Amino Alcohols as Potential Antibiotic and Antifungal Leads

Five focused compound libraries (forty-nine compounds), based on prior studies in our laboratory were synthesized and screened for antibiotic and anti-fungal activity against S. aureus, E. coli, K. pneumoniae, P. aeruginosa, A. baumannii, C. albicans and C. neoformans. Low levels of activity, at the initial screening concentration of 32 μg/mL, were noted with analogues of (Z)-2-(3,4-dichlorophenyl)-3-phenylacrylonitriles which made up the first two focused libraries produced. The most promising analogues possessing additional substituents on the terminal aromatic ring of the synthesised acrylonitriles. Modifications of the terminal aromatic moiety were explored through epoxide installation flowed by flow chemistry mediated ring opening aminolysis with discreet sets of amines to the corresponding amino alcohols. Three new focused libraries were developed from substituted anilines, cyclic amines, and phenyl linked heterocyclic amines. The aniline-based compounds were inactive against the bacterial and fungal lines screened. The introduction of a cyclic, such as piperidine, piperazine, or morpholine, showed >50% inhibition when evaluated at 32 μg/mL compound concentration against methicillin-resistant Staphylococcus aureus. Examination of the terminal aromatic substituent via oxirane aminolysis allowed for the synthesis of three new focused libraries of afforded amino alcohols. Aromatic substituted piperidine or piperazine switched library activity from antibacterial to anti-fungal activity with ((Z)-2-(3,4-dichlorophenyl)-3-(4-(2-hydroxy-3-(4-methylpiperazin-1-yl)propoxy)phenyl)acrylonitrile), ((Z)-2-(3,4-dichlorophenyl)-3-(4-(2-hydroxy-3-(4-(4-hydroxyphenyl)piperazin-1-yl)propoxy)-phenyl)acrylonitrile) and ((Z)-3-(4-(3-(4-cyclohexylpiperazin-1-yl)-2-hydroxypropoxy)-phenyl)-2-(3,4-dichlorophenyl)-acrylonitrile) showing >95% inhibition of Cryptococcus neoformans var. grubii H99 growth at 32 μg/mL. While (Z)-3-(4-(3-(cyclohexylamino)-2-hydroxypropoxy)phenyl)-2-(3,4-dichlorophenyl)-acrylonitrile, (S,Z)-2-(3,4-dichlorophenyl)-3-(4-(2-hydroxy-3-(piperidin-1-yl)propoxy)phenyl)acrylonitrile, (R,Z)-2-(3,4-dichlorophenyl)-3-(4-(2-hydroxy-3-(piperidin-1-yl)propoxy)phenyl)acrylonitrile, (Z)-2-(3,4-dichlorophenyl)-3-(4-(2-hydroxy-3-(D-11-piperidin-1-yl)propoxy)phenyl)-acrylonitrile, and (Z)-3-(4-(3-(4-cyclohexylpiperazin-1-yl)-2-hydroxypropoxy)-phenyl)-2-(3,4-dichlorophenyl)-acrylonitrile 32 μg/mL against Staphylococcus aureus.     

Influence of trimethoxy-substituted positions on fluorescence of heteroaryl chalcone derivatives

Three series of heteroaryl chalcones, (E)-1-(2-pyridyl)-3-(X)prop-2-en-1-one (Ia-Ic), (E)-1-(2-thienyl)-3-(X)prop-2-en-1-one (IIa-IIc), and (E)-1-(2-furyl)-3-(X)prop-2-en-1-one (IIIa-IIIc), where X = 2,4,5-trimethoxyphenyl (for series a), X = 2,4,6-trimethoxyphenyl (for series b), and X = 3,4,5-trimethoxyphenyl (for series c) were synthesised using basic catalysed aldol condensation and characterised using 1H NMR and FT-IR spectroscopies. Compound IIa was also characterised by single crystal X-ray analysis. The absorption and fluorescence emission spectra of these compounds revealed that the absorption and fluorescence depended on the heterocycle rings and trimethoxysubstituted phenyl rings linked to the enone system. The position of methoxy groups substantially affected the fluorescent properties. Compounds Ia-IIIa containing the 2,4,5-trimethoxyphenyl moiety exhibited the red-shift phenomenon and strong emission fluorescence.     

