Measuring gas-liquid partition coefficients of aroma compounds by solid phase microextraction, sampling either headspace or liquid.

Hydrophobic compounds are important odorants and nutrients in foods and beverages, as well as environmental contaminants and pharmaceuticals. Factors influencing their partitioning within multi-component systems and/or from the bulk liquid phase to the air are critical for understanding aroma quality and nutrient bioavailability. The equilibrium partitioning of hydrophobic analytes between air and water was analyzed using solid phase microextraction (SPME) in the headspace (HS-SPME) and via direct immersion in the liquid (DI-SPME). The compounds studied serve as models for hydrophobic aroma compounds covering a range of air-water partition coefficients that extends over four orders of magnitude. By varying the total amount of analyte as well as the ratio of vapor to liquid in the closed, static system, the partition coefficient, K(vl), can be determined without the need for an external calibration, eliminating many potential systematic errors. K(vl) determination using DI-SPME in this manner has not been demonstrated before. There was good agreement between results determined by DI-SPME and by HS-SPME over the wide range of partitioning behavior studied. This shows that these two methods are capable of providing accurate, complementary measurements. Precision in K(vl) determination depends strongly on K(vl) magnitude and the ratio of the air and liquid phases.

A new diarylheptanoid from the rhizomes of Zingiber mekongense.

A new diarylheptanoid, (3S,5S)-3,5-diacetoxy-1,7-bis(3,4,5-trimethoxyphenyl)heptane (1), together with the known docosyl trans-ferulate (2), (1S,2S,4S)-p-menthan-1,2,4-triol (3), 5αH-eudesmane-4α,11-diol (4), 5αH-eudesmane-4ß,11-diol (5), 4α,10ß-dihydroxy-1ßH,5αH-guaia-6-ene (guaianediol) (6), (+)-galanolactone (7), (E)-labda-8(17),12(13)-dien-15,16-olide (8), labda-8(17),13(14)-dien-15,16-olide (9), 3,5-dihydroxy-7,4'-dimethoxyflavone (10) and 3,5,3'-trihydroxy-7,4'-dimethoxyflavone (11) were isolated from the rhizomes of Zingiber mekongense. Their structures were determined by spectroscopic methods. The stereochemistry of 1 was proved through chemical conversion. Compounds 1, 4-7 and 9-11 exhibited anti-HIV-1 activities in the anti-syncytium assay using (∆Tat/rev)MC99 virus and 1A2 cell line system, while only compounds 7 and 11 were found active in the HIV-1 reverse transcriptase assay.

Three new antibacterial active diarylheptanoids from Alpinia officinarum.

Three new diarylheptanoids, together with ten known ones, were isolated from the ethanol extract from the rhizomes of Alpinia officinarum Hance. The structural identification of these compounds was mainly achieved by spectroscopic methods. The new compounds were elucidated as 7-(4", 5"-dihydroxy-3"-methoxyphenyl)-1-phenyl -4-heptene-3-one (1), 1, 7-diphenyl-5-heptene-3-one (2) and 4-phenethyl-1, 7-diphenyl -1-heptene-3, 5-dione (3), respectively. All of the compounds showed antibacterial activity against Helicobactor pylori. Especially, the three new compounds showed strong antibacterial activity against Hp-Sydney strain 1 with the MIC values of 9-12 µg/mL, and against Hp-F44 with the MIC values of 25-30 µg/mL.

Cytotoxic alkyl benzoquinones and alkyl phenols from Ardisia virens.

