221018-02-6Relevant articles and documents
Structure-Based Optimization of N-Substituted Oseltamivir Derivatives as Potent Anti-Influenza A Virus Agents with Significantly Improved Potency against Oseltamivir-Resistant N1-H274Y Variant
Zhang, Jian,Murugan, Natarajan Arul,Tian, Ye,Bertagnin, Chiara,Fang, Zengjun,Kang, Dongwei,Kong, Xiujie,Jia, Haiyong,Sun, Zhuosen,Jia, Ruifang,Gao, Ping,Poongavanam, Vasanthanathan,Loregian, Arianna,Xu, Wenfang,Ma, Xiuli,Ding, Xiao,Huang, Bing,Zhan, Peng,Liu, Xinyong
, p. 9976 - 9999 (2018/12/11)
Due to the emergence of highly pathogenic and oseltamivir-resistant influenza viruses, there is an urgent need to develop new anti-influenza agents. Herein, five subseries of oseltamivir derivatives were designed and synthesized to improve their activity toward drug-resistant viral strains by further exploiting the 150-cavity in the neuraminidases (NAs). The bioassay results showed that compound 21h exhibited antiviral activities similar to or better than those of oseltamivir carboxylate (OSC) against H5N1, H5N2, H5N6, and H5N8. Besides, 21h was 5- to 86-fold more potent than OSC toward N1, N8, and N1-H274Y mutant NAs in the inhibitory assays. Computational studies provided a plausible rationale for the high potency of 21h against group-1 and N1-H274Y NAs. In addition, 21h demonstrated acceptable oral bioavailability, low acute toxicity, potent antiviral activity in vivo, and high metabolic stability. Overall, the above excellent profiles make 21h a promising drug candidate for the treatment of influenza virus infection.
Highly efficient and magnetically recyclable graphene-supported Pd/Fe3O4 nanoparticle catalysts for Suzuki and Heck cross-coupling reactions
Elazab, Hany A.,Siamaki, Ali R.,Moussa, Sherif,Gupton, B. Frank,El-Shall, M. Samy
, p. 58 - 69 (2015/05/05)
Herein, we report a facile and efficient one-step method for the synthesis of highly active, Pd/Fe3O4 nanoparticles supported on graphene nanosheets (Pd/Fe3O4/G) that exhibit excellent catalytic activity for Suzuki and Heck coupling reactions and that can be magnetically separated from the reaction mixture and recycled multiple times without loss of catalytic activity. The synthesis approach is based on the Microwave (MW)-assisted reduction of palladium and ferric nitrates in the presence of graphene oxide (GO) nanosheets using hydrazine hydrate as the reducing agent. The results provide a fundamental understanding of the system variables by comparing the catalytic activity and recyclability of four different catalysts with different properties. The most active and recyclable catalyst contains 7.6 wt% Pd nanoparticles with 4-6nm diameters in Pd(0) oxidation state well-dispersed with 30wt% Fe3O4 nanoparticles with 12-16 nm diameters on highly reduced GO containing a C/O ratio of 8.1. These combined properties produce remarkable catalytic activity for Suzuki cross coupling reactions under MW reaction conditions with an extremely high turnover number (TON) of 9250 and turn over frequency (TOF) of 111,000 h-1 at 80 °C. The magnetic properties imparted by the Fe3O4 component of the catalyst enables the catalyst to be easily isolated and recycled, thus greatly simplifying the ability to purify the reaction products and increasing the economic value of the catalyst. The utility of these magnetic catalysts towards Suzuki and Heck cross coupling reactions with a variety of functionalized substrates was also demonstrated.
Microwave-assisted synthesis of palladium nanoparticles supported on graphene: A highly active and recyclable catalyst for carbon-carbon cross-coupling reactions
Siamaki, Ali R.,Khder, Abd El Rahman S.,Abdelsayed, Victor,El-Shall, M. Samy,Gupton, B. Frank
experimental part, p. 1 - 11 (2011/05/19)
We have developed an efficient method to generate highly active Pd nanoparticles supported on graphene (Pd/G) by microwave-assisted chemical reduction of the corresponding aqueous mixture of a palladium salt and dispersed graphite oxide (GO) sheets. The Pd/G demonstrated excellent catalytic activity for the carbon-carbon cross-coupling reactions (Suzuki, and Heck) with a broad range of utility under ligand-free ambient conditions in an environmentally friendly solvent system. It also offers a remarkable turnover frequency (108,000 h-1) observed in the microwave-assisted Suzuki cross-coupling reactions with easy removal from the reaction mixture, recyclability with no loss of activity, and significantly better performance than the well-known commercial Pd/C catalyst. The catalyst was fully characterized by a variety of spectroscopic techniques including X-ray diffraction (XRD), Raman, TGA, electron microscopy (SEM, TEM), and X-ray photoelectron spectroscopy (XPS). The remarkable reactivity of the Pd/G catalyst toward Suzuki cross-coupling reactions is attributed to the high degree of the dispersion and concentration of Pd(0) nanoparticles supported on graphene sheets with small particle size of 7-9 nm due to an efficient microwave-assisted reduction method.
