Steroids interfere with human carbonic anhydrase activity by using alternative binding mechanisms

Figures & data

Figure 1. Structures of bile acids 1–10.

Figure 2. Structures of steroids 11–22.

Table 1. Inhibition data of human CA isoforms hCA I, II, IV and IX with compounds reported here and the standard sulfonamide inhibitor acetazolamide (AAZ) by a stopped flow CO₂ hydrase assay.

	KI (µM)*
Compound	hCAI	hCA II	hCA IV	hCA IX
Chenodeoxycholic acid (1)	>100	53.9	>100	63.0
Cholic acid (2)	>100	48.9	>100	47.1
Lithocholic acid (3)	>100	64.5	>100	70.2
Deoxycholic acid (4)	>100	51.0	>100	55.0
Ursodeoxycholic acid (5)	95.9	71.4	>100	73.1
Glycoursodeoxycholic acid (6)	>100	78.4	>100	89.9
Tauroursodeoxycholic acid (7)	>100	82.9	>100	42.9
Hyodeoxycholic acid (8)	>100	58.4	>100	67.7
Hyocholic acid (9)	83.3	38.9	>100	71.9
Dehydrocholic acid (10)	>100	57.8	>100	53.9
Cholesterol (11)	>100	>100	>100	>100
Coprostan-3-ol (12)	>100	>100	>100	>100
Testosterone (13)	>100	>100	>100	>100
Androsterone (14)	>100	>100	>100	>100
Trans-dehydroandrosterone (15)	>100	>100	>100	>100
Androstanolone (16)	>100	>100	>100	>100
Progesterone (17)	>100	>100	>100	>100
11α-Hydroxyprogesterone (18)	>100	>100	>100	>100
α-Estradiol (19)	87.8	40.4	>100	49.6
Estron (20)	>100	50.8	>100	71.4
Hydrocortisone (21)	>100	>100	>100	>100
Diosgenin (22)	>100	>100	>100	>100
AAZ	0.25	0.012	0.074	0.025

* Mean from 3 different assays, by a stopped flow technique (errors were in the range of ±5–10% of the reported values).

Figure 3. Dockings of (A) α-estradiol (19) and (B) tauroursodeoxycholic acid (7) within hCA II. (C) Superposed docked hyocholic acid (9) (blue) and cholic acid (2) (yellow) X-ray solved orientation within hCA II.

Figure 4. Analysis of the MD simulation of 9 docked to hCA II. (A) Coordination and H-bonds occupancies within 10 ns MD for 9 - hCA II complex. (B) Rmsd representation of the heavy atoms of the receptor and the ligand from the starting model structure during the simulation.

Figure 5. Superposed representative orientations of the four identified clusters within superposed protein backbones of 200 frames of MD.

Figure 6. Conformer families of 9 identified over the 10 ns MD period.