Selective in vitro and in silico cholinesterase inhibitory activity of isoflavones and stilbenes from Belamcandae chinensis rhizoma

Isoflavonoids and stilbenes were suggested as potential lead structures for inhibition of cholinesterases and in management of dementia. The Traditional Chinese (TCM) herb Belamcandae chinensis rhizoma (the rhizome of Iris domestica (L.) Goldblatt & Mabb) contains both classes of natural products. Here, we isolated eight isoflavonoids: irisflorentin (1), tectorigenin(2), iristectorigenin B(3), irigenin (4), irilin D (5), iridin (6), tectoridin (7), iristectorin B (8), two stilbenes; piceatannol (9) and resveratrol (10) as well as the xanthone glucoside - mangiferin (11). The compounds weretested against acetyl-(AChE) and butyrylcholinesterase (BChE) using ELISA microtiter assay. Molecular docking studies were also performed on the active compounds. Among the tested polyphenols, piceatannol inhibited both cholinesterases (up to 67% and 91% of AChE and BChE, respectively) whereas irilin D and resveratrol were only active against BChE. Irisflorentin was selective but weak inhibitor against AChE (36% inhibition at 100 mu g/mL). The remaining isoflavones were moderately active against BChE (below 40% inhibition). In conclusion, the TCM and pharmacopoeial drug - Belamcandae chinensis rhizoma is rich in potential cholinesterase inhibitors that can provide lead structures for further development of selective drugs. Moreover, the in vitro results would suggest a novel indication of this traditional anti-inflammatory, phytoestrogenic and antiallergic herb.