Synthesis and analgesic activity of new heterocyclic compounds derived from monoterpenoids

A set of new heterocyclic compounds with different types of framework, including a new type of framework, were synthesized by reactions of verbenol epoxide and (1R,2R,6S)-3-methyl-6-(prop-1-en-2-yl)cyclohex-3-ene-1,2-diol with aromatic aldehydes containing three methoxy groups. The analgesic activity of these substances was studied. Three compounds possessed considerable activity in vivo in the acetic acid-induced writhing test. (2S,4R,4aR,8S,8aR)-4,7-Dimethyl-2-(2,4,5-trimethoxyphenyl)-3,4,4a,5,8,8a-hexahydro-2H-4,8-epoxychromene exhibited high analgesic activity in both acetic acid-induced writhing and hot plate tests; its selectivity index IS₅₀ exceeded 60.     

Synthesis of novel triazolyl pyranochromen-2(1<Emphasis Type="Italic">H</Emphasis>)-ones and their antibacterial activity evaluation

A series of thirty-three novel triazolyl pyranochromen-2(1H)-one derivatives have been synthesized via Cu (I) catalysed Huisgen 1,3-dipolar cycloaddition reaction. All of the synthesized compounds have been fully characterized from their spectral data and evaluated for antibacterial activity against both gram-positive and gram-negative bacteria. The activity results revealed that amongst all the compounds screened, six compounds, i.e. 2-[4-(((7-ethyl-2,2,6-trimethyl-8-oxo-2,3,4,8-tetrahydropyrano[3,2-g]chromen-10-yl)oxy)methyl)-1H-1,2,3-triazol-1-yl]acetic acid (41), 10-[(1-(1,3-dihydroxypropan-2-yl)-1H-1,2,3-triazol-4-yl)methoxy]-3-ethyl-4,8,8-trimethyl-7,8-dihydropyrano[3,2-g]chromen-2(6H)-one (44), 3-ethyl-4,8,8-trimethyl-10-[(1-((2R,3R,4S,5S,6R)-3,4,5-trihydroxy-6-(hydroxymethyl)tetrahydro-2H-pyran-2-yl)-1H-1,2,3-triazol-4-yl)methoxy]-7,8-dihydropyrano[3,2-g]chromen-2(6H)-one (46), 2-[4-(((7-hexyl-2,2,6-trimethyl-8-oxo-2,3,4,8-tetrahydropyrano[3,2-g]chromen-10-yl)oxy)methyl)-1H-1,2,3-triazol-1-yl]acetic acid (52), 10-[(1-(1,3-dihydroxypropan-2-yl)-1H-1,2,3-triazol-4-yl)methoxy]-3-hexyl-4,8,8-trimethyl-7,8-dihydropyrano[3,2-g]chromen-2(6H)-one (55) and 3-hexyl-4,8,8-trimethyl-10-[(1-((2R,3R,4S,5S,6R)-3,4,5-trihydroxy-6-(hydroxymethyl)tetrahydro-2H-pyran-2-yl)-1H-1,2,3-triazol-4-yl)methoxy]-7,8-dihydropyrano[3,2-g]chromen-2(6H)-one (57), exhibited moderate activity against all the strains studied with zone of inhibition between 10 and 16 mm and MIC values in the range of 75–170 µg/mL as compared to the standard used. The information obtained from structure–activity relationship can be used to design and develop the next generation of compounds with higher antibacterial efficacy.     

Synthesis of some novel C-5 and N-3 substituted 2-(2-hydroxyphenylimino)thiazolidin-4-one derivatives with broad-spectrum antimicrobial activity

In the present article, compounds 5-((substituted-2-chloroquinolin-3-yl)methylene)-2-(2-hydroxyphenylimino)thiazolidin-4-ones (3a–k), 1-(2-(2-(2-hydroxyphenylimino)-4-oxothiazolidin-3-yl)-2-oxoethyl)pyrimidine-2,4,6(1H,3H,5H)-trione (6) and 1-(2-(5-((substituted-2-chloroquinolin-3-yl)methylene)-2-(2-hydroxyphenylimino)-4-oxothiazolidin-3-yl)-2-oxoethyl)pyrimidine-2,4,6(1H,3H,5H)-triones (8a–k) have been synthesized by substituting C-5 and N-3 position of parent compound 2-(2-hydroxyphenylimino)thiazolidin-4-one (1). Structures of the newly synthesized compounds were assigned on the basis of elemental analyses, IR, ¹H NMR, ¹³C NMR, and mass spectra. In vitro antimicrobial activity of target compounds (3a–k, 6 and 8a–k) was investigated against two Gram-positive, two Gram-negative bacteria and three fungal strains. Among the tested compounds (3e), (3f), and (3h) showed very good antifungal activity, while compound (6) showed very good antibacterial activity. Compounds (8e), (8f), and (8h) showed excellent antifungal and antibacterial activities.     

