Terpenes Show Nanomolar Affinity and Selective Binding with Cucurbit[8]uril

Eucalyptol, fenchyl alcohol, and geranylamine were tested for the binding to cucurbit[8]uril. Nanomolar affinities were found, giving rise to a highly selective binding of the terpenes by cucurbit[8]uril when compared to the smaller cucurbit[7]uril. This was rationalized with a better size fit with the larger macrocycle. These notions were supported by the calculation of the packing coefficient and NMR measurements of the free and complexed terpenes. The binding process is mainly enthalpically driven, which is associated with the release of high-energy water.     

Fate of the Dietary Terpene, P-Cymene, in the Male Koala

The fate of the dietary terpene, p-cymene, is reported in a specialist Eucalyptus leaf folivore, the koala (Phascolarctos cinereus). Six male koalas were given two single oral doses of p-cymene (0.37 mmol/kg and 1.49 mmol/kg). Urine and feces were collected for two 24-hr periods after each dose and analyzed for metabolites by extraction, gas chromatography, and mass spectrometry. A total of six metabolites were detected in the urine. A novel, extensively oxidized metabolite, 4-(1,2-dihydroxy-1-methylethyl)-benzoic acid, was identified and its structure elucidated by high resolution and chemical ionization mass spectrometry. Minor amounts of two glycine conjugated metabolites were also detected. Five metabolites were present in sufficient amounts to quantify, using isolated urinary metabolites as reference standards. The mean fractional recovery of administered p-cymene was 0.77 ± 0.09 and 0.84 ± 0.12 for the low and high dose, respectively. The major metabolite excreted was the novel carboxy diol compound. No fecal metabolites were found. Thus, the koala employs a strategy in the metabolism of p-cymene that promotes the production of extensively oxidized metabolites that consequently have increased polarity and enhanced renal excretion. This strategy is compared with that employed by other Eucalyptus leaf folivores.     

含萜烯树脂丙烯酸酯乳液型压敏胶的制备与性能研究

以混合丙烯酸酯为共聚单体,萜烯树脂为增黏树脂,过硫酸钾(KPS)为引发剂,十二烷基硫酸钠(SDS)、烷基酚聚氧乙烯醚(OP-10)和十二烷基二苯醚二磺酸钠盐(2A1)为乳化剂,采用预乳化半连续乳液聚合法制备压敏胶(PSA)用丙烯酸酯乳液。研究结果表明:当m(OP-10)∶m(SDS)∶m(2A1)=16.5∶3.6∶7.9、w(KPS)=0.5%、单体滴加时间为3.5 h和反应温度为80～82℃时,含萜烯树脂PSA的综合性能相对最好,其初粘力(19#钢球)和剥离强度(5.8 N/25 mm)优于不含萜烯树脂PSA,但前者的持粘力(22 h)低于后者。     

不同植物抑制剂对黄曲霉菌生长和产毒的影响

目的研究不同植物抑制剂对黄曲霉菌生长和产毒的影响。方法将产毒的黄曲霉菌接种在EMA培养基上,活化后分别培养在含不同浓度抑制剂的培养基中,在30℃的温度下恒温培养,通过观察抑菌圈直径的大小判断不同抑制剂对黄曲霉生长的影响,并将菌丝抽提使用酶标仪测定不同抑制条件下黄曲霉毒素含量。结果 0.2mg/mL的紫苏醛、烟草萜和香芹醇在第2d对黄曲霉菌生长抑制率分别为100%、67%和79%,第5d时分别降低到46%、63%和55%。柠檬醛、紫苏醛、香茅醇和芳樟醇处理组培养基中第5d时黄曲霉毒素含量很低,对照组中黄曲霉毒素含量是这4个处理组的2000倍以上,第6d时,6种植物抑制剂的抑制黄曲霉菌产毒能力都有所降低,但是0.2mg/mL的柠檬醛、紫苏醛、香茅醇、烟草萜和香芹醇仍具有较高的抑制黄曲霉菌产毒能力。结论柠檬醛、紫苏醛、烟草萜和香芹醇对黄曲霉菌的生长和产毒有着明显的抑制作用。     

THE RELEASE OF MONOTERPENES DURING CONVECTIVE DRYING OF WOOD CHIPS

ABSTRACT

The release of volatile organic components (VOC) during high temperature convective drying of wood chips was studied experimentally and theoretically. The drying medium was superheated steam with a pressure of two bar. Two different temperature levels of the drying medium, 160 and 180 °C, and two different materials, Scots Pine and Norway Spruce, were investigated. It was found that the main components released consist of various types of monoterpenes, with α-pinene dominating in each of the two materials. The amount released is dependent on the drying temperature as well as the time of the drying process.

