Objective In this study,Knoevenagel derivatives of curcumin were synthesized,and their oil-water partition coefficient were determined.Our aim is to provide an experimental basis for further development of curcumin derivatives.Methods Two Knoevenagel derivatives of curcumin,including 4-(thiophen-2-ylidene)curcumin(3a)and 4-(pyridine-4-ylidene)curcumin(3b),were obtained by using the methylene group of curcumin as the modification site and purified by column chromatography.The structures of these derivatives were confirmed by nuclear magnetic resonance spectroscopy(NMR),infrared(IR)and high-resolution liquid mass spectrometry(HRLC-MS).The oil-water partition coefficient of the derivatives in n-octanol aqueous solution was determined by quantitative analysis using HPLC.Results Knoevenagel derivatives of curcumin were successfully synthesis.The oil-water partition coefficients(lgPap)of curcumin derivatives 3a and 3b are 0.96 and 0.82,respectively.Compared with the oil-water partition coefficient of curcumin(lgPap=3.85),it suggested that curcumin derivatives showed better water solubility than curcumin.Conclusion Compared to the curcumin prototype,Knoevenagel derivatives of curcumin increased water solubility and improved bioavailability.Thus,it may provide experimental basis for introducing heteroarylene moiety of the methylene position of curcumin to enhance pharmacological activity.