Isolation and Identification of Cholinesterase Inhibitors from the Bulbs of Iris pseudacorus L.

Most of the bulbous plants are known for their medicinal purposes in addition to their ornamental value. Turkey is one of the home country of many beautiful bulbous plants. In continuation of our extensive studies on finding new natural cholinesterase inhibitors from Turkish medicinal plants, Iris L. species were investigated for their in vitro cholinesterase inhibitory effects designed to assess cholinesterase inhibitor activities on both acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) and antioxidant capacities with respect to their neuroprotective potential in this study. The dichloromethane and methanol extracts prepared from the bulbs of 47 Iris taxa were screened by using modified Ellmann method and the highest butyrylcholinesterase inhibitory effect was found in the methanol extract of the bulbs of Iris pseudacorus L. The dichloromethane sub-extract, which is obtained bioactivity-guided fractionation of methanol extract of I. pseudacorus L., was exhibited significant butyrylcholinesterase inhibitory activity (73.65 ± 2.06 %). These active sub-extract was subjected to fractionation on column chromatography and obtained six fractions. Among the fractions, coded as N5 was shown the significant butyrylcholinesterase inhibitory activity (93.78 ± 1.49 %) compared with galanthamine (80.02 ± 0.12 %). Fractionation of N5 on flash chromatography the highest butyrylcholinesterase inhibitory activity of sub-fraction coded as DS-5 was determined as 94.00 ± 1.03 %. The responsible compound from the activity of this sub-fraction was detected as irisolidone glucopyranoside based on its mass data by using LC-ESI-Q/TOF-MS-MS technique.