Isoprenylated phenolic compounds with PTP1B inhibition from Morus alba

- Four new isoprenylated phenolics and sixteen known compounds were isolated from the root bark of Morus alba.
- All the new compounds and most of the known ones showed significant inhibitory effects on PTP1B.
- Albasin A is the first Diels-Alder adduct biogenetically derived from a dehydrogeranylated 2-arylbenzofuran as diene.

Two new Diels-Alder adducts, albasins A and B (1 and 2), one new isoprenylated 2-arylbenzofuran, albasin C (3), one new isoprenylated flavone, albasin D (4), together with sixteen known phenolic compounds, were isolated from the root bark of Morus alba. Their structures were elucidated by extensive spectroscopic analysis, including NMR, MS, and ECD data. All the new compounds and most of the known ones showed significant inhibitory effects on PTP1B in vitro with IC50 values ranging from 0.57 to 7.49 μM.

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