New Alk(en)ylhydroxycyclohexanes with Tyrosinase Inhibition Potential from Harpephyllum caffrum Bernh. Gum Exudate

This work presents the first report on the phytochemical investigation of Harpephyllum caffrum Bernh. gum exudate. A known cardanol, 3-heptadec-12′-Z-enyl phenol (1) and three new alk(en)ylhydroxycyclohexanes, namely, (1R,3R)-1,3-dihydroxy-3-[heptadec-12′(Z)-enyl]cyclohexane (2) (1S,2S,3S,4S,5R)-1,2,3,4,5-pentahydroxy-5-[octadec-13′(Z)-enyl]cyclohexane (3) and (1R,2S,4R)-1,2,4-trihydroxy-4-[heptadec-12′(Z)-enyl]cyclohexane (4) were isolated from the gum. The structures of the compounds were determined by extensive 1D and 2D NMR spectroscopy and HR-ESI-MS data. The ethanolic extract of the gum was found to be the most potent tyrosinase inhibitor with IC₅₀ of 11.32 µg/mL while compounds 2 and 3, with IC₅₀ values of 24.90 and 26.99 µg/mL, respectively, were found to be potential anti-tyrosinase candidates from the gum. Gum exudate may be a potential source for non-destructive harvesting of selective pharmacologically active compounds from plants. The results also provide evidence that H. caffrum gum may find application in cosmetics as a potential anti-tyrosinase agent.     

Chemical Variability and In Vitro Anti-Inflammatory Activity of Leaf Essential Oil from Ivorian Isolona dewevrei (De Wild. & T. Durand) Engl. & Diels

The chemical variability and the in vitro anti-inflammatory activity of the leaf essential oil from Ivorian Isolona dewevrei were investigated for the first time. Forty-seven oil samples were analyzed using a combination of CC, GC(RI), GC-MS and ¹³C-NMR, thus leading to the identification of 113 constituents (90.8–98.9%). As the main components varied drastically from sample to sample, the 47 oil compositions were submitted to hierarchical cluster and principal components analyses. Three distinct groups, each divided into two subgroups, were evidenced. Subgroup I−A was dominated by (Z)-β-ocimene, β-eudesmol, germacrene D and (E)-β-ocimene, while (10βH)-1β,8β-oxido-cadina-4-ene, santalenone, trans-α-bergamotene and trans-β-bergamotene were the main compounds of Subgroup I−B. The prevalent constituents of Subgroup II−A were germacrene B, (E)-β-caryophyllene, (5αH,10βMe)-6,12-oxido-elema-1,3,6,11(12)-tetraene and γ-elemene. Subgroup II−B displayed germacrene B, germacrene D and (Z)-β-ocimene as the majority compounds. Germacrene D was the most abundant constituent of Group III, followed in Subgroup III−A by (E)-β-caryophyllene, (10βH)-1β,8β-oxido-cadina-4-ene, germacrene D-8-one, and then in Subgroup III−B by (Z)-β-ocimene and (E)-β-ocimene. The observed qualitative and quantitative chemical variability was probably due to combined factors, mostly phenology and season, then harvest site to a lesser extent. The lipoxygenase inhibition by a leaf oil sample was also evaluated. The oil IC₅₀ (0.020 ± 0.005 mg/mL) was slightly higher than the non-competitive lipoxygenase inhibitor NDGA IC₅₀ (0.013 ± 0.003 mg/mL), suggesting a significant in vitro anti-inflammatory potential.     

