Novel N-acyl dehydroalanine derivatives as antioxidants: Studies on rat liver lipid peroxidation levels and DPPH free radical scavenging activity

Figures & data

Figure 1 General structure of AD^23,25 and N-acetyl DHA derivatives.

Figure 2 Synthesised N-Acetyl dehydroalanine derivatives.

Table I.  Physical and spectral data of synthesised compounds.

No	Formula	Yield (%)	m.p°C	^1H NMR Data (δ ppm)	Mass Data
c	C8H14N2O2	48	75–78	CDCl3: 0.95 (t, 3H, CH2-CH3), 1.57 (m, 2H, CH2), 2.14 (s, 3H, COCH3), 3.31 (q, 2H, NHCH2), 5.18 (s, 1H, = CH), 6.26 (brs, NH), 6.43 (s, 1H, = CH), 8.18 (brs, NH)	209 (M+K, 18.20), 194 (M+1+Na, 16.15), 193 (M+Na, 100),150 (12.26), 129 (39.64)
e	C9H16N2O2	27	92–94	CDCl3: 0.94 (t, 3H, CH2-CH3), 1.19 (d, 3H, CHCH3), 1.59 (m, 2H, CH2), 2.14 (s, 3H, COCH3), 3.37 (m, 1H, CH), 5.14 (s, 1H, = CH), 5.86 (brs, NH), 6.43 (s, 1H, = CH), 8.01 (brs, NH)	223 (M+K, 17.32), 208 (M+1+Na, 19.80), 207 (M+Na, 100), 185 (M+1, 97.01), 186 (M+2, 12.17), 169 (25, 63), 147 (22.58)
f	C10H18N2O2	25	82–85	d6-DMSO: 0.89 (d, 6H, (CH3)2) 1.35 (m, 2H, CH2-CH), 1.57 (m, 1H, CH), 2.00 (s, 3H, COCH3), 3.15 (t, 2H, NHCH2), 5.32 (s, 1H, = CH), 6.01 (s, 1H, = CH), 8.27 (brs, NH), 9.02 (brs, NH)	237 (M+K, 12.10), 221 (M+Na, 100), 199 (M+1, 28.76), 157 (59.05), 155 (11.18), 147 (14.14)
g	C10H18N2O2	18	Oily	CDCl3: 0.81 (t, 3H, CH2CH3) 1.18-1.28 (m, 8H, (CH3)2CH2), 2.04 (s, 3H, COCH3), 5.02 (s, 1H, = CH), 5.85 (brs, NH), 6.33 (s, 1H, = CH), 8.02 (brs, NH)	237 (M+K, 13.29), 225 (100) (M+Na, 35.67), 199 (M+1, 17.52), 169 (18.95), 147 (13.35)
h	C9H14N2O2	15	Oily	d6-DMSO: 1.79 (m, 4H, N(CH2- CH2)2) 1.89 (s, 3H, COCH3), 3.25 (m, 4H, N(CH2- CH2)2), 4.65 (s, 1H, = CH), 5.28 (s, 1H, = CH), 9.56 (brs, NH), second NH not observed	205 (M+Na, 7.38), 183 (M+1, 9.55), 169 (29.85), 147 (49.59) 137 (24.36)
i	C9H15N3O2	20	Decomp. at 40	d6-DMSO: 1.73 (m, 4H, CH2)2NH), 1.96 (s, 3H, COCH3), 3.10 (m, 4H, N(CH2)2), 5.27 (s, 1H, = CH), 6.01 (s, 1H, = CH), 8.18 (brs, NH), 9.05 (brs, NH)	236 (M+K, 11.02), 225 (100), 221 (M+1+Na, 19.89), 174 (33.56), 166 (21.16), 143 (62.75), 139 (14.25), 125 (28.61)
j	C10H16N2O2	31	80–83	d6-DMSO: 1.33-1.58 (m, 10 H, cyclic-H), 1.89 (s, 3H, COCH3), 5.15 (s, 1H, = CH), 5.90 (s, 1H, = CH), 8.80 (brs, NH), 9.78 (brs, NH)	235 (M+K, 23.27), 225 (100), 219 (M+Na, 58.61), 165 (19.37), 141 (47.32), 112 (28.15)

Suzen et al., Antioxidant behaviour of N-acetyl dehydroalanine derivatives

Table II.  Effects of the compounds a-k, on LP levels and scavenging activity of DPPH radical^a.

Compound No	Concentration in incubation medium (M)	LP (Percent of control)	DPPH free radical scavenging activity (percent of control)
Control^b ^DMSO-EtOH		100	100
a	10^− 3	10 ± 1	103 ± 1
	10^− 4	17 ± 2	101 ± 1
b	10^− 3	46 ± 3	102 ± 2
	10^− 4	93 ± 1	100 ± 1
c	10^− 3	42 ± 1	73 ± 1
	10^− 4	102 ± 2	99 ± 2
d	10^− 3	24 ± 2	98 ± 1
	10^− 4	40 ± 1	102 ± 2
e	10^− 3	15 ± 3	95 ± 3
	10^− 4	88 ± 2	97 ± 1
f	10^− 3	10 ± 1	54 ± 2
	10^− 4	25 ± 1	101 ± 2
g	10^− 3	11 ± 1	91 ± 1
	10^− 4	40 ± 2	100 ± 3
h	10^− 3	18 ± 2	103 ± 2
	10^− 4	43 ± 1	104 ± 1
i	10^− 3	34 ± 2	90 ± 1
	10^− 4	91 ± 1	100 ± 2
j	10^− 3	202 ± 3	44 ± 2
	10^− 4	240 ± 4	99 ± 2
k	10^− 3	203 ± 2	90 ± 2
	10^− 4	168 ± 4	99 ± 2
α-tocopherol	10^− 3	5 ± 1	10 ± 2
	10^− 4	10 ± 1	13 ± 2

^a Each value represents the mean ± SE of 2–4 independent experiments

^b DMSO, control for compounds and α\-tocopherol

Figure 3 Possible antioxidant mechanisms of N-acetyl DHA derivatives.