Bioassay-guided fractionation of roots and stems of Ardisia virens Kurz (Myrsinaceae) led to isolation of fourteen compounds, (2'R)-6-(2'-acetoxypentadecyl)-5-hydroxy-2-methoxy-1,4-benzoquinone (1), (2'R)-6-(2'-acetoxytridecyl)-5-hydroxy-2-methoxy-1,4-benzoquinone (2), (2'R)-6-(2'-acetoxytridecyl)-2-methoxy-1,4-dihydroxybenzene (3), (2'R)-6-(2'-acetoxytridecyl)-5-formyl-2-methoxy-1,4-dihydroxybenzene (4), 1-(3,5-dihydroxyphenyl)nonan-1-one (5), 1-(3-hydroxy-5-methoxyphenyl)pentan-1-one (6), (2'S)-3-hydroxy-5-methoxyphenyl-2'-tridecanol (7), (2'S)-3-hydroxy-5-methoxyphenyl-2'-pentadecanol (8), (2'S)-5-acetoxy-3-hydroxyphenyl-2'-tetradecanol (9), 1-acetoxy-2-methoxy-6-pentadecyl-4-hydroxybenzene (10), 1-acetoxy-2-methoxy-6-tridecyl-4-hydroxybenzene (11), (2'R)-1-acetoxy-6-(2'-acetoxy-tridecyl)-2-methoxy-4-hydroxybenzene (12), (2'R)-1-acetoxy-6-(2'-acetoxypentadecyl)-2-methoxy-4-hydroxybenzene (13), and 1-acetoxy-6-(2'-ketopentadecyl)-2-methoxy-4-hydroxylbenzene (14), together with thirty-four other known compounds, of which three, 1-(3,5-dihydroxyphenyl)pentan-1-one (15), 1-(3,5-dihydroxyphenyl)heptan-1-one (16), and 1-(3,5-dihydroxyphenyl)pentadecan-1-one (17), were isolated for the first time from a natural source. Their structures were elucidated by analyses of spectroscopic data. Seven cytotoxic constituents were found to be 3, 10-12, ardisianone (18), cornudentanone (19), and ardisianol (31) with cytotoxic properties (IC(50) values < or =4 microg/mL) against MCF-7, NCI-H460 and SF-268 cancer cell lines in vitro.

Semipreparative-scale gas-chromatographic separation of filbertone enantiomers.

The enantioselectivity of heptakis(2,3-di-O-acetyl-6-O-tert-butyldimethylsilyl-beta-CD) toward racemic filbertone (E-5-methyl-hep-2-en-4-one) was studied by performing the chiral separation on a capillary column, a thick-film wide-bore column and a semipreparative column. The semipreparative enantioseparation of filbertone was achieved at 80 degrees C by using a packed column providing (R)- and (S)-enantiomers of filbertone with ee 90 and 96%, respectively. The isolated enantiomers (approximately 250 microg each, ee = 90-96%) may be used for studies on the relationship of chirality and biological activity by olfactory screening and toxicological studies.

Isolation and absolute configuration determination of aliphatic sulfates as the Daphnia kairomones inducing morphological defense of a phytoplankton.

2,6-Dimethylheptyl sulfate (1) and 6-methyloctyl sulfate (3) were isolated from Daphnia pulex as the Daphnia kairomones that induced morphological defense of a freshwater phytoplankton Scenedesmus gutwinskii var. heterospina (NIES-802). The absolute stereochemistry at C2 of 1 was determined by (1)H-NMR analysis of the (R)-MTPA ester of alcohol 2. The absolute configuration at C6 of 3 was determined by Ohrui's method applied to alcohol 4.

Determination of diarylheptanoids from Alpinia officinarum (Lesser Galangal) by HPLC with photodiode array and electrochemical detection.

Normal-phase column chromatography followed by semi-preparative reversed-phase HPLC has been used to isolate, from the rhizomes of Alpinia officinarum, five diarylheptanoids identified as 5-hydroxy-7-(4"-hydroxy-3"-methoxyphenyl)-1-phenyl-3-heptanone, 5-methoxy-7-(4"-hydroxy-3"-methoxyphenyl)-1-phenyl-3-heptanone, 7-(4"-hydroxyphenyl)-1-phenylhept-4-en-3-one, 7-(4"-hydroxy-3"-methoxyphenyl)-1-phenyl-hept-4-en-3-one, 1,7-diphenylhept-4-en-3-one. The levels of these five diarylheptanoids in root material were determined quantitatively by HPLC with UV detection and the assay methods so developed were simple, rapid and accurate. Four of the diarylheptanoids could also be detected by HPLC with electrochemical detection (ECD) in the oxidative mode, and ECD was found to have a higher sensitivity than photodiode array detection.

