The aim of the current study is to evaluate the biological activity of F. caspica M. Bieb. which is used for the treatment of diabetes in traditional Turkish medicine and to compare with F. halophila Peşmen. Antioxidant capacities and total phenolic contents of the plants' extracts were tested by DPPH radical scavenging assay and Folin Ciocalteu assay, respectively. Acetylcholinesterase inhibitory activities of the extracts were investigated with the aim of indicating whether there was a correlation with their antioxidant capacities. Different quinic acid and flavonoid derivatives which may be responsible for the activities of the extracts were detected using LC-MS screening in the methanol extracts. The methanol extract from the aerial parts of F. caspica was found to show most antioxidant capacity and acetylcholinesterase inhibitory activity.