PAF-antagonistic bicyclo[3.2.1]octanoid neolignans from leaves of Ocotea macrophylla Kunth. (Lauraceae)

Di-nor-benzofuran neolignan aldehydes, Δ⁷-3,4-methylenedioxy-3′-methoxy-8′,9′-dinor-4′,7-epoxy-8,3′-neolignan-7′-aldehyde (ocophyllal A) 1, Δ⁷-3,4,5,3′-tetramethoxy-8′,9′-dinor-4′,7-epoxy-8,3′-neolignan-7′-aldehyde (ocophyllal B) 2, and macrophyllin-type bicyclo[3.2.1]octanoid neolignans (7R, 8R, 3′S, 4′S, 5′R)-Δ⁸′-4′-hydroxy-5′-methoxy-3,4-methylenedioxy-2′,3′,4′,5′-tetrahydro-2′-oxo-7.3′,8.5′-neolignan (ocophyllol A) 3, (7R, 8R, 3′S, 4′S, 5′R)-Δ⁸′-4′-hydroxy-3,4,5′-trimethoxy-2′,3′,4′,5′-tetrahydro-2′-oxo-7.3′,8.5′-neolignan (ocophyllol B) 4, (7R, 8R, 3′S, 4′S, 5′R)-Δ⁸′-4′-hydroxy-3,4,5,5′-tetramethoxy-2′,3′,4′,5′-tetrahydro-2′-oxo-7.3′,8.5′-neolignan (ocophyllol C) 5, as well as 2′-epi-guianin 6 and (+)-licarin B 7, were isolated and characterized from leaves of Ocotea macrophylla (Lauraceae). The structures and configuration of these compounds were determined by extensive spectroscopic analyses. Inhibition of platelet activating factor (PAF)-induced aggregation of rabbit platelets were tested with neolignans 1–7. Although compound 6 was the most potent PAF-antagonist, compounds 3–5 showed some activity.     

Two chromones from Peperomia vulcanica

Two chromones: 5-hydroxy-2-(14′-(E)-nonadecenyl) chromone (1) and 5-hydroxy-2-[12′-(3″,4″-methylenedioxyphenyl)dodecanyl] chromone (2), together with six known compounds have been isolated from Peperomia vulcanica Baker & C. H. Wright (Piperaceae). Their structures were determined by spectroscopic analysis including 2D NMR techniques.     

Phthalide mono- and dimers from the radix of Angelica sinensis

Phytochemical investigation of the radix of Angelica sinensis has led to the isolation and identification of a new phthalide dimer, (3Z)-(3aR,6S,3′R,8′S)-3a.8′,6.3′-diligustilide (1), along with three known phthalide dimers, including riligustilide (2), levistolide A (3), senkyunolide O (4), and three known phthalide monomers, including 3,9-dihydroxyl-ligustilide (5), (Z)-butylidene phthalide (6), (Z)-ligustilide (7). Their structures were determined by spectroscopic methods including IR, NMR (¹H NMR, ¹³C NMR, COSY, HSQC, HMBC and NOESY) and MS. Meanwhile, the possible biosynthesis pathways of compounds 1 and 5 were hypothesized.     

Hemiterpene glucosides and other constituents from Spiraea canescens

Five glycosides, 2-(trans-cinnamoyloxy-methyl)-1-butene-4-O-β-d-glucopyranoside (1), 4-(6′-O-trans-cinnamoyl)-(2-hydroxymethyl-4-hydroxy-butenyl-β-d-glucopyranoside (2), 6′′-O-trans-p-coumaroyl-(4-hydroxybenzoyl)-β-d-glucopyranoside (3), 6′-O-(4-methoxy-trans-cinnamoyl) α/β-d-glucopyranose (4) 6′-O-(4′′-methoxy-trans-cinnamoyl)-kaempferol-3-β-d-glucopyranoside (7) along with six known compounds, (+)-isolariciresinol 3a-O-β-d-glucopyranoside (8) (+)-lyoniresinol 3a-O-β-d-glucopyranoside (9), apigenin 7-O-β-d-glucopyranoside (10), quercetin 3-O-β-d-glucopyranoside (11), 6′-O-cinnamoyl-α/β-d-glucopyranose (6) 6’-O-p-coumaroyl-α/β-d-glucopyranose (5) were isolated from the whole plant of Spiraea canescens. Some of these compounds showed potent radical scavenging activity in relevant non-physiological assays. Their structures were determined by NMR spectroscopic and CID mass spectrometric techniques.     

