Total phenolics, flavonoids, condensed tannins content of eight centaurea species and their broad inhibitory activities against cholinesterase, tyrosinase, α-amylase and α-glucosidase

Several bioactive compounds originate from natural sources and their uses are generally related with traditional or folk medicine. Synthetic drugs can have adverse side effects and, for this reason, the investigation of novel, safe, and naturaloccurring products can account for the development of new drugs. The genus Centaurea L. is one of the most important genera of the Asteraceae family, containing more than 200 species in the Turkish flora, about 140 of which are endemic. The aim of the present work was to determine enzyme inhibitory potentials of two extracts (chloroform and ethyl acetate) from eight Centaurea species against cholinesterase, tyrosinase, amylase, and glucosidase. The total phenolics, flavonoids and condensed tannin contents were also reported for each extract. These components in the extracts varied according to species and extraction solvents as well as enzyme inhibitory effects. The highest level of phenolics was found to be in the chloroform extract of C. pulchella (119.23 mg GAEs/g extract). Generally, chloroform extracts exhibited stronger enzyme inhibitory effects as compared to ethyl acetate. Additionally, possible correlations with total phenolics, flavonoids, and condensed tannins content were also highlighted. This paper is the first report of the inhibitory capacities of the eight Centaurea species on the selected enzymes. The present results may be a valuable starting point in the development of new bioactive formulations.