Xanthones Isolated from the Pericarp of Mangosteen Inhibit Neurotransmitter Receptors Expressed in Xenopus Oocytes.

Objective: This study aimed to evaluate inhibitory effects of 7 xanthones and 3 extracts obtained from the pericarp of mangosteen on serotonin (5-HT), N-methyl-D-aspartate (NMDA) and glycine receptors expressed in Xenopus oocytes.
Material and Method: Xenopus oocytes were injected with RNA of either 5-HT NMDA or glycine receptor and inhibitory effects of the xanthones and extracts were investigated using the two-electrode voltage clamp technique.
Results: Xanthones from the pericarp of mangosteen affected 5-HT NMDA and glycine receptor functions with different degree of inhibition. Alpha-mangostin, garcinone-D and 9-hydroxycalaba xanthone inhibited 5-H T-induced currents by more than 80%. Gamma-mangostin and garcinone-E did by more than 50%, but not more than 80%. Garcinone-C and garcinone- D inhibited glutamate-induced currents by more than 80%. The alcohol extract did by more than 50%, but not more than 80%. Alpha-mangostin, garcinone-C, garcinone-D, non-tannin extract and the alcohol extract inhibited glycine-induced currents between 50-70%, neither compounds inhibited the currents up to 80%.
Conclusion: These results suggest that each xanthone derivatives has different selectivity to different types of neurotransmitter receptors.