Synthesis and Anticancer Activity Evaluation of 5-[2-Chloro-3-(4-nitrophenyl)-2-propenylidene]-4-thiazolidinones

A series of novel 5-[(Z,2Z)-2-chloro-3-(4-nitrophenyl)-2-propenylidene]-thiazolidinones (Ciminalum–thiazolidinone hybrid molecules) have been synthesized. Anticancer activity screening toward the NCI60 cell lines panel, gastric cancer (AGS), human colon cancer (DLD-1), and breast cancer (MCF-7 and MDA-MB-231) cell lines allowed the identification of 3-{5-[(Z,2Z)-2-chloro-3-(4-nitrophenyl)-2-propenylidene]-4-oxo-2-thioxothiazolidin-3-yl}propanoic acid (2h) with the highest level of antimitotic activity with mean GI₅₀/TGI values of 1.57/13.3 μM and a certain sensitivity profile against leukemia (MOLT-4, SR), colon cancer (SW-620), CNS cancer (SF-539), melanoma (SK-MEL-5), gastric cancer (AGS), human colon cancer (DLD-1), and breast cancers (MCF-7 and MDA-MB-231) cell lines. The hit compounds 2f, 2i, 2j, and 2h have been found to have low toxicity toward normal human blood lymphocytes and a fairly wide therapeutic range. The significant role of the 2-chloro-3-(4-nitrophenyl)prop-2-enylidene (Ciminalum) substituent in the 5 position and the substituent’s nature in the position 3 of core heterocycle in the anticancer cytotoxicity levels of 4-thiazolidinone derivatives have been established     

Michael addition of phenylacetonitrile to the acrylonitrile group leading to diphenylpentanedinitrile. Structural data and theoretical calculations

Knoevenagel condensation of phenylacetonitrile with 4-diphenylaminophenylacetonitrile in the presence of piperidine was carried out to obtain a novel conjugated compound. In addition to the expected compound 2-(phenyl)-3-(4-diphenylaminophenyl)acrylonitrile (I), the 3-((4-diphenylamino)phenyl)-2,4-diphenylpentanedinitrile (II) was also obtained with a good yield. Compound II was obtained as a result of the Michael addition of phenylacetonitrile with 2-(phenyl)-3-(4-diphenylaminophenyl)acrylonitrile (I). Conversely, when the same reaction was performed in the presence of KOH as catalyst, only the α,β-unsaturated nitrile (I) was afforded with a 92 % yield. The structures were confirmed with IR, EI-MS and NMR spectroscopy. Single crystals I and II were formed and their structures were determined by X-ray single-crystal diffraction analysis. Crystal I belongs to the monoclinic system with space group P2₁/n having unit cell parameters of a = 16.8589(5) Å, b = 6.68223(17) Å, c = 19.8289(7) Å, β = 111.133(4)○ and Z = 4. Crystal II belongs to the same monoclinic system with space group P2₁/c, having unit cell parameters of a = 10.8597(4) Å, b = 24.7533(10) Å, c = 9.7832(4) Å, β = 91.297(3)○ and Z = 4. In addition to the structural data analysis, some theoretical calculations that reveal the nature of relevant structure-property relationships are also reported.     

Steric consequence of the diastereoselective addition of chiral lithium 2-(1-dimethylaminoethyl)phenyl cuprates to some enones

Conjugate addition of the mixed chiral species lithium [(S)-2-(1-dimethylaminoethyl)phenyl](2-thienyl)cuprate to (E)-4-phenyl-3-buten-2-one, 2-cyclohexenone or to 2-cyclopentenone proceeds with high diastereoselectivity. The first two enones gave crystalline adducts directly, while the non-crystalline cyclopentenone adduct was converted into a crystalline methiodide. The crystal structures of the compounds have been determined from single-crystal X-ray diffractometer data in order to reveal the configurations at the new chiral centres. In all three cases the configuration at the new asymmetric centre is S. (S,S)-4-[2-(1-Dimethylaminoethyl)phenyl]-4-phenyl-2-butenone, C₂₀H₂₅NO, crystallizes in space group P2₁ with a 7.604(2), b 9.398(5), c 12.290(6) Å, β 92.30(3)° and Z = 2. Full-matrix least-squares refinement of 273 structural parameters gave R = 0.066 for 1015 observed independent reflections. (S,S)-3-[2-(1-Dimethylaminoethyl)phenyl]-2-cyclohexanone, C₁₆H₂₃NO crystallizes in space group P2₁2₁2₁ with a 12.499(4), b 6.645(3), c 17.568(7) Å and Z = 4. Full-matrix least-squares refinement of 142 structural parameters gave R = 0.068 for 1507 observed independent reflections. (S,S)-1-[2-(3-Oxocyclopentyl)phenyl]ethyltrimethylammonium iodide, C₁₆H₂₄NOI, crystallizes in space group P4₁, with a 10.569(3), c 30.895(7) Å and Z = 8; there are thus two crystallographically independent cations in the asymmetric unit. Full-matrix least-squares refinement of 342 structural parameters gave R = 0.054 for 2119 observed independent reflections.The (S,S)-configuration observed in these adducts indicates that the conjugate addition gives the least crowded lithium enolate as the major product.     

