Junji Kumamoto

Isolation and identification of mosquito repellents inArtemisia vulgaris

The mugwortArtemisia vulgaris L. (Compositae: Anthemideae) contains insect repellents which can be released from the plant tissues by combustion. Work was carried out to isolate and identify the repellent compounds. The dried, pulverized whole plants were steam-distilled to give a repellent essential oil which was fractionated by column chromatography. Active fractions were analyzed by capillary GC and by combined GC-MS. A number of compounds, mainly monoterpenoids, were identified. When tested as repellents against the yellow fever mosquitoAedes aegypti L. (Diptera: Culicidae), (±)-linalool, (±)-camphor, (+)-camphor, (−)-camphor, isoborneol, (−)-borneol, terpinen-4-ol, and isobornyl acetate were active at 0.14 mg/cm2 or higher. Nonanone-3, (α+β)-thujone, and bornyl acetate were active at 0.28 mg/cm2 or higher. β-Pinene, myrcene, α-terpinene, (+)− limonene, and cineole were active at 1.4 mg/cm2. Of the repellent compounds identified, terpinen-4-ol was the most active and was as effective as dimethyl phthalate.

Activity of volatile compounds in glandular trichomes ofLycopersicon species against two insect herbivores

Several major chemicals in the glandular heads of type VI trichomes ofLycopersicon species were identified and quantified by gas chromatography and mass spectrometry. Two normal odd-chained ketones, 2-undecanone (47 ng) and 2-tridecanone (146 ng), and one unknown sesquiterpene (5 ng), comprised approximately 95% of the contents of a gland ofL.hirsutum f.glabratum Mull. In a closely related plant,L.hirsutum Humb. & Bonpl. (LA 361), two unknown insecticidal sesquiterpenes accounted for 6% of the gland contents. Additionally, small amounts of one unknown monoterpene and another unknown sesquiterpene were found in type VI glands of a commercial tomato variety,L.esculentum Mill. Bioassays comparing the gland exudate (by direct contact) and isooctane extracts of glands to neonate larvae ofKeiferia lycopersicella (Walsingham) (Lepidoptera: Gelechiidae) andSpodoptera exigua (Hübner) (Lepidoptera: Noctuidae) indicated that: (1) 2-tridecanone and 2-undecanone were the major insecticidal compounds inL.hirsutum f.glabratum, (2) the two unknown sesquiterpenes inL.hirsutum were acutely toxic to both species, and (3) gland contents in the commercial tomato variety provided only a physical barrier toK.lycopersicella, and were not detrimental toS.exigua. In topical bioassay trials, synthetic mixtures of 2-tridecanone and 2-undecanone (3 ∶1) demonstrated potentiation. Concentrations of these chemicals decreased as trichomes aged. Quantities of insecticidal chemicals and density of type VI trichomes varied with plant age and location within plants.

Allelopathic activity of Chenopodium ambrosioides L.

Abstract In the chinampas of San Andres Mixquic, Mexico, the farmers allow Chenopodium ambrosioides L. to grow only where there are no crops. Previous studies suggest that this plant interferes with the growth of other plants. Given current concerns over pesticide use, it is important to understand the management and chemical properties of certain plant species with allelopathic potential since these species may help lessen herbicide dependency in agriculture. Extracts of C. ambrosioides L. were bioassayed in germination and hypocotyl growth inhibition tests of Amaranthus hypochondriacus L. A volatile active fraction was found. At a concentration of 0.552 μ/petri dish, C. ambrosioides essential oil inhibited germination of A. hypochondriacus by 50%, while the hypocotyl growth of previously-germinated seeds of the same species was inhibited by 50% with 0.509 μ/petri dish. α-Terpinene, γ-terpinene, p -cymene, limonene and ascaridole (1-methyl-4(l-methylethyl)-2-3-dioxibicyclo[2.2.2]oct-5-ene) were identified in the essential oil of C. ambrosioides . Ascaridole was the principal allelochemical; 0.098 μ/petri dish caused a 50% inhibition of A. hypochondriacus germination and 0.216 μ/petri dish inhibited hypocotyl growth of the same species by 50%. Another crop species, Phaseolus acutifolius A. Gray, grown hydroponically, was inhibited significantly with the lowest concentration of C. ambrosioides essential oil tested (0.15 ml/I). With higher concentrations, the primary root died and plant growth was visibly stunted. The management of C. ambrosioides as a means of pest control with allelopathy in the chinampa agroecosystem is discussed.

