Table 1. The results of IR spectra of α-mangostin.

Wavenumber/cm-1	Group
1380	symmetric bending vibration of -CH3
2860, 2920	stretching vibration of C-H
1640	stretching vibration of C = C
1460, 1610	skeletal vibration of C = C of aromatic hydrocarbon
850	flexural vibration of C-H of aromatic hydrocarbon
1080, 1190	stretching vibration of C-O connected to hydroxyls
3260, 3420	stretching vibration of intermolecular hydrogen bonding
3620	stretching vibration of free hydroxyls
667	distortion of vibration of O-H
1280	stretching vibration of C-O-C of -OCH3 on the benzene ring
1080, 1190	stretching vibration of C-O-C
1280, 1640	stretching vibration of C = O of aromatic ketones
2360	Asymmetric stretching vibration (noise) of CO2