13C NMR spectroscopy of neolignans

The ¹³C NMR spectra of 15 neolignans of several structural types and two lignans were analyzed and their carbon shifts assigned. The shifts of pyrogallol ether and ethyl phenyl carbinyl ether models were used in this connection. The stereochemistry of a dimeric sideproduct in the preparation of the latter models was determined by ¹³C NMR analysis.     

Aryl hydrocarbon receptor activity downstream of IL-10 signaling is required to promote regulatory functions in human dendritic cells

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Insecticidal secondary metabolites from entomogenous fungi: Entomophthora virulenta

Two strains of the insect pathogenic fungus Entomophthora virulenta have been examined for their pathogenicity to adult blowflies, Calliphora erythrocephala, for their ability to grow on defined media, and for the production of biologically active secondary metabolites. The fungus proved highly pathogenic to blowflies and hyphal bodies isolated from diseased insects were successfully cultivated on egg yolk medium and subsequently grown in shake culture on a glucose-asparagine medium. Both strains were found to produce a mixture of 4,4′-azoxybenzene dicarboxylic acid and 4,4′-hydroxymethyl azoxybenzene carboxylic acid. The hydroxy acid proved toxic by intrahemocoelic injection into adult blowflies and accounted for all the extractable insecticidal activity.     

Structure-Activity Studies on Nematicidal Activity of Dialkyl Carbamates and Thiocarbamates

In laboratory tests, 129 dialkyl carbamates of types ROC(O)NHR'', RSC(O)NHR'', and ROC(S)NHR'' were tested in a screening bioassay against Panagrellus redivivus. The 10 most active were lethal at concentrations from 5 ppm down to ca. 1 ppm. Eight of these (the only ones active below 2.5 ppm) were thiolcarbamates (RSC(O)NHR''). Decyl N-methyhhiolcarbamate was also lethal to Meloidogyne incognita at approximately 1 ppm in direct contact tests.     

HPLC with carbohydrate carbamate chiral phases: Influence of chiral phase structure on enantioselectivity

The enantioselective resolution of trans-stilbene oxide and of 23 chiral sulfoxides was investigated on cellulose and amylose tris(arylcarbamate) stationary phases coated on aminopropylated 7 μm spherical silica with 500 Å diameter pores. Cellulose tris-(3,5 dimethylphenylcarbamate) showed good resolving power for many of the sulfoxides and amylose tris-(3,5 dimethoxyphenylcarbamate) showed advantages for the resolution of certain sulfoxides which were not separated on other phases. © 1994 Wiley-Liss, Inc.     

Aryl hydrocarbon hydroxylase induction in mouse liver cells--relationship to position in the cell cycle

The inducibility of aryl hydrocarbon hydroxylase (AHH) by benzo[a]-pyrene (BaP) has been studied in synchronously grown cultures of mouse liver cells. These cells (NMuLi cl 8) have low basal levels of AHH which can be induced greater than 100-fold by BaP. Cells were synchronized in G1(G0) by serum starvation and in S by release from serum starvation in combination with excess thymidine. When released from G1(G0) by replating at lower cell density in fresh medium with 20% serum, cells began entering S with a lag of 12 h. Addition of BaP (1 microgram/ml) 8 h before serum stimulation, at the time of stimulation or 7.5 h after stimulation all gave similar induction kinetics: the AHH activity peaked as the cells began entering S regardless of when the BaP was added. Cells blocked in various parts of S by excess thymidine were inducible for AHH activity as efficiently as cells moving through S and into G2. These results indicate that the inducibility of AHH is greater when cells are actively proliferating and may be a contributing factor to why growing cells are more sensitive to mutagenesis and transformation than quiescent cells.     

Synthesis and DNA-cleaving activity of a series of substituted arenediazonium ions

We investigated the reactions of substituted aryl radicals and aryl cations derived from arenediazonium ions and their ability to cause cleavage of supercoiled DNA and their tendency toward free radical or cation formation in the presence and absent of copper (I) chloride. It was found that the substituted arenediazonium salts can cleave supercoiled DNA to the open circular form II DNA and linear form III DNA. Results methodical studies indicate that both carbon-centered radicals and aryl cations participate in the cleavage pathways.