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Biomedical subjects

F J Evans

Publications and source records attributed to F J Evans.

At least 91 records · Page 5Linked to original sources
PubMed1979

An assay procedure for the comparative irritancy testing of esters in the tigliane and daphnane series.

A method is described for testing of diterpene esters for irritancy. The technique involves the application of acetone solutions of the toxins to the inside ears of female LACA mice. The number of mice responding per group and the log10 dose data were evaluated using probit analysis with the assistance of a computer program. This evaluation has the advantage that approximations inherent with an arithmetical evaluation were eliminated, and limits may be placed upon the standard deviation of the irritant dose 50% (ID50). In addition, the use of a chi2 test automatically eliminated results which were not attributed to random biological variation. Observations of the time to onset and the persistence of the inflammation have led to the suggestion that daphnane orthoester diterpenes may elicit their effect by means of a direct action at a receptor site in skin, whereas the tigliane O-acyl esters may in part act by causing more general tissue damage.

Animals↗
PubMed1979

Investigations into the skin-irritant properties of resiniferonol ortho esters.

A series of esters were produced by partial synthesis from 9,13,14-orthophenylacetyl-resiniferonol. These compounds were tested for irritant effects by means of a mouse ear assay. All of the derivatives, including the parent compound, produced short-term inflammation of mice ears within 1-2 h and the effects did not persist for 24 h. This is in contrast to esters of structurally related tigliane diterpenes which produce a longer-term on mice ears. Highly potent irritants were synthesized which exhibited irritant doses 50% in the 0.0012-0.00021 nmol range. These esters were all substituted phenylacetates of the C-20 position of 9,13,14-orthophenylacethyl-resiniferonol. The meta or para positions of the phenylacetate moiety were substituted with electronegative groups for maximum activity. Compounds exhibiting substituted phenyl propionates at C20 were not irritants in the test used.

Animals↗
PubMed1979

The succulent euphorbias of Nigeria. III. Structure and potency of the aromatic ester diterpenes of Euphorbia poissonii Pax.

The latex of Euphorbia poissonii was found to contain irritant aromatic diterpene esters based upon resiniferonol, 12-deoxy-16-hydroxy-phorbol and 12-deoxyphorbol. Four resiniferonol esters, 9,13,14-ortho-phenylacetyl-resiniferonol-20-0-[p-hydroxy-phenylacetate]; 9,13,14-orthophenylacetyl-resiniferonol-20-0-[m-methoxy-m'-hydroxy-phenylacetate]; 9,13,14-orthophenylacetyl-resiniferonol-20-0-acetate and resiniferonol-14-0-phenylacetate-20-0-[m-methoxy-m'-hydroxy-phenylacetate], were identified. Two further esters were identified as 12-deoxy-16-0-[2-methylbutyroyl]-phorbol-13-0-phenylacetate-20-0-acetate and 12-deoxy-16-0-[2-methylbutyroyl]-phorbol-13-0-phenylacetate. These compounds represent the first aromatic esters of this parent diterpene to be obtained from natural sources. The third group of compounds were identified as 12-deoxyphorbol-13-0-[p-hydroxy-phenylacetate]-20-0-acetate; 12-deoxyphorbol-13-0-[p-acetoxy-phenylacetate]-20-0-acetate; 12-deoxyphorbol-13-0-phenylacetate-20-0-acetate and 12-deoxyphorbol-13-0-phenylacetate. The irritant potency of the ten pure compounds was obtained using a mouse ear method for assessment of the irritant dose 50%.

Animals↗
PubMed1977

Appetitive and replacement naps: EEG and behavior.

Consistent subjective, behavioral, and electroencephalographic sleep-stage differences were found between afternoon naps of 11 habitual appetitive nappers (who nap lightly for psychological reasons apparently unrelated to reported sleep needs) and 10 replacement nappers (who apparently nap regularly in response to temporary sleep deficits). Both types of naps were compared with naps of 12 confirmed non-nappers.

Adult↗
PubMed1977

Cascarosides A and B.

Electron-impact and field desorption mass spectrometry, together with NMR and circular dichroism spectroscopy, were used to confirm that cascarosides A and B are C-10 isomers of 8-O-(beta-D-glucopyranosyl)barbaloin. Several batches of cascarosides A and B were prepared and oxidatively hydrolyzed to aloe-emodin. The results are discussed in relation to the assay for cascara given in the European Pharmacopoeia, 1971.

Anthraquinones↗