Regioselective synthesis and theoretical calculations of Bis(pyrido[2′,3′:3,4]pyrazolo[1,5-a]pyrimidines) linked to benzofuran units via piperazine spacer: A DFT, MM2, and MMFF94 study

3-Aminopyrazolo[3,4-b]pyridine: Effective Precursor for Barium Hydroxide-Mediated Three Components Synthesis of New Mono- and Bis(pyrimidines) with Potential Cytotoxic Activity

In this study, an efficient one-pot procedure for preparing a new series of pyrazolo[3,4-b]pyridine-fused pyrimidines was described. The target hybrids were developed through a three-component reaction of 3-amino-1H-pyrazolo[3,4-b]pyridine, benzaldehydes, and acetophenones (molar ratio 1 : 1 : 1). The best conditions for the previous reaction were 2.5 equivalents of barium hydroxide in DMF at 150 °C for 6 h. New bis(pyrimidines) were synthesized in high yields using a similar one-pot reaction protocol with some modifications. Thus, two equivalents of each of the appropriate acetophenones and 3-aminopyrazolopyridine were reacted with one equivalent of the appropriate bis(aldehydes). The reaction was carried out at 150 °C for 8 h using 4.5 equivalents of barium hydroxide in DMF. Repeating the previous reaction with the appropriate bis(acetyl) derivatives and benzaldehydes resulted in good yields of the target bis(pyrimidines). The in vitro cytotoxic activity of new pyrimidines against the MCF-7, HEPG2, and Caco2 cell lines was evaluated using the reference doxorubicin (IC₅₀ values of 4.34-6.97 μM). Hybrid 6h had the best activity against Caco2 and MCF-7 cell lines, IC₅₀ values of 12.62 and 14.50 μM, respectively. The IC₅₀ values for hybrids 6c, 6e, and 6f against MCF-7 and Caco2 cell lines were 23.99-41.69 and 33.14-43.33 μM, respectively. Furthermore, hybrid 6e displayed IC₅₀ value of 20.06 μM HEPG2 cell lines, while the hybrids 6c, 6f and 6h exhibited IC₅₀ values ranging between 26.29-50.51 μM. Furthermore, hybrid 6e had an IC₅₀ value of 20.06 μM for the HEPG2 cell lines, whereas hybrids 6c, 6f, and 6h had IC₅₀ values ranging from 26.29 to 50.51 μM.

New pyrido[3′,2′:4,5]thieno[3,2-d]pyrimidin-4(3H)-one hybrids linked to arene units: synthesis of potential MRSA, VRE, and COX-2 inhibitors

In the current study, we reported the tandem synthesis of two series of arene-linked pyrimidinone hybrids with related fused thieno[2,3-b]pyridine moiety. The target hybrids were prepared, in moderate to excellent yields, by the reaction of a ternary mixture of the appropriate of 3-aminothieno[2,3-b]pyridine-2-carboxylate, DMF-DMA, and a series of aryl amines in dioxane at 110 °C for 8 h. The antibacterial activity of the new hybrids was estimated against six susceptible ATCC strains. Hybrids 5g and 7g, linked to a sulfonamide unit, showed the best efficacy against S. aureus and E. faecalis strains with minimum inhibitory concentration (MIC) values of 1.7–1.8 μM, which exceed ciprofloxacin. Furthermore, some of new hybrids were examined as potential inhibitors of four different MRSA and VRE strains. Hybrids 5g and 7g demonstrated more potent efficacy than linezolid against MRSA strains with MIC values of 3.6/3.4 and 1.8/1.7 μM against ATCC:33591 and ATCC:43300 strains, respectively. The prior hybrids displayed a comparable efficacy with linezolid against VRE strains with MIC values of 7.3/6.9 and 3.6/3.4 μM against ATCC:51299 and ATCC:51575 strains, respectively. Additionally, some of the new hybrids were examined as potential COX-2 inhibitors using the reference celecoxib (IC50 of 0.117 µM). Hybrid 7g revealed more potent inhibitory efficacy than celecoxib with IC50 of 0.112 µM, whereas hybrid 5g showed almost inhibitory activity equivalent to celecoxib with IC50 of 0.121 µM. Molecular docking was performed to predict the possible binding interactions between hybrids 5g and 7g with the target COX-2 enzyme.

Intermolecular interactions between β-cyclodextrin and water

This study focused on demonstrating the intermolecular interactions between β-cyclodextrin and water, with the aim to better understand the transfer of small molecules to β-cyclodextrin. The intermolecular interaction strength between β-cyclodextrin and water was analyzed using different methods such as the dynamic adsorption of water, the TG-DSC of β-cyclodextrin and molecular modeling employing MM2 force field calculations. The experiments for the adsorption of water on β-cyclodextrin was aimed to systematically investigate the adsorption characteristics, such as adsorption capacity, adsorption rate, adsorption heat and activation energy, influenced by the adsorption temperature and vapor pressure of water. The results indicated that the water adsorption on β-cyclodextrin is an exothermic process. The hysteresis loop type in the adsorption isotherms at multiple temperatures indicated that water adsorption is not purely a traditional physical adsorption due to the existence of structure effects such as the cavity effect and hydrogen bonding. The activation energy during water adsorption was 7.4 kJ mol-1. However, the activation energy during water desorption was in the range of 35-45 kJ mol-1, which decreased with an increase in the amount of water adsorbed. This indicated that water adsorption is much easier than water desorption from β-cyclodextrin and that water desorption is more difficult with a small amount of adsorbed water compared with a large amount of adsorbed water. Subsequently, the obtained average intermolecular interaction strength between β-cyclodextrin and water under the experimental conditions was 67.5 kJ mol-1 (water), which was verified by DSC.