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Nucleophilic Substitution Reactions of α-Chloroacetanilides with Pyridines in Dimethyl Sulfoxide
Dey, Shuchismita,Adhikary, Keshab Kumar,Kim, Chan-Kyung,Lee, Bon-Su,Lee, Hai-Whang Korean Chemical Society 2005 Bulletin of the Korean Chemical Society Vol.26 No.5
The kinetic studies of the reactions of $\alpha$-chloroacetanilides $(YC_6H_4NRC(=O)CH_2Cl;\;R=H\;(4)\;and\;CH_3$ (5)) with pyridines have been carried out in dimethyl sulfoxide at 95 ${^{\circ}C}$. The pyridinolysis rates are faster with 4 than with 5 whereas the aminolysis rates with benzylamines are faster with 5 than with 4. The Brønsted ${\beta}_X$ values are in the range from 0.30 to 0.32 and the cross-interaction constants, $\rho_{XY}$, are small negative values; $\rho_{XY}$ = -0.06 and -0.10 for 4 and 5, respectively. Based on these and other results, the pyridinolyses of $\alpha$-chloroacetanilides are proposed to proceed via a stepwise mechanism with rate-limiting addition of the nucleophile to the carbonyl group to form zwitterionic tetrahedral intermediate ($T^{\pm}$) followed by a bridged type transition state to expel the leaving group.
Complementary and alternative therapies for obesity
Dey Lucy,Yuan Chun-Su Kyung Hee Oriental Medicine Research Center 2002 Oriental pharmacy and experimental medicine Vol.2 No.1
Obesity is a serious medical disorder because it can cause a myriad of health problems, such as heart disease, hypertension, and adult-onset diabetes. While conventional medical treatment for obesity has limitations, there is enormous public enthusiasm for complementary and alternative treatments of obesity. This article reviews currently commonly used complementary and alternative therapies for obesity, such as medicinal herbs, nutritional supplements and acupuncture. Beneficial effects and possible adverse effects associated with these treatment are discussed.
Dey, Nilay Kumar,Hoque, Md. Ehtesham Ul,Kim, Chan Kyung,Lee, Bon-Su,Lee, Hai Whang John Wiley Sons, Ltd. 2009 Journal of physical organic chemistry Vol.22 No.5
<P>The reactions of dimethyl phosphinic chloride (1) and methyl phenyl phosphinic chloride (2) with X-anilines have been studied kinetically in acetonitrile at 15.0 and 55.0 °C, respectively. The deuterium kinetic isotope effects (KIEs) involving deuterated aniline nucleophiles (XC<SUB>6</SUB>H<SUB>4</SUB>ND<SUB>2</SUB>) are also reported for the same reactions. The obtained KIEs for 1 are secondary inverse (k<SUB>H</SUB>/k<SUB>D</SUB> = 0.703–0.899 < 1), while those for 2 are primary normal (k<SUB>H</SUB>/k<SUB>D</SUB> = 1.62–2.10 > 1). A concerted mechanism involving predominantly backside nucleophilic attack is proposed for the anilinolysis of 1. A concerted mechanism involving predominantly frontside attack via a hydrogen-bonded four-center-type transition state is proposed for the anilinolysis of 2. The degree of steric hindrance is the major factor that determines both the reactivity of the phosphinates and the direction of the nucleophilic attack on the phosphinates. Copyright © 2008 John Wiley & Sons, Ltd.</P> <B>Graphic Abstract</B> <P>Phosphoryl transfer reactions are known to proceed via two main types of mechanisms: a stepwise mechanism involving a trigonal bipyramidal pentacoordinate (TBP-5C) intermediate and a concerted mechanism via a single TBP-5C transition state (TS). When the nucleophile attacks the reaction center from the side opposite the leaving group (backside attack), the configuration is inversed. However, when the nucleophile attacks from the leaving group side (frontside attack), the configuration is retained. <img src='wiley_img/08943230-2009-22-5-POC1478-gra001.gif' alt='wiley_img/08943230-2009-22-5-POC1478-gra001'> </P>
Kinetics and mechanism of the anilinolysis of dimethyl and diethyl chloro(thiono)phosphates
Kumar Dey, Nilay,Hoque, Md. Ehtesham Ul,Kim, Chan Kyung,Lee, Bon-Su,Lee, Hai Whang John Wiley Sons, Ltd. 2008 Journal of physical organic chemistry Vol.21 No.7
<P>The deuterium kinetic isotope effects (KIEs) involving deuterated aniline nucleophiles (XC<SUB>6</SUB>H<SUB>4</SUB>ND<SUB>2</SUB>) are reported for the reactions of dimethyl chlorophosphate (1), dimethyl chlorothionophosphate (2), diethyl chlorophosphate (3) and diethyl chlorothionophosphate (4) in acetonitrile at 55.0 °C. The obtained k<SUB>H</SUB>/k<SUB>D</SUB> values are 0.798–0.979, 0.945–1.06, 0.714–0.919 and 1.01–1.10 for 1, 2, 3 and 4, respectively. A concerted mechanism with dominant backside nucleophilic attack is proposed for the reactions of 1 and 3. A concerted mechanism involving partial frontside attack through a hydrogen-bonded four-centre-type transition state (TS) is proposed for the reactions of 2 and 4. Copyright © 2008 John Wiley & Sons, Ltd.</P> <B>Graphic Abstract</B> <P>Kinetic results yield secondary inverse and primary kinetic isotope effects with deuterated aniline nucleophiles. A concerted mechanism with dominant backside nucleophilic attack is proposed for the reactions of dimethyl and diethyl chloro phosphates, and also a concerted mechanism involving partial frontside nucleophilic attack through a hydrogen-bonded four-center-type TS is proposed for the reactions of dimethyl and diethyl chlorothionophosphate. <img src='wiley_img/08943230-2008-21-7-8-POC1314-gra001.gif' alt='wiley_img/08943230-2008-21-7-8-POC1314-gra001'> </P>
Hoque, Md. Ehtesham Ul,Dey, Nilay Kumar,Guha, Arun Kanti,Kim, Chan-Kyung,Lee, Bon-Su,Lee, Hai-Whang Korean Chemical Society 2007 Bulletin of the Korean Chemical Society Vol.28 No.10
The kinetics and mechanism of the nucleophilic substitution reactions of diphenyl phosphinic (1) and thiophosphinic (2) chlorides with substituted X-pyridines are investigated kinetically in acetonitrile at 35.0 and 55.0 oC, respectively. A concerted mechanism with backside nucleophilic attack is proposed for the pyridinolysis of 1, on the basis of the linear Bronsted plot with the βX value of 0.68. In the case of the pyridinolysis of 2, the Hammett and Bronsted plots are biphasic concave upwards with the break point at 3- phenyl pyridine. These results indicate a change in mechanism from a concerted SN2(P) process with direct backside nucleophilic attack for less basic nucleophiles (X = 3-CN-3-Ph) to a stepwise process with frontside attack for more basic nucleophiles (X = 4-MeO-3-Ph). Apparent secondary inverse kinetic isotope effects with deuterated pyridine (C5D5N), kH/kD < 1, are observed for the pyridinolysis of 1 and 2.
