Lactones in the Flavor of Heated Pork Fat

Pork fat was heated at 160~170°C for 3 hr under bubbling with air, and the volatile compounds were collected in the cold trap. After the acidic compounds were removed from the volatile compounds by extraction with 3% aqueous sodium carbonate solution, lactones were obtained from the nonacidic compounds by saponification. Gas chromatographic analyses of lactones were carried out on the PEG-20M and Apiezon L packed columns, and then each lactone was fractionated by repeated gas chromatography. Each isolated lactone was identified by infrared spectrometry, and also three major lactones were identified by mass spectrometry. Consequently, γ-C₅—C₁₂ and δ-C₉, δ-C₁₀, δ-C₁₂ and δ-C₁₄ lactones were found in the flavor of heated pork fat. Gamma-lactones, especially γ-C₇, γ-C₈ and γ-C₉, were predominant in the flavor, and unsaturated lactones were not detected. Mechanisms for the formation of the lactones were discussed.     

Volatile Acidic Compounds in Heat-Degradated Pork Fat

Pork fat was heated at 160~170°C for 3 hr under bubbling with air, and the volatile acidic compounds were extracted with 3 % aqueous sodium carbonate solution from the total volatile compounds collected during heating. Gas chromatographic identification of the acidic compounds was carried out on PEG-20M and Apiezon L columns. Some of the isolated compounds were identified by infrared and mass spectrometry. The compounds identified include; saturated acids, trans-2, trans-3, cis-3 alkenoic acids, hydroxy acids, keto acids, and dicarboxylic acids. Each of the unsaturated acid and γ-keto acid might be one of the precursors of γ- and δ-lactones reported previously.     

Isolation and Identification of Lipase Activators from Saccharomycopsis lipolytica

Three types of lipase activators (α, β, γ) were isolated from the culture broth of Saccharomycopsis lipolytica using high performance liquid chromatography. Activator γ was the most active for the lipase reaction. One of them (β) was identified with a mixture of 3,5-dihydro xy-7-tetradecenoic acid and related compounds by the method of NMR and GC-MS analyses. The free carboxyl group in the compounds was essential for the activation of the lipase reaction.     

Chemical Composition and Aroma Evaluation of Essential Oils from Evolvulus alsinoides L.

The aim of this study was to investigate the chemical composition and the odor‐active compounds of the essential oils from Evolvulus alsinoides, which is a well‐known edible and medicinal plant. The volatile compounds in the oils were identified by hydrodistillation (HD) and solvent‐assisted flavor evaporation (SAFE) in combination with GC, GC/MS, GC/O (=olfactometry), aroma extract dilution analysis (AEDA), and relative flavor activities (RFA values). The most abundant compound in the HD oil was cis‐α‐necrodol (12.62%), an irregular monoterpene with a cyclopentane skeleton, which is very unusual in the plant kingdom. In the SAFE oil, the main components included 2‐butoxyethanol (9.01%), benzyl alcohol (8.01%), and γ‐butyrolactone (7.37%). Through sensory analysis, 21 aroma‐active compounds were identified by GC/O. The most intense aroma‐active compounds in the HD oil were hexan‐1‐ol and γ‐nonalactone, both of which showed high RFA values. α‐Methyl‐γ‐butyrolactone and dimethyl sulfone contributed more strongly to the aroma of the SAFE oil. These results imply that the essential oils of E. alsinoides deserve further investigation in the food industry.     

Purification and Characterization of γ-Hexachlorocyclohexane (γ-HCH) Dehydrochlorinase (LinA) from Pseudomonas paucimobilis

The linA gene from Pseudomonas paucimobilis was highly expressed in Escherichia coli, and the linA product (LinA), named γ-HCH dehydrochlorinase, was purified to homogeneity. LinA released three chloride ions per one molecule of γ-HCH. Degradation assay of halogenated compounds by purified LinA showed that the substrate specificity of LinA is very narrow.     

Purification and Characterization of Lactobacillus bulgaricus Diaphorase

γ-Isomer of 1,2,3,4,5,6-hexachlorocyclohexane (BHC) showed greater decomposition on γ or UV irradiation of five isomers of BHC in crystalline state or in 2-propanol solution. The α- and δ-isomer of BHC and known la, 2a, 3e, 4e, 5e-pentachlorocyclohexane were separated from the irradiation product of crystalline γ-BHC. Four compounds were isolated from the irradiation product of γ-BHC in 2-propanol. Two compounds were tetrachloro-cyclohexenes (C₆H₆C1₄): γ-isomer (mp 86 ~87°C) and ?-isomer (mp 99 ~ 100°C). The other two were isomers of pentachlorocyclohexane (C₆H₇C1₅). One of them (mp 78 ~ 8.5°C) was consistent with known meso-1e,2a,3a,4a,5e isomer. The molecular structure of the other (mp 75°C) established by X-ray crystal structure analysis was 1α, 2α, 3α, 4β, 5α configuration or le 2a 3e 4e 5e conformation of CI atoms. A reaction mechanism was proposed that included a radical chain reaction and chlorine atom migration.     

