Unusual Prenylated Stilbene Derivatives with PTP1B Inhibitory Activity from Artocarpus styracifolius

In an effort to identify agents from natural products that inhibit protein tyrosine phosphatase 1B (PTP1B), 5 new prenylated stilbenes, (±)-styrastilbene A (1: ), styrastilbene B (2: ), and (±)-styrastilbenes C - E (3, 4: , and 7: ), along with 4 known structurally related compounds (5, 6, 8: , and 9: ), were isolated from the roots of Artocarpus styracifolius. Their structures were elucidated by spectroscopic methods, including 1D and 2D nuclear magnetic resonance (NMR), high-resolution electrospray ionization mass spectrometry (HRESIMS), ultraviolet (UV), and infrared (IR). Based on these isolates, a new plausible biosynthetic pathway for the unusual stilbene derivatives 3: -8: with a tetracyclic ring system is proposed. Among these compounds, 1: -3, 8: , and 9: displayed significant PTP1B inhibitory effects with IC₅₀ values ranging from 2.40 (95% confidence interval [CI]: 2.21 - 2.59) to 8.80 (95% CI: 8.28 - 9.32) µM. Moreover, kinetic analysis and molecular docking simulations were performed to provide insight into the inhibition type as well as the interaction and binding mode of these active isolates with PTP1B. Our results revealed mixed-type PTP1B inhibition for all compounds tested. Docking simulations of these stilbene derivatives showed negative binding energies and close proximity to residues at the allosteric and catalytic sites of PTP1B. These findings suggest that these compounds may have a potential to be further developed as agents for the management of type 2 diabetes mellitus.