ABSTRACT
The metabolism of deuterium-labelled analogues of ABA by normal and flacca mutant tomato plants was investigated. Comparison of the biological activity of ABA, ABA alcohol, ABA aldehyde and their 2-trans isomers was made in both mutant and non-mutant genotypes. While in normal plants ABA alcohol and ABA aldehyde were as effective as ABA in inducing stomatal closure, in the flacca mutants only ABA itself was biologically active. Both ABA alcohol and ABA aldehyde were converted to the inactive compound trans- ABA alcohol instead of ABA when fed to flacca plants. As trans-ABA aldehyde was also readily converted to trans-ABA alcohol by flacca plants, it was not possible to establish whether isomerization precedes reduction or vice versa in the synthesis of trans-ABA alcohol from ABA aldehyde.
ABSTRACT
The minimum inhibitory concentration values against Gram-negative and Gram-positive bacteria were determined and compared for a selected group of synthesized alpha-substituted 2-methyl-5-nitrofuran derivatives. In vitro oxidation of thiols to disulfides by 2-(iodomethyl)-5-nitrofuran indicated that oxidation of enzyme-thiol groups to disulfide bonds was a possible mode of action; but was discounted by noninhibition of thiol enzymes by these compounds. Electron-microscopic studies of the morphology of bacteria after treatment with these derivatives showed the formation of unusual elongation, branching and atypical rod shapes in E. coli, while S. aureus manifested multibud formation with some cytoplasmic protrusions. The possible mode of action of these compounds is discussed.
Subject(s)
Anti-Bacterial Agents/pharmacology , Bacteria/drug effects , Nitrofurans/pharmacology , DNA Damage , Microbial Sensitivity Tests , Structure-Activity RelationshipABSTRACT
The minimum inhibitory concentration values for a group of synthesized heterocyclic derivatives of 1-methyl-1-nitroethyl sulphide were determined for Gram-positive and Gram-negative bacteria, yeast, and fungi. The active compounds were further screened. The effect of these compounds on growth, morphology and incorporation of 3H-uridine was also tested. Comments on the possible model of action of such compounds is included.
Subject(s)
Anti-Infective Agents/pharmacology , Nitro Compounds/pharmacology , Anti-Bacterial Agents , Cell Survival/drug effects , Disulfides/metabolism , Fungi/drug effects , Gram-Negative Bacteria/drug effects , Gram-Positive Bacteria/drug effects , Microbial Sensitivity Tests , Nitro Compounds/metabolism , Species Specificity , Structure-Activity Relationship , Transcription, Genetic/drug effectsABSTRACT
A new abscisic acid (ABA) analogue has been isolated from tomato plants. High levels of the compound are found in flacca mutants compared with normal isogenic controls. The analogue also accumulates in response to water stress. Three alternative structures, consistent with the mass spectrum, have been proposed. The possibility that the compound may be a biosynthetic precursor of ABA is considered.
Subject(s)
Abscisic Acid/genetics , Plants/genetics , Abscisic Acid/metabolism , Cyclohexanecarboxylic Acids , Models, Chemical , Mutation , Plants/metabolismABSTRACT
Sec-alpha-halo-nitro compounds are active antibacterial and antifungal agents, and the sec-bromo derivatives are the most active and stable.
