Substituent

About: Substituent is a research topic. Over the lifetime, 42877 publications have been published within this topic receiving 516716 citations. The topic is also known as: side chain & side group.

Antimicrobial and DNA Gyrase-Inhibitory Activities of Novel Clorobiocin Derivatives Produced by Mutasynthesis

Abstract: Twenty-eight novel clorobiocin derivatives obtained from mutasynthesis experiments were investigated for their inhibitory activity towards Escherichia coli DNA gyrase and for their antibacterial activities towards clinically relevant gram-positive and gram-negative bacteria in comparison to novobiocin and clorobiocin. Clorobiocin was the most active compound both against E. coli DNA gyrase in vitro and against bacterial growth. All tested modifications of the 3-dimethylallyl-4-hydroxybenzoyl moiety reduced biological activity. The highest activities were shown by compounds containing a hydrophobic alkyl substituent at position 3 of the 4-hydroxybenzoyl moiety. Polar groups in this side chain, especially amide functions, strongly reduced antibacterial activity. Replacement of the alkyl side chain with a halogen atom or a methoxy group at the same position markedly reduced activity. Transfer of the pyrrole carboxylic acid moiety from O-3" to O-2" of L-noviose moderately reduced activity, whereas the complete absence of the pyrrole carboxylic acid moiety led to a loss of activity. Desclorobiocin derivatives lacking the chlorine atom at C-8 of the 3-amino-4,7-dihydroxycoumarin moiety also showed low activity. Lack of a methyl group at O-4" of L-noviose resulted in an inactive compound. From these findings it appears that clorobiocin represents a "highly evolved" structure optimized for bacterial transport and DNA gyrase inhibition.

Indole-type derivatives as inhibitors of p38 kinase

Abstract: The invention is directed to methods to inhibit p38-α kinase using compounds comprising a phenyl or thienyl coupled through a piperidine or piperazine nucleus to an indole residue wherein the indole residue mandatorily has a substituent on the ring nitrogen which is an amino or substituted amino group.

Substituent variation in azabicyclic triazole- and tetrazole-based muscarinic receptor ligands.

Abstract: The effect of variation of the 1-azabicyclic substituent on the novel 1,2,3-triazol-4-yl-, 1,2,4-triazol-1-yl, tetrazol-5-yl-, and tetrazol-2-yl-based muscarinic receptor ligands has been studied, and the exo-azabicyclic[2.2.1]hept-3-yl substituent was found to give the most potent and efficacious compounds. In addition, variation of the second substituent on 1,2,4-triazol-1-yl- and tetrazol-2-yl-based muscarinic receptor ligands has yielded a series of novel compounds with high potencies and efficacies, ranging from full agonists to antagonists. Small lipophilic electron withdrawing substituents give potent but low efficacy compounds, while small polar electron donating substituents give potent and efficacious compounds. The activity of these compounds is described in terms of a model of the receptor involving lipophilic and hydrogen bonding interactions. These compounds provide muscarinic ligands with high potency and a range of efficacies suitable for testing as candidate drugs in the treatment of Alzheimer's disease.

Herbicidal cyclohexane-1,3-dione derivatives

Abstract: The invention concerns compounds of formula I ##STR1## wherein: X and Y are independently selected from the group consisting of hydrogen, C 1 to C 4 alkyl, C 1 to C 4 haloalkyl, and the group wherein X and Y together from a three or four-membered carbon bridge the bridge optionally comprising one or both of a double bond and a carbonyl group; Z is selected from the group consisting of hydrogen, halogen, C 1 to C 4 alkyl and C 1 to C 4 alkanoyl; R 1 is selected from the group consisting of: hydrogen; an acyl group; and an inorganic or organic cation; R 2 is selected from the group consisting of: C 1 to c 6 alkyl; C 2 to C 6 alkenyl; C 2 to C 6 haloakenyl; C 2 to C 6 alkynyl; and substituted C 1 to C 6 alkyl wherein the alkyl group is substituted with a substituent selected from the group consisting of halogen, phenyl, and substituted phenyl wherein the benezene ring is substituted with from one to three substituents selected from the group consisting of halogen, and C 1 to C 6 alkyl; R 3 is selected from the group consisting of: C 1 to C 6 alkyl; and R 4 is selected from the group consisting of: hydrogen; C 1 to C 6 alkyl; and (C 1 to C 6 alkoxy) carbonyl. The compounds are herbicides and in further embodiments the invention provides processes for the preparation of compounds of formula I, herbicidal compositions comprising the compounds of formula I and processes for severly damaging or killing unwanted plants by application of compounds of formula I.

4‐methoxy substituted trityl groups in 6‐O protection of cellulose: Homogeneous synthesis, characterization, detritylation

Abstract: The reaction of cellulose with methoxy-substituted triphenylmethyl chlorides under homogeneous conditions in the presence of pyridine was carried out with the aim to develop new protective groups for cellulose simply introducable and completely removable under mild conditions. The obtained cellulose ethers dissolve well in solvents such as N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, 1,4-dioxane and tetrahydrofuran and show a high 6-O selectivity. The study proves that the speed of tritylation as well as of detritylation increases in the order unsubstituted trityl/monomethoxytrityl/dimethoxytrityl/trimethoxytrityl. The substituent distribution of the methoxy-substituted triphenylmethyl ethers of cellulose was determined by means of 13 C NMR spectroscopy of the polymers and by high-performance liquid chromatography after chain-degradation. Since the methoxy substituted trityl groups were introduced faster and removed easier than the unsubstituted trityl group, they are, therefore, useful tools for a regioselective synthesis of 2,3-functionalized cellulose derivatives.