Rubrolides as Model for the Development of New Lactones and Their Aza Analogs as Potential Photosynthesis Inhibitors

Natural phytotoxins and their synthetic analogs are a potential source of new bioactive compounds for agriculture. Analogs of rubrolides, a class of γ‐alkylidene‐γ‐lactones isolated from different ascidians, have been shown to interfere with the photosynthetic electron‐transport chain, yet their activity needs to be improved. With this aim, ten 5‐aryl‐6‐benzyl‐4‐bromopyridazin‐3(2H)‐ones were prepared in yields ranging from 44 to 88% by reaction of their correspondent γ‐alkylidene‐γ‐lactones with NH₂NH₂. The structures of these rubrolide analogs were determined by ¹H‐ and ¹³C‐NMR, 2D‐NMR (COSY and HETCOR), NOE difference, and MS techniques. These compounds were evaluated for their abilities of interfering with the light‐driven reduction of ferricyanide by isolated spinach chloroplasts. Lactones with electron‐withdrawing substituents in the para‐position of the benzylidene ring were the most effective inhibitors. Characterization of the activity of 11b / 11b′ suggested a mechanism based on the interaction with the plastoquinone binding site of photosystem II. Addition of several compounds to the culture medium of a cyanobacterial model strain was found to inhibit algal growth. However, the relative effectiveness was not consistent with their activity in vitro, suggesting the occurrence of multiple targets and/or detoxyfication mechanisms. Indeed, the compounds showed differential effects on the heterotrophic growth of some crop species, Cucumis sativus and Sorghum bicolor. Pyridazin‐3(2H)‐ones 12e, 12i , and 12j , which have been found poorly active against the photosynthetic electron transport, were the most effective in inhibiting the growth of some weeds, Ipomoea grandifolia and Brachiaria decumbens, under greenhouse conditions.     

Studies on the Changes of Meat Fats by Various Processings

Data are presented to show the gas chromatographic identification of a total of 18 saturated aliphatic γ- and δ-lactones obtained from melted beef depot fat, namely, δ-C₆, γ-C₇, γ-C₈, γ-C₉, and a homologous series of γ- and δ-lactones of the even-carbon numbers C₁₀ to C₁₆ and of smaller amount of the odd-carbon numbers C₁₁ to C₁₅. These lactones were isolated by steam distillation and silicic acid adsorption chromatography, and identified through gas chromatography and infrared spectroscopy.

Lactones obtained had a peach-like flavor, and it was suggested that lactones were important in heated beef fat as the flavor compounds.     

Incorporation of 14C-Labelled Glycerol and γ-Aminobutyric Acid into Vitamin B6 in a Cell-suspension of Achromobacter cycloclastes

Incorporation of ¹⁴C from various ¹⁴C-labelled compounds into vitamin B₆ (abbreviate as B₆) in a cell-suspension of B₆-producing bacteria, Achromobacter cycloclastes A.M.S. 6021, was studied by using a newly designed purification procedure of the radioactive B₆. The procedure consisted of Sephadex G–25 gel filtration, Dowex 50W–X8 column chromatography, Amberlite CG–50 column adsorption, powdered cellulose partition column chromatography, crystallization and sublimatography. It was observed that the labels both from 1,3- and from 2-labelled glycerol were clearly incorporated into B₆ and the label of ¹⁴C-labelled γ-aminobutyric acid was also incorporated. The incorporation of ¹⁴C from ¹⁴C-labelled glycerol or γ-aminobutyric acid was affected by the addition of cold γ-aminobutyric acid or glycerol. The implication of these compounds as precursors of B₆ was discussed.     

Structure‐Based Design and Synthesis of Fluorene Derivatives as Novel RORγt Inverse Agonists

A new series of fluorene derivatives was designed and synthesized as novel retinoic acid receptor‐related orphan receptor gamma t (RORγt) inverse agonists utilizing a molecular hybridization approach. The new compounds 10 – 15 were evaluated for their RORγt activity using biochemical FRET and cellular reporter gene assays. Moreover, the inhibitory activity of the fluorene derivatives 10 – 15 in mouse Th17 cell differentiation assay was assessed. The hybrid compound 15 that combines both fluorene and arylsulfone moieties displayed promising RORγt activity with IC₅₀ values of 68.6 and 99.5 nm in FRET and cellular assays, respectively. In addition, molecular modeling studies were employed to investigate potential binding mode of 15 to RORγt. These results render 15 a potential lead compound for development of therapeutics for Th17‐driven autoimmune diseases.     

