Anti-α-glucosidase and anti-oxidative isoflavonoids from the immature fruits of Maclura tricuspidata

The composition of a plant, together with its efficacy, vary depending on its maturity and plant parts. In this study, the chemical constituents of immature fruits of Maclura tricuspidata (Moraceae) were investigated together with their anti-diabetic and antioxidant effects. A total of 34 compounds were isolated from the immature fruits of M. tricuspidata using various chromatographic methods. Structure elucidation using extensive spectroscopic analysis led to the characterization of isolated compounds as isoflavonoids with prenyl substituents. Among them, macluraisoflavones A-O were first isolated from nature. The anti-diabetic and antioxidant activity of the isolated compounds were also suggested by α-glucosidase inhibitory activity and DPPH radical scavenging activity, respectively. In particular, macluraisoflavone I, an isoflavonoid with 2,2-dimethylpyran and 2-hydroperoxy-3-methylbut-3-enyl moieties, showed potent α-glucosidase inhibitory activity and DPPH radical scavenging activity. Further molecular docking analysis suggested hydrogen bond and alkyl interactions between α-glucosidase and macluraisoflavone I. Therefore, the immature fruits of M. tricuspidata can be used as an important natural product with antioxidant and anti-diabetic properties.