Pheromone synthesis. Part 249: Syntheses of methyl (R,E)-2,4,5-tetradecatrienoate and methyl (2E,4Z)-2,4-decadienoate,the pheromone components of the male dried bean beetle,Acanthoscelides obtectus (Say)

The enantiomers of methyl (E)-2,4,5-tetradecatrienoate (1), a component of the male pheromone of Acanthoscelides obtectus, were synthesized from the enantiomers of 1-undecyn-3-ol (6), which were obtained via asymmetric acetylation of (±)-1-trimethylsilyl-1-undecyn-3-ol (4) with vinyl acetate as catalyzed by lipase PS (Amano). The ortho ester Claisen rearrangement of 6 with triethyl orthoacetate was the key-step to generate the chiral allenic system. A new synthesis of (±)-1 was also executed starting from (±)-6. Three different syntheses of methyl (2E,4Z)-2,4-decadienoate (2), another component of the male pheromone of A. obtectus, were achieved by means of either palladium-catalyzed Heck reaction or a Claisen and an Al₂O₃ catalyzed thermal rearrangements.     

A simple pyridine-based colorimetric chemosensor for highly sensitive and selective mercury(II) detection with the naked eye

Two easily-prepared pyridine-based derivatives of (Z)-2-(4-amino-phenyl)-3-(pyridine-4-yl)acrylonitrile (I)and (Z)-2-phenyl-3-(pyridin-4-yl)acrylonitrile (II) were designed, synthesised and characterised. Due to the formation of a complex with Hg²⁺, hence leading to an enhanced ICT effect, I exhibits a visible colour change from light yellow to orange, rendering it suitable for use as a naked-eye sensor for rapid detection of Hg²⁺ in an aqueous ethanol solution. When mixed with Hg²+, I interacts with Hg²⁺ in a2:1 (Y1-Hg²⁺) stoichiometry via a coordination bond with an association constant of 7.7 × 10⁸ M^−2 (R² = 0.96). The present probe I exhibits excellent reproducibility, reversibility, sensitivity and selectivity with the presence of low concentration of Hg²⁺ (1.74 × 10^−10 M).     

Novel and enantioselective syntheses of (R)- and (S)-3-hydroxy-4-(2,4,5-trifluorophenyl)butanoic acid: a synthon for sitagliptin and its derivatives

A new synthetic strategy for (R)- and (S)-3-hydroxy-4-(2,4,5-trifluorophenyl)butanoic acid, a building block in the preparation of sitagliptin and its derivatives, was developed. Pd(OAc)₂ catalyzed coupling of 2,4,5-trifluoro-1-iodobenzene with allyl alcohol gave 3-(2,4,5-trifluorophenyl)propanal in a yield of 95%. l-Proline catalyzed reaction of the 3-phenylpropanal (in only 1.2 molar equiv) with nitrosobenzene followed by reduction with NaBH₄ and Pd/C catalyzed hydrogenation gave (R)-3-(2,4,5-trifluorophenyl)propane-1,2-diol with >99% ee and 65% yield. Selective tosylation of primary hydroxyl group of the 1,2-propandiol unit followed by cyanide displacement afforded (R)-3-hydroxy-4-(2,4,5-trifluorophenyl)butanenitrile (80%). The nitrile was converted to the title β-hydroxy acid under basic hydrolysis in a yield of 90%. Thus, (R)-3-hydroxy-4-(2,4,5-trifluorophenyl)butanoic acid was prepared enantioselectively from the starting material in four steps and 45% overall yield. The reaction sequence was repeated with d-proline as the catalyst to give (S)-3-hydroxy-4-(2,4,5-trifluorophenyl)butanoic acid in 45% overall yield and >99% enantiomeric excess.     

