Neutral compounds from male castoreum of North American beaver,Castor canadensis

North American beavers (Castor canadensis) mark their territories with castoreum, the strong-smelling paste in their castor sacs. In their own territories, beavers respond with scent marking to experimental scent marks that consist of strange castoreum (or selected components). In part, the unique odor of castoreum is due to large amounts of phenolic compounds and neutral compounds. Purified neutral compounds were analyzed by GC. GC-MS, and NMR; identities of the neutral compounds were confirmed by comparing the properties of authentic compounds with those of the isolated compounds. We identified 13 neutral compounds that had not been reported before for castoreum. Most of these are oxygen-containing monoterpenes. Of the nine neutral compounds reported by Lederer (1949), only three are confirmed in our analysis; the other six neutral compounds are either absent or are not volatile enough to be detected by our methods. Eight compounds—6-methyl-l-heptanol, 4,6-dimethyl-l-heptanol, isopinocamphone, pinocamphone, two linalool oxides, and their acetates—were synthesized for structure identification and bioassays.     

Fumigant toxic activity and reproductive inhibition induced by monoterpenes on Acanthoscelides obtectus (Say) (coleoptera), a bruchid of kidney bean (Phaseolus vulgaris L.)

The toxic activity of some characteristic monoterpenoids: p-cymene, -pinene, camphor, linalool, terpineol, cuminaldehyde, cinnamaldehyde, anethole, carvacrol, thymol, estragole and eugenol, was tested against Acanthoscelides obtectus (Say), a bruchid pest of kidney bean (Phaseolus vulgaris L.). A fumigant toxic effect was observed and LC₅₀ concentrations for 24h and 48h were calculated for adults.

Besides this effect, a reproductive inhibition was observed. This inhibition involved female fecundity, oviposition, and the development of neonate and intracotyledonal larvae. The effects of monoterpenes on oviposition, larval penetration inside the seeds and emergence were determined. All monoterpenes revealed a more or less pronounced vapour toxicity and significantly inhibited beetle reproduction. Oxygenated monoterpenoids: carvacrol, thymol, eugenol, linalool and terpineol were identified as the most efficient compounds in both respects and the structure-activity relationship is discussed.     

单萜烯的超临界液相色谱法研究

用(超)临界液相色谱法分析了单萜烯混合物。该方法操作简单、灵敏度较高、重复性好，在单萜烯的研究中有一定的参考价值。     

Monoterpenes: Their effects on ecosystem nutrient cycling

This article explores the evidence for monoterpenes to alter rates of nutrient cycling, with particular emphasis on the nitrogen (N) cycle, from an ecosystem perspective. The general N cycle is reviewed and particular processes are noted where monoterpenes could exert control. The theoretical and conceptual basis for a proposed mode of action by which monoterpenes effect the processes of N mineralization and nitrification is presented, along with recent developments. It is hypothesized that monoterpenes retained in litter enhance the frequency of fire, which in turn changes many N-cycling processes. Experimental support for these roles is presented that includes effects at the cellular level and progresses through populations and communities (microbial and invertebrate) involved in N mineralization and immobilization processes. Since many inhibitors of ammonium oxidation also inhibit methane oxidation, monoterpenes also may alter processes within the carbon cycle. Finally, areas for future research that appear most promising are suggested.     

采后苯并噻重氮处理对‘玉金香’甜瓜单萜类香气及其代谢关键酶的影响分析

以‘玉金香’甜瓜（Cucumis melo L.）为实验材料,监测采后常温贮藏期间单萜类香气组分代谢l-脱氧-D-木酮糖-5-磷酸还原异构酶（l-deoxy-D-xylulose-5-phosphate reductoisomerase,DXR）活力及其单萜类香气组分的变化,探讨采后苯并噻重氮（benzo-(1,2,3)-thiadiazole-7-carbothioic acid S-methyl ester,BTH）诱抗处理对DXR活力和单萜类香气构成的影响,分析DXR活力与单萜类香气物质释放量的相关性。结果表明：贮藏期间,样品中共检出9 种单萜类香气组分,其中8 种单萜类香气物质含量与DXR活力呈正相关;采后BTH处理抑制了甜瓜DXR活力和单萜类香气物质的释放,延迟了DXR活力峰值出现,改变了单萜类香气释放规律及其释放量与DXR活力的相关性。与CC组（蒸馏水浸泡）相比,BTH处理组果皮、果肉样DXR活力分别降低了19.48%、25.49%;条件因子水可增大DXR活力峰值,但对DXR活力和单萜类香气的影响无明显规律。由此可见,采后BTH处理可通过抑制‘玉金香’甜瓜DXR活力,延迟活性峰值出现,改变单萜类香气释放量与DXR活力的相关性,影响单萜类香气的释放。     

