Table 1.

IC₅₀ (µM) values of caffeic acid (CA) and caffeic acid phenethyl ester (CAPE) in relation to breast cancer MDA-MB-231 for 24 h and 48 h, using different methods (XTT, NR, SRB, respectively: 2,3-bis[2methoxy-4-nitro-5-sulfopheny]-2H-tetrazolium-5-carboxyanilide inner salt, neutral red, Sulforhodamine B). All data demonstrated that lower doses of CAPE (ca. twice as low as CA) are needed to receive a similar mortality effect on MDA-MB-231 cells.

Method	Compound	Time of Incubation	Time of Incubation
		24 h	48 h
XTT	CA	150.94	108.42
	CAPE	68.82	55.79
NR	CA	135.85	103.23
	CAPE	64.04	53.25
SRB	CA	139.80	103.98
	CAPE	66.86	47.73