Electrophysiological Responses of Bactrocera kraussi (Hardy) (Tephritidae) to Rectal Gland Secretions and Headspace Volatiles Emitted by Conspecific Males and Females

Pheromones are biologically important in fruit fly mating systems, and also have potential applications as attractants or mating disrupters for pest management. Bactrocera kraussi (Hardy) (Diptera: Tephritidae) is a polyphagous pest fruit fly for which the chemical profile of rectal glands is available for males but not for females. There have been no studies of the volatile emissions of either sex or of electrophysiological responses to these compounds. The present study (i) establishes the chemical profiles of rectal gland contents and volatiles emitted by both sexes of B. kraussi by gas chromatography–mass spectrometry (GC–MS) and (ii) evaluates the detection of the identified compounds by gas chromatography–electroantennogram detection (GC–EAD) and –electropalpogram detection (GC–EPD). Sixteen compounds are identified in the rectal glands of male B. kraussi and 29 compounds are identified in the rectal glands of females. Of these compounds, 5 were detected in the headspace of males and 13 were detected in the headspace of females. GC–EPD assays recorded strong signals in both sexes against (E,E)-2,8-dimethyl-1,7-dioxaspiro[5.5]undecane, 2-ethyl-7-mehtyl-1,6-dioxaspiro[4.5]decane isomer 2, (E,Z)/(Z,E)-2,8-dimethyl-1,7-dioxaspiro[5.5]undecane, and (Z,Z)-2,8-dimethyl-1,7-dioxaspiro[5.5]undecane. Male antennae responded to (E,E)-2,8-dimethyl-1,7-dioxaspiro[5.5]undecane, 2-methyl-6-pentyl-3,4-dihydro-2H-pyran, 6-hexyl-2-methyl-3,4-dihydro-2H-pyran, 6-oxononan-1-ol, ethyl dodecanoate, ethyl tetradecanoate and ethyl (Z)-hexadec-9-enoate, whereas female antennae responded to (E,E)-2,8-dimethyl-1,7-dioxaspiro[5.5]undecane and 2-methyl-6-pentyl-3,4-dihydro-2H-pyran only. These compounds are candidates as pheromones mediating sexual interactions in B. kraussi.     

Carbonylation of aryl- and vinyl-tellurium compounds with carbon monoxide in the presence of palladium(II) salts

Aryl- and vinyl-tellurium(II or IV) compounds react with carbon monoxide (CO) in suitable organic solvents to give the corresponding carboylic acids in moderate to quantitative yields in the presence of a stoichiometric amount of a palladium(II) salt. Treatment of (Z)-styrylphenyl telluride with atmospheric pressure of CO at room temperature in the presence of palladium(II) chloride or lithium chloropalladate(II) affords predominantly (E)-cinnamic acid, while in the presence of palladium(II) acetate similar reaction gives the (Z)-acid highly selectively. Under higher CO pressures (5–50 atm), however, the (Z)-acid becomes the major product, even when palladium(II) chloride is used. The following pathways are proposed for this carbonylation: (1) in the first step organotellurium compounds form the monomeric and/or dimeric palladium complexes such as [(R₂Te)PdCl₂]₂ and/or (R₂Te)₂PdCl₂ (R = aryl, vinyl), then (2) the migration of R moiety from tellurium to palladium (transmetallation) occurs to afford the reactive aryl- or alkenyl-palladium compounds, and (3) the compounds react with CO to give the corresponding acylpalladium compounds, after alkaline hydrolysis, the carboxylic acids are formed. The presence of an ionic carbene-like organopalladium complex is proposed for the formation of the (Z)-acid from (Z)-telluride.     

