Brian M. Lawrence

Chemical composition and genetic basis for the isopinocamphone chemotype of Mentha citrata hybrids

Abstract The dominant I gene found in Mentha citrata causes only 1.0–1.5% isopinocamphone and 0.5–2.5% β-pinene in this species that is characterized by 60–90% linalool/linalyl acetate. If the gene Is is separated from the linked I gene that causes linalool and is substituted into M. aquatica having 66.5% menthofuran and the recessive ii genotype, the resulting hybrids will have 22.3% β-pinene, 29.9% isopinocamphone and a number of related monoterpenoids seldom observed in Mentha oils. Crosses with tester strains show that the Is gene almost entirely prevents the development of monoterpenes with a p-menthane carbon skeleton substituted at the 2- and/or 3-position which commonly occur in Mentha species. A generalized biogenetic scheme is used to hypothesize the position of the action of the Is gene in biosynthesis and its interaction with other genes controlling monoterpenoid formation in Mentha species.

Examinations of the matrix isolation fourier transform infrared spectra of organic compounds: Part XII

Matrix isolation Fourier transform infrared spectra (MI/FT-IR), mass spectra (MS), carbon-13 Nuclear Magnetic Resonance (13C-NMR) spectra, condensed-phase infrared spectra, and vapor-phase infrared (IR) spectra are presented for a series of terpene compounds. Subtle differences in positional and configurational isomers commonly found with terpenes could be easily detected by the MI/FT-IR spectra. The results are comparable in some aspects to those obtainable from 13C-NMR and thin-film IR; however, most importantly, they are acquired at the low nanogram level for MI/FT-IR, as compared to the milligram level for the other techniques. These results represent an advance in the technology available for the analysis of complex mixtures such as essential oils containing terpene-like molecules.

Essential Oil of Mentha diemenica (Lamiaceae)

ABSTRACT The leaf essential oil of Mentha diemenica Sprengel, was produced in 1% yield based on fresh weight of leaves. The principal components of this oil were menthone (32%), neomenthyl acetate (0.0–18.3%), pulegone (25–44%), neomenthol (2.5–9.0%), menthyl acetate (2.7–5.7%), menthol (1.8–2.7%) and isomenthone (1–3%).

Volatile Components of Pocket Melon (Cucumis melo L. ssp. dudaim Naud.)

ABSTRACT The volatile components of Cucumis melo ssp. dudaim (pocket melon), which were isolated by continuous extraction with isopentane, were identified by a combination of retention indices and GC/MS. Forty-eight constituents were identified in the aroma concentrate, from which hexanol (11.52%), chavicol (11.33%), (Z)-3-hexenol (6.84%), benzyl alcohol (3.54%) and eugenol (3.48%) were found to be the major constituents. The amount of chavicol found in the aroma concentrate was thought to contribute to the unique aroma character of the pocket melon.

The Essential Oil of Micromeria teneriffae Benth.

Abstract Twenty-two compounds have been characterized in an oil of Micromeria teneriffae. The major components were α-pinene (20.3%), borneol (14.9%), and nerolidol (10.9%).

Essential Oil of Torreya taxifolia Arnott

ABSTRACT The leaf oil of the Florida torreya, Torreya taxifolia, an endangered species, which was obtained by simultaneous steam distillation-solvent extraction was analyzed by GC and GC/MS. Although 24 components were identified in the oil, it was found to be hydrocarbon-rich with limonene (40.78%), α-pinene (7.59%), (E)-β-farnesene (6.16%), and δ-cadinene (6.60%) being in greatest abundance.

Temperature Effect on the Volatiles Formed from the Reaction of Glucose and Ammonium Hydroxide: A Model System Study

Summary A study of the reaction between glucose and ammonium hydroxide revealed that in general, the number and amount of volatiles increased as the reaction temperature increased from 75 to 150°C. At low temperatures, imidazole formation was predominant, while at higher temperatures the predominant compounds were alkyl pyrazines and hydroxyalkyl pyrazines. Positive identification of the hydroxymethyl pyrazines was confirmed by synthesis. As the products obtained from the reactions between glucose/NH4OH and glyceraldehyde/NH4OH were very similar, this supports the postulate that the initial step in glucose degradation is glyceraldehyde formation. It is proposed that hydroxymethyl dihydropyrazine generated from glyceraldehyde may follow oxidation and dehydration pathways to form 2-hydroxymethyl pyrazine and methyl pyrazine, respectively.

Chemical Composition of the Essential Oil of Pycnanthemum floridanum E. Grant and Epling

ABSTRACT The essential oils of two clones of Pycnanthemum floridanum, an endemic species in N. America, were examined by GC and GC/MS. Forty constituents were identified in the oils, of which menthone (32.15%), pulegone (39.83%) and piperitone (10.43%) were the major constituents of one clone, while the predominant components of the second clone were neomenthol (13.72%) and pulegone (59.97%).