Preparation, carbonic anhydrase enzyme inhibition and antioxidant activity of novel 7-amino-3,4-dihydroquinolin-2(1H)-one derivatives incorporating mono or dipeptide moiety

Figures & data

Scheme 1. Synthesis pathways of the new dihydroquinolinone conjugates of N-protected amino acids and dipeptide. Conditions and reagents: (i) r.t., 2 h in THF; 70 °C, 30 min in THF.

Table 1. Inhibition data of hCA I, hCA II, hCA IX and hCA XII with compounds 1–6 and the standard sulphonamide inhibitor acetazolamide (AAZ) by a stopped flow CO₂ hydrase assay.

Ki (µM)^a
Cmp. no.	hCA I	hCAII	hCA IX	hCA XII
1	>100	>100	86.8	2.0
2	>100	>100	41.2	3.8
3	>100	>100	42.6	8.5
4	>100	>100	65.4	5.7
5	>100	>100	37.7	7.0
6	>100	>100	47.6	8.6
AAZ	0.250	0.012	26.0	0.006

a Mean from three different assays, by a stopped flow technique (errors were in the range of ±5–10% of the reported values).

Table 2. Antioxidant activities of the synthesised mono and dipeptide–dihydroquinolinone conjugates.

Comp. no.			Antioxidant activity, %
	12.5 μg/ml	25 μg/ml	37.5 μg/ml	62.5 μg/ml	125 μg/ml
1	3.8	2.2	2.5	1.6	0.6
2	3.1	2.2	0.0	0.9	0.6
3	0.9	0.3	nd	nd	nd
4	2.5	1.6	0.9	2.2	1.6
5	2.8	1.9	1.9	2.8	2.8
6	1.9	6.3	8.8	16.4	30.8
α-Toc.	62.9	63.4	68.4	72.8	74.0
BHA	61.1	63.0	67.5	71.0	72.4

nd, not detected.