Synthesis of peptide nucleic acids containing pyridazine derivatives as cytosine and thymine analogs, and their duplexes with complementary oligodeoxynucleotides

The anticancer and anti-inflammatory activity screening of pyridazinone-based analogs against human epidermoid skin cancer with detailed mechanistic analyses

3(2H)-Pyridazinone derivatives based on 4-biphenyl, naphtha-2-yl, pyridine, or piperidine moiety were synthesized and characterized using I-R and 1HNMR spectra. The activity and cytotoxicity of some synthesized compounds on the skin epidermoid cancer cell proliferation and progression were investigated. The pyridazine isomer with pyridine revealed a significant decrease in the level of nitric oxide p < 0.01 than the activity of caffeine phenecyl ester. The activity of the three active isomers recorded significant activity for their total antioxidant content that triggers their ability for the scavenging the oxygen free radicals significantly p < 0.01. Moreover, revealing the pharmaceutical activity of the isomers as anti-inflammatory agents, IL-6, IL10, and IL12 have been decreased by variable significant values. Additionally, the active isomers revealed variable actions on the skin cancer cell to induce apoptosis using annexin V-FITC/PI. Pyridine was the highest isomer to induce late apoptosis and necrosis for the skin cancer cells against the use of cisplatin. Importantly, Molecular modeling experiments including docking and dynamic simulations were done for the most active 3 analogs to explore the ligand binding and stability leading to exploring the structure-activity relationship with biological target PARP1 which showed a good binding propensity to pyridazine binding site which supports the in vitro data. In conclusion, the pyridazine moieties with piperdine, naphthayl, and pyridine have pharmacological activities against skin cancer epidermoid by triggering action in inhibition of the proliferation and progression with an up-regulated apoptotic mechanism that evades the emergence of cisplatin resistance among different cancer cells.Communicated by Ramaswamy H. Sarma.

Synthesis and DNA/RNA complementation studies of peptide nucleic acids containing 5-halouracils

The monomers of peptide nucleic acids containing 5-halouracils (5-XU-PNA), incorporated into heptameric PNA in the middle position, have been synthesized. Thermodynamic analyses revealed that the heptameric PNA oligomer with DNA and RNA showed higher duplex stability compared to the unmodified PNA counterpart. NMR studies suggested that the electron withdrawing effect of the halogen atom increased the strength of the XU-A hydrogen bond.

Synthesis of Some New Pyridazine Derivatives for Anti-HAV Evaluation

4-(2-(4-Halophenyl)hydrazinyl)-6-phenylpyridazin-3(2H)-ones 1a,b were prepared and treated with phosphorus oxychloride, phosphorus pentasulphide and ethyl chloroformate to give the corresponding chloropyridazine, pyridazinethione, oxazolopyridazine derivatives 2–4, respectively. Compound 2 reacted with hydrazine hydrate to afford hydrazinylpyridazine 7. The reaction of 4-(2-(4-chlorophenyl)hydrazinyl)-3-hydrazinyl-6-phenylpyridazine (7) with acetic anhydride, p-chlorobenzaldehyde and carbon disulphide gave the corresponding pyridazinotriazine derivatives 8–10. On the other hand, 5-(4-chlorophenylamino)-7-(3,5-dimethoxybenzylidene)-3-phenyl-5H-pyridazino[3,4-b][1,4]thiazin-6(7H)-one (11) was prepared directly from the reaction of compound 3 with chloroacetic acid in presence of p-chlorobenzaldehyde. Compound 11 reacted with nitrogen nucleophiles (hydroxylamine hydrochloride, hydrazine hydrate) and active methylene group-containing reagents (malononitrile, ethyl cyanoacetate) to afford the corresponding fused compounds 12–15, respectively. Pharmacological screening for antiviral activity against hepatitis A virus (HAV) was performed for the new compounds. 4-(4-Chlorophenylamino)-6-phenyl-1,2-dihydropyridazino[4,3-e][1,2,4]triazine-3(4H)-thione (10) showed the highest effect against HAV.