Systematic Development of Vanadium Catalysts for Sustainable Epoxidation of Small Alkenes and Allylic Alcohols

The catalytic epoxidation of small alkenes and allylic alcohols includes a wide range of valuable chemical applications, with many works describing vanadium complexes as suitable catalysts towards sustainable process chemistry. But, given the complexity of these mechanisms, it is not always easy to sort out efficient examples for streamlining sustainable processes and tuning product optimization. In this review, we provide an update on major works of tunable vanadium-catalyzed epoxidations, with a focus on sustainable optimization routes. After presenting the current mechanistic view on vanadium catalysts for small alkenes and allylic alcohols' epoxidation, we argue the key challenges in green process development by highlighting the value of updated kinetic and mechanistic studies, along with essential computational studies.

HFIP in Organic Synthesis

1,1,1,3,3,3-Hexafluoroisopropanol (HFIP) is a polar, strongly hydrogen bond-donating solvent that has found numerous uses in organic synthesis due to its ability to stabilize ionic species, transfer protons, and engage in a range of other intermolecular interactions. The use of this solvent has exponentially increased in the past decade and has become a solvent of choice in some areas, such as C-H functionalization chemistry. In this review, following a brief history of HFIP in organic synthesis and an overview of its physical properties, literature examples of organic reactions using HFIP as a solvent or an additive are presented, emphasizing the effect of solvent of each reaction.

Evaluation of a quick one-step sample preparation method for the determination of the isotopic fingerprint of rapeseed (Brassica napus): Investigation of the influence of the use of 2,2-dimethoxypropane on compound-specific stable carbon and hydrogen isotope analyses by gas chromatography combustion/pyrolysis isotope ratio mass spectrometry

RATIONALE

Gas chromatographic analyses for vegetable oils require transesterification, which generally involves multiple steps, mainly to generate fatty acid methyl esters (FAMEs). A quick method based on acid-catalyzed transesterification using 2,2-dimethoxypropane (DMP) enables the conversion in one step, in a single reactor. For compound-specific stable carbon and hydrogen isotope analyses (C- and H-CSIA) of individual fatty acids (FAs) in oil, the verification of this one-step method has not yet been reported.

METHODS

In this study, we evaluated the feasibility of the one-step method for C- and H-CSIA of individual FAMEs in rapeseed samples. The focus was on the investigation of the influence of methanol, which was produced from the reactions of DMP with glycerol and water during transesterification, on the accuracy of isotope composition of FAMEs, consequently of the FAs. The reproducibility of the one-step method was assessed by the measurement of the FAMEs from rapeseed and rapeseed oil. For the C- and H-CSIA of individual FAMEs, a gas chromatography combustion/pyrolysis isotope ratio mass spectrometry system was used.

RESULTS

Our results showed that no significant differences arise in the carbon and hydrogen isotope compositions of the selected main FAMEs produced with and without DMP except for the H-CSIA value of C18:3. The reproducibility of the one-step method for rapeseed was in the range of ±0.1 mUr to ± 0.3 mUr for C-CSIA and ±1 mUr to ±3 mUr for H-CSIA of the main FAMEs.

CONCLUSIONS

DMP improves the transesterification efficiency without influencing the accuracy of the C- and H-CSIA of FAMEs. The performance of the one-step method for rapeseed samples for the determination of C- and H-CSIA values of FAMEs is satisfactory. Thus, the applicability of the one-step method for isotopic fingerprint analyses of FAs in oilseeds is reported for the first time.

Phenylpropanoid-conjugated pentacyclic triterpenoids from the whole plants of Leptopus lolonum induced cell apoptosis via MAPK and Akt pathways in human hepatocellular carcinoma cells

Our present and previous phytochemical investigations on Leptopus lolonum have resulted in the isolation of almost 30 phenylpropanoid-conjugated pentacyclic triterpenoids (PCPTs). During the continuous study on PCPTs, this kind of triterpenoid ester is considered as a natural product with low toxicity because of it's widely distribution in natural plants and edible fruits including kiwi fruit, durian, jujube, pawpaw, apple and pear. In the present work, we report the isolation, structural elucidation and cytotoxic evaluation of four new PCPTs (1-4) which obtained from L. lolonum. In addition, the possible biosynthesis pathway for 28-norlupane triterpenoid and potent effect of phenylpropanoid moiety for increasing the cytotxic effect of triterpenoids were also discussed. Among these compounds, compound 1 exhibited the highest cytotoxic effect on HepG2 cells with IC₅₀ value of 11.87 μM. Further flow cytometry and western blot analysis demonstrated that 1 caused G1 cell cycle arrest by up-regulated the expression of phosphorylated p53 protein in HepG2 cells and induced cell apoptosis via MAPK and Akt pathways. These results emphasized the potential of PCPTs as lead compounds for developing anti-cancer drugs.

