From the Vietnamese plant Macrosolen tricolor (Lecomte) Danser, one new diarylpropanoid, named macrotricolorin A (1) together with three diarylheptanoids including bisdemethoxycurcumin (2), demethoxycurcumin (3) and curcumin (4), were isolated. Their structures were elucidated by intensive analyses of their IR, UV, HR-ESI-MS and NMR (1 D & 2 D) spectra. It is the first time that diarylalkanoids have been reported from the genus Macrosolen. Compound 1 exhibited anti-inflammatory activity against the nitric oxide (NO) production in lipopolysaccharide (LPS)-induced RAW264.7 with an IC50 value of 27.54 ± 1.75 μM.