Caffeates and Caffeamides: Synthetic Methodologies and Their Antioxidant Properties

Table 1

Antioxidant activity of caffeic acid derivatives against DPPH^•.

Entry	Compound	Structure		DPPH radical scavenging activity^a	Reference
1	Caffeic acid			63% (500 μM)	[118]
				0.17 μmol/μmol DPPH	[117]
				0.17 mol/mol DPPH	[86]
				IC50 15.3 μM	[123]
				EC50 30.88 µM	[41]
2	Caffeic acid methyl ester			62% (500 μM)	[118]
				0.17 μmol/μmol DPPH	[117]
3	Caffeic acid allyl ester			64% (500 μM)	[118]
				IC50 12.3 µM	[123]
4	Caffeic acid propyl ester			63% (500 μM)	[118]
5	Caffeic acid butyl ester			62% (500 μM)	[118]
6	Caffeic acid pentyl ester			62% (500 μM)	[118]
7	Caffeic acid hexyl ester			61% (500 μM)	[118]
8	Caffeic acid heptyl ester			63% (500 μM)	[118]
9	Caffeic acid nonyl ester			61% (500 μM)	[118]
10	Caffeic acid 3,4-dihydroxyphenetyl ester			0.09 mol/mol DPPH	[86]
11	Rosmarinic acid			0.12 mol/mol DPPH	[86]
				61% (500 μM)	[118]
12	3-Caffeoylbetulinic acid			IC50 of 3.57 μg/mL	[119]
13	3- and 4-[(2E,4E,6E)-octa-2,4,6-trienoyl]caffeic acid			96.25% (5 mM)	[120]
14	3,4-Dioctatrienoyl caffeic acid			100% (5 mM)	[120]
15	N-(3,4-Dihydroxyphenethyl) caffeamide			64% (500 µM)	[118]
16	N-Pentyl caffeamide			53% (500 µM)	[118]
17	2-Phenylethyl cinnamate			<10%	[118]
18	Caffeic acid phenetyl ester (CAPE)			IC50 11.9 µM	[123]
19	Caffeic acid propargylic esters		R = H	IC50 11.1 µM	[123]
20			R = Ph	IC50 12.7 µM	[123]
21			R = 4-CH3-Ph	IC50 11.5 µM	[123]
22			R = 4-CH3O-Ph	IC50 13.7 µM	[123]
23			R = 4-NO2-Ph	IC50 10.6 µM	[123]
24			R = 4-F-Ph	IC50 10.7 µM	[123]
25			R = 1-naphthyl	IC50 13.7 µM	[123]
26			R = 4-Ph-Ph	IC50 15.0 µM	[123]
27	Bis-caffeoyl propargyl derivative			IC50 5.6 µM	[123]
28	Caffeic acid allyl esters		R = Ph	IC50 12.4 µM	[123]
29			R = 4-CH3-Ph	IC50 13.1 µM	[123]
30			R = 4-CH3O-Ph	IC50 11.6 µM	[123]
31			R = 4-NO2-Ph	IC50 12.3 µM	[123]
32			R = 4-F-Ph	IC50 12.31 µM	[123]
33			R = 1-naphthyl	IC50 13.0 µM	[123]
34			R = 4-Ph-Ph	IC50 12.03 µM	[123]
35	Bis-caffeoyl allyl derivative			IC50 6.1 µM	[123]
36	N-(3,5-Dichloro-4-hydroxyphenyl)-caffeamide			EC50 5.51 µM	[41]
37	N-(4-Nitrophenyl)-caffeamide			EC50 7.21 µM	[41]
38	N-(4-Aminophenyl)-caffeamide			EC50 36.01 µM	[41]

^aIC₅₀: Inhibitory concentration, EC₅₀: Effective concentration.