Six New Phenylpropanoid Derivatives from Chemically Converted Extract of Alpinia galanga (L.) and Their Antiparasitic Activities

Chemical conversion of the extract of natural resources is a very attractive way to expand the chemical space to discover bioactive compounds. In order to search for new medicines to treat parasitic diseases that cause high morbidity and mortality in affected countries in the world, the ethyl acetate extract from the rhizome of Alpinia galanga (L.) has been chemically converted by epoxidation using dioxirane generated in situ. The biological activity of chemically converted extract (CCE) of A. galanga (L.) significantly increased the activity against Leishmania major up to 82.6 ± 6.2 % at 25 μg/mL (whereas 2.7 ± 0.8% for the original extract). By bioassay-guided fractionation, new phenylpropanoids (1-6) and four known compounds, hydroquinone (7), 4-hydroxy(4-hydroxyphenyl)methoxy)benzaldehyde (8), isocoumarin cis 4-hydroxymelein (9), and (2S,3S,6R,7R,9S,10S)-humulene triepoxide (10) were isolated from CCE. The structures of isolated compounds were determined by spectroscopic analyses of 1D and 2D NMR, IR, and MS spectra. The most active compound was hydroquinone (7) with IC50 = 0.37 ± 1.37 μg/mL as a substantial active principle of CCE. In addition, the new phenylpropanoid 2 (IC50 = 27.8 ± 0.34 μg/mL) also showed significant activity against L. major compared to the positive control miltefosine (IC50 = 7.47 ± 0.3 μg/mL). The activities of the isolated compounds were also evaluated against Plasmodium falciparum, Trypanosoma brucei gambisense and Trypanosoma brucei rhodeisense. Interestingly, compound 2 was selectively active against trypanosomes with potent activity. To the best of our knowledge, this is the first report on the bioactive "unnatural" natural products from the crude extract of A. galanga (L.) by chemical conversion and on its activities against causal pathogens of leishmaniasis, trypanosomiasis, and malaria.

Assignment of Absolute Configuration of Bromoallenes by Vacuum-Ultraviolet Circular Dichroism (VUVCD)

A new application of vacuum-ultraviolet circular dichroism (VUVCD), which enables the measurement of CD spectra in the vacuum-ultraviolet region (140–200 nm), for the assignment of the absolute configurations of bromoallenes is described. Bromoallene moieties are found in natural products obtained from many marine organisms. To date, the absolute configuration of bromoallenes has been assigned almost exclusively with Lowe’s rule, which is based on specific rotation. However, exceptions to Lowe’s rule have been reported arising from the presence of other substituents with large specific rotations. For the unambiguous assignment of the absolute configuration of the bromoallene moiety with its characteristic absorption wavelength at 180–190 nm due to the π–π* transition, VUVCD was applied to four pairs of bromoallene diastereomers prepared by modifying the synthetic scheme of omaezallene. The VUVCD spectra clearly showed positive or negative Cotton effects around 180–190 nm according to the configuration of the bromoallene employed, revealing the potential of VUVCD for determining absolute stereochemistry.

Isolation and Characterization of Phenylpropanoid and Lignan Compounds from Peperomia pellucida [L.] Kunth with Estrogenic Activities

