الفهرس 
IntroductionOnly 14 pages are availabe for public view
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Abstract
Expression of tumor associated human carbonic anhydrases (hCA) IX and XII isoforms is limited in normal physiological conditions, although they are overexpressed in hypoxic tumors such as colon, ovaries, breast, and lung cancers. We have targeted inhibition of hCA IX by designing and synthesizing twenty-eight new benzenesulfonamide derivatives, which have been evaluated as anti-proliferative agents. Two novel series of benzenesulfonamides were designed relying on the structural features of SLC 1110, a selective inhibitor of tumor related hCA IX. In series (A), seventeen compounds, 5a-c, 6a-j, 7a and 8a-c, were constructed enclosing the 1,3,5- dihydrotriazine ring as a rigid cyclic linker between the zinc binding group (ZBG), benzenesulfonamide, and alkyl or spirocycloalkyl lipophilic tails. In series (B), eleven compounds, 10 and 12a-j, were designed comprising 1,3,5- triazine ring as a linker. In analogues, 12a-j, cyanoethenyl spacer was assembled at C4 of the 1,3,5-triazine linker while, substituted phenyl rings were retained as the lipophilic tails. Target compounds of series (A) and (B) were screened as inhibitors of hCAs I, II, IX and XII, then selectivity indexes (SI) were calculated. Human CA IX was inhibited by series (A) with Ki in the range of 134.8 to 2280 nM, where compound 5a, reported the best inhibitory outcome with Ki = 134.8 nM. Meanwhile, hCA IX was inhibited by series (B) in the range of Ki values from 38.8 to 2454 nM, whereas the best inhibitor 12i, revealed Ki = 38.8 nM. Analogue 12i, demonstrated significant selectivity towards hCA IX and XII (tumor-associated isoforms) over hCA I and II (off-target isoforms). Furthermore, US-NCI protocol was followed to evaluate the anticancer activity of target compounds against a panel of sixty cancer cell lines. Compound 12d, exposed the best activity towards breast cancer (MDA-MB-468) with mean GI% = 62%. The most active analogues, 12d and 12i were further screened for in vitro cytotoxic activity under hypoxic conditions against breast cancer (MDA-MB-468) and Abstract II leukemia (CCRF-CM) cell lines. Compounds 12d and 12i inhibited the growth of MDA-MB-468 cells with IC50 = 3.99 μM and 1.48 μM, respectively, while they exhibited IC50 = 4.51 μM and 9.83 μM, toward leukemia (CCRF-CM) cell lines respectively, in comparison to staurosporine as reference drug (IC50 = 6.07 μM on MDA-MB-468 cells and 2.17 μM against CCRF-CM cells). In addition, 12d was screened for cell cycle disturbance and apoptosis induction against breast cancer cells, (MDA-MB- 468) and the results exhibited that 12d arrest the cell cycle in G0-G1 and S phases with significant increase in pre-G1 cell population by 20 fold in comparison to the control. Molecular docking was performed for selected compounds, within the active site of hCA IX crystal structure to understand their biological outcomes. The most active compounds 12d and 12i coordinated zinc ion in the active site with negatively charged NH- in primary sulfonamide group (ZBG) in addition to hydrogen bond interaction with neighboring amino acids His94, His96, His119, Thr199 and Thr200 in similar to the binding mode of the reference compound acetazolamide AAZ. Moreover, 12d and 12i differed from binding mode of AAZ in that their substituted phenyl tail accommodated in additional hydrophobic pocket lined mainly with Val131.