea aphylla. The objectives of this study were to analyze the antioxidant power and the scavenging capacity of infusions obtained from those six medicinal plants, to characterize the phenolic profle, and to study in vitro their safety or cytotoxicity. Additionally, the potential use of two infusions as antioxidant additives in a food model was evaluated. The results indicated that the analyzed plant species are rich in phenolic acids (e.g., cafeic, ferulic, and chlorogenic acid), and favonoids (e.g., quercetin and kaempferol), with high antioxidant power. The infusion blend obtained with G. chiloensis and L. cuneifolia exhibited the highest value of antioxidant capacity measured with the FRAP technique (193.4 μg EAA/mg DW). On the other hand, L. cuneifolia infusion showed the greatest antioxidant capacity determined by FRAP (131.9±5.2 μg EAA/mg DW) and DPPH assays (0.453 mL/mg s). Additionally, L. cuneifolia infusion showed the highest phenolic content (232.8 μg GAE/mg DW) and favonoid content (153.3 μg QE/mg DW). None of the infusions showed toxicity in mammalian cells, except for G. chiloensis. Furthermore, the L. cuneifolia and L. nitida infusions showed a high inhibitory efect on lipid oxidation in ground beef (55% and 51% at 4 days of storage, respectively). The results suggest that the studied infusions are safe and a rich source of antioxidants, which supports their use in traditional medicine. However, further exhaustive studies of G. chiloensis infusion are needed to ensure its safety, as it has shown cytotoxicity. Besides, it is worthwhile to advance the study of L. cuneifolia and L. nitida as sources of dietary antioxidants, due to their high antioxidant power and ability to protect against lipid peroxidation.