Extracts of Peperomia pellucida [L.] Kunth have previously been demonstrated to have in vivo estrogenic-like effects, thereby functioning as an anti-osteoporotic agent. However, the compounds responsible for these effects have not yet been determined. Therefore, the aim of this study is to isolate and elucidate potential compounds with estrogenic activity. The structures of the isolated compounds were identified using 1D 1H and 13C-NMR and confirmed by 2D FT-NMR. The estrogenic activity was evaluated using the E-SCREEN assay, and a molecular docking study was performed to predict the binding affinity of the isolated compounds to estrogen receptors. In this experiment, we successfully isolated three phenylpropanoids and two lignan derivatives, namely, 6-allyl-5-methoxy-1,3-benzodioxol-4-ol (1), pachypostaudin B (2), pellucidin A (3), dillapiole (4), and apiol (5). Among these compounds, the isolation of 1 and 2 from P. pellucida is reported for the first time in this study. Activity assays clearly showed that the ethyl acetate extract and its fractions, subfractions, and isolated compounds exerted estrogenic activity. Methanol fraction of the ethyl acetate extract produced the highest estrogenic activity, while 1 and 2 had partial agonist activity. Some compounds (derivates of dillapiole and pellucidin A) also had, in addition, anti-estrogenic activity. In the docking study, the estrogenic activities of 1-5 appeared to be mediated by a classical ligand-dependent mechanism as suggested by the binding interaction between the compounds and estrogen receptors; binding occurred on Arg 394 and His 524 of the alpha receptor and Arg 346 and His 475 of the beta receptor. In summary, we reveal that P. pellucida is a promising anti-osteoporotic agent due to its estrogenic activity, and the compounds responsible for this activity were found to be lignan and phenylpropanoid derivatives. The presence of other compounds in either the extract or fraction may contribute to a synergistic effect, as suggested by the higher estrogenic activity of the methanol fraction. Hence, we suggest further research on the osteoporotic activity and safety of the identified compounds, especially regarding their effects on estrogen-responsive organs.

Streamlined Catalytic Enantioselective Synthesis of α-Substituted β,γ-Unsaturated Ketones and Either of the Corresponding Tertiary Homoallylic Alcohol Diastereomers

A widely applicable, practical, and scalable strategy for efficient and enantioselective synthesis of β,γ-unsaturated ketones that contain an α-stereogenic center is disclosed. Accordingly, aryl, heteroaryl, alkynyl, alkenyl, allyl, or alkyl ketones that contain an α-stereogenic carbon with an alkyl, an aryl, a benzyloxy, or a siloxy moiety can be generated from readily available starting materials and by the use of commercially available chiral ligands in 52-96% yield and 93:7 to >99:1 enantiomeric ratio. To develop the new method, conditions were identified so that high enantioselectivity would be attained and the resulting α-substituted NH-ketimines, wherein there is strong C═N → B(pin) coordination, would not epimerize before conversion to the derived ketone by hydrolysis. It is demonstrated that the ketone products can be converted to an assortment of homoallylic tertiary alcohols in 70-96% yield and 92:8 to >98:2 dr-in either diastereomeric form-by reactions with alkyl-, aryl-, heteroaryl-, allyl-, vinyl-, alkynyl-, or propargyl-metal reagents. The utility of the approach is highlighted through transformations that furnish other desirable derivatives and a concise synthesis route affording more than a gram of a major fragment of anti-HIV agents rubriflordilactones A and B and a specific stereoisomeric analogue.

HFIP-Promoted Synthesis of Substituted Tetrahydrofurans by Reaction of Epoxides with Electron-Rich Alkenes

In the present work, the employment of fluorinated alcohols, specifically 1,1,1,3,3,3-hexafluoroisopropanol (HFIP), as solvent and promoter of the catalyst-free synthesis of substituted tetrahydrofuranes through the addition of electron-rich alkenes to epoxydes is described. The unique properties of this fluorinated alcohol, which is very different from their non-fluorinated analogs, allows carrying out this new straightforward protocol under smooth reaction conditions affording the corresponding adducts in moderate yields in the majority of cases. Remarkably, this methodology has allowed the synthesis of new tetrahydrofuran-based spiro compounds as well as tetrahydrofurobenzofuran derivatives. The scope and limitations of the process are also discussed. Mechanistic studies were also performed pointing towards a purely ionic or a SN2-type process depending on the nucleophilicity of the alkene employed.

Triazoxins: Novel nucleosides with anti-Giardia activity

Novel nucleoside analogues named "triazoxins" were synthesized. Of these, two analogues were found to be highly effective against Giardia lamblia, an intestinal parasite and a major cause of waterborne infection, worldwide. While compound 7 reduced the growth of trophozoites in culture (IC50, ~5 μM), compound 21 blocked the in vitro cyst production (IC50 ~5 μM). Compound 21 was also effective against trophozoites (IC50, ~36 μM). A third analogue (compound 8) was effective against both trophozoites (IC50, ~36 μM) and cysts (IC50, ~20 μM) although at higher concentration. Thus triazoxin analogues are unique and exhibit morphology (i.e., trohozoites or cysts) -specific effects against Giardia.

