Explicit expressions have been derived for the response coefficients for the effect of activator and inhibitor concentrations on the fraction in the active state of the target enzyme of a monocyclic interconvertible enzyme cascade. These allow one to assess the adequacy of such a cascade for producing a highly sensitive response to an effector. Numerical studies indicate that this type of syste...

the synthesis of some 13-lactams is described. 'the electronic activation of monocyclic b-lactams provided by a quinonemethine function was found to instabilize the 13-lactam ring toward nucleophilic: attack by water

We report a Lewis acid catalyzed reaction sequence involving a 1,2-shift and subsequent C-H insertion that gives monocyclic and fused bicyclic cyclopentenone products. This reaction sequence, which is initiated by treating β-hydroxy-α-diazo ketones with a Lewis acid, proceeds through vinyl cation intermediates that insert at non-activated gamma C-H bonds. This reaction represents an alternative...

Sampling of monoterpenes from air on the Tenax porous polymer may introduce analytical errors owing to oxidation and acid rearrangements on the adsorbent. Particularly terpenes which react rapidly with ozone, e.g. myrcene and limonene, are partially lost when sampling air with high photooxidant levels. On acidified adsorption cartridges, a-pinene and ~-pinene may be converted to camphene, limon...

Essential oils are complex natural mixtures, their main constituents, e.g. terpenes and phenylpropanoids, being responsible for their biological properties. Essential oils from eucalyptus, tea tree and thyme and their major monoterpene compounds alpha-terpinene, gamma-terpinene, alpha-pinene, p-cymene, terpinen-4-ol, alpha-terpineol, thymol, citral and 1,8-cineole were examined for their antivi...

Bark beetles oxidize the defensive monoterpenes of their host trees both to detoxify them and convert them into components of their pheromone system. This oxidation is catalyzed by cytochrome P450 enzymes and occurs in different tissues of the insect, including the gut (i.e., the site where the beetle's pheromones are produced and accumulated) and the antennae (i.e., the olfactory organs used f...

Six distinct chemotypes of the mediterranean 7’lzymus vulgaris L. are characterized by differences in the major monoterpenes produced. The nature of the monoterpenes is shown to be controlled by a series of loci. Each locus probably has a dominant and a recessive allele. Epistatic relationships between these loci are interpreted by assuming that terpenes are end products of branches from the sa...

The monoterpenes are secondary metabolites of plants. They have various pharmacological properties including antifungal, antibacterial, antioxidant, anticancer, anti-spasmodic, hypotensive, and vasorelaxant. The purpose of this research was to review the cardiovascular effects of monoterpenes. The data in this resarch were collected using the Internet portals Pubmed, Scopus, and ISI Web of Know...