Activation of V

Indeed, the observation that vanadate is a potent inhibiter of phosphate-recognizing enzyme systems was a great stimulus to work in this area, but it now seems likely that its action is more complicated than simple mimicry of phosphates.This is germane to obtaining an understanding of the antitumor activity of [V( j -C5H5)2Cl2]. 

The mutagenic activity of /V-acyloxy-/V-alkoxyamides is believed to involve Sn2 reactions of guanine N7 at the amide nitrogen with displacement of carboxylate 49 Remarkably, their biological activity is similarly affected by substituents at the amide nitrogen (vide infra). 

G. K. E. Scriba, D. M. Lambert, Synthesis and Anticonvulsant Activity of V-Benzyl-oxycarbonyl-amino Acid Prodrugs of Phenytoin , J. Pharm. Pharmacol. 1999, 51, 549-553. 

The high activity of V-W-Ti-0 and of V-Mo-Ti-O is due to a synergistic effect between V and W (Mo) oxide species and is related to the superior redox properties of the ternary catalysts. 

Gichner, T. Veleminsky, J. (1987) The organic solvents acetone, ethanol and dimethylformamide potentiate the mutagenic activity of V-methyl-V -nitro-V-nitrosoguanidine, but have no effect on the mutagenic potential of -mcthyl- -nitrosourea. Mutat. Res., 192, 31-35... 

Pepicelli O., Fedele E., Bonanno G., Raiteri M., Ajmone-Cat M. A., Greco A., Levi G., and Minghetti L. (2002). In vivo activation of /V-methyI-D-aspartatc receptors in the rat hippocampus increases prostaglandin ft 2 extracellular levels and triggers lipid peroxidation through cyclooxygenase-mediated mechanisms. J. Neurochem. 81 1028-1034. 

Both alkyl side chains are necessary for activity of. v-triazinc dealkylating enzymes from Rhodococcus strain B-30 (Behki and Khan, 1994). 

JA Jamison, DJ Zeckner, MJ Rodriguez. The synthesis and antifungal activity of V-alkylated analogs of echinocandin B. J. Antibiot 50 562-566, 1997. 

This material successfully withstands a series of tests for successful anchoring, for example, (i) no activity in the clear filtrate, (ii) no further conversion on addition of new oxidant and reactant, and (iii) full activity of V and no release of active V on preexposure of the catalyst to t-BuOOH. In contrast, in comparative tests, V02+ on polyvinylpyridine, V-A1PO-5, and V on SiC>2 underwent varying degrees of leaching (49). 

Silica gel is also the support of choice for the activation of V-halosuccinimides. The silica functions both as a proton donor which increases the electrophilic nature of the reagent, and as a support with geometrical constraints which contributes to the stereoselectivity. Alkyl and aryl sulfoxides are readily halogenated at the a position with yields of48-80%91. The reactions are carried in the solid state on the surface of TLC plates. The conversion of the optically active alkyl 4-methylphenyl sulfoxide into 1-haloalkyl 4-methylphenyl sulfoxide is accompanied by inversion of configuration at the S-atom. The stereoselectivity in these reactions is much higher than that observed in liquid-phase halogenation. 

A-(nitrobenzimidazol-2-yl)pyridinium derivatives have been synthesized in order to study their antiprotozoal activity [693-695], A H and 13C NMR study has been carried out for structural determination of these compounds (S13C in Table 3.25). Quantitative structure-activity relationships (QSAR) between the in vitro antileish-manial activity of /V- ben zazolylpyridinium salts and their 13C NMR chemical shifts have been studied in order to determine the influence of benzimidazole substituents upon antileishmanial activity [695],... 

Cytidine monophosphate-sialic acid synthetase (EC 2.7.7.43) catalyzes the activation of /V-acetylneuraminic acid (NANA) by CTP to form CMP-NANA. 

Qiu FH, Ray P, Brown K, Barker PE, Jhan-war S, et al. 1988. Primary structure of c-kit relationship with the CSF-l/PDGF receptor kinase family-oncogenic activation of v-kit involves deletion of extracellular domain and C terminus. EMBO J. 7 1003-11... 

Farad FM, Breese KR (1993) Nitric oxide mediates vasodilatation in response to activation of /V-methyl-D-asp-artate receptors in brain. Circ Res 72 476-480. 

Metabolism of foreign compounds is not necessarily detoxication. This has already been indicated in examples and will become more apparent later in this book. This may involve activation by a phase 1 or phase 2 pathway or transport to a particular site followed by metabolism. Thus, sulphate conjugation and acetylation may be involved in the metabolic activation of /V-hydroxy aromatic amines, glutathione conjugation may be important in the nephrotoxicity of compounds, methylation in metal toxicity, glucuronidation in the carcinogenicity of /1-naphthylamine and 3, 2 -dimethyl-4-aminobiphenyl. 

The catalytic activities of calcined samples of V-MFI (B), V-MEL (B3) and V-Al-P (3) which possess most of the vanadium in framework positions are presented in Table 4. Additionally, the activity of V-Al-P (1) containing mostly nonframework (extractable) V is also compared. It is noticed that the first three samples containing mostly framework V have similar activities (TON) and exhibit similar product selectivities. V-Al-P (1) with more nonframework ions possesses a lower activity and a different product selectivity, producing more catechol than the others. In the the case of TS-1, the formation of catechol is believed to take place over the active sites at the external surface, while hydroquinone is formed over the sites inside the pore system. The above observation and the rapid extraction of V by H2O2 during the reaction suggest that the extra-framework V-species are present mostly at the external surface of the crystallites. An important conclusion of the studies is that the intrinsic activity of the framework V ion is independent of the structure of the zeolite. This suggests that the framework V species are similar in nature and environment in all the above three systems. 

---