Synthesis and Studies of the Inhibitory Effect of Hydroxylated Phenylpropanoids and Biphenols Derivatives on Tyrosinase and Laccase Enzymes

The impaired activity of tyrosinase and laccase can provoke serious concerns in the life cycles of mammals, insects and microorganisms. Investigation of inhibitors of these two enzymes may lead to the discovery of whitening agents, medicinal products, anti-browning substances and compounds for controlling harmful insects and bacteria. A small collection of novel reversible tyrosinase and laccase inhibitors with a phenylpropanoid and hydroxylated biphenyl core was prepared using naturally occurring compounds and their activity was measured by spectrophotometric and electrochemical assays. Biosensors based on tyrosinase and laccase enzymes were constructed and used to detect the type of protein-ligand interaction and half maximal inhibitory concentration (IC50). Most of the inhibitors showed an IC50 in a range of 20-423 nM for tyrosinase and 23-2619 nM for laccase. Due to the safety concerns of conventional tyrosinase and laccase inhibitors, the viability of the new compounds was assayed on PC12 cells, four of which showed a viability of roughly 80% at 40 µM. In silico studies on the crystal structure of laccase enzyme identified a hydroxylated biphenyl bearing a prenylated chain as the lead structure, which activated strong and effective interactions at the active site of the enzyme. These data were confirmed by in vivo experiments performed on the insect model Tenebrio molitur.

The Tapetal Major Facilitator NPF2.8 Is Required for Accumulation of Flavonol Glycosides on the Pollen Surface in Arabidopsis thaliana

The exine of angiosperm pollen grains is usually covered by a complex mix of metabolites including pollen-specific hydroxycinnamic acid amides (HCAAs) and flavonoid glycosides. Although the biosynthetic pathways resulting in the formation of HCAAs and flavonol glycosides have been characterized, it is unclear how these compounds are transported to the pollen surface. In this report we provide several lines of evidence that a member of the nitrate/peptide transporter family is required for the accumulation and transport of pollen-specific flavonol 3-o-sophorosides, characterized by a glycosidic β-1,2-linkage, to the pollen surface of Arabidopsis (Arabidopsis thaliana). Ectopic, transient expression in Nicotiana benthamiana epidermal leaf cells demonstrated localization of this flavonol sophoroside transporter (FST1) at the plasmalemma when fused to green fluorescent protein (GFP). We also confirmed the tapetum-specific expression of FST1 by GFP reporter lines driven by the FST1 promoter. In vitro characterization of FST1 activity was achieved by microbial uptake assays based on ¹⁴C-labeled flavonol glycosides. Finally, rescue of an fst1 insertion mutant by complementation with an FST1 genomic fragment restored the accumulation of flavonol glycosides in pollen grains to wild-type levels, corroborating the requirement of FST1 for transport of flavonol-3-o-sophorosides from the tapetum to the pollen surface.

N,O-Nucleoside Analogues: Metabolic and Apoptotic Activity

Two new families of N,O-nucleoside analogues containing the anthracene moiety introduced through the nitrosocarbonyl ene reaction with allylic alcohols were prepared. The core structure is an isoxazolidine heterocycle that introduces either atom either a phenyl ring or dimethyl moiety at the C3 carbon. Different heterobases were inserted at the position 5 of the heterocyclic ring. One of the synthesized compounds demonstrated a good capacity to induce cell death and an appreciable nuclear fragmentation was evidenced in treated cells.

Hybrid cardiovascular sourced extracellular matrix scaffolds as possible platforms for vascular tissue engineering

The aim when designing a scaffold is to provide a supportive microenvironment for the native cells, which is generally achieved by structurally and biochemically imitating the native tissue. Decellularized extracellular matrix (ECM) possesses the mechanical and biochemical cues designed to promote native cell survival. However, when decellularized and reprocessed, the ECM loses its cell supporting mechanical integrity and architecture. Herein, we propose dissolving the ECM into a polymer/solvent solution and electrospinning it into a fibrous sheet, thus harnessing the biochemical cues from the ECM and the mechanical integrity of the polymer. Bovine aorta and myocardium were selected as ECM sources. Decellularization was achieved using sodium dodecyl sulfate (SDS), and the ECM was combined with polycaprolactone and hexafluoro-2-propanol for electrospinning. The scaffolds were seeded with human umbilical vein endothelial cells (HUVECs). The study found that the inclusion of aorta ECM increased the scaffold's wettability and subsequently lead to increased HUVEC adherence and proliferation. Interestingly, the inclusion of myocardium ECM had no effect on wettability or cell viability. Furthermore, gene expression and mechanical changes were noted with the addition of ECM. The results from this study show the vast potential of electrospun ECM/polymer bioscaffolds and their use in tissue engineering.