Two pairs of phenylpropanoid enantiomers from the leaves of Eucommia ulmoides

Abstract

Two pairs of phenylpropanoid enantiomers, (+)-(7S,8S)-alatusol D (1a), (?)-(7R,8R)-alatusol D (1b), (?)-(7S,8R)-alatusol D (2a) and (+)-(7R,8S)-alatusol D (2b) were isolated from the leaves of Eucommia ulmoides Oliver. Among them, 1a and 2b were firstly obtained by chiral enantiomeric resolution. Their structures were elucidated based on extensive spectroscopic analysis and the induced CD (ICD) spectrum caused by adding Mo₂(AcO)₄ in DMSO. All compounds were tested on Hep G2 tumor cell lines. However, none of the compounds showed potential cytotoxic activity against Hep G2 in vitro.     

Enantioselective synthesis of tri-deuterated (–)-geosmin to be used as internal standard in quantitation assays

For the accurate and sensitive quantitation of the off-flavor compound geosmin, particularly in complex matrices, a stable isotopologue as internal standard is highly advantageous. In this work, we present a versatile synthetic strategy leading from (4aR)-1,4a-dimethyl-4,4a,5,6,7,8-hexahydronaphthalen-2(3H)-one to tri-deuterated (–)-geosmin ((4S,4aS,8aR)-4,8a-dimethyl(3,3,4-²H₃)octahydronaphthalen-4a(2H)-ol). The starting material was readily accessible from inexpensive 2-methylcyclohexan-1-one using previously published procedures.     

Aromatic compounds from the halotolerant fungal strain of <Emphasis Type="Italic">Wallemia sebi</Emphasis> PXP-89 in a hypersaline medium

A new cyclopentanopyridine alkaloid, 3-hydroxy-5-methyl-5,6-dihydro-7H-cyclopenta[b]pyridin-7-one (1), together with 11 known aromatic compounds were isolated from the secondary metabolites of the halotolerant fungal strain Wallemia sebi PXP-89 in 10% NaCl. Their structures including the absolute configurations of (2S,3S)-1-(4-hydroxyphenyl)butane-2,3-diol (2), (2R,3S)-1-(4-hydroxyphenyl)butane-2,3-diol (3), and (S)-3-hydroxy-4-(4-hydroxyphenyl)-2-one (4) were elucidated by spectroscopic analysis and a modified Mosher’s method. Compound 1 exhibited antimicrobial activity against Enterobacter aerogenes with a MIC of 76.7 μM. The absolute configurations of compounds 2–4 were determined for the first time.     

Three new 5,6,7,8-tetrahydroxy-5,6,7,8-tetrahydrochromone derivatives enantiomeric to agarotetrol from agarwood

Agarwood (jinkoh in Japanese) is a resinous wood from Aquilaria species of the family Thymelaeaceae and has been used as incense and in traditional medicines. Characteristic chromone derivatives such as agarotetrol have been isolated from agarwood. In previous study, we isolated two new 2-(2-phenylethyl)chromones together with six known compounds from MeOH extract of agarwood. Further chemical investigation of the MeOH extract led to isolation of eighteen 2-(2-phenylethyl)chromones, including three new 5,6,7,8-tetrahydroxy-5,6,7,8-tetrahydrochromones with stereochemistry enantiomeric to agarotetrol-type, viz. (5R,6S,7S,8R)-2-[2-(3′-hydroxy-4′-methoxyphenyl)ethyl]-5,6,7,8-tetrahydroxy-5,6,7,8-tetrahydrochromone (2), (5R,6S,7S,8R)-2-[2-(4′-methoxyphenyl)ethyl]-5,6,7,8-tetrahydroxy-5,6,7,8-tetrahydrochromone (6), and (5R,6S,7S,8R)-2-[2-(4′-hydroxy-3′- methoxyphenyl)ethyl]-5,6,7,8-tetrahydroxy-5,6,7,8-tetrahydrochromone (13). The absolute configurations of the new compounds were determined by exciton chirality method. All isolated compounds were tested for their phosphodiesterase (PDE) 3A inhibitory activity by fluorescence polarization method. Compounds 8, 12–15, 21–24 showed moderate PDE 3A inhibitory activity.     

