Neolignan Constituents with Potential Beneficial Effects in Prevention of Type 2 Diabetes from Viburnum fordiae Hance Fruits

Nine new neolignan glycosides (1–9), viburfordosides A–I, two new neolignans, fordianes A and B (10, 11), and seven known analogues (12–18) have been isolated and identified from the fruits of Viburnum fordiae Hance. The structures and absolute configurations of undescribed neolignan constituents were identified by chemical methods and spectroscopic analyses. The α-glucosidase inhibitory, ABTS^•+ and DPPH^• scavenging, and anti-inflammatory activities of these secondary metabolites were evaluated. Some of them exhibited significant potency in inhibiting α-glucosidase and scavenging free radicals. Among the 14 metabolites that were found to have the capacity to inhibit NO production in LPS-stimulated RAW264.7 macrophage cells, compounds 2, 4, 6, 10, 11, 14, 17, and 18 were potent with IC₅₀ values of 10.88–41.10 μM. These results support that V. fordiae fruits possessing the neolignan compounds may serve as both a functional food and a medicinal resource to prevent and treat type 2 diabetes (T2D).