Coleifolides A and B,Two New Sesterterpenoids from the Aerial Parts of Scutellaria coleifolia H.Lév.

Coleifolides A and B ( 1 and 2 ), two new sesterterpenoids with a β‐methyl‐α,β‐unsaturated‐γ‐lactone moiety, were isolated from the aerial parts of Scutellaria coleifolia H.Lév . (Lamiaceae), together with three known compounds. Their structures were elucidated by NMR and MS examinations. Coleifolides A and B were concluded to be partially racemic compounds by the HPLC analysis using a chiral column or introduction of chiral derivatizing agents. The absolute configuration of the major isomer was determined by analyses of the CD spectrum as well as NMR data of (R)‐ and (S)‐2‐NMA derivatives. Coleifolides A and B are structurally similar to manoalide derivatives, previously isolated from marine sponges, and appear to be the first examples of this type of compounds being isolated from higher plants.     

Chemotaxonomic Screening of Seed Oils from the Family Saxifragaceae and Comparison with Data on Seed Oils from Grossulariaceae Obtained from Literature

Seeds of 25 members of the family Saxifragaceae, 1 × Astilbe, 1 × Darmera, 1 × Leptarrhena, 1 × Tellima, 3 × Mitella, and 18 × Saxifraga were investigated regarding oil content, as well as composition and content of fatty acids and vitamin E active compounds. The results were compared with results obtained from literature for members of the genus Ribes belonging to the closely related family Grossulariaceae to find chemometric differences between the different genera and between members of the family Saxifragaceae and Grossulariaceae, respectively. Members of the family Saxifragaceae are dominated by high amounts of linoleic and α‐linolenic acid which together account for about 80% of the total fatty acids. While α‐linolenic acid is characteristic for members of the genus Saxifraga, in other genera, linoleic acid is predominant. In comparison to members of the family Saxifragaceae members of the family Grossulariaceae also contain γ‐linolenic acid and stearidonic acid which allow a significant differentiation between both families. By principle component analysis, members of both families were divided into three distinct groups, i) species with a high content of α‐linolenic acid (genus Saxifraga), ii) species with high amounts of γ‐linolenic acid and stearidonic acid (genus Ribes), and iii) species with higher amounts of linoleic acid (other members of the family Saxifragaceae). The composition of the vitamin E active compounds was characterized by a high content of γ‐tocopherol in most members of the family Saxifragaceae, but no chemotaxonomic relevance.     

A New Metabolic Pathway for meta Ring-fission Compounds of Biphenyl

The double bonds of 2-hydroxy-6-oxo-6-phenylhexa-2,4-dienoic acid (HOPDA) were stabilized by methylation to establish which of the double bonds of the meta ring-fission compound of biphenyl was reduced by the HOPDA reducing enzyme. HOPDA reducing enzyme III converted 2-methoxy-6-oxo-6-phenylhexa-2,4-dienoic acid methyl ester into 2-methoxy-6-oxo-6-phenylhexa-2-enoic acid methyl ester. To discover the metabolic pathway of HOPDA, partially purified enzyme fractions were used. The eluate from a 2nd column of DEAE-cellulose transformed HOPDA to γ-benzoylbutyric acid, 2,6-dioxo-6-phenylhexanoic acid, and γ-benzoylbutyraldehyde. Fractions passed through the 1st column of DEAE-cellulose formed γ-benzoylbutyric acid and 2-hydroxy-6-oxo-6-phenylhexanoic acid from HOPDA. Based on these data and previous reports, a new metabolic divergence of biphenyl and related compounds was proposed.     

Pyrolysis of Chlorogenic Acid and Rutin

Chlorogenic acid and rutin, major polyphenols in tobacco, were pyrolysed with a furnace type pyrolyser connected directly to a gas Chromatograph and 22 compounds (including catechol, benzoic acid, 4-vinylcatechol and quinic acid γ-lactone) from chlorogenic acid and 24 compounds [including catechol, 5-methyl-2-furaldehyde, 4-methylcatechol and 1,6-anhydroglucopyranose (levoglucosan)] from rutin have been identified as pyrolysis products. The gas Chromatograph was also replaced by a capillary cold trap which allowed collection of the pyrolysis products prior to a quantitative determination using an internal standard. Comparison of the pyrolysis products produced from chlorogenic acid or rutin with those derived from tobacco and analysis of the pyrolysis products from a mixture of tobacco and chlorogenic acid or rutin indicated that fairly large proportions of catechol, 4-vinylcatechol and quinic acid γ-lactone produced by the pyrolysis of tobacco may originate from endogenous chlorogenic acid.     

