John P. Toth

Chemical synthesis of deuterated folate monoglutamate and in vivo assessment of urinary excretion of deuterated folates in man

the synthesis and in vivo application of stable-isotopically labeled folic acid was investigated to devise methods suitable for studies of folate metabolism in human subjects. Glutamate-labeled tetradeutero-pteroylglutamic acid (d4-folic acid) was prepared by mixed anhydride coupling of N10-trifluoroacetylpteroic acid and dimethyl L-[3,3,4,4-2H4]glutamic acid, saponification in sodium deuteroxide, and chromatographic purification. Retention of the isotopic label was verified by proton NMR and mass spectrometry of the para-aminobenzoylglutamic acid product of C9-N10 bond cleavage. A method was devised for determination of of isotopic enrichment of urinary d4-folates derived from orally administered d4-folic acid using affinity chromatographic purification, chemical cleavage of the C9-N10 bond, HPLC isolation of the p-[2H4]aminobenzoylglutamate product, followed by negative-ion chemical-ionization gas chromatography/mass spectrometry. Data concerning the urinary excretion of d4-folates derived from an oral dose of d4-folic acid in an adult human are presented.

Systemic induction of terpenoid aldehydes in cotton pigment glands by feeding of larval Spodoptera exigua

Pigment glands in cotton contain terpenoid aldehydes that are toxic and deterrent to feeding of several generalist lepidopteran insects. We hypothesized that previously observed systemically induced feeding deterrence may be associated with pigment glands. We conducted experiments to determine the dynamics and chemical nature of inducible feeding deterrents in leaves of cotton, Gossypium hirsutum L, to larvae of the beet armyworm, Spodoptera exigua. Production and/or filling of pigment glands was influenced by physiological age of Deltapine 90 cotton plants. In undamaged plants, successively formed leaves contained more pigment glands, up to the seventh or eighth true-leaf developmental stage. Feeding choice tests conducted one or seven days after initial feeding damage revealed that third instars of S. exigua consumed more of the two youngest leaves from control cotton plants than from plants whose two oldest leaves had been fed on previously for 24 hr by S. exigua. The preference for leaves from control plants was significant one day after initial damage and highly significant seven days after damage. Consumption of mature foliage (leaf immediately above initially damaged leaves) from control plants and damaged plants did not differ. More pigment glands were counted on the youngest leaf of damaged plants than on the youngest leaf of control plants one day after initial damage. HPLC analysis revealed greater amounts of hemigossypolone, heliocides 1 and 2 (H1 and H2), and total terpenoid aldehydes per gland in young foliage of damaged plants than control plants one day after initial injury. By seven days after initial injury, greater quantities of hemigossypolone and all heliocides except H4 were detected in young foliage from damaged plants compared to control plants. Concentrations of H1 per gland in young leaves from damaged plants increased the most of all terpenoid aldehydes measured (3.4× the amount found in leaves from control plants). Mature leaves from damaged plants did not contain more terpenoid aldehydes than mature leaves from control plants. We suggest that systemically induced feeding deterrence to S. exigua in young leaves of glanded cotton was due to increased amounts of terpenoid aldehydes in pigment glands.

Caribbean fruit fly,Anastrepha suspensa (Loew), attraction to host fruit and host kairomones

Extracts of 22 fruits were tested for their attractancy toAnastrepha suspensa (Loew), the Caribbean fruit fly. Box-orange, calamondin, carambola, cattley guava, loquat, and Surinam-cherry were about equal in attractiveness to males and females. Nine synthetic chemicals, including four found in box-orange ripe seed, were attractive to females. Five synthetic chemicals, including two in box-orange ripe seed, were attractive to males. Farnesol,α-phellandrene, and 3-carene were highest in attractiveness to both males and females. Females were more attracted than males to 12 synthetic chemicals. These data suggest that host chemicals serve as attractants and that female and male specific attractants and traps could be developed from host kairomone data. These data also suggest that the volatilization of chemicals from water may play an important role in kairomone biology.

