Bioactive Benzofuran Derivatives from Cortex Mori Radicis, and Their Neuroprotective and Analgesic Activities Mediated by mGluR1

Four new benzofuran-type stilbene glycosides and 14 known compounds including 8 benzofuran-type stilbenes and 6 flavonoids were isolated from the traditional Chinese medicine, Cortex Mori Radicis. The new compounds were identified as (9R)-moracin P 3′-O-α-l-arabinopyranoside (1), (9R)-moracin P 9-O-β-d-glucopyranoside (2), (9R)-moracin P 3′-O-β-d-glucopyranoside (3), and (9R)-moracin O 10-O-β-d-glucopyranoside (4) based on the spectroscopic interpretation and chemical analysis. Three benzofuran-type stilbenes, moracin O (5), R (7), and P (8) showed significant neuroprotective activity against glutamate-induced cell death in SK-N-SH cells. In addition, moracin O (5) and P (8) also demonstrated a remarkable inhibition of the acetic acid-induced pain. The molecular docking with metabotropic glutamate receptor 1 (mGluR1) results indicated that these neuroprotective benzofuran-type stilbenes might be the active analgesic components of the genus Morus, and acted by mediating the mGluR1 pathway.