Bioactive compounds and in vitro biological activity of Euphrasia rostkoviana Hayne extracts

Euphrasia rostkoviana is an edible medicinal species growing in Himalayas. Despite their chemical and biological importance, E. rostkoviana leaves are still poorly studied. In order to improve the knowledge on its metabolite profile and biological properties of two different polar extracts (infusion and ethanol:water) were studied. Phenolic compounds, organic acids, sterols and fatty acids were determined by different chromatographic methods. 6 Hydroxycinnamic acids, nine flavonoids, seven organic acids, 9 fatty acids and two sterols were identified. In general way, infusion presents a greater richness in these metabolites. The antioxidant, acetylcholinesterase, butyrylcholinesterase and antibacterial activity were checked by in vitro assays. A concentration-dependent activity was noticed against DPPH, superoxide and nitric oxide radicals, scavenging against the last two radicals was reported for the first time. Infusion was the most active against all radicals. The same effect was observed in both cholinesterase inhibitory assays. Antibacterial capacity of both extracts was investigated here for the first time against Gram-positive and Gram-negative bacteria, being more effective against the first one. Additionally, α-glucosidase inhibitory activity was also evaluated, but no effect was found. The bioactivities observed may be due, at least partially, to the presence of the metabolite determined in the present study. The results suggest that the extracts may be interesting to use as pharmaceutical incorporations and food additive due to its antiradical and antibacterial activity. However, toxicological studies in vivo should be performed in the future to ensure their safety.