Carbonic anhydrase inhibitors: guaiacol and catechol derivatives effectively inhibit certain human carbonic anhydrase isoenzymes (hCA I, II, IX and XII)

Figures & data

Figure 1. Chemical structures of the phenolic compounds (1–11) were studied for their inhibition parameters of cytosolic isoforms hCA I and II and transmembrane tumour-associated isoforms of hCA IX and XII.

Table 1. Inhibition constants of certain phenolic compounds derived from guaiacol and catechol against four human carbonic anhydrase isoenzymes (hCA I, II, IX and XII) using an esterase bioassay.

						Ki (μM)
Compounds		R1	R2	R3	Name	hCA I	hCA II	hCA IX	hCA XII
1		H	H	–	Guaiacol	7.50	5.63	9.98	9.83
2		H	CH3	–	4-Methylguaiacol	9.15	7.74	9.89	8.55
3		H	CH2–CH2–CH3	–	4-Prophylguaiacol	10.34	8.51	9.01	9.12
4		H	CH2–CH2 = CH2	–	Eugenol	8.32	7.27	9.62	8.89
5		H	CH = CH–CH3	–	Isoeugenol	10.29	6.73	9.32	9.13
6		H	CHO	–	Vanillin	11.37	7.15	9.81	8.39
7		OCH3	CHO	–	Syringaldehyde	10.92	6.68	9.11	7.70
8			OH	H	H	Catechol	247.50	5.51	373.23	515.98
9	OH		CH3	H	3-Methyl catechol	5.95	4.69	9.55	7.22
10	OH		H	CH3	4-Methyl catechol	6.16	2.76	8.11	6.58
11	OH		OCH3	H	3-Methoxy catechol	6.32	2.20	7.83	7.53

Figure 2. Schematic representation of the proposed interaction between guaiacol (1) and the active site region of hCA II.