( Sachan Richa ),( Prasanta Dey ),( Chaeun Park ),( Jungho Yang ),( Ji Yeon Son ),( Jae Hyeon Park ),( Su Hyun Lee ),( Mee-young Ahn ),( In Su Kim ),( Hyung Ryong Moon ),( Hyung Sik Kim ) 한국응용약물학회 2020 Biomolecules & Therapeutics(구 응용약물학회지) Vol.28 No.2
Histone deacetylase (HDAC) inhibitors represent a novel class of anticancer agents, which can be used to inhibit cell proliferation and induce apoptosis in several types of cancer cells. In this study, we investigated the anticancer activity of MHY4381, a newly synthesized HDAC inhibitor, against human prostate cancer cell lines and compared its efficacy with that of suberoylanilide hydroxamic acid (SAHA), a well-known HDAC inhibitor. We assessed cell viability, apoptosis, cell cycle regulation, and other biological effects in the prostate cancer cells. We also evaluated a possible mechanism of MHY4381 on the apoptotic cell death pathway. The IC<sub>50</sub> value of MHY4381 was lower in DU145 cells (IC<sub>50</sub>=0.31 µM) than in LNCaP (IC<sub>50</sub>=0.85 µM) and PC-3 cells (IC<sub>50</sub>=5.23 µM). In addition, the IC<sub>50</sub> values of MHY4381 measured in this assay were significantly lower than those of SAHA against prostate cancer cell lines. MHY4381 increased the levels of acetylated histones H3 and H4 and reduced the expression of HDAC proteins in the prostate cancer cell lines. MHY4381 increased G2/M phase arrest in DU145 cells, and G1 arrest in LNCaP cells. It also activated reactive oxygen species (ROS) generation, which induced apoptosis in the DU145 and LNCaP cells by increasing the ratio of Bax/Bcl-2 and releasing cytochrome c into the cytoplasm. Our results indicated that MHY4381 preferentially results in antitumor effects in DU145 and LNCaP cells via mitochondria-mediated apoptosis and ROS-facilitated cell death pathway, and therefore can be used as a promising prostate cancer therapeutic.
Kim, Jae-Ouk,Rho, Semi,Kim, Su Hee,Kim, Heejoo,Song, Hyo Jin,Kim, Eun Jin,Kim, Ryang Yeo,Kim, Eun Hye,Sinha, Anuradha,Dey, Ayan,Yang, Jae Seung,Song, Man Ki,Nandy, Ranjan Kumar,Czerkinsky, Cecil,Kim, American Society for Microbiology 2015 CLINICAL AND VACCINE IMMUNOLOGY Vol.22 No.4
<P>In developing countries, <I>Shigella</I> is a primary cause of diarrhea in infants and young children. Although antibiotic therapy is an effective treatment for shigellosis, therapeutic options are narrowing due to the emergence of antibiotic resistance. Thus, preventive vaccination could become the most efficacious approach for controlling shigellosis. We have identified several conserved protein antigens that are shared by multiple <I>Shigella</I> serotypes and species. Among these, one antigen induced cross-protection against experimental shigellosis, and we have named it pan-<I>Shigella</I> surface protein 1 (PSSP-1). PSSP-1-induced protection requires a mucosal administration route and coadministration of an adjuvant. When PSSP-1 was administered intranasally, it induced cross-protection against <I>Shigella flexneri</I> serotypes 2a, 5a, and 6, <I>Shigella boydii</I>, <I>Shigella sonnei</I>, and <I>Shigella dysenteriae</I> serotype 1. Intradermally administered PSSP-1 induced strong serum antibody responses but failed to induce protection in the mouse lung pneumonia model. In contrast, intranasal administration elicited efficient local and systemic antibody responses and production of interleukin 17A and gamma interferon. Interestingly, blood samples from patients with recent-onset shigellosis showed variable but significant mucosal antibody responses to other conserved <I>Shigella</I> protein antigens but not to PSSP-1. We suggest that PSSP-1 is a promising antigen for a broadly protective vaccine against <I>Shigella</I>.</P>