Synthesis of monodeoxy and mono-O-methyl congeners of methyl β-d-mannopyranosyl-(1→2)-β-d-mannopyranoside for epitope mapping of anti-Candida albicans antibodies

A panel of six complementary monodeoxy and mono-O-methyl congeners of methyl β-d-mannopyranosyl-(1→2)-β-d-mannopyranoside (1) were synthesized by stereoselective glycosylation of monodeoxy and mono-O-methyl monosaccharide acceptors with a 2-O-acetyl-glucosyl trichloroacetimidate donor, followed by a two-step oxidation–reduction sequence at C-2′. The β-manno configurations of the final deprotected congeners 2–7 were confirmed by measurement of ¹J_C1,H1 heteronuclear and ³J_1′,2′ homonuclear coupling constants. These disaccharide derivatives will be used to map the protective epitope recognized by a protective anti-Candida albicans monoclonal antibody C3.1 (IgG3) and to determine its key polar contacts with the binding site.     

Derivatives of β- -fructofuranosyl α- -galactopyranoside

De-etherification of 6,6′-di-O-tritylsucrose hexa-acetate (2) with boiling, aqueous acetic acid caused 4→6 acetyl migration and gave a syrupy hexa-acetate 14, characterised as the 4,6′-dimethanesulphonate 15. Reaction of 2,3,3′4′,6-penta-O-acetylsucrose (5) with trityl chloride in pyridine gave a mixture containing the 1′,6′-diether 6 the 6′-ether 9, confirming the lower reactivity of HO-1′ to tritylation. Subsequent mesylation, detritylation, acetylation afforded the corresponding 4-methanesulphonate 8 1′,4-dimethanesulphonate 11. Reaction of these sulphonates with benzoate, azide, bromide, and chloride anions afforded derivatives of β- -fructofuranosyl α- -galactopyranoside (29) by inversion of configuration at C-4. Treatment of the 4,6′-diol 14 the 1,′4,6′-triol 5, the 4-hydroxy 1′,6′-diether 6 with sulphuryl chloride effected replacement of the free hydroxyl groups and gave the corresponding, crystalline chlorodeoxy derivatives. The same 4-chloro-4-deoxy derivative was isolated when the 4-hydroxy-1′,6′-diether 6 was treated with mesyl chloride in N,N-dimethylformamide.     

Synthesis of Neu5Ac- and Neu5Gc-α-(2→6′)-lactosamine 3-aminopropyl glycosides

In order to prepare 3-aminopropyl glycosides of Neu5Ac-α-(2→6′)-lactosamine trisaccharide 1, and its N-glycolyl containing analogue Neu5Gc-α-(2→6′)-lactosamine 2, a series of lactosamine acceptors with two, three, and four free OH groups in the galactose residue was studied in glycosylations with a conventional sialyl donor phenyl [methyl 5-acetamido-4,7,8,9-tetra-O-acetyl-3,5-dideoxy-2-thio- -glycero-α- and β- -galacto-2-nonulopyranosid]onates (3) and a new donor phenyl [methyl 4,7,8,9-tetra-O-acetyl-5-(N-tert-butoxycarbonylacetamido)-3,5-dideoxy-2-thio- -glycero-α- and β- -galacto-2-nonulopyranosid]onates (4), respectively. The lactosamine 4′,6′-diol acceptor was found to be the most efficient in glycosylation with both 3 and 4, while imide-type donor 4 gave slightly higher yields with all acceptors, and isolation of the reaction products was more convenient. In the trisaccharides, obtained by glycosylation with donor 4, the 5-(N-tert-butoxycarbonylacetamido) moiety in the neuraminic acid could be efficiently transformed into the desired N-glycolyl fragment, indicating that such protected oligosaccharide derivatives are valuable precursors of sialo-oligosaccharides containing N-modified analogues of Neu5Ac.     

