Benzothiazole derivatives bearing amide moiety: potential cytotoxic and apoptosis-inducing agents against cervical cancer

Synthesis of some new benzoxazole derivatives and investigation of their anticancer activities

Phortress is an anticancer prodrug, which has active metabolite (5F-203) being potent agonist of the aryl hydrocarbon receptor (AhR). The 5F-203 switches on cytochrome P450 CYP1A1 gene expression and thus exhibits anticancer activity. In this study, it is aimed to obtain new phortress analogues by bioisosteric replacement of benzothiazole core in the structure to benzoxazole ring system. Synthesis of compounds (3a-3p) were performed according to literature methods. Their structures were elucidated by IR, ¹H NMR, ¹³C NMR, 2D-NMR and HRMS spectroscopic methods. Cytotoxicity (MTT), inhibition of DNA synthesis and flow cytometric analysis assays were applied to determine anticancer activity of the compounds on colon (HT-29), breast (MCF7), lung (A549), liver (HepG2) and brain (C6) carcinoma cell types. When compared reference agent doxorubicin, compounds 3m and 3n displayed very attractive anticancer effect against carcinogenic cell lines. Due to structural similarity to phortress, biotransformation studies for 3m and 3n were examined by LCMS-IT-TOF system and probable metabolites of these compounds were determined. Induction potential of these compounds on CYP1A1/2 enzymes was also investigated to clarify possible mechanism of action. Interaction modes between CYP1A1 enzyme and compound 3n or its some metabolites were investigated by docking studies. In conclusion, findings of these study indicate that compounds 3m and 3n possess significant anticancer activity, probably with the same mechanism of action to Phortress.

2-substituted benzothiazoles as antiproliferative agents: Novel insights on structure-activity relationships

Given the wide spectrum of biological activities, benzothiazoles represent privileged scaffolds in medicinal chemistry, useful in drug discovery programs to modulate biological activities of lead compounds. A large body of knowledge about benzothiazoles has been reported in scientific literature, describing their antimicrobial, anticonvulsant, neuroprotective, anti-inflammatory, and antiproliferative effects. This review summarizes the results obtained in the structure-activity relationship studies on antiproliferative benzothiazoles, focusing on 2-substituted derivatives and on mechanism of action responsible for the antitumor effects of this class of compounds.

A Review on Anticancer Potentials of Benzothiazole Derivatives

Benzothiazole is an organic compound bearing a heterocyclic nucleus (thiazole) which imparts a broad spectrum of biological activities to it. The significant and potent activity of benzothiazole moiety influenced distinctively by nature and position of substitutions. This review summarizes the effect of various substituents in recent trends and approaches to design and develop novel benzothiazole derivatives for anticancer potential in different cell lines by interpreting the Structure- Activity Relationship (SAR) and mechanism of action of a wide range of derivatives. The list of derivatives is categorized into different groups and reviewed for their anticancer activity. The structure-activity relationship for the various derivatives revealed an excellent understanding of benzothiazole moiety in the field of cancer therapy against different cancer cell line. Data obtained from the various articles showed the potential effect of benzothiazole moiety and its derivatives to produce the peculiar and significant lead compound. The important anticancer mechanisms found are tyrosine kinase inhibition, topoisomerase inhibition and induction of apoptosis by Reactive Oxygen Species (ROS) activation. Therefore, the design and development of novel benzothiazole have broad scope in cancer chemotherapy.

Benzothiazole derivative bearing amide moiety induces p53-mediated apoptosis in HPV16 positive cervical cancer cells