In order to describe the release rate of monoterpenes during drying, two separate models, called the communicating and the non-communicating model respectively, were developed. The mechanisms included for the transport of monoterpenes are, in the communicating model, transport by diffusion and with the advective gas and liquid flow within the tracheids and, in the non-communicating model, diffusion within the resin canal system.

The results obtained using the communicating model largely overpredict the experimental results. To avoid this rapid release, additional mass transfer resistance for the transport of monoterpenes between the two canal systems could be introduced. The non-communicating model was found to be useful in explaining the release rate when drying spruce. This model, however, can not distinguish between the two temperature levels studied.     

Consumer Acceptability and Sensory Profile of Three New Celery (Apium graveolens) Hybrids and Their Parental Genotypes

Celery is a stalky green vegetable that is grown and consumed globally and used in many cuisines for its distinctive taste and flavour. Previous investigations identified the aroma composition of celery and profiled its sensory characteristics using a trained panel; however, evaluation of the sensory characteristics of celery combined with a consumer panel, where consumer preferences and acceptability are determined, is novel. In this study, three parental genotypes (12, 22 and 25) and three new hybrids (12x22, 22x12 and 25x12) were presented to a trained sensory panel (n = 12) for profiling and a consumer panel (n = 118), where liking and preference were assessed. Celery samples were analysed by SPME GC–MS and significant differences in aroma composition between all samples were identified, causing significant differences in the sensory profile. Furthermore, significant differences in attributes assessed for liking (appearance, aroma, texture and overall) were identified. Consumer segmentation identified three groups of consumers exhibiting differences in the hedonic reaction to the samples. Sweet and bitter taste along with overall flavour were identified as drivers of liking. Hybrid 25x12 was found to be the hybrid that exhibited high intensities for most of the attributes assessed.     

GRASr2 Evaluation of Aliphatic Acyclic and Alicyclic Terpenoid Tertiary Alcohols and Structurally Related Substances Used as Flavoring Ingredients

This publication is the 1st in a series of publications by the Expert Panel of the Flavor and Extract Manufacturers Assoc. summarizing the Panel's 3rd re‐evaluation of Generally Recognized as Safe (GRAS) status referred to as the GRASr2 program. In 2011, the Panel initiated a comprehensive program to re‐evaluate the safety of more than 2700 flavor ingredients that have previously met the criteria for GRAS status under conditions of intended use as flavor ingredients. Elements that are fundamental to the safety evaluation of flavor ingredients include exposure, structural analogy, metabolism, pharmacokinetics, and toxicology. Flavor ingredients are evaluated individually and in the context of the available scientific information on the group of structurally related substances. Scientific data relevant to the safety evaluation of the use of aliphatic acyclic and alicyclic terpenoid tertiary alcohols and structurally related substances as flavoring ingredients are evaluated. The group of aliphatic acyclic and alicyclic terpenoid tertiary alcohols and structurally related substances was reaffirmed as GRAS (GRASr2) based, in part, on their rapid absorption, metabolic detoxication, and excretion in humans and other animals; their low level of flavor use; the wide margins of safety between the conservative estimates of intake and the no‐observed‐adverse effect levels determined from subchronic studies and the lack of significant genotoxic and mutagenic potential.     

化石资源中生物标志物的研究与分析

生物标志物记录了原始生物母质的特殊分子结构信息,具有特殊的标志性意义。以揭示化石资源中的生物标志物为出发点,分析比较了3类典型的生物标志物,即类异戊二烯、萜类和甾类。重点阐述了生物标志物研究进展,包括化石资源中生物标志物的生物来源、成因及成熟演化等特征,具有重要的有机地球化学意义。     

Volatile Terpenes from Actinomycetes: A Biosynthetic Study Correlating Chemical Analyses to Genome Data

The volatile terpenes of 24 actinomycetes whose genomes have been sequenced (or are currently being sequenced) were collected by use of a closed‐loop stripping apparatus and identified by GC/MS. The analytical data were compared against a phylogenetic analysis of all 192 currently available sequences of bacterial terpene cyclases (excluding geosmin and 2‐methylisoborneol synthases). In addition to the several groups of terpenes with known biosynthetic origin, selinadienes were identified as a large group of biosynthetically related sesquiterpenes that are produced by several streptomycetes. The detection of a large number of previously unrecognised side products of known terpene cyclases proved to be particularly important for an in depth understanding of biosynthetic pathways to known terpenes in actinomycetes. Interpretation of the chemical analytical data in the context of the phylogenetic tree of bacterial terpene cyclases pointed to the function of three new enzymes: (E)‐β‐caryophyllene synthase, selina‐3,7(11)‐diene synthase and aristolochene synthase.