1-Methoxy-, 1-deoxy-11-hydroxy- and 11-Hydroxy-1-methoxy-Δ-tetrahydrocannabinols: new selective ligands for the CB2 receptor

Three series of new cannabinoids were prepared and their affinities for the CB₁ and CB₂ cannabinoid recptors were determined. These are the 1-methoxy-3-(1′,1′-dimethylalkyl)-, 1-deoxy-11-hydroxy-3-(1′,1′-dimethylalkyl)- and 11-hydroxy-1-methoxy-3-(1′,1′-dimethylalkyl)-Δ⁸-tetrahydrocannabinols, which contain alkyl chains from dimethylethyl to dimethylheptyl appended to C-3 of the cannabinoid. All of these compounds have greater affinity for the CB₂ receptor than for the CB₁ receptor, however only 1-methoxy-3-(1′,1′-dimethylhexyl)-Δ⁸-THC (JWH-229, 6e) has effectively no affinity for the CB₁ receptor (K_i=3134±110 nM) and high affinity for CB₂ (K_i=18±2 nM).     

3-(1′,1′-Dimethylbutyl)-1-deoxy-Δ-THC and related compounds: synthesis of selective ligands for the CB2 receptor

The synthesis and pharmacology of 15 1-deoxy-Δ⁸-THC analogues, several of which have high affinity for the CB₂ receptor, are described. The deoxy cannabinoids include 1-deoxy-11-hydroxy-Δ⁸-THC (5), 1-deoxy-Δ⁸-THC (6), 1-deoxy-3-butyl-Δ⁸-THC (7), 1-deoxy-3-hexyl-Δ⁸-THC (8) and a series of 3-(1′,1′-dimethylalkyl)-1-deoxy-Δ⁸-THC analogues (2, n=0–4, 6, 7, where n=the number of carbon atoms in the side chain−2). Three derivatives (17–19) of deoxynabilone (16) were also prepared. The affinities of each compound for the CB₁ and CB₂ receptors were determined employing previously described procedures. Five of the 3-(1′,1′-dimethylalkyl)-1-deoxy-Δ⁸-THC analogues (2, n=1–5) have high affinity (K_i=<20 nM) for the CB₂ receptor. Four of them (2, n=1–4) also have little affinity for the CB₁ receptor (K_i=>295 nM). 3-(1′,1′-Dimethylbutyl)-1-deoxy-Δ⁸-THC (2, n=2) has very high affinity for the CB₂ receptor (K_i=3.4±1.0 nM) and little affinity for the CB₁ receptor (K_i=677±132 nM).

Scheme 3. (a) (C₆H₅)₃PCH₃⁺ Br⁻, n-BuLi/THF, 65°C; (b) LiAlH₄/THF, 25°C; (c) KBH(sec-Bu)₃/THF, −78 to 25°C then H₂O₂/NaOH.     

Synthesis and evaluation of bioactive naphthoquinones from the Brazilian medicinal plant, Tabebuia avellanedae

A series of naphthoquinones based on the naphtho[2,3-b]furan-4,9-dione skeleton such as (−)-5-hydroxy-2-(1′-hydoxyethyl)naphtho[2,3-b]furan-4,9-dione (1) and its positional isomer, (−)-8-hydroxy-2-(1′-hydoxyethyl)naphtho[2,3-b]furan-4,9-dione (2), which are secondary metabolites found in the inner bark of Tabebuia avellanedae, were stereoselectively synthesized and their biological activities were evaluated in conjunction with those of their corresponding enantiomers. Compound 1 exhibited potent antiproliferative effect against several human tumor cell lines, but its effect against some human normal cell lines was much lower than that of mitomycin. On the other hand, its enantiomer (R)-1 was less active toward the above tumor cell lines than 1. The antiproliferative effect of 2 against all tumor cell lines was significantly reduced. These results indicated the presence of the phenolic hydroxy group at C-5 is of great important for increasing antiproliferative effect. In addition, 1 also showed higher cancer chemopreventive activity than 2, while there were no significant differences between 1 and 2 in antimicrobial activity. Both compounds displayed modest antifungal and antibacterial activity (Gram-positive bacteria), whereas they were inactive against Gram-negative bacteria.     

