Results α-mangostin All calculations used HF/MIDI! geometries. The 1H chemical shifts for α-mangostin were computed at WP04/6-311+G(2d,p) and B3LYP/6-311+G(2d,p). And the 13C chemical shifts were computed at WC04/6-311+G(2d,p) and B3LYP/6-311+G(2d,p).