Synthesis, computational studies and assessment of in vitro inhibitory activity of umbelliferon-based compounds against tumour-associated carbonic anhydrase isoforms IX and XII

Figures & data

Figure 1. (A) Chemical structures of coumarin 1, 6-(1-S-hydroxy-3methylbutyl)-7-methoxy-2H-chromen-2-one (2) and corresponding hydrolytic products 2a and 2b; (B) cocrystal structure of hydrolytic product of 6-(1-S-hydroxy-3methylbutyl)-7-methoxy-2H-chromen-2-one (2) in complex with hCA II (PDB code: 3F8E)¹².

Figure 2. Chemical structures of umbelliferon, 3 and 4 as coumarin-based hCAIs.

Scheme 1. (i) H₂SO₄, 0 °C to rt, 18–22 h; (ii) A: (MeCO)₂O, H₂SO₄, Et₃N, 0 °C to rt, 2 h; B: PheCOCl or EtCOCl, Et₃N, DCM, rt, 24 h; (iii) AlCl_3, 320 °C, 6 h; (iv) NH₂NH₂-H₂O, Pd/C, EtOH, 70 °C, 1 h.

Table 1. Inhibition data for hCA I, II, IX and XII with compounds 7–11, 15 and 17 as well as umbelliferon and 3–4 as reference compounds^a.

	R1	R2	R3	hCA I	hCA II	hCA IX	hCA XII
Umbelliferon^b				>10,000	>10,000	24.9	45.1
3^b	H	H	OH	>10,000	>10,000	47.2	90.8
4 ^b	Me	NH2	OH	>10,000	>10,000	24.2	5.5
7	H	H	OCOMe	>10,000	>10,000	56.2	734.1
8	H	H	OCOEt	>10,000	>10,000	97.8	523.5
9	H	H	OCOPh	>10,000	>10,000	21.8	384.6
10	COMe	H	OH	>10,000	>10,000	176.5	24.9
11	COEt	H	OH	>10,000	>10,000	3042	868.5
15	Cl	H	OH	>10,000	>10,000	261.3	32.0
17	Cl	NH2	OH	>10,000	>10,000	180.3	29.3

^aErrors in the range of ± 10% of the reported value, from 3 different assays.

^bData from reference 29.

Figure 3. (A) Predicted binding mode of compound 10 (coloured in light blue) overlaid with compound 17 (coloured in wheat) into hCA XII cleft (PDB code 1JCZ).⁴² (B) Chemical structures of hydrolytic forms 10a and 10b. Predicted binding mode of (E)-10a (C, coloured in blue) and (Z)-10b (D, coloured in yellow) as hydrolysed forms of coumarin 10 into hCA XII cleft (PDB Code: 1JCZ)⁴². Compounds and crucial residues are shown as sticks; dashed lines represent hydrogen bond interactions. The protein structure is shown as pale-cyan surface and light grey cartoons. Zinc ion is depicted as a yellow sphere. Figures made by Pymol (https://pymol.org).

Maresca A, Temperini C, Vu H, et al. Non-zinc mediated inhibition of carbonic anhydrases: coumarins are a new class of suicide inhibitors. J Am Chem Soc 2009;131:3057–62.

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Whittington DA, Waheed A, Ulmasov B, et al. Crystal structure of the dimeric extracellular domain of human carbonic anhydrase XII, a bitopic membrane protein overexpressed in certain cancer tumor cells. Proc Natl Acad Sci USA 2001;98:9545–50.

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