Bioassay-guided fractionation of the 60% ethanol extract of the stems of Calophyllum membranaceum using the RXR α transcription activation assay led to the isolation of two new chromanones, calopolyanic acid methyl ester ( 1 ) and isopinetoric acid methyl ester ( 2 ), two new xanthones, calophylixanthones A–B ( 3 – 4 ), and one new C-glycoside, calophymembranside C ( 5 ), along with 13 known compounds. Their structures were elucidated on the basis of extensive spectroscopic data. Compounds 5 , 11 and 18 showed transcriptional inhibitory activity of RXR α with 50% inhibitory concentration (IC 50 ) values of 29.95 ± 1.08, 31.06 ± 9.02, and 25.88 ± 1.62 μM, respectively. [ABSTRACT FROM AUTHOR]