Characterization of free flavor compounds in traminette grape and their relationship to vineyard training system and location

ABSTRACT:  Free volatile flavor compounds in Traminette grape were characterized and compared to those in benchmark white cultivars by gas chromatography-mass spectrometry with headspace solid phase microextraction. In addition, the effects of vineyard site location (hot compared with cool based on growing degree days) and various training systems on yield components, standard characteristics (Brix, pH, and TA), and flavor compounds in Traminette grape juice were also evaluated for 2 seasons. Twenty-two free volatiles were identified in Traminette juice. The most abundant volatile compounds included hexanal, trans -2-hexenal, linalool, nerol, and geraniol. These compounds were quantified and compared with those in Chardonnay, Gewürztraminer, and Riesling juice. The hexanal concentration was the highest in Chardonnay, and trans -2-hexenal concentration was the lowest in Riesling. Traminette contained the highest amount of monoterpenes, especially geraniol. Concentrations of free volatile compounds in Traminette varied between the hot site and the cool site. In fact, the concentrations of 6-carbon aldehydes were higher in Traminette grown in the cool site than those grown in the hot site, whereas monoterpenes were higher in the hot site than in the cool site. Among the 5 training systems, vines on the vertical shoot-positioned produced the highest amount of monoterpenes, specifically geraniol. Our study suggests that Traminette is a flavorful cultivar that contains free volatile flavor compounds similar to the parent Gewürztraminer, but at much higher concentrations. The accumulation of odor chemicals in Traminette was affected by vineyard location and training system. Finally, geraniol was the most characteristic odor in Traminette, and its presence can be used as a quality indicator for this cultivar.     

Sources of Variation in Concentration and Composition of Foliar Monoterpenes in Tamarack (Larix laricina) Seedlings: Roles of Nutrient Availability, Time of Season, and Plant Architecture

The effects of foliage class, time of season, and nutrient availability on monoterpene composition and concentration were evaluated. In the first experiment, we compared foliar monoterpenes of long shoots versus short shoots, which differ in age and origin, and differences due to nutrient availability and time of season. Both the concentrations and compositions of these monoterpenes were higher in the foliage of the long shoots. The only exceptions were the concentration of -3-carene and the composition of -pinene. Within a foliage class, the concentrations of seven monoterpenes and the percentages of five monoterpenes changed over the season. Of these, almost all declined, with the exceptions of -pinene and an unknown. Nutrient availability significantly affected the concentration or composition of some monoterpenes, but only to a slight extent. -Pinene and the unknown increased with nutrient availability, whereas -pinene and myrcene decreased. A more comprehensive analysis of four foliage classes on a separate cohort of trees showed that all monoterpenes, except sabinene and terpinolene, differed between foliage classes, but there were few general patterns. Overall, within-tree variation in tamarack monoterpenes related to foliage class and age appears more important than between-tree variation due to nutrient availability. These results suppport the view that products of mevalonic acid biosynthesis, such as terpenes, do not follow predictions of the carbon–nutrient balance and growth differentiation hypotheses. Our overall results show that individual hosts need to be considered as phytochemical mosaics when interpreting herbivore–plant interactions.     

酒花与啤酒中单萜化合物的研究进展

单萜化合物是酒花和啤酒中香气化合物的重要组成部分,具有典型的酒花香气特征,在自然界中以游离态和糖苷结合态两种形式存在。本文重点阐述了酒花中单萜化合物的生物合成途径、控制其合成的关键酶和基因以及酒花中单萜醇化合物相互转化关键酶的研究进展。此外,本文还综述了酒花与啤酒中单萜化合物的变化及其影响因素,糖苷结合态单萜化合物的结构、含量及其分析方法,并对单萜化合物在啤酒中的研究前景进行展望。