In our previous study, we screened the anti-cancer properties of 10 benzothiazole derivatives in cervical cancer cell lines. In the present study, we aimed to delineate the mechanism of the apoptotic pathway (whether intrinsic or extrinsic) following the treatment of N-(4-(benzo[d]thiazol-2-yl)phenyl)-5-chloro-2-methoxybenzamide (named as A-07) on cervical cancer cell lines. Cellular stress by reactive oxygen species was measured using DCFDA dye by flowcytometry. Protein expression and localization was checked by immunofluorescence for γH2A.X, TP53, and CASP-3. Expression profiles of BAX and BCL-2 was done by semi-quantitative RT-PCR and PARP-1 (Poly(ADP-ribose) polymerase-1) by Western blot analysis. Bioinformatic studies were done using PDB websites, metaPocket 2.0 server, YASARA software and Discovery Studio 3.5 Visualizer. We demonstrate that the compound A-07 leads to ROS generation and double strand breaks in SiHa and C-33A cells. The induction of apoptosis in SiHa cells is associated with increased nuclear expression of the tumor suppressor protein, TP53. The shift in BAX/BCL-2 ratio, increased expression of Caspase-3 and cleaved Poly(ADP-ribose) polymerase-1 favour apoptotic signal in SiHa. In silico studies revealed that A-07 has inhibiting capabilities to the E6/E6AP/P53 complex. Our data suggest that treatment of A-07 causes p53 and caspase dependent apoptosis in HPV 16 infected SiHa cells.

Synthesis, QSAR studies, and metabolic stability of novel 2-alkylthio-4-chloro-N-(5-oxo-4,5-dihydro-1,2,4-triazin-3-yl)benzenesulfonamide derivatives as potential anticancer and apoptosis-inducing agents

A series of novel 2-alkylthio-4-chloro-N-(5-oxo-4,5-dihydro-1,2,4-triazin-3-yl)benzenesulfonamide derivatives 12-46 have been synthesized by the reaction of aminoguanidines with an appropriate alpha-oxo-acids hydrates in glacial acetic acid. All the synthesized compounds were evaluated for their anticancer activity against HeLa, HCT-116, and MCF-7 human tumor cell lines. Two compounds 33 and 34 displayed outstanding cytotoxic effect selectively toward HeLa cancer cells (IC50  = 19 μm) and did not exhibit toxicity to the non-cancerous HaCaT cells. QSAR analysis determined the most important parameters controlling cytotoxic activity of 5-oxo-1,2,4-triazines against HeLa cells. QSAR model showed five significant descriptors: HATS6s (GETAWAY descriptor), RDF125 m (radial distribution function), SpMax7_Bh(p) (Burden descriptor), SM3_G (3D matrix descriptor), and Hy (hydrophilic factor). The apoptotic potential of the most active compounds was thoroughly analyzed through various assays: cells' morphology, DNA fragmentation, mitochondrial potential disruption, and phosphatidylserine translocation. Selected compounds were tested for metabolic stability in the presence of pooled human liver microsomes and NADPH. Compound 34 was the most resistant for human metabolism (t1/2  = 38.5 min) and can be pointed as a hit compound for further investigations.

Novel 5-Substituted 2-(Aylmethylthio)-4-chloro-N-(5-aryl-1,2,4-triazin-3-yl)benzenesulfonamides: Synthesis, Molecular Structure, Anticancer Activity, Apoptosis-Inducing Activity and Metabolic Stability

A series of novel 5-substituted 2-(arylmethylthio)-4-chloro-N-(5-aryl-1,2,4-triazin-3-yl) benzenesulfonamide derivatives 27-60 have been synthesized by the reaction of aminoguanidines with an appropriate phenylglyoxal hydrate in glacial acetic acid. A majority of the compounds showed cytotoxic activity toward the human cancer cell lines HCT-116, HeLa and MCF-7, with IC50 values below 100 μM. It was found that for the analogues 36-38 the naphthyl moiety contributed significantly to the anticancer activity. Cytometric analysis of translocation of phosphatidylserine as well as mitochondrial membrane potential and cell cycle revealed that the most active compounds 37 (HCT-116 and HeLa) and 46 (MCF-7) inhibited the proliferation of cells by increasing the number of apoptotic cells. Apoptotic-like, dose dependent changes in morphology of cell lines were also noticed after treatment with 37 and 46. Moreover, triazines 37 and 46 induced caspase activity in the HCT-116, HeLa and MCF-7 cell lines. Selected compounds were tested for metabolic stability in the presence of pooled human liver microsomes and NADPH, both R² and Ar = 4-CF₃-C₆H₄ moiety in 2-(R²-methylthio)-N-(5-aryl-1,2,4-triazin-3-yl)benzenesulfonamides simultaneously increased metabolic stability. The results pointed to 37 as a hit compound with a good cytotoxicity against HCT-116 (IC50 = 36 μM), HeLa (IC50 = 34 μM) cell lines, apoptosis-inducing activity and moderate metabolic stability.