Special Issue: Development of Asymmetric Synthesis

Biological systems usually respond differently to enantiomers of a chiral molecule due to the inherent chirality of the active receptor sites of enzymes in nature [...].

Divergent Asymmetric Total Synthesis of All Four Pestalotin Diastereomers from (R)-Glycidol

All four chiral pestalotin diastereomers were synthesized in a straightforward and divergent manner from common (R)-glycidol. Catalytic asymmetric Mukaiyama aldol reactions of readily-available bis(TMSO)diene (Chan’s diene) with (S)-2-benzyloxyhexanal derived from (R)-glycidol produced a syn-aldol adduct with high diastereoselectivity and enantioselectivity using a Ti(iOPr)₄/(S)-BINOL/LiCl catalyst. Diastereoselective Mukaiyama aldol reactions mediated by catalytic achiral Lewis acids directly produced not only a (1′S,6S)-pyrone precursor via the syn-aldol adduct using TiCl₄, but also (1′S,6R)-pyrone precursor via the antialdol adduct using ZrCl₄, in a stereocomplementary manner. A Hetero-Diels-Alder reaction of similarly available mono(TMSO)diene (Brassard’s diene) with (S)-2-benzyloxyhexanal produced the (1′S,6S)-pyrone precursor promoted by Eu(fod)₃ and the (1′S,6R)-pyrone precursor Et₂AlCl. Debenzylation of the (1′S,6S)-precursor and the (1′S,6R)-precursor furnished natural (−)-pestalotin (99% ee, 7 steps) and unnatural (+)-epipestalotin (99% ee, 7 steps), respectively. Mitsunobu inversions of the obtained (−)-pestalotin and (+)-epipestalotin successfully produced the unnatural (+)-pestalotin (99% ee, 9 steps) and (−)-epipestalotin (99% ee, 9 steps), respectively, in a divergent manner. All four of the obtained chiral pestalotin diastereomers possessed high chemical and optical purities (optical rotations, ¹H-NMR, ¹³C-NMR, and HPLC measurements).

Self-associating cellulose-graft-poly(ε-caprolactone) to design nanoparticles for drug release

The growing interest in the use of polysaccharides nanoparticles for biomedical applications is related to the recent progresses on the synthesis of cellulose-based polymers with the specific functionalities. In particular, cellulose graft copolymers are emerging as amphiphilic materials suitable to fabricate smart nanoparticles for drug delivery applications. In this work, a cellulose-graft-poly(ε-caprolactone) (cell-g-PCL) was synthetized and characterized by FTIR, TGA and DSC in order to validate the synthesis process. We demonstrated that fast evaporation processes promoted cell-g-PCL self-assembly to form nanomicellar structures with hydrodynamic radius ranged from 30 to 60 nm as confirmed by TEM analysis. Moreover, the application of controlled electrostatic forces on solvent evaporation - namely electrospraying - allowed generating round-like nanoscaled particles, as confirmed by SEM supported via image analysis. We demonstrated also that sodium diclofenac (DS) drastically influenced the mechanism of particle formation, favoring the deposition of erythrocyte-like particles with highly concave surfaces, not penalizing the encapsulation efficiency of nanoparticles (>80%). The release profile showed a fast delivery of DS - about 60% during the first 24 h - followed by a sustained release - about 20% during the next 6 days - strictly related to the peculiar weak interactions among amphiphilic polymer segments and water molecules, thus suggesting a successful use of electrosprayed cell-g-PCL nanoparticles for therapeutic treatments in nanomedicine.

Structure Water-Solubility Relationship in α-Helix-Rich Films Cast from Aqueous and 1,1,1,3,3,3-Hexafluoro-2-Propanol Solutions of S. c. ricini Silk Fibroin

Silk fibroin (SF) produced by the domesticated wild silkworm, Samia cynthia ricini (S. c. ricini) is attracting increasing interest owing to its unique mechanical properties, biocompatibility, and abundance in nature. However, its utilization is limited, largely due to lack of appropriate processing strategies. Various strategies have been assessed to regenerate cocoon SF, as well as the use of aqueous liquid fibroin (LFaq) prepared by dissolution of silk dope obtained from the silk glands of mature silkworm larvae in water. However, films cast from these fