Richard T. Mayer

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The individual members of a homologous series of phenoxazone ethers related to ethoxyresorufin were O-dealkylated, and the parent compound phenoxazone was ring-hydroxylated, each at different rates with hepatic microsomes of untreated rats. A structure-activity relationship (SAR) was plotted, relating the rate of O-dealkylation to the length and type of the(More)
The O-dealkylations of ethoxyresorufin and pentoxyresorufin are widely used activity probes for measuring the cytochrome P450 forms, CYP1A1 and CYP2B1, respectively, and their induction by xenobiotics, but there is confusion in the literature about which P450 forms are detected in human and rat liver microsomes by these and homologous alkoxyresorufins. High(More)
Interactions of six naturally occurring flavonoids (acacetin, diosmetin, eriodictyol, hesperetin, homoeriodictyol, and naringenin) with human cytochrome P450 (CYP1) enzymes were studied. The flavones acacetin and diosmetin were potent inhibitors of ethoxyresorufin O-dealkylase (EROD) activity of CYP1A and CYP1B1. Hydroxy and/or methoxy substitutions at the(More)
The O-dealkylation of pentoxyresorufin (7-pentoxyphenoxazone) by rat liver microsomes was examined. The reaction appeared highly specific for certain phenobarbital inducible forms of cytochrome P-450 and was increased 95- to 140-fold by animal pretreatment with phenobarbital (75 mg/kg/day, four ip injections) and approximately 50-fold by Aroclor 1254 (500(More)
The metabolism and cytochrome P-450-binding of phenoxazone and a homologous series of its n-alkyl ethers (1-8C) was studied in hepatic microsomes of control, phenobarbitone-pretreated (PB) and 3-methylcholanthrene-pretreated (3MC) C57/BL10 mice. Phenoxazone and its ethers were hydroxylated and O-dealkylated respectively to a common metabolite, resorufin.(More)
We conducted a controlled experiment to test the plant vigor and the plant stress hypotheses. The two hypotheses associate plant physiological conditions to insect feeding mode and performance. We exposed tomato, Lycopersicon esculentum, to different types of growing conditions: optimal (vigorous plants), resource based stress (water and/or nutrient(More)
Whether or not chemical changes in plants in response to pests (insects and pathogens) are general or specific remains unclear. Some evidence indicates that an induced response (IR) to arthropods via the octadecanoid pathway represents a distinct mechanism from the salicylic acid-based pathway of systemic acquired resistance (SAR) to pathogens. To further(More)
Some elicitors of plant defensive systems can induce biochemical changes that enable the plant to reduce disease incidence; however, little is known about the effect of these induced responses on insect herbivores. We approached this problem using exogenous field applications of several abiotic elicitors of defensive systems in tomatoes (Lycopersicon(More)