Distribution of essential oils in leaf tissue of an F2 population of Citrus

SummaryThe identification and distribution of 17 mono- and sesquiterpenes in an F2 population produced from selfing of an interspecific F1 hybrid is presented. A mode of inheritance for most of these components is attempted, percentages of leaf oil components and a correlation matrix are given.

[23] Polarographic determination of phase changes in mitochondrial membranes in response to temperature

Publisher Summary Phase transitions in biological membranes have been determined by a variety of techniques and assays; including X-ray diffraction, differential calorimetry, z enzymatic activity, and electron spin resonance spectroscopy with spin labels. Polarographic measurement of mitochondrial oxidation has also been used successfully to indirectly determine the appearance of membrane phase changes in response to temperature. This method is based on the observation that the respiratory enzymes of mitochondria undergo a change in conformation at the same temperature at which the associated membranes undergo a phase transition. The material presented indicates the particular techniques and problems associated with polarographic assay at different temperatures.

Utilization of model membranes in a test for the mechanism of ethylene action

SummaryReversible alteration of the surface tension of thin films of lipids, proteins and mixtures of both resulted when the thin films were treated with ethylene and other aliphatic gases. This effect appeared to be a nonspecific surface effect related to the molecular size of the gases. Ethylene produced no change which would ascribe to it any specific properties in this test system. The conductivity of an egg lecithin-cholesterol bilayer membrane separating two electrolytes was unaffected by all the test gases (including ethylene), but chloroform vapors markedly altered the conductivity in a reversible manner. In each of the test systems empoloyed, there was no specificity exhibited by ethylene, either qualitatively or quantitatively, indicating the mechanism of ethylene action cannot be explained as a simple physical effect on membranes.

The volatile oils of Ambrosia (Compositae: Ambrosieae)

This study demonstrates the occurrence of 29 oil components in 20 ragweed species and in species from related genera. The occurrence of each of the 29 volatile compounds in all species examined supports an interpretation of the complex as a natural assemblage. Evidence suggests that the oils are under genetic control. However, strong support linking oil variation and patterns of relationship hypothesized on morphological grounds was lacking, except for the tendency of morphologically less-specialized elements to have greater amounts of the components with lower retention times. This lack of correlation may be related in part to intraspecific variability.

Variations of Leaf Oil Composition of Citrus Budded on Different Rootstocks

Variation in composition of essential leaf oils in Citrus resulting from changes in rootstock have been correlated by an analysis of variance. Some com- ponents of leaf oil show significant variations with such changes.

A phytochemical investigation of Citrus halimii

Abstract Essential leaf oils, isoenzymes, protein and polyphenol oxidase-catalyzed browning patterns of Citrus halimii (Rutaceae) are investigated and compared with those of other species of Citrus in order to support the species standing of the recently described C. halimii .

Phytochemical investigations in Photinia

Abstract Leaves of Photinia glabra, P. serrulata, P. glabra × serrulata, P. × fraseri, Heteromeles arbutifolia, Cotoneaster pannosa , and Eriobotrya japonica were investigated for oil and n -alkane content and for hydrogen cyanide production. Benzaldehyde proved to be the major volatile oil component in all taxa except Eriobotrya which yielded no oil upon steam distillation. A conjugated aldehyde was present in all taxa of Asian origin but essentially absent from the New World form Heteromeles . The presence of cyanogenic compounds was indicated in all species again excepting Eriobotrya . C 24 H 50 to C 33 H 68 n -alkanes were presentin all taxa. The patterns of composition showed distinct differences along generally recognizable generic limits and again supported the separate placement of Heteromeles .