Design, synthesis, cytotoxic activity and molecular docking studies of new 20(S)-sulfonylamidine camptothecin derivatives

20(S)-Sulfonylamidine CPT-derivatives were prepared and tested for cytotoxicity.Several analogs showed superior cytotoxic activity compared to irinotecan.Key structural features related to cytotoxicity were identified by SAR analysis.Compounds 9 and 15c interacted with Topo I-DNA by a different binding mode from CPT.These compounds are new generation CPT-derived antitumor agents.In an ongoing investigation of 20-sulfonylamidine derivatives (9, YQL-9a) of camptothecin (1) as potential anticancer agents directly and selectively inhibiting topoisomerase (Topo) I, the sulfonylamidine pharmacophore was held constant, and a camptothecin derivatives with various substitution patterns were synthesized. The new compounds were evaluated for antiproliferative activity against three human tumor cell lines, A-549, KB, and multidrug resistant (MDR) KB subline (KBvin). Several analogs showed comparable or superior antiproliferative activity compared to the clinically prescribed 1 and irinotecan (3). Significantly, the 20-sulfonylamidine derivatives exhibited comparable cytotoxicity against KBvin, while 1 and 3 were less active against this cell line. Among them, compound 15c displayed much better cytotoxic activity than the controls 1, 3, and 9. Novel key structural features related to the antiproliferative activities were identified by structure–activity relationship (SAR) analysis. In a molecular docking model, compounds 9 and 15c interacted with Topo I-DNA through a different binding mode from 1 and 3. The sulfonylamidine side chains of 9 and 15c could likely form direct hydrogen bonds with Topo I, while hydrophobic interaction with Topo I and π–π stacking with double strand DNA were also confirmed as binding driving forces. The results from docking models were consistent with the SAR conclusions. The introduction of bulky substituents at the 20-position contributed to the altered binding mode of the compound by allowing them to form new interactions with Topo I residues. The information obtained in this study will be helpful for the design of new derivatives of 1 with most promising anticancer activity.CPT (green), 9 (magenta), and 15c (blue) in the binding site of DNA-Topo-I

Synthesis and crystal structure of dimeric silver (I) complex: Ag₂[phen₂][S₂P(OPr)₂]₂

1659-1661The dinuclear complex, Ag2[phen2][S2P(OPr)2]2 (phen = 1,10-phenanthroline; Pr = propyl), was prepared by the reaction of bis(dipropyldithiophosphato)silver(I) complex with 1,10-phenanthroline ligand, and its structure was determined by X-ray crystallography. It crystallizes in the triclinic system, space group Pi. with lattice parameters a= 9.875(2), b = 10.992(2), c =11.232(2)Å, α = 68.32(3), β= 74.93(3), γ = 65.16(3)o, and Z = 2. Each of the two dipropyldithiophosphato ligands bridges two silver atoms to form an eight-membered Ag2S4P2 ring, while the 1,10- phenanthroline coordinates to the silver atom to complete the local tetrahedral geometry for the silver metal ion. The Ag .. . Ag separation in the dimer is 3.207(1)Å

Photodynamic Antimicrobial Therapy Based on Conjugated Polymers

Pathogenic microorganisms have been a serious threat to human life and have become a public health problem of global concern. However, in the actual treatment there is a lack of efficient antimicrobial strategies which do not easily develop drug resistance; this can lead to inaccurate drug treatment that worsens the infection and even threatens life. With the emergence of a variety of drug-resistant bacteria and fungi, photodynamic therapy has gradually become one of the most promising treatment methods for drug-resistant bacteria infection; this is because it is controllable, non-invasive, and not prone to cause the development of drug resistance. Organic conjugated polymers that possess high fluorescence intensity, a large molar extinction coefficient, excellent light stability, an adjustable energy band, easy modification, good biocompatibility, and the ability to photosensitize oxygen to produce reactive oxygen species have been widely used in the fields of solar cells, highly sensitive detection systems, biological imaging, and anti-cancer and anti-microbial treatment. Photodynamic therapy is non-invasive and has high temporal and spatial resolution and is a highly effective antimicrobial treatment that does not easily induce drug resistance; it has also stimulated the scientific research enthusiasm of researchers and has become a research hotspot in the antimicrobial field. In this review, the photodynamic antibacterial applications of conjugated polymers with different structure types are summarized, and their development directions are considered

Synthesis and crystal structures of <i>N</i>-(2,3,4,6<i>-</i>Tetra-<i>O</i>-acetyl-<i>β</i>-<i>D</i>-glycosyl)thiocarbamoyl <span style="font-size:12.0pt;line-height:115%;font-family:"Times New Roman"; mso-fareast-font-family:"Times New Roman";mso-ansi-language:NL;mso-fareast-language: EN-IN;mso-bidi-language:HI" lang="NL">methylene diamine</span>

1072-1075The structure of N-(2,3,4,6-Tetra-O-acetyl-β-D-glycosyl)thiocarbamoyl methylene diamine, C16H25N3O9S has been determined by X-ray diffraction method. It crystallizes in the monoclinic system, space group P2l, with lattice parameters a = 7.6560(2), b = 10.3113(3), c = 14.1813(1)Å, β = 100.879 (2)o, and Z = 2. The hexapyranosyl ring adopts a chair conformation. All the ring substituents are in the equatorial position. The acetoxylmethyl group is in the gauche- gauche conformation. The S atom is in synperiplanar conformation, while the N-C-N-C linkage is antiperiplanar. The N-H...O intermolecular hydrogen bonds link the molecules into infinite chains and these are connected by C-H...O interaction

How firms cope with social crisis: The mediating role of digital transformation as a strategic response to the COVID-19 pandemic.

The COVID-19 pandemic has drawn attention to the strategic responses of Chinese firms on digital transformation and led to a call for enhancing competitive advantage via accelerating digital transformation. Besides the physical health issue, the pandemic has triggered an extraordinary social and economic crisis in which service industries have been attacked hard. In this situation, firms are meeting increasing competitive pressure, which urges them to achieve better performance with the help of digital transformation. Based on the technology-organization-environment framework and dynamic capabilities theory, this research proposed two studies with two methods, including a structural equation model and a regression discontinuity design with a fixed-effect model. The findings suggest digital transformation mediates the relationship between competitive pressure and firm performance among Chinese small- and medium-sized enterprises and large firms after the outbreak of COVID-19, respectively. It confirms that digital transformation is a practical strategic decision for Chinese service firms to respond to increasing competitive pressure in the COVID-19 pandemic. Besides, the results also illustrate the moderating effects of absorptive, innovative, and adaptive capability on the relationship between digital transformation and firm performance among large firms

Lung Ventilation Monitoring Incorporating Prior Information by Electrical Impedance Tomography

Electrical impedance tomography (EIT), as a relatively new medical imaging method, has the preferable features as inexpensive, safe, non-invasive and portable. Complementary to existing methods, it is expected to reconstruct accurate images of impedance changes in the object. One of the approaches to producing an accurately reconstructed image is the inclusion of prior information regarding the physical geometry of the object. A physical model incorporating the prior information of human thorax has been developed using a commercial software tool COMSOL. In this paper the developed model is presented along with lung ventilation experimental data The visualization results of lung ventilation indicate that EIT incorporating prior information is a promising technique which has the potential to be applied in future for clinical diagnoses and monitoring