In order to isolate the compounds with inhibitory activity against influenza neuraminidase, the methanol extract of C. longa was subjected to a succession of chromatographic procedures including silica gel chromatography, Shephadex LH-20, RP-C18, and HPLC to afford thirteen compounds, including 3 new (1–3) and 10 known (4–13) curcumin derivatives ( Fig. 1).