Three new polymeric isopropenyl benzofurans from Ligularia stenocephala.

Three new polymeric isopropenyl benzofurans, 4-methyl-2,4-bis(5,6-dimethoxy-2-benzofuranyl)-1-pentene, stenocephalin A (1), 4,6-dimethyl-2,4,6-tri(5,6-dimethoxy-2-benzofuranyl)-1-heptene, stenocephalin B (2) and 4,6,8-trimethyl-2,4,6,8-tetra(5,6-dimethoxy-2-benzofuranyl)-1-nonene, stenocephalin C (3), together with seven known compounds (4-10) were isolated from the roots of Ligularia stenocephala. The structures of the new compounds were elucidated on the basis of spectral evidence, especially on 2D NMR. In addition, the cytotoxic activity and the anti-bacterial activity of compounds 2, 3, 5 and 6 were tested.

Determination of methylmercury in fish using focused microwave digestion following by Cu2+ addition, sodium tetrapropylborate derivatization, n-heptane extraction, and gas chromatography-mass spectrometry.

The analytical procedure for analysis of methylmercury in fish was developed. It involves microwave-assisted digestion with alkaline solution (tetramethylammonium hydroxide), addition of Cu2+, aqueous-phase derivatization of methylmercury with sodium tetrapropylborate, and subsequent extraction with n-heptane. The methylmercury derivative was desorbed in the splitless injection port of a gas chromatograph and subsequently analyzed by electron impact mass spectrometry. Optimum conditions allowed sample throughout to be controlled by the instrumental analysis time (near 7 min per sample) but not by the sample preparation step. At the power of 15-30, 45, and 60-75 W, sample preparation time is only 3.5, 2.5, and 1.5 min, respectively. The proposed method was finally validated by the analysis of three biological certified reference materials, BCR CRM 464 tuna fish, NRC DORM-2 dogfish muscle, and NRC DOLT-2 dogfish liver. The detection limit of the overall procedure was found to be 40 ng/g of biological tissue for methylmercury. The recovery of methylmercury was 91.2-95.3% for tuna, 89.3-94.7% for marlin, and 91.7-94.8% for shark, respectively. The detected and certified values of methylmercury of three biological certified reference materials were as follows: 5.34 +/- 0.30 microg/g (mean +/- S.D.) and 5.50 +/- 0.17 microg/g for CRM 464 tuna fish, 4.34 +/- 0.24 and 4.47 +/- 0.32 microg/g for NRC DORM-2 dogfish muscle, and 0.652 +/- 0.053 and 0.693 +/- 0.055 microg/g for NRC DOLT-2 dogfish liver, respectively. It indicated that the method was well available to quantify the methylmercury in fish.

5-Hydroxy-7-(4'-hydroxy-3'-methoxyphenyl)-1-phenyl-3-heptanone: a pancreatic lipase inhibitor isolated from Alpinia officinarum.

A pancreatic lipase inhibitor, 5-hydroxy-7-(4'-hydroxy-3'-methoxyphenyl)-1-phenyl-3-heptanone (HPH), from the rhizome of Alpinia officinarum (AO) was isolated and its antihyperlipidemic activity was measured. HPH inhibited a pancreatic lipase with an IC(50) value of 1.5 mg/ml (triolein as a substrate). HPH significantly lowered the serum TG level in corn oil feeding-induced triglyceridemic mice, and reduced serum triglyceride (TG) and cholesterol in Triton WR-1339-induced hyperlipidemic mice. However, HPH did not show hypolipidemic activity in high cholesterol diet-induced hyperlipidemic mice. Based on these findings, we propose that PL inhibitors may be effective as hypolipidemic agents.

Novel diarylheptanoids of Alpinia blepharocalyx.

The seeds of Alpinia blepharocalyx K. Schum. (Zingiberaceae) is used in Chinese traditional medicine for the treatment of stomach disorders. From the ether fraction of a 95% ethanolic extract, which showed hepatoprotective and antiproliferative activities, we isolated 16 novel diarylheptanoids bearing a chalcone or a flavanone moiety [calyxins A-H; epicalyxins B-D, G, and H; 6-hydroxycalyxin F; and blepharocalyxins A and B] together with seven known compounds, while the residual fraction of the ethanolic extract gave 32 novel diarylheptanoids namely, calyxins A, E-G, and I-M; epicalyxins B, F, I-K, and M; deoxycalyxin A; blepharocalyxins C-E; neocalyxins A and B; (3S,5S)- and (3S,5R)-3-hydroxy-1-(4-hydroxyphenyl)-5-methoxy-7-phenyl-6E-heptene, (3S,5S)- and (3S,5R)-3-hydroxy-1-(4-hydroxyphenyl)-5-ethoxy-7-phenyl-6E-heptene, (3S)-3-methoxy-1,7-bis(4-hydroxyphenyl)-6E-hepten-5-one, 1,7-bis(4-hydroxyphenyl)-hepta-4E,6E-dien-3-one, (3S,7R)-5,6-dehydro-1,7-bis(4-hydroxy-phenyl)-4"-de-O-methyl-centrolobine, (3S,5S,6S,7R)-5,6-dihydroxy-1,7-bis(4-hydroxyphenyl)-4"-de-O-me-thylcentrolobine, (3S,5R,6S,7R)- and (3S,5S,6R,7R)-5,6-dihydroxy-1,7-bis(4-hydroxyphenyl)-4"-de-O-methyl-centrolobine, 1,2- dihydro-bis(de-O-methyl)curcumin, and (3S,7S)-5,6-dehydro-4"-de-O-methylcentrolobine, and one known diarylheptanoid [(3S,5S)-3,5-dihydroxy-1,7-bis(4-hydroxyphenyl)heptane] together with 12 other known phenolic compounds. Moreover, in vitro NO inhibitory and antiproliferative activities of the isolated compounds were also tested and the active constituents identified.

New diarylheptanoids and diarylheptanoid glucosides from the rhizomes of Tacca chantrieri and their cytotoxic activity.

Two new diarylheptanoids (1, 2) and seven new diarylheptanoid glucosides (3-9) were isolated from the rhizomes of Tacca chantrieri. Their structures were determined by spectroscopic analysis, including 2D NMR data, and the results of hydrolytic cleavage. The absolute configurations of the 3,5-dihydroxyheptane moieties of the new diarylheptanoids were determined to be 3R and 5R by the application of the CD exciton chirality method to the corresponding 3,5-bis-p-bromobenzoyl derivatives. The cytotoxic activities of the isolated compounds and some derivatives against HL-60 human promyelocytic leukemia cells, HSC-2 human oral squamous carcinoma cells, and normal human gingival fibroblasts (HGF) are reported.

Photocatalytic oxidation of heptane in the gas-phase over TiO2.

In this paper, gas-phase photocatalytic oxidation (PCO) of heptane over UV-illuminated TiO2 was carried out at ambient temperature in a batch reactor. Complete oxidation of heptane with almost stoichiometric production of CO2 and H2O was observed. The intermediates detected were propanal, butanal, 3-heptanone, 4-heptanone and carbon monoxide. A scheme of the possible mechanism for PCO of heptane over TiO2 was suggested. Langmuir-Hinshelwood kinetics equation was obtained from the results at different initial concentrations of heptane, oxygen, moisture and light intensity. The photocatalytic activity of TiO2 can be sustained indefinitely. This can be attributed to the production of water in the system, which can replenish the consumed hydroxyl radicals.

A cytotoxic diarylheptanoid from Viscum cruciatum.

A diarylheptanoid, 1,7-di-(3',4'-dihydroxyphenyl)-4-hepten-3-one, hirsutanone, has been isolated from the methanolic extract of the aerial parts of Viscum cruciatum (Viscaceae) and characterized by spectroscopic methods and chemical transformations. This compound showed cytotoxic activity against melanoma (UACC-62), renal (TK-10) and breast (MCF-7) cancer cell lines.

Eleven novel diarylheptanoids and two unusual diarylheptanoid derivatives from the seeds of Alpinia blepharocalyx.