Secoiridoid Glucosides and Anti-Inflammatory Constituents from the Stem Bark of Fraxinus chinensis

Qin Pi (Fraxinus chinensis Roxb.) is commercially used in healthcare products for the improvement of intestinal function and gouty arthritis in many countries. Three new secoiridoid glucosides, (8E)-4′′-O-methylligstroside (1), (8E)-4′′-O-methyldemethylligstroside (2), and 3′′,4′′-di-O-methyl-demethyloleuropein (3), have been isolated from the stem bark of Fraxinus chinensis, together with 23 known compounds (4–26). The structures of the new compounds were established by spectroscopic analyses (1D, 2D NMR, IR, UV, and HRESIMS). Among the isolated compounds, (8E)-4′′-O-methylligstroside (1), (8E)-4′′-O-methyldemethylligstroside (2), 3′′,4′′-di-O-methyldemethyloleuropein (3), oleuropein (6), aesculetin (9), isoscopoletin (11), aesculetin dimethyl ester (12), fraxetin (14), tyrosol (21), 4-hydroxyphenethyl acetate (22), and (+)-pinoresinol (24) exhibited inhibition (IC₅₀ ≤ 7.65 μg/mL) of superoxide anion generation by human neutrophils in response to formyl-L-methionyl-L-leuckyl-L-phenylalanine/cytochalasin B (fMLP/CB). Compounds 1, 9, 11, 14, 21, and 22 inhibited fMLP/CB-induced elastase release with IC₅₀ ≤ 3.23 μg/mL. In addition, compounds 2, 9, 11, 14, and 21 showed potent inhibition with IC₅₀ values ≤ 27.11 μM, against lipopolysaccharide (LPS)-induced nitric oxide (NO) generation. The well-known proinflammatory cytokines, tumor necrosis factor-alpha (TNF-α) and interleukin 6 (IL-6), were also inhibited by compounds 1, 9, and 14. Compounds 1, 9, and 14 displayed an anti-inflammatory effect against NO, TNF-α, and IL-6 through the inhibition of activation of MAPKs and IκBα in LPS-activated macrophages. In addition, compounds 1, 9, and 14 stimulated anti-inflammatory M2 phenotype by elevating the expression of arginase 1 and Krüppel-like factor 4 (KLF4). The above results suggested that compounds 1, 9, and 14 could be considered as potential compounds for further development of NO production-targeted anti-inflammatory agents.     

Synthesis of 2-(2,3,4-trimethoxyphenyl)-1-(substituted-phenyl)acrylonitriles: in vitro anticancer activity against MCF-7, PC-3 and A2780 cancer cell lines

A series of 2-(2,3,4-trimethoxyphenyl)-1-(substituted-phenyl)acrylonitrile (2–9) were designed and synthesized to develop new cancer drugs. The structures of synthesized compounds 2–9 were described by using melting point, mass (MALDI-TOF-MS), FT-IR, elemental analysis, ¹H, ¹³C, ¹³C-APT and 2D NMR spectroscopy. The in vitro anticancer activities of 2–9 against human breast cancer (MCF-7), human prostate cancer (PC-3) and human ovarian cancer cells (A2780) were investigated by [3-(4,5-dimethylthiazol)-2-yl]-2,5-diphenyl-2H-tetrazolium bromide] (MTT) assay method. Additionally, the LogIC₅₀ values of these compounds on A2780, MCF-7 and PC-3 cell lines were calculated by using inhibition % values by the GraphPad Prism 6 program on a computer. The results indicated that these compounds have high anticancer activity against MCF-7, PC-3 and A2780 cell lines (especially A2780 cell lines, p < 0.05).     

Z/E‐Isomerism of 3‐[4‐(dimethylamino)phenyl]‐2‐(2,4,6‐tribromophenyl)acrylonitrile: crystal structures and secondary intermolecular interactions

