Antioxidant and anticholinesterase constituents from the petroleum ether and chloroform extracts of Iris suaveolens

Abstract

The aim of this study was to investigate the phytochemical, antioxidant and anticholinesterase activities of Iris suaveolens. After determining total phenolic and flavonoid contents of the petroleum ether, chloroform and methanol extracts prepared from the rhizomes, the antioxidant capacity of the extracts was established using β-carotene-linoleic acid and CUPRAC methods. The chloroform extract which was rich in phenolic content exhibited the highest inhibition of lipid peroxidation in the β-carotene-linoleic acid system, and the best cupric reducing antioxidant capacity among the tested extracts. The petroleum ether extract indicated moderate anticholinesterase activity while the chloroform extract revealed significant butyrylcholinesterase inhibitory activity (75.03 ± 1.29%). Spectroscopic methods were used for the structural elucidation of the compounds (1-13) isolated from the petroleum ether and chloroform extracts. Coniferaldehyde (6), having the highest antioxidant activity in the β-carotene-linoleic acid assay at 25 and 50 µg/mL, demonstrated also the best effect in the CUPRAC method among the tested compounds (1-12). 3-Hydroxyirisquinone (10) showed the best anticholinesterase activity among the tested compounds (1-4, 6-12), and coniferaldehyde exhibited almost the same butyrylcholinesterase inhibitory activity (82.60 ± 2.33%) as galantamine (86.26 ± 0.66%).