R. V. Madrigal

Taxus baccata seed oil: A new source ofcis-5,cis-9-octadecadienoic acid

Methyl esters prepared from the seed oil of the coniferTaxus baccata L. were found by gas liquid chromatography to contain 12% of a component which, when isolated by preparative thin layer chromatography and characterized by mass spectrometry, ozonolysis and nuclear magnetic resonance, was identified ascis-5,cis-9-octadecadienoic acid.

Carduus nigrescens seed oil—A rich source of pentacyclic triterpenoids

Pentacyclic triterpene alcohols (3%), their acetates (18%), and their long chain fatty acid esters (11%), together with triterpene acids (18%), represent ca. 50% of the oil from the seed and pericarp of the thistleCarduus nigrescens Vill. (Compositae). Along with the usual fatty acids, alkaline hydrolysis of this oil gave triterpene alcohols, some of which were identified by gas chromatography-mass spectrometry. Composition of the triterpenoid fraction, as indicated by gas chromatography of the corresponding acetates, was: α-amyrin (6%), β-amyrin (15%), lupeol plus ϕ-taraxasterol (3%), erythrodiol (6%), and oleanolic acid (3%). Several components, representing 16% of the oil, were not identified. The content of pentacyclic triterpenoids is the largest found in plant seed oils.

Estolide triglycerides ofTrewia nudiflora seed oil

The seed oil ofTrewia nudiflora is known to contain glycerides of α-kamlolenic (18-hydroxy-cis-9,trans-11,trans-13-octadecatrienoic) acid. We have shown that a large part of these glycerides contain estolides in which the hydroxyl group of α-kamlolenic acid is esterified to a molecule of another acid, either a hydroxy acid or an ordinary fatty acid. By preparative thin layer chromatography, we isolated a series of tri-, tetra-, penta- and hexaacyl glycerols. By lipolysis and gas chromatography-mass spectrometry, we isolated and characterized estolide-linked fatty acids containing two acid moieties.

Alkyl-and alkenylresorcinols inRapanea laetevirens seed lipids

The seed lipids ofRapanea laetevirens (Myrsinacea) were found to contain a series of 5-alkylresorcinols. Some of these alkylresorcinols have been reported previously in other plant families, but never before in the Myrsinaceae. The various homologs were shown by mass spectrometry to have alkyl side chains that included C11 and C13 saturated as well as C11, C13, and C15 monoenoic substituents. This is the first report of the natural occurrence of tridecenylresorcinol, the homolog with the C13 monoenoic side chain. The positions of the double bonds in the side chains were determined by mass spectrometry of their methoxy trimethylsilyloxy derivatives. Also found were embelin and rapanone, benzoquinone pigments which occur commonly in the Myrsinaceae. The fatty acid composition ofRapanea seed triglycerides was not unusual, consisting mainly of 16∶0 (27%), 18∶1 (22%), and 18∶2 (44%).

Biological activities ofTrewia nudiflora extracts against certain economically important insect pests

An ethanol extract ofTrewia nudiflora (Euphorbiaceae) seed was tested as an agent for controlling several economically important insects. Results suggest that this plant extract acts as an antifeedant for the spotted cucumber beetle (Diabrotica undecimpunctata howardi Barber) and the European corn borer [Ostrinia nubilalis (Hübner)] but not for the other insects tested. Also indicated were morphogenic effects on the codlingmoth [Laspeyresia pomonella (L.)], disruption of the normal life cycle of the redbanded leafroller [Argyrotaenia velutinana (Walker)], and reduction in the progeny of the plum curculio [Conotrachelus nenuphar (Herbst)]. In addition, the extract was toxic to the striped cucumber beetle [Acalymma vittatum (F.)] and gave 100% control of the chicken body louse [Menacanthus stramineus (Nitzsch)] from 5 to 28 days. Fractionation of the extract was monitored by a bioassay usingO. nubilalis. This fractionation yielded six pure compounds, the most abundant of which was trewiasine. Its LD50 was 7.4 ppm when incorporated into the diet ofO. nubilalis. Dose-mortality relationships for the other compounds withO. nubilalis are presented.

Polygala virgata seed oil—A new source of acetotriglycerides

The seed oil ofPolygala virgata (family Polygalaceae) contains 74% of monoacetotriglycerides, the first found in nature with the acetate group in position 2 ofsn-glycerol. Naturally occurring triglycerides characterized previously all have the acetate at position 3. The configuration of the acetoglyceride fromP. virgata was established by a combination of thin layer chromatography, optical rotatory dispersion, and nuclear magnetic resonance.

Structure-activity relationships among maytansinoids in their effect on the European corn borer, Ostrinia nubilalis (Hübner)

Five maytansinoids fromMaytenus (Celastraceae) andPutterlickia (Rhamnaceae) species were tested for biological activity against the European corn borerOstrinia nubilalis. Maytanbutine, maytansine, and maytanvaline, all of which contain an amino acid residue at C-3, were active and comparable in their effect on larvae to trewiasine, a known active, amino acid-containing maytansinoid fromTrewia nudiflora. Maytanacine, which has an acetate group at C-3, was not as active as maytansine, maytanvaline, maytanbutine, or trewiasine, but significantly retarded the development of the larvae. Normaysine, which has no oxygen substituent at C-3, had no significant effect on mortality and only moderate effect on development of the larvae. The presence of the amino acid moiety at C-3 appears to be an important factor for the biological activity of maytansinoids.