Phenolic compounds and bioactivity of Scorzonera pygmaea Sibth. & Sm. aerial parts: In vitro antioxidant, anti-inflammatory and antimicrobial activities

Background and Aims: Scorzonera L. genus contains several medicinal and edible plants. Both roots and aerial parts of Scorzonera species are used. S. pygmaea is endemic to Turkey. In a previous study, nine phenolic compounds were reported from the roots of the plant alongside certain biological activities. The current study was designed to investigate the aerial parts of the plant in the same manner and compare the potentials of the two parts. Methods: Chromatographic and spectroscopic methods were used to isolate and identify the phenolics. Total phenolic contents were determined by Folin-Ciocalteu method. FRAP assay, anti-LPO, scavenging DPPH, ABTS and superoxide radicals were employed to evaluate the antioxidant activity. COX inhibition test and micro broth dilution technique were used for antiinflammatory and antimicrobial activities, respectively. Results: Seven phenolic compounds; thunberginol C (1), protocatechuic acid (2), chlorogenic acid methyl ester (3), cudrabibenzyl A (4), scorzocreticin (5), scorzocreticoside I (6) and II (7) were purified. All the compounds are new for the aerial parts of the plant and 2 is new for the genus. The aerial parts showed a high antioxidant capacity which correlated with its phenolic content. COX inhibitory activity was found to be lower compared to Indomethacin. Weak antimicrobial activity was determined against Staphylococcus aureus and S. epidermidis. Conclusion: Aerial parts possess significant/infrequent phenolics and the ethyl acetate (EtOAc) fraction of the ethanol extract is the most promising fraction for isolating these compounds. Phenolic compositions of aerial parts and roots are very similar. However, aerial parts can be a better rich source of natural antioxidants with protocatechuic acid and higher antioxidant potential. Keywords: Scorzonera pygmaea, phenolics, antioxidant, protocatechuic acid