No carrier added synthesis of O-(2'-[18F]fluoroethyl)-L-tyrosine via a novel type of chiral enantiomerically pure precursor, NiII complex of a (S)-tyrosine Schiff base

O-(2′-[¹⁸F]fluoroethyl)-l-tyrosine ([¹⁸F]FET) has gained much attention as a promising amino acid radiotracer for tumor imaging with positron emission tomography (PET) due to favorable imaging characteristics and relatively long half-life of ¹⁸F (110 min) allowing remote-site application. Here we present a novel type of chiral enantiomerically pure labeling precursor for [¹⁸F]FET, based on NiII complex of a Schiff’s base of (S)-[N-2-(N′-benzylprolyl)amino]benzophenone (BPB) with alkylated (S)-tyrosine, Ni-(S)-BPB-(S)-Tyr-OCH2CH2X (X = OTs (3a), OMs (3b) and OTf (3c)). A series of compounds 3a–c was synthesized in three steps from commercially available reagents. Non-radioactive FET as a reference was prepared from 3a in a form of (S)-isomer and (R,S) racemic mixture. Radiosynthesis comprised two steps: (1) n.c.a. nucleophilic fluorination of 3a–c (4.5–5.0 mg) in the presence of either Kryptofix 2.2.2.or tetrabutylammonium carbonate (TBAC) in MeCN at 80 °C for 5 min, followed by (2) removal of protective groups by treating with 0.5 M HCl (120 °C, 5 min). The major advantages of this procedure are retention of enantiomeric purity during the ¹⁸F-introduction step and easy simultaneous deprotection of amino and carboxy moieties in 3a–c. Radiochemically pure [¹⁸F]FET was isolated by semi-preparative HPLC (C18 μ-Bondapak, Waters) eluent aq 0.01 M CH₃COONH₄, pH 4/C₂H₅OH 90/10 (v/v). Overall synthesis time operated by Anatech RB 86 laboratory robot was 55 min. In a series of compounds 3a–c, tosyl derivative 3a provided highest radiochemical yield (40–45%, corrected for radioactive decay). Enantiomeric purity was 94–95% and 96–97%, correspondingly, for Kryptofix and TBAC assisted fluorinations. The suggested procedure involved minimal number of synthesis steps and suits perfectly for automation in the modern synthesis modules for PET radiopharmaceuticals. Preliminary biodistribution study in experimental model of turpentine-induced aseptic abscess and Glioma35 rat’s tumor (homografts) in Wistar rats has demonstrated the enhanced uptake of radiotracer in the tumor area with minimal accumulation in the inflamed tissues.     

In vitro effects of l-ascorbic acid (vitamin C) on aryl hydrocarbon hydroxylase activity in hepatic microsomes of mice

When aromatic hydrocarbon (Ah)-responsive and -non-responsive strains of mice were pretreated with 3-methylcholanthrene (MC) or 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), vitamin C reduced the microsomal aryl hydrocarbon hydroxylase (AHH) activity. The AHH inhibitors 7,8-benzoflavone (7,8-BF) and 3-methylsulfonyl-3′,4,4′,5-tetrachlorobiphenyl (3-MSF-3′,4,4′,5-tetraCB) showed various inhibitory effects depending upon the types of microsomes, whereas vitamin C exhibited inhibition irrespective of the types of microsomes. 7,8-BF and 3-MSF-3′,4,4′,5-tetraCB as well as vitamin C suppressed the reverse mutation of the Salmonella typhimurium tester strains TA98 and TA100 induced by benzo[a]pyrene.     

Thermomyces lanuginosus lipase-catalyzed regioselective acylation of nucleosides: Enzyme substrate recognition

Substrate recognition of Thermomyces lanuginosus lipase in the acylation of nucleosides was revealed through rational substrate engineering for the first time. T. lanuginosus lipase displayed higher catalytic activities and excellent 5′-regioselectivities (94–>99%) in the acylation of ribonucleosides 1f–1j as compared to those in the acylation of 2′-deoxynucleosides 1a–1e. The higher reaction rates and excellent 5′-regioselectivities might derive from a favorable hydrogen bonding between the 2′-hydroxyl group of 1f–1j and phenolic hydroxyl group of Tyr21 present in the hydrophilic region of the lipase.     