Design,Synthesis, and Antiplasmodial Activity of Hybrid Compounds Based on (2R,3S)-N-Benzoyl-3-phenylisoserine

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Compounds from Gum Ammoniacum with Acetylcholinesterase Inhibitory Activity

The use of herbal medicinal preparations in dementia therapy has been studied based on experience from traditional medicine. A dichloromethane extract of gum ammoniacum, the gum-resin from Dorema ammoniacum D. Don had shown acetylcholinesterase (AChE) inhibitory activity in a previous study. The aim of this study was the isolation and characterization of the active compounds from this resin. The extract was investigated by a respective colorimetric microplate assay and the active zones were identified via TLC bioautography and isolated using several chromatographic techniques. The structures of the active components were characterized by one- and two-dimensional ¹H and ¹³C NMR spectroscopy and mass spectrometry as (2′S,5′S)-2′-ethenyl-5′-(3-hy-droxy-6-methyl-4-oxohept-5-en-2-yl)-7-methoxy-2′-methyl-4H-spiro[chromene-3,1′-cyclopentane]-2,4-dione (1), which is an analogue of doremone A and a new natural compound, and as (2′S,5′R)-2′-ethenyl-5′-[(2R,4R)-4-hydroxy-6-methyl-3-oxohept-5-en-2-yl]-7-methoxy-2′-methyl-4H-spiro[chromene-3,1′-cyclo-pentane]-2,4-dione (2 = doremone A), (4E,8E)-1-(2,4-dihydroxyphenyl)-5,9,13-trimethyltetradeca-4,8,12-trien-1-one (3 = dshamirone), and 4,7-dihydroxy-3-[(2E,6E)-3,7,11-trimethyldodeca-2,6,10-trien-1-yl]-2H-chromen-2-one (4 = am-moresinol). Dshamirone turned out to be the most active compound with an IC₅₀ value for AChE inhibitory activity of 23.5 μM, whereas the other substances showed weak activity. The concentrations of the analytes in the resin were determined by HPLC as 3.1%, 4.6%, 1.9%, and 9.9%, respectively.     

Polyphenols in lahpet-so and two new catechin metabolites produced by anaerobic microbial fermentation of green tea

The phenolic constituents of lahpet-so, a traditional postfermented tea of Myanmar produced under anaerobic conditions, were examined. The major polyphenols were identified to be pyrogallol and 4′-hydroxyphenyl-3-(2′′,4′′,6′′-trihydroxyphenyl)-propan-2-ol, 3′,4′-dihydroxyphenyl-3-(2′′,4′′,6′′-trihydroxyphenyl)-propan-2-ol, and 3′,4′,5′-trihydroxyphenyl-3-(2′′,4′′,6′′-trihydroxyphenyl)-propan-2-ol. The hydroxydiphenylpropan-2-ols were identical to the initial metabolites produced from green tea catechins by mammalian intestinal bacteria. In addition, an anaerobic mixed-fermentation experiment using lahpet-so and Japanese commercial green tea afforded two new catechin degradation products together with known compound bruguierol B and the above-mentioned catechin metabolites. Based on spectroscopic evidence, the structures of the new compounds were concluded to be 4-(2,5-dihydroxyhexyl)benzene-1,2-diol and (5S,8R)-6,7,8,9-tetrahydro-5-methyl-5·8-epoxy-5H-benzocycloheptene-2,3,4-triol. Interestingly, the production mechanism was deduced to be the inverse of the biosynthesis of the flavan-3-ol A ring.     

Novel 2-(E)-substituted benzylidene-6-(N-substituted aminomethyl)cyclohexanones and cyclohexanols as analgesic and anti-inflammatory agents

Twenty-two new 2-(E)-substituted benzylidene-6-(N-substituted aminomethyl)cyclohexanones (6a–6j) and cyclohexanols (7a–7l) were designed and synthesized. Target compounds were obtained through Stork enamine, Mannich, and Grignard reactions taking cyclohexanone as starting material. The structures were confirmed by the application of IR, ¹H NMR, MS, and HR-MS data. The analgesic activities were evaluated by acetic acid-induced writhing test and hot plate method. The anti-inflammatory activities were assayed by xylene-induced ear swelling and carrageenan-induced paw edema in mice model. All tested compounds showed analgesic and anti-inflammatory capacities in oral administration. Some compounds (6a, 6c, 6h, 6i, 7c, 7h, and 7i) displayed the moderate analgesic activity compared with positive control ibuprofen, and some compounds (6a, 6b, 6d, 6h, 7a, and 7d) exhibited more anti-inflammatory activity than ibuprofen. Among them, compound 6a could be a potential nonsteroidal anti-inflammatory agent with significant analgesic activities and remarkable anti-inflammatory activities. Further research is being conducted.     