An EtOH extract of the seeds of Alpinia blepharocalyx afforded 11 novel diarylheptanoids, named deoxycalyxin A (1), epicalyxin F (2), calyxin K (3), epicalyxin K (4), calyxin I (5), epicalyxin I (6), calyxin J (7), epicalyxin J (8), and calyxin L (9), an epimeric mixture of calyxin M (10) and epicalyxin M (11), and two unusual diarylheptanoid derivatives, named neocalyxins A (12) and B (13), together with four known calyxins, calyxins A (14), F (15), E (16), and G (17). Structures were elucidated by spectroscopic techniques including 2D NMR spectroscopy. All compounds were examined for cytotoxicity toward murine colon 26-L5 carcinoma and human HT-1080 fibrosarcoma cells. Diarylheptanoids 2, 3, and 5 were cytotoxic against both cell lines, while 4 and 6-8 were cytotoxic against human fibrosarcoma cells.

Diarylheptanoids from Myrica arborea.

Investigations of the stem and root bark of Myrica arborea (Myricaceae) have yielded two novel diarylheptanoids, myricarborin and 11-O-beta-D-xylopyranosylmyricanol along with the known myricanol and 5-O-beta-D-glucopyranosylmyricanol. The structures of the novel compounds were determined by spectroscopic methods.

Diarylheptanoids with in vitro inducible nitric oxide synthesis inhibitory activity from Alnus hirsuta.

Four diarylheptanoids were isolated from the leaf of Alnus hirsuta (Betulaceae) and have been assessed for nitric oxide (NO) production inhibitory effects in vitro. Oregonin (1) and hirsutanonol (2) were found to be potent inducible nitric oxide synthase (iNOS) inhibitors. Compounds 1 and 2 showed inhibition of NO synthesis in dose-dependent manners by murine macrophage-like RAW 264.7 cells stimulated with interferon-gamma (IFN-gamma) plus lipopolysaccharide (LPS). Their 50% inhibitory concentrations (IC50) were 3.8 and 14.3 microM, respectively. The inhibitory effects of these compounds on NO synthesis were due to suppression of iNOS mRNA expression as determined by Northern blotting.

Cartorimine, a new cycloheptenone oxide derivative from Carthamus tinctorius.

Cartorimine (1), a new cycloheptenone oxide derivative, was isolated from Carthamus tinctorius, and its structure was established from spectral data interpretation and single-crystal X-ray analysis.

Minor diarylheptanoid glycosides of Alnus rubra bark.

The diarylheptanoid (S)-1,7-bis-(4-hydroxyphenyl)-heptan-3-one-5-O-beta-D-xylopyranosi de, and two known compounds, 1,7-bis-(3,4-dihydroxyphenyl)-heptan-3-one-5-O-beta-D-glucopyranos ide and platyphylloside were isolated from Alnus rubra bark. Structures were established by application of spectrometric techniques.

Non-phenolic linear diarylheptanoids from Curcuma xanthorrhiza: a novel type of topical anti-inflammatory agents: structure-activity relationship.

The topical anti-inflammatory activity of three non-phenolic linear 1,7-diarylheptanoids, previously isolated from a Thai medicinal plant, Curcuma xanthorrhiza (Zingiberaceae) and four new semi-synthetic derivatives of the naturally occurring compounds were assessed in the murine model of ethyl phenylpropiolate-induced ear edema. The naturally occurring compound 1E,3E,1,7-diphenylheptadien-5-one (6) exerted the most potent anti-inflammatory activity, with an ID50 value of similar magnitude to that of the reference drug oxyphenbutazone (67 vs. 46 micrograms/ear, respectively). None of the semi-synthetic diarylheptanoids was more active than 6. The chemical structures and pharmacological data of the natural and semi-synthetic derivatives identified a distinct structure-activity relationship. The degree of unsaturation in positions 1 and 3, and the nature of the oxygenated functional group in position 5 of the C7-chain were found to play significant roles in determining the observed in vivo activity. Based on these findings, the non-phenolic linear 1,7-diarylheptanoids-are proposed to represent a novel class of topical anti-inflammatory agents.