Liquid Chromatography–Electrospray Ionization Tandem Mass Spectrometry (LC-ESI-MS/MS) Identification of Phytochemicals and the Effects of Solvents on Phenolic Constituents, Antioxidant Capacity, Skin-Whitening and anti-Diabetic Activity of Onosma mitis

To the best of our knowledge, this is the first study on the effect of solvent (water, methanol, and ethyl acetate) upon phenolics extracted from Onosma mitis. The antioxidant capacities together with the enzyme inhibitory properties toward tyrosinase and α-amylase were also assessed. The yields of the extract were 2.62, 10.93, and 21.68% for ethyl acetate, methanol, and water, respectively. The concentrations of phenolic compounds were from 11.89 (ethyl acetate) to 2.66 mg gallic acid equivalent/g extract (methanol). Twenty-five molecules were identified and quantified by liquid chromatography – electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS). Significant differences were present between the extracts; methanol presented the highest number of compounds (25) while ethyl acetate provided the lowest (18). Chlorogenic acid, luteolin 7-glucoside, rosmarinic acid, and apigenin 7-glucoside were the major compounds regardless of solvent. Antioxidant and inhibitory enzyme assays showed that O. mitis exhibited interesting biological properties. The results illustrate the use of O. mitis as a promising source of biomolecules for industrial applications. [ABSTRACT FROM AUTHOR]