见血封喉内生真菌Acremonium sp. J1化学成分研究

目的 研究见血封喉内生真菌Acremonium sp. J1发酵液的化学成分。方法 采用多种柱色谱技术对发酵液中的化学成分进行分离纯化,根据波谱数据和理化性质鉴定化合物的结构。结果 分离鉴定了8个化合物,分别为3-(2S,4S-dihydroxypentyl)-6,8-dihydroxyisocoumarin (1)、3-(2S-hydroxy-4-oxopentyl)-6,8-dihydroxy- isocoumarin (2)、(3β,22E)-麦角甾-5,7,22-三烯-3-醇 (3)、(3β,5α,6α,7α,22E)-5,6-环氧麦角甾-8(14),22-二烯-3,7-二醇 (4)、(3β ,5α,6β,22E)-麦角甾-7,22-二烯-3,5,6-三醇 (5)、腺苷 (6)、胸腺嘧啶脱氧核苷 (7)和2-(4-羟苯基)乙酸乙酯 (8)。结论 8个化合物均是首次从见血封喉内生真菌中分离得到。     

On the mechanism of the antidepressant-like action of group II mGlu receptor antagonist, MGS0039

Rationale  

Several studies have suggested that modulation of the glutamatergic system could be a new, efficient way to achieve antidepressant activity. Behavioral data showed that group II mGlu receptor antagonists (i.e., (1R, 2R, 3R, 5R, 6R)-2-amino-3-(3,4-dichlorobenzyloxy)-6-fluorobicyclo[3.1.0]hexane-2,6-dicarboxylic acid (MGS0039) and (2S)-2-amino-2-[(1S,2S)-2-carboxycycloprop-1-yl]-3-(xan th-9-yl) propanoic acid (LY341495)) elicited antidepressant activity in several animal models of depression in rats and/or mice. Although the antidepressant-like activity of MGS0039 and LY341495 is well documented, the mechanism of the antidepressant action of these compounds is still not clear.     

Synthesis, analgesic, anti-inflammatory, and in vitro antimicrobial activities of some novel quinazolin-4(3H)-one derivatives

With the aim of developing potent analgesic, anti-inflammatory, and antimicrobial agents a series of novel quinazolin-4(3H)-one derivatives were synthesized and characterized by FT-IR, ¹H-NMR, mass spectroscopy and bases of elemental analysis. Tail-flick technique, carrageenan-induced foot paw edema test, and agar streak dilution test were performed for screening analgesic, anti-inflammatory, and in vitro antimicrobial activity, respectively. Moreover, all compounds were examined for its ulcerogenicity. Results revealed that entire series of compounds exhibited mild to good analgesic, anti-inflammatory, and antimicrobial activity with low to moderate ulcer index. The relationship between the functional group variation and the biological activity of the evaluated compounds were discussed. Compound 2-(2-(4-(trifluoromethyl)benzylidene)hydrazinyl)-N-(4-(2-methyl-4-oxoquinazolin-3(4H)-yl) phenyl) acetamide 5e was determined to be the most active compound.     

Synthesis,antimicrobial, and antioxidant activity of benzofuran barbitone and benzofuran thiobarbitone derivatives

The synthesis of novel series of benzofuran derivatives, containing barbitone moiety, 5-[(2/4-substitutedphenyl)(5-substituted-1-benzofuran-2-yl) methylidene]pyrimidin-2,4,6(1H,3H,5H)-trione (4a–i) and thiobarbitone moiety, 5-[(2/4-substitutedphenyl)(5-substituted-1-benzofuran-2-yl)methylidene]-2-thioxodihydropyrimidin-4,6(1H, 5H)-dione (5a–i) have been reported. The target compounds (4a–i) and (5a–i) were synthesized by the Knoevenagel condensation of (5-substituted-1-benzofuran-2-yl)(2/4-substitutedphenyl) methanone (3a–i) with barbituric acid and thiobarbituric acid, respectively, in acid medium. These compounds were screened for the antimicrobial and antioxidant activities. From antimicrobial activity results it was found that compounds 4a, 5a, 4c, and 5c displayed good antibacterial and antifungal activity against all tested strains. Further, the synthesized compounds were studied for docking on the enzyme, Glucosamine-6-phosphate synthase and the compounds 4c and 5c have emerged has an active antimicrobial agent with least binding energy (?5.27 and ?4.85 kJ mol^?1). Compounds 4e, 4f, 5e, and 5f showed promising free radical scavenging activity and compounds 5a and 5b showed good chelating ability with Fe²⁺ ions.     

