Assessment of antioxidant activities of Epidendrum secundum Jacq, a terrestrial orchid from southern Ecuadorian highlands

Abstract

A comparison of antioxidant and antibacterial activities among in vitro cultured seedlings and Orchidarium plant specimens of Epidendrum secundum Jacq, a terrestrial orchid from southern Ecuadorian highlands, was performed. The aim of this work was to evaluate the enzymatic and non-enzymatic antioxidant compounds production from in vitro cultured seedlings and Orchidarium plants from the orchid species under study. For this purpose, a group of spectrophotometric assays was set up, comparing the free radical scavenging capacity, phenolic and flavonoids content from seedling leaves and plant leaves organic extracts, as non-enzymatic antioxidant indicators. In addition, the antibacterial activity of the organic plant extracts was evaluated versus Escherichia coli and Staphylococcus aureus. Catalase and ascorbate peroxidase activities were assessed as enzymatic antioxidant systems in aqueous extracts. The results showed higher non-enzymatic antioxidant activity for leaves from Epidendrum secundum Orchidarium plants compared with leaves from in vitro seedling cultures. The organic extracts from the orchid under study displayed moderate antibacterial activity against Staphylococcus aureus. In the enzymatic antioxidant evaluation, catalase activity was significantly higher at in vitro conditions.

The results from this work allow us to highlight the potential of Epidendrum secundum Jacq as a source of bioactive metabolites with promising antioxidant and antibacterial activities.