Interactive self-modeling multivariate analysis of thermolysis mass spectra

Abstract Snyder, A.P., Windig, W. and Toth, J.P., 1991. Interactive self-modeling multivariate analysis of thermolysis mass spectra. Chemometrics and Intelligent Laboratory Systems , 11: 149–160. Traditionally, multivariate data analysis has been characterized as cross-reference (i.e. principal components, spectra, loading and score lists) intensive in terms of data reduction, as well as conceptually difficult to understand. The variance diagram (VARDIA) greatly simplified multivariate analysis by shifting the burden from complex lists of data variable statistics to visually informative depictions of the data set. The visually oriented VARDIA technique was combined with the KEY SET algorithm developed by Malinowski, and their union, the Interactive Self-Modeling Multivariate Analysis (ISMA) technique, was shown to be particularly effective for identifying pure component spectra in time-resolved Raman and Fourier transform IR spectral data sets. Furthermore, color labeling of the pure variables and components, which also characterizes the ISMA approach, provided enormous benefits with respect to data analysis and user interaction. In the present study, time-resolved atmospheric pressure ionization thermolysis mass spectra of biopolymers, biopolymer mixtures and microorganisms are investigated by the ISMA approach. A straightforward, user-friendly resolution of the mass spectra was realized by color-graphics displays of the ISMA technique. Color is not only a convenient tool in the data reduction process, but it also acts as a link between the multivariate and original data sets. Separate components could be traced via their color in the VARDIA, pure masses and standard deviation mass spectra.

[14C]Acetate incorporation by cultured normal, familial hypercholesterolemia and Down's syndrome fibroblasts☆

Fibroblasts from patients with homozygous familial hypercholesterolemia (FH), a disease characterized by accelerated atherogenesis, are known to lack functional low-density-lipoprotein receptors, which ultimately results in increased cholesterol biosynthesis in the cultured cells. [14C]Acetate incorporation in these cells was compared to that of normal fibroblasts and to fibroblasts from patients with Downs syndrome, a disease in which atherosclerosis is rare. Total [14C]acetate incorporation did not differ significantly between normal and Downs fibroblasts, nor did its partitioning into the hexane-extractable and aqueous fractions of the cell hydrolysates. [14C]Acetate incorporation was much greater in FH cells in both the aqueous and hexane-extractable fractions. Preincubation in fetal bovine serum increased acetate incorporation only by FH cells, while 50 micrograms low-density lipoprotein/ml medium depressed acetate incorporation in all three groups. A C27 sterol, identified by gas chromatography-mass spectrometry as a probable isomer of cholesterol, was present in small amounts in FH fibroblasts, but was not detectable in the normal or Downs cells. The absolute amounts of [14C]acetate incorporated into the non-sterol lipids were greater in the FH fibroblasts, indicating that these cells may have to synthesize, in addition to cholesterol, other required cellular lipids which are delivered to the normal cells by low-density lipoproteins.

Composition of adult exocrine gland secretions from three species of burrower bugs (Hemiptera: Cydnidae) in Florida

The adult exocrine gland secretions of three cydnid species, Rhytidoporus indentatus Uhler, Pangaeus bilineatus (Say), and Cyrtomenus ciliatus (Palisot de Beauvois), were analyzed by gas chromatography-mass spectrometry. All species produced E-2-octenal and n-tridecane as major secretory components. Only C. ciliatus yielded 4-oxo-E-2-hexenal whereas n-undecane was unique to R. indentatus. 2-Decenal, pentadecane, and hexadecane were also identified from these cydnids.

Soldier defensive secretions of two rare nearctic desert termite species

Termite defensive secretions were analysed by GC-MS from hexane extracts of the heads of soldiers from five colonies of A. emersoni and a single foraging group of A. coachellae collected in southern Califomia. The sesquiterpene ether, 4,11-epoxy-cis-eudesmane, was the major component (ca 90%) in soldier secretions of both species. Limonene, three sesquiterpene hydrocarbons, and additional unknown compounds, including a possible diterpene hydrocarbon, were also detected. Intracolony variability of secretions among individual soldiers from one colony of A. emersoni was not observed; however, some minor interspecific differences were found. The occurrence of 4,11-epoxy-cis-eudesmane in four Nearctic and at least four Amitermes spp. from other zoogeographic regions suggests a pre-Cretaceous evolution and dispersal of ancestral Amiterrnes.