Onosma polyantha vs. Onosma mollis: Analysis of Phenolic Compounds Using Liquid Chromatography–Electrospray Ionization Tandem Mass Spectrometry (LC-ESI-MS/MS) and Assessment of the Antioxidant Activity

Abstract

To our knowledge, this is the first work on the influence of species upon the bioactive molecules, antioxidant properties, and enzyme inhibitory capacities against tyrosinase and α-amylase of Onosma polyantha and O. mollis. The levels of phenolic compounds were from 6.55 to 10.37 mg gallic acid equivalent/g extract. The concentrations of total flavonoids varied from 2.71 to 10.78 mg quercetin equivalent/g extract. Twenty-five compounds were quantified via liquid chromatography – electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS). Significant differences were found between the two species. Chlorogenic acid, rosmarinic acid, hesperidin, and luteolin 7-glucoside were the major compounds in both species. Four antioxidant assays together with two enzyme tests confirmed that O. polyantha and O. mollis extracts exhibited remarkable antioxidant and enzyme inhibitory capacities. Statistical analyses confirmed that the biological activities depend on the synergism between phenolic compounds and radicals. The results proposed O. polyantha and O. mollis species as potential sources of bioactive compounds for industrial application.

Keywords:

• Antioxidant capacity
• liquid chromatography–electrospray ionization–tandem mass spectrometry (LC-ESI-MS/MS)
• phenolic compounds

Acknowledgment

The authors would like to thank to Dr. Olcay Ceylan for his kind help in identifying the plant materials used in this study.