The Z and E isomers of 3‐[4‐(dimethylamino)phenyl]‐2‐(2,4,6‐tribromophenyl)acrylonitrile, C₁₇H₁₃Br₃N₂, ( 1 ), were obtained simultaneously by a Knoevenagel condensation between 4‐(dimethylamino)benzaldehyde and 2‐(2,4,6‐tribromophenyl)acetonitrile, and were investigated by X‐ray diffraction and density functional theory (DFT) quantum‐chemical calculations. The (Z)‐( 1 ) isomer is monoclinic (space group P2₁/n, Z′ = 1), whereas the (E)‐( 1 ) isomer is triclinic (space group P, Z′ = 2). The two crystallographically‐independent molecules of (E)‐( 1 ) adopt similar geometries. The corresponding bond lengths and angles in the two isomers of ( 1 ) are very similar. The difference in the calculated total energies of isolated molecules of (Z)‐( 1 ) and (E)‐( 1 ) with DFT‐optimized geometries is ∼4.47 kJ mol⁻¹, with the minimum value corresponding to the Z isomer. The crystal structure of (Z)‐( 1 ) reveals strong intermolecular nonvalent Br…N [3.100 (2) and 3.216 (3) Å] interactions which link the molecules into layers parallel to (10). In contrast, molecules of (E)‐( 1 ) in the crystal are bound to each other by strong nonvalent Br…Br [3.5556 (10) Å] and weak Br…N [3.433 (4) Å] interactions, forming chains propagating along [110]. The crystal packing of (Z)‐( 1 ) is denser than that of (E)‐( 1 ), implying that the crystal structure realized for (Z)‐( 1 ) is more stable than that for (E)‐( 1 ).     

Stereospecific preparation of symmetrical (1Z, 3Z)- and (1E, 3E)-2,3-difluoro-1,4-disubstituted-buta-1,3-dienes from 1-bromo-1-fluoroalkenes

A straightforward method to prepare symmetrical (1Z, 3Z)- and (1E, 3E)-2,3-difluoro-1,4-disubstituted-buta-1,3-dienes is described. High E/Z ratio 1-bromo-1-fluoroalkenes, prepared by isomerization from the E/Z ≈ 1:1 isomeric mixtures, reacted with Bu₃SnSnBu₃ and Pd(PPh₃)₄ to afford (1Z, 3Z)-2,3-difluoro-1,4-disubstituted-buta-1,3-dienes in good yield. (Z)-1-Bromo-1-fluoroalkenes, which were prepared by kinetic reduction from 1-bromo-1-fluoroalkenes (E/Z ≈ 1:1), can undergo similar reaction with Bu₃SnSnBu₃ and Pd(PPh₃)₄/CuI to prepare (1E, 3E)-2,3-difluoro-1,4-disubstituted-buta-1,3-dienes.     

Synthesis of (±)-2R,4R,5S-2-methoxy-4-nitro-5-(2,3,4-trimethoxyphenyl)cyclohexanone and (±)-2R,4S,5R-2-methoxy-5-nitro-4-(2,3,4-trimethoxyphenyl)cyclohexanone as colchicine mimetics

Colchicine mimetic (±)-4S,5R-4-nitro-5-(2,3,4-trimethoxyphenyl)cyclohexene (1) was epoxidized to afford a mixture of epoxides. The epoxides were separately converted in two steps, with high stereoselectivity, to two regioisomeric α-methoxyketones. One regioisomer, (±)-2R,4S,5R-2-methoxy-5-nitro-4-(2,3,4-trimethoxyphenyl)cyclohexanone (17), proved to be about 12-fold more potent than synthetic precursor 1 against HCT-116 tumor cells while the other regioisomer, (±)-2R,4R,5S-2-methoxy-4-nitro-5-(2,3,4-trimethoxyphenyl)cyclohexanone (16), and the synthetic intermediates tested showed no improvement in potency.     

Synthesis and X-ray structure of two isomeric aminocarbene complexes of tungsten containing a free carbon-carbon double bond

The reaction of allylamine with (CO)₅WC(OCH₂CH₃)CH₃ gives two isomeric aminocarbene complexes (CO)₅WC(NHCH₂CHCH₂)CH₃ 2E and 2Z. Refluxing of a solution of this mixture in benzene gives the complexes (CO)₄WC(η²NHCH₂CHCH₂)CH₂ (3) and 2E, which have been separated. 2E was fully characterized by X-ray diffraction. Crystals of 2E are monoclinic, space group P2₁/n with Z = 4, a 7.188(3), b 14.312(2), c 12.530(2) Å and β 91.06(3)°.The same mixture when treated with lithium diisopropylamide (LDA) followed by allyl bromide gives a mixture of (CO)₅WC(N(CH₂CHCH₂)₂)CH₃ (4) and 2Z. These complexes were separated, and 2Z fully characterized by X-ray diffraction. Crystals of 2Z are monoclinic, space group P2₁/c, with Z = 4, a 6.593(5), b 14.584(3), c 13.323(1) Å and β 95.13(4)°.     