Microwave assisted synthesis of novel pyrazolone derivatives attached to a pyrimidine moiety and evaluation of their anti-inflammatory, analgesic and antipyretic activities

In the present research work, the motto was to develop new chemical entities as potential anti-inflammatory, analgesic and antipyretic agents. Various 4-(2-amino-6-(substituted)pyrimidin-4-yl)-3-methyl-1-(substituted)-1H-pyrazol-5(4H)-one derivatives (5a–5j) and their Schiff bases (6a–6j) were synthesized. The newly synthesized compounds were characterized by TLC and spectral data. The compounds containing pyrazolone and amino pyrimidine as basic moieties (5a–5j), were screened for their anti-inflammatory, analgesic and antipyretic activities, compounds 5a, 5c–5f, 5h exhibited activities nearly similar to the standard. The pharmacological studies reveal that the presence of 4-hydroxy, 4-methoxy, 4-(N,N-dimethylamino) or 2-hydroxy groups on phenyl ring at C₆ of amino pyrimidine exhibits anti-inflammatory, analgesic and antipyretic activities nearly similar to the standard and substitutions like 4-chloro, 2-nitro, 3-nitro or 4-nitro on same phenyl ring lead to a decrease in activities.     

In-vitro Pharmacology of Sarpogrelate and the Enantiomers of its Major Metabolite: 5-HT2A Receptor Specificity,Stereoselectivity and Modulation of Ritanserin-induced Depression of 5-HT Contractions in Rat Tail Artery

The new antiplatelet agent sarpogrelate (MCI-9042), its major metabolite (R,S)-1-[2-[2-(3-methoxyphe-nyl)ethyl]phenoxy]-3-(dimethylamino)-2-propanol ((R,S)-M-1) and the enantiomers of (R,S)-M-1 were studied as antagonists at 5-HT_2A receptors, 5-HT₁-like receptors, 5-HT₃ receptors, α₁-adrenoceptors, β-adrenoceptors, histamine H₁ receptors, histamine H₂ receptors and muscarinic M₃ receptors in various functional in-vitro assays. Sarpogrelate, (R,S)-M-1, (S)-M-1 and (S)-M-1, respectively, were competitive antagonists of 5-hydroxytryptamine (5-HT) at 5-HT_2A receptors of rat tail artery with calculated pA₂ values of 8·53, 9·04, 9·00 and 8·81, respectively. Sarpogrelate lacked prominent 5-HT_t like, 5-HT₃, β, H_t, H₂ and M₃ antagonist activity and weakly blocked α₁-adrenoceptors (pK_B = 6·30). (S)-M-1 showed weak affinity for 5-HT₁-like receptors (pK_B = 6·30), α₁ (pK_B = 6·80) and β (pK_B = 6·54) adrenoceptors, while (R)-M-1 was a weak antagonist at histamine H₁ receptors (pK_B = 6·49). Stereoselectivity of M-1 enantiomers was low. (R)-M-1 showed 1·6-fold, 2·3-fold and 2·5-fold higher antagonist activity than (S)-M-1 for 5-HT_2A, H₁ and M₃ receptor, respectively. Affinity at β-adrenoceptors and 5-HT₁-like receptors was 5-fold and 3-fold higher for (S)-M-1 than for (R)-M-1. The depression of the maximum effect of 5-HT-induced contractions of rat-tail artery which amounted to 58–72% in the presence of ritanserin (1 nm ), was totally prevented after preincubation with sarpogrelate (1 μm ) and (R)- and (S)-M-1 (30 and 300 nm ), respectively, and partially prevented after preincubation with (R)- and (S)-M-1 (0·3-3 nm ). (R)- and (S)-M-1 failed to differ in restoring the ritanserin-induced depression of the 5-HT maximum response. It is concluded that sarpogrelate, its major metabolite (R, S)-M-1 and M-1 enantiomers are specific antagonists of 5-HT at 5-HT_2A receptors. The stereochemical configuration of the ligands does not seem to be crucial for binding to the 5-HT_2A receptor. Like ketanserin, sarpogrelate and M-1 enantiomers appear to be allosteric activators of the 5-HT_2A receptor system in rat tail artery.     

