Bioactive Asarone-Derived Phenylpropanoids from the Rhizome of <i>Acorus tatarinowii</i> Schott

Abstract

Eight new ( 1a / 1b, 2a, 3a, 4a / 4b, and 5a / 5b ) and seven known ( 2b, 3b, and 6 – 10 ) asarone-derived phenylpropanoids, a known asarone-derived lignan ( 12 ), and four known lignan analogues ( 11 and 13 – 15 ) were isolated from the rhizome of Acorus tatarinowii Schott. The structures were elucidated via comprehensive spectroscopic analyses, modified Mosher’s method, and quantum chemical calculations. Compounds 1 – 8 were present as enantiomers, and 1 – 5 were successfully resolved via chiral-phase HPLC. Compounds 1a / 1b were the first cases of asarone-derived phenylpropanoids with an isopropyl C-3 side-chain tethered to a benzene core from nature. Hypoglycemic, antioxidant, and AChE inhibitory activities of 1 – 15 were assessed by the α-glucosidase inhibitory, ORAC, DPPH radical scavenging, and AChE inhibitory assays, respectively. All compounds except 3a showed α-glucosidase inhibitory activity. Compound 3b has the highest α-glucosidase inhibitory effect with an IC 50 of 80.6 μM (positive drug acarbose IC 50 of 442.4 μM). In the antioxidant assays, compounds 13 – 15 exhibited ORAC and DPPH radical scavenging activities. The results of the AChE inhibitory assay indicated that all compounds exhibited weak AChE inhibitory activities.