Objective: α-Mangostin ( 1 ), a xanthone predominantly abundant in Garcinia mangostana , exhibits diverse pharmacological activities. As reported in our previous study, it also shows inhibitory activities against neuraminidase of the influenza virus. In the present study, we investigated α-mangostin derivatives produced by γ-irradiation to identify more effective neuraminidase inhibitors. Methods: α-Mangostin ( 1 ) in methanol (2.439 mM) was treated with 200 Gy of gamma ( 60 Co) irradiation (10 kGy/h). Five radiolysis products were isolated using combined chromatographic techniques, and their structures were identified using one- and two-dimensional nuclear magnetic resonance and high-resolution electrospray ionization mass spectroscopy. The neuraminidase inhibitory activities of all compounds were evaluated and compared. Results: Five derivatives ( 2 − 6 ) including two new compounds, 13,6-trihydroxy-2-(2-hydroxyethyl)-7-methoxy-8-(3-methylbut-2-enyl)-9 H -xanthen-9-one ( 5 ) and 13,6-trihydroxy-2-(4-hydroxy-2-methoxy-3,3-dimethylbutyl)-7-methoxy-8-(3-methylbut-2-enyl)-9 H -xanthen-9-one ( 6 ), were obtained by γ-irradiating α-mangostin dissolved in methanol. All derivatives exhibited IC 50 values of 7.84–44.66 μM against neuraminidase. Mangostanin ( 4 ) exhibited an IC 50 of 7.84 μM, which is 1.6- and 1.8-fold more potent than that of 1 and quercetin (positive control), respectively. In addition, all compounds exhibited competitive inhibition. Conclusion: Our results suggest that γ-irradiation is an effective method for structural modification of α-mangostin and it derivative, mangostanin is potential neuraminidase inhibitor.
Han et al. (2024) studied this question.