Synthesis, antimicrobial, analgesic activity, and molecular docking studies of novel 1-(5,7-dichloro-1,3-benzoxazol-2-yl)-3-phenyl-1H-pyrazole-4-carbaldehyde derivatives

Condensation of 5,7-dichloro-2-hydrazino-1,3-benzoxazole 3 with different aromatic acetophenones in methanol using catalytic amount of glacial acetic acid afforded the corresponding 1-phenylethanone(5,7-dichloro-1,3-benzoxazol-2-yl)hydrazones 5a–e in good yield. The compounds 5a–e, when subjected to Vilsmeier–Haack reaction with POCl₃ in DMF yielded (5,7-dichloro-1,3-benzoxazol-2-yl)-3-phenyl-1H-pyrazole-4-carbaldehyde derivatives 6a–e. The structural assignments of the compounds 6a–e are based on their spectral data and elemental analysis. The obtained compounds were tested for antimicrobial and analgesic activities, and subjected to molecular docking studies with respect to antimicrobial activity. The compound 6b showed pronounced antimicrobial and analgesic activity and exhibited an interesting binding profile with very high receptor affinity.     

Sub-anesthetic concentrations of (R,S)-ketamine metabolites inhibit acetylcholine-evoked currents in α7 nicotinic acetylcholine receptors

The effect of the (R,S)-ketamine metabolites (R,S)-norketamine, (R,S)-dehydronorketamine, (2S,6S)-hydroxynorketamine and (2R,6R)-hydroxynorketamine on the activity of α7 and α3β4 neuronal nicotinic acetylcholine receptors was investigated using patch-clamp techniques. The data indicated that (R,S)-dehydronorketamine inhibited acetylcholine-evoked currents in α7-nicotinic acetylcholine receptor, IC₅₀=55±6 nM, and that (2S,6S)-hydroxynorketamine, (2R,6R)-hydroxynorketamine and (R,S)-norketamine also inhibited α7-nicotinic acetylcholine receptor function at concentrations ≤1 μM, while (R,S)-ketamine was inactive at these concentrations. The inhibitory effect of (R,S)-dehydronorketamine was voltage-independent and the compound did not competitively displace selective α7-nicotinic acetylcholine receptor ligands [¹²⁵I]-α-bungarotoxin and [³H]-epibatidine indicating that (R,S)-dehydronorketamine is a negative allosteric modulator of the α7-nicotinic acetylcholine receptor. (R,S)-Ketamine and (R,S)-norketamine inhibited (S)-nicotine-induced whole-cell currents in cells expressing α3β4-nicotinic acetylcholine receptor, IC₅₀ 3.1 and 9.1 μM, respectively, while (R,S)-dehydronorketamine, (2S,6S)-hydroxynorketamine and (2R,6R)-hydroxynorketamine were weak inhibitors, IC₅₀ >100 μM. The binding affinities of (R,S)-dehydronorketamine, (2S,6S)-hydroxynorketamine and (2R,6R)-hydroxynorketamine at the NMDA receptor were also determined using rat brain membranes and the selective NMDA receptor antagonist [³H]-MK-801. The calculated K_i values were 38.95 μM for (S)-dehydronorketamine, 21.19 μM for (2S,6S)-hydroxynorketamine and>100 μM for (2R,6R)-hydroxynorketamine. The results suggest that the inhibitory activity of ketamine metabolites at the α7-nicotinic acetylcholine receptor may contribute to the clinical effect of the drug.     

Two new 2-(2-phenylethyl)chromones from Chinese eaglewood

Two new 2-(2-phenylethyl)chromones, (5S ^*,6R ^*,7S ^*)-5,6,7-trihydroxy-2-(3-hydroxy-4-methoxyphenethyl)-5,6,7,8-tetrahydro-4H-chromen-4-one (1) and (5S ^*,6R ^*,7R ^*)-5,6,7-trihydroxy-2-(3-hydroxy-4-methoxyphenethyl)-5,6,7,8-tetrahydro-4H-chromen-4-one (2), were isolated from the Chinese eaglewood of Aquilaria sinensis (Lour.) Gilg. Their structures were established by detailed MS and NMR spectroscopic analysis, as well as comparison with the literature data.