Distribution Patterns of 14C in the Labelled Vitamin B6 Prepared with the Cell-suspension of Achromobacter cycloclastes

The biosynthetic pathway of vitamin B₆ (abbreviated as Be) has been studied with the cell-suspension of B₆-producing bacteria, Achromobacter cycloclastes A.M.S. 6201. The distribution of ¹⁴C in the Be molecule prepared with the cell-suspensions containing glycerol-1,3-¹⁴C, glycerol-2-¹⁴C or γ-aminobutyric acid-U-¹⁴C was investigated by using three novel degradation methods. The results showed that carbon skeletons of glycerol and γ-aminobutyric acid were used for the formation of the major part of B₆ carbon skeleton respectively. The implication of these compounds as precursors of B₆ was discussed.     

Studies on the Biosynthesis of Vitamin B6

The production of vitamin B₆ (B₆) compounds with a cell-suspension of Achromobacter cycloclastes A.M.S. 6201 under various conditions were examined. An obvious accumulation of B₆ compounds in the incubation medium with a cell-suspension of the organism harvested at the middle to later part of exponential phase of growth was observed. γ-Aminobutyric acid or β-alanine was found to stimulate the B₆ production markedly, when they were added to the incubation mixture together with glycerol. Some discussion on the implication of these compounds as precursors of B₆ was presented.     

Identification of GABA A receptor modulators in Kadsura longipedunculata and assignment of absolute configurations by quantum-chemical ECD calculations

A petroleum ether extract of Kadsura longipedunculata enhanced the GABA-induced chloride current (I_GABA) by 122.5 ± 0.3% (n = 2) when tested at 100 μg/ml in Xenopuslaevis oocytes expressing GABA A receptors (α₁β₂γ_2S subtype) in two-microelectrode voltage clamp measurements. Thirteen compounds were subsequently identified by HPLC-based activity profiling as responsible for GABA A receptor activity and purified in preparative scale. 6-Cinnamoyl-6,7-dihydro-7-myrceneol and 5,6-dihydrocuparenic acid were thereby isolated for the first time. The determination of the absolute stereochemistry of these compounds was achieved by comparison of experimental and calculated ECD spectra. All but one of the 13 isolated compounds from K. longipedunculata potentiated I_GABA through GABA A receptors composed of α₁β₂γ_2S subunits in a concentration-dependent manner. Potencies ranged from 12.8 ± 3.1 to 135.6 ± 85.7 μM, and efficiencies ranged from 129.7 ± 36.8% to 885.8 ± 291.2%. The phytochemical profiles of petroleum ether extracts of Kadsura japonica fruits (114.1 ± 2.6% potentiation of I_GABA at 100 μg/ml, n = 2), and Schisandra chinensis fruits (inactive at 100 μg/ml) were compared by HPLC-PDA-ESIMS with that of K. longipedunculata.     

Isomerization of 1,3,4,5,6-Pentachlorocyclohexene-1 Isomers in Dimethyl Sulfoxide

In dimethyl sulfoxide, isomerization of 1,3,4,5,6-pentachlorocyclohexene-1 isomers was studied. Exchange of the allylic chlorine was indicated by the experiments with ³⁶Cl-labeled compounds. Isomerization at the position-3 proceeded faster than at the position-6. Initial reaction rates for the isomers decreased in the order: 34/56 > 35/46 (δ) > 346/5> 356/4 ? 36/45 (γ)^??. The specific rates at the initial stages increased by increasing the initial concentration of the substrates. After a prolonged reaction, the γ-isomer (36/45) was the most abundant component.

The isomers of the configuration: (34/56), (346/5), and (356/4) were isolated for the first time, on which PMR studies were performed.     

Similarity between γ-Casein and a Product of β-Casein Hydrolysis by Milk Protease

A γ-casein-like fraction (FIV) was isolated from the β-casein A hydrolyzate by milk protease and compared with γ-casein. The mobility in polyacrylamide gel electrophoresis, sedimentation coefficient, molecular weight, amino acid composition and terminal amino acids of FIV were almost coincided with those of γ-casein. It is suggested that γ-casein is possibly a product of β-casein hydrolysis by milk protease.     

Relationship between Microbial Degradability and Polarographic Half-Wave Potential of Poly-chlorocyclohexenes and BHC Isomers

Partially purified, cell-free extracts of Clostridium rectum effectively degraded lindane (γ-BHC) and related polychlorocyclohexenes, in the presence of dithiothreitol. The first step of the reaction was proved to be reductive dechlorination. These compounds were also reductively dechlorinated by polarography. The half-wave potentials had a linear relationship to the logarithmic values of the biodegradation rates.