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BACKGROUND: Graphene oxide (GO)-based systems are among the drug delivery systems and have drawn a lot of interest in the field of medicine. METHODS: In this work, two novel phosphoramides with the formulas of (NHCHCH2C(CH3)2NHC(CH3)2CH2P(S)(OEt)2 (L1) and (NHCHCH2C(CH3)2 NHC (CH3)2CH2P (O) (NHC6H5) (OC5H6) (L2) were synthesized and characterized by spectroscopic methods. Then, graphene oxide (GO) was functionalized by L1 and L2. FT-IR, XRD, FE- SEM/ MAP, and Zeta potential analyses were applied to confirm the synthesis of phosphoramide-functionalized graphene oxides (GO-L1 and GO-L2). Cytotoxicity of synthesized compounds was evaluated against breast cancer cell line (SK-BR-3) using MTT assay. Moreover, the flow cytometry assay was performed to evaluate the cell death mechanisms. RESULTS: The results showed that GO-L1 and GO-L2 had a more inhibitory effect against cancer cells than that of L1 and L2, and GO-L2 showed the highest cytotoxicity with an IC50 value of 38.13 µg/ml. Quantum calculations were employed to optimize structures. HOMO and LUMO energy values and physical adsorption of synthesized compounds were obtained by the DMol3 module in the Material Studio 2017. The docking studies were used to investigate the binding of L1, L2, GO-L1, and GO-L2 to DNA polymerase IIα. CONCLUSION: Anticancer activity of phosphoramide compounds was increased after attachment on the GO surface, and the docking studies' results were in good accordance with the experimental cytotoxicity results.

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In this study, two new phosphoramides containing imidazolidine; diphenyl (2-imidazolidinone-1-yl)phosphonate (DIOP) and diphenyl (2-Imidazolidinethione -1-yl)phosphonate (DITP) as cytotoxic agents, were synthesized and characterized by using IR, 1H NMR, 13C NMR, 31P NMR, Mass spectroscopy and elemental analysis. The target products were obtained in moderate to good yields (69-86%) by using the time (3 h) and solvent (MeCN). The crystal structure of DIOP was investigated using X-ray crystallography. The main non-covalent intermolecular interactions were also studied by Hirshfeld surface analysis and fingerprint plots. The anticancer and growth inhibitory activities of the synthesized compounds were investigated against human breast cancer cell line MDA-MB-231 using MTT assay; DITP was found to be a better cytotoxic agent than DIOP. The cytotoxicity results were supported by a molecular docking study and in order to know the structure-activity relationship (SAR) of synthesized compounds, the values of HOMO and LUMO energies, dipole moments, hardness, softness, and electrophilicity index were investigated computationally by DFT method. These results were in good accordance with those of in vitro investigation and molecular docking study.

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In an attempt to obtain the modified and novel insecticides with low human toxicity, a series of novel mono-, bis-, and tetraphosphonic acid derivatives were designed and characterized by infrared, 1H, 13C, and 31P NMR spectroscopy and X-ray crystallography. The inhibitory effects of the synthesized compounds were evaluated using the in vitro Ellman method on human and insect acetylcholinesterase (AChE). Some of these compounds, which had low human and high insect toxicity, were chosen to assess the killing effects (in vivo) on third larval instar of elm leaf beetle (X. luteola). In vivo and in vitro evidence has revealed that bisphosphonic acids, containing hydrophobic systems, have a good selectivity of insect AChE inhibition. In the present study, docking results showed that bisphosphonic acids had lower binding energy and higher inhibition compared with tetraphosphonic acids due to the type of their topology and the ability of their hydrogen to interact with the catalytic triad (the main active site of the enzyme). Additionally, the QSAR results demonstrated that the major effecting factors on the insecticidal activity of the subject compounds are the hydrophobicity, size, shape, and ability to form a hydrogen bond. The present study can be helpful in the development of new insecticides.

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The recent prevalence of coronavirus disease in 2019 (COVID-19) has triggered widespread global health concerns.Antiviral drugs based on phosphoramides have significant inhibitory activity against the main protease (Mpro) of the virus and prevent transcription and viral replication. Hence, in order to design and introduce a group of inhibitors affecting the coronavirus, 35 phosphoramide compounds based on phospho-guanine and phospho-pyrazine derivatives were selected for molecular docking study. The results showed that most phosphoguanides containing the amino benzimidazole have a high interaction tendency with COVID-19. Among them, compound 19 was identified as the strongest inhibitor with the -9.570 kcal/mol binding energy whereas, the binding energy of Remdesivir is -6.75 kcal/mol. The quantitative structure-activity relationship (QSAR) results demonstrated that the number of aromatic rings, amide's nitrogens and their ability in π-staking, and hydrogen interactions with Mpro active sites are major factors contributing to the inhibitory activity of these compounds.Also, the NCI-RDG and DFT results were in good accordance with those of QSAR and molecular docking. The findings of this investigation can be underlying the synthesis of effective and efficient drugs against COVID-19.

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Novel phospho guanidine and phospho pyrazine derivatives were synthesized and characterized by 31P, 13C, 1HNMR and IR spectroscopy to obtain novel and human-safe insecticides. Compound 35 [(C4H4N2NH)2P(O)(C6H6)] was investigated by X-ray crystallography. The inhibitory effects of synthesized compounds were evaluated on human and insect acetylcholinesterase (AChE) using in vitro Ellman method. A few of these compounds, which had low human toxicity, were selected for assessing the killing effects (in vivo) on the elm leaf beetle (X.luteola). The in vitro and in vivo results indicated that compounds bearing both phosphoryl groups and aromatic systems were found to possess a good selectivity for the inhibition of insect AChE over human AChE; up to 550-fold selectivity was achieved for compound 19. Docking studies were performed to explain reasons for the selective behavior of AChE inhibitors. Additionally, the quantitative structure-activity relationship (QSAR) and density functional theory (DFT) results of AChEs demonstrated that the size, shape, dipole moment, and ability to form hydrogen bond played the main role in both models. In addition, the aromatic π - π interactions and charge of the amide nitrogen had a major effect on insecticidal activity of the compounds. The present research can be helpful to gain a better understanding of the interactions between the insect AChE and its inhibitors and introduces compounds which are capable of becoming human-safe insecticides.

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In an attempt to achieve a new class of phosphoramide inhibitors with high potency and resistance to the hydrolysis process against urease enzyme, we synthesized a series of bisphosphoramide derivatives (01-43) and characterized them by various spectroscopic techniques. The crystal structures of compounds 22 and 26 were investigated using X-ray crystallography. The inhibitory activities of the compounds were evaluated against the jack bean urease and were compared to monophosphoramide derivatives and other known standard inhibitors. The compounds containing aromatic amines and their substituted derivatives exhibited very high inhibitory activity in the range of IC50 = 3.4-1.91 × 10-10 nM compared with monophosphoramides, thiourea, and acetohydroxamic acid. It was also found that derivatives with PO functional groups have higher anti-urease activity than those with PS functional groups. Kinetics and docking studies were carried out to explore the binding mechanism that showed these compounds follow a mixed-type mechanism and, due to their extended structures, can cover the entire binding pocket of the enzyme, reducing the formation of the enzyme-substrate complex. The quantitative structure-activity relationship (QSAR) analysis also revealed that the interaction between the enzyme and inhibitor is significantly influenced by aromatic rings and PO functional groups. Collectively, the data obtained from experimental and theoretical studies indicated that these compounds can be developed as appropriate candidates for urease inhibitors in this field.

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