Synthesis of Novel Phthalazine Derivatives as Potential Anticancer and Antioxidant Agents Based on 1‐Chloro‐4‐(4‐phenoxyphenyl)phthalazine

A new series of phthalazine derivatives was synthesized from the reaction of 1‐chloro‐4‐(4‐phenoxyphenyl)phthalazine as a reactive starting material with different carbon, nitrogen, oxygen, and sulfur nucleophiles. The structural formulae of all products were confirmed and characterized by elemental analyses and spectral data (IR, ¹H NMR, ¹³C NMR, and mass spectra). Some of the synthesized derivatives were screened for their antitumor activity against four human tumor cell lines using MTT assay. In comparison with doxorubicin as standard drug, compounds 1 , 20 , and 25 showed the most potent cytotoxic effect. In addition, investigation of antioxidant activity revealed that hydrazinylphthalazine 20 has the highest activity.     

Facile Synthesis of Novel 3‐(4‐phenylisothiazol‐5‐yl)‐2H‐chromen‐2‐one Derivatives as Potential Anticancer Agents

A series of 3‐(4‐phenylisothiazol‐5‐yl)‐2H‐chromen‐2‐one ( 6a – l ) derivatives has been efficiently synthesized by straightforward sequential reactions. Tandem Vilsmeier Hack reaction/cyclization/bromination/Suzuki cross‐coupling reactions were successfully applied to the preparation of title compounds in good‐to‐high yields. In the synthetic sequences, 3‐chloro‐3‐(2‐oxo‐2H‐chromen‐3‐yl)acrylaldehydes ( 2 ) were found to react with ammonium thiocyanate to yield the corresponding 3‐(isothiazol‐5‐yl)‐2H‐chromen‐2‐ones ( 3 ). These derivatives were brominated with N‐bromo succinamide to yield the corresponding regioselective 3‐(4‐bromoisothiazol‐5‐yl)‐2H‐chromen‐2‐one ( 4 ). Finally, compound 4 was treated with various phenyl/pyrazole/7H –pyrrolo[2,3‐d]pyrimidinyl boronic acids 5a – l in the presence of K₂CO₃ and Pd catalyst in dimethylformamide to yield the corresponding title derivatives 6a – l . All the synthesized compounds were characterized by analytical and spectral studies. All the final compounds were screened against different cancer cell lines (A549, PC3, SKOV3, and B16F10), and among these compounds, 6b , 6g , 6h , and 6l displayed moderate cytotoxic activity against the tested cell lines.     

Design and Synthesis of Novel 3‐(Phenyl)‐2‐(3‐substituted propylthio) Quinazolin‐4‐(3H)‐ones as a New Class of H1‐Antihistaminic Agents

A series of novel 3‐(phenyl)‐2‐(3‐substituted propylthio) quinazolin‐4‐(3H)‐ones were synthesized by the reaction of 2‐(3‐bromopropylthio)‐3‐(phenyl) quinazolin‐4‐(3H)‐one with various amines. The starting material, 2‐(3‐bromopropylthio)‐3‐(phenyl) quinazolin‐4‐(3H)‐one was synthesized from aniline. When tested for their in vivo H₁‐antihistaminic activity on conscious guinea pigs, all the test compounds protected the animals from histamine‐induced bronchospasm significantly. Compound 2‐(3‐(4‐methylpiperazin‐1‐yl) propylthiothio)‐3‐(phenyl) quinazolin‐4(3H)‐one ( Ph5 ) emerged as the most active compound (73.23% protection) of the series when compared with the reference standard chlorpheniramine maleate (70.09% protection). Compound Ph5 shows negligible sedation (5.01 %) compared with chlorpheniramine maleate (29.58%). Therefore, compound Ph5 can serve as the leading molecule for further development into a new class of H₁‐antihistaminic agents.     

Transition Metal Complexes of N‐(4,6‐Dimethoxypyrimidin‐2‐Ylcarbamothioyl)Benzamide: Design,Synthesis and Herbicidal Activity

Transition metal (Cu(II), Zn(II), Co(II)) complexes of N‐(4,6‐dimethoxypyrimidin‐2‐ylcarbamothioyl)benzamide were prepared. The structures of all the newly synthesized complexes were identified by elemental analyses, IR, ¹H NMR, XPS, MS and TG. Their herbicidal activities were evaluated against a variety of weeds. The preliminary results showed that the target complexes had moderate biological activities against both broad leaf weeds and monocotyledon plants. More importantly, the complexes exhibited some improved herbicidal activities over their non‐complexed counterparts. The present work provides a novel class of transition metal‐based derivatives with potent herbicidal activities for further optimization.     

Design,Synthesis, and Biological Evaluation of 2‐(4‐Aminophenyl)benzothiazole Analogues as Antiproliferative Agents

A series of 28 novel 2‐(4‐aminophenyl)benzothiazole analogues have been synthesized and characterized using various analytical techniques like ¹H NMR, ¹³C NMR, electrospray ionization mass spectrometry, and IR and bioevaluated for their antiproliferative activity over a group of three human cancer cell lines, namely, lung cancer (A549), cervical cancer (HeLa), and breast cancer (MDA‐MB‐231), using sulforhodamine B assay method. Few synthesized molecules ( 5a , 5c , 5d , 5f , 7b , and 7j ) displayed effective growth inhibition (GI₅₀) activity against the tested human cancer cell lines at lower micromolar concentration (GI₅₀) values in the range 0.2–1.7 μM. Noticeably, compound 7b exhibited reasonable activity in all three cancer cell lines in the GI₅₀ range 0.55–1.2 μM. Further, when 7b was screened for tubulin polymerization inhibition, it exhibited more than 55% inhibition at concentration of 5.0 μM. The molecular docking simulations supported the molecular interactions of the derivatives with the targeted receptor. These derivatives may serve as lead structures for development of potential anticancer drug candidates, and 7b might act as a potential microtubule polymerization inhibitor.