Chemical Profile of Lipophilic Fractions of Different Parts of Zizyphus lotus L. by GC-MS and Evaluation of Their Antiproliferative and Antibacterial Activities

Zizyphus lotus L. is a perennial shrub particularly used in Algerian folk medicine, but little is known concerning the lipophilic compounds in the most frequently used parts, namely, root bark, pulp, leaves and seeds, which are associated with health benefits. In this vein, the lipophilic fractions of these morphological parts of Z. lotus from Morocco were studied by gas chromatography–mass spectrometry (GC–MS), and their antiproliferative and antimicrobial activities were evaluated. GC–MS analysis allowed the identification and quantification of 99 lipophilic compounds, including fatty acids, long-chain aliphatic alcohols, pentacyclic triterpenic compounds, sterols, monoglycerides, aromatic compounds and other minor components. Lipophilic extracts of pulp, leaves and seeds were revealed to be mainly composed of fatty acids, representing 54.3–88.6% of the total compounds detected. The leaves and seeds were particularly rich in unsaturated fatty acids, namely, (9Z,12Z)-octadeca-9,12-dienoic acid (2431 mg kg⁻¹ of dry weight) and (9Z)-octadec-9-enoic acid (6255 mg kg⁻¹ of dry weight). In contrast, root bark contained a high content of pentacyclic triterpenic compounds, particularly betulinic acid, accounting for 9838 mg kg⁻¹ of dry weight. Root bark extract showed promising antiproliferative activity against a triple-negative breast cancer cell line, MDA-MB-231, with a half-maximal inhibitory concentration (IC₅₀) = 4.23 ± 0.18 µg mL⁻¹ of extract. Leaf extract displayed interesting antimicrobial activity against Escherichia coli, methicillin-sensitive Staphylococcus aureus and Staphylococcus epidermis, presenting minimum inhibitory concentration (MIC) values from 1024 to 2048 µg mL⁻¹ of extract. Our results demonstrate that Zizyphus lotus L. is a source of promising bioactive components, which can be exploited as natural ingredients in pharmaceutical formulations.     

Responses of Adult Hypera rumicis L. to Synthetic Plant Volatile Blends

The behavioral responses of Hypera rumicis L. adults to varying blends of synthetic plant volatiles (SPVs) at various concentrations in lieu of single compounds are reported for the first time. For this study, Rumex confertus plants were treated with two blends of SPVs at different quantities that act as either attractants or repellents to insects. Blend 1 (B1) consisted of five green leaf volatiles (GLVs), namely (Z)-3-hexenal, (E)-2-hexenal, (Z)-3-hexenol, (E)-2-hexenol, and (Z)-3-hexen-1-yl acetate. Blend 2 (B2) contained six plant volatiles, namely (Z)-ocimene, linalool, benzyl acetate, methyl salicylate, β-caryophyllene, and (E)-β-farnesene. Each blend was made available in four different amounts of volatiles, corresponding to each compound being added to 50 µL of hexane in amounts of 1, 5, 25 and 125 ng. The effects of the two blends at the different concentrations on the insects were evaluated using a Y-tube olfactometer. Both sexes of the insects were found to be significantly repelled by the highest volatile levels of B1 and by two levels of B2 (25 and 125 ng). Females were also observed to be repelled using B2 with 5 ng of each volatile. Attraction was observed for both sexes only for B1 at the three lower volatile levels (1, 5 and 25 ng). In additional experiments, using only attractants, unmated females were found to be attracted to males, whereas mated females were only attracted to B1. Both unmated and mated males (previously observed in copula) were attracted only to females.