A new ecdysteroid and other constituents from two Dioscorea species

Phytochemical investigation of the rhizome of Dioscorea dumetorum has led to the isolation by several chromatographic steps on normal and reversed phase silica gel of a new ecdysteroid, (20R)-5β,11α,20-trihydroxyecdysone (1), and two known ecdysteroids, ajugasterone C (2) and herkesterone (3). Their structures were determined by spectroscopic methods including 1D- and 2D-NMR (COSY, TOCSY, HSQC and HMBC). This is the first report on the occurrence of phytoecdysteroids in the Dioscoreaceae family. These compounds were devoid of antifungal activity against three Candida species (Candida albicans, Candida glabrata and Candida tropicalis, MIC > 200 μg/ml).     

An unusual halogenated meroditerpenoid from Stypopodium flabelliforme: Studies by NMR spectroscopic and computational methods

Meroditerpenoids, 2-[2′(E)-3′,7′,11′,15′-tetramethylhexadec-2-en-1′-yl]-6-methyl-1,4-benzohydroquinone diacetate and 4′-chlorostypotriol triacetate, along with eight known compounds isolated from the dichloromethane extract of the brown alga Stypopodium flabelliforme after peracetylation are reported. One of them, 2-(1-oxo-hexadecyl)-1,3,5-trihydroxybenzene, is described for the first time within this genus. Structural elucidation was carried out on the basis of spectroscopic data and theoretical studies using GIAO/DFT analysis at B3LYP/6-31G(d) and mPW1PW91/6-31G(d) levels of theory for 4′-chlorostypotriol. This isomer is the first metabolite from the Stypopodium genus possessing one halogen atom.     

Half-sandwich Ru[9]aneS3 complexes structurally similar to antitumor-active organometallic piano-stool compounds: Preparation, structural characterization and in vitro cytotoxic activity

The preparation, structural characterization, and chemical behavior in aqueous solution of a series of new Ru[9]aneS₃ half-sandwich complexes of the type [Ru([9]aneS₃)Cl(NN)][CF₃SO₃] and [Ru([9]aneS₃)(dmso-S)(NN)][CF₃SO₃]₂ (5–15, NN = substituted bpy or 2 × 1-methylimidazole) are described. The X-ray structures of [Ru([9]aneS₃)Cl(3,3′-H₂dcbpy)][CF₃SO₃] (9) (3,3′-H₂dcbpy = 3,3′-dicarboxy-2,2′-bipyridine), [Ru([9]aneS₃)Cl(4,4′-dmobpy)][CF₃SO₃] (13) (4,4′-dmobpy = 4,4′-dimethoxy-2,2′-bipyridine), and [Ru([9]aneS₃)Cl(1-MeIm)₂][CF₃SO₃] (15) (1-MeIm = 1-methylimidazole) were also determined. The new compounds are structurally similar to anticancer-active organometallic half-sandwich complexes of formula [Ru(η⁶-arene)Cl(NN)][PF₆]. Three chloro compounds (5, 9, 15) were tested in vitro for cytotoxic activity against two human cancer cell lines in comparison with the previously described [Ru([9]aneS₃)Cl(en)][CF₃SO₃] (1, en = ethylenediamine), [Ru([9]aneS₃)Cl(bpy)][CF₃SO₃] (2), and with their common dmso precursor [Ru([9]aneS₃)Cl(dmso-S)₂][CF₃SO₃] (3). Only the ethylenediamine complex 1 showed some antiproliferative activity, ca. one order of magnitude lower than the reference organometallic half-sandwich compound RM175 that contains biphenyl instead of [9]aneS₃. This compound was further tested against a panel of human cancer cell lines (including one resistant to cisplatin).     

Isoflavones with unusually modified B-rings and their evaluation as antiproliferative agents

Six novel isoflavone derivatives along with four known isoflavones were isolated from a culture of a highly nickel-resistant strain of Streptomyces mirabilis from a former uranium mining area. The structures of 7-hydroxy-3′,5′-dihydroxyisoflavone (5), 5,7-dihydroxy-3′,5′-dihydroxyisoflavone (6), 2′-hydroxy-3′-methoxygenistein (7), as well as hydroisoflavones A–C (8–10) were elucidated by MS and NMR analyses. Compounds 8–10 feature yet unprecedented types of non-aromatic, hydroxylated B rings, which result from plant isoflavone biotransformation. All new compounds display weak cytotoxic but potent antiproliferative activities. The anti-oestrogenic properties of 8 against MCF-7 human breast cancer cell line (GI₅₀: 6 μM) is even higher than the reference compound genistein.     

Elderberry flavonoids bind to and prevent H1N1 infection in vitro

A ionization technique in mass spectrometry called Direct Analysis in Real Time Mass Spectrometry (DART TOF-MS) coupled with a Direct Binding Assay was used to identify and characterize anti-viral components of an elderberry fruit (Sambucus nigra L.) extract without either derivatization or separation by standard chromatographic techniques. The elderberry extract inhibited Human Influenza A (H1N1) infection in vitro with an IC₅₀ value of 252 ± 34 μg/mL. The Direct Binding Assay established that flavonoids from the elderberry extract bind to H1N1 virions and, when bound, block the ability of the viruses to infect host cells. Two compounds were identified, 5,7,3′,4′-tetra-O-methylquercetin (1) and 5,7-dihydroxy-4-oxo-2-(3,4,5-trihydroxyphenyl)chroman-3-yl-3,4,5-trihydroxycyclohexanecarboxylate (2), as H1N1-bound chemical species. Compound 1 and dihydromyricetin (3), the corresponding 3-hydroxyflavonone of 2, were synthesized and shown to inhibit H1N1 infection in vitro by binding to H1N1 virions, blocking host cell entry and/or recognition. Compound 1 gave an IC₅₀ of 0.13 μg/mL (0.36 μM) for H1N1 infection inhibition, while dihydromyricetin (3) achieved an IC₅₀ of 2.8 μg/mL (8.7 μM). The H1N1 inhibition activities of the elderberry flavonoids compare favorably to the known anti-influenza activities of Oseltamivir (Tamiflu^®; 0.32 μM) and Amantadine (27 μM).     

Optical resolution of hexamethylbiphenol by cholesterol esterase and porcine pancreas lipase

Both enantiomers of 2,2′-dihydroxy-4,4′,5,5′,6,6′-hexamethybiphenyl (2), a potentially useful chiral synthon, were obtained with >99% ee in high enantioselectivity by cholesterol esterase or porcine pancreas lipase (PPL)-mediated hydrolysis of the corresponding (±)-dipentanoate or (±)-dihexanoate, respectively. Absolute configuration of (S)-3-bromo-2,6′-dimethoxy-4,5,6,2′,3′,4′-hexamethyl-biphenyl (2h) was determined by X-ray analysis.     

Approach to a metallacycling polymerization — reactions of [(η-C5H5)Co(PPh3)2] with α,β-diynes and Me3SiCCC6H4C6H4CCSiMe3

Reactions of [CpCo(PPh₃)₂](Cp=η⁵-cyclopentadienyl) with conjugated diacetylenes were investigated in terms of the synthesis of π-conjugated organometallic polymers. The reaction of an α,β-diyne, PhCC---CCPh, gave three geometric isomers of dialkynylcobaltacyclopentadienes, 1a-c, and an insoluble polymeric product, 1d. A 2,4-dialkynyl complex, 2, and a 2,5-dialkynyl complex, 3, were obtained solely from Me₃SiCC---CCSiMe₃ and MeCC---CCMe, respectively. 1,1′-Bis(trimethylsilylethynyl)-4,4′-biphenyl afforded two isomers of 1,3-dialkynylcyclobutadiene complexes, 4a and 4b. The stability of the one-electron oxidized forms of the cobalacyclopentadiene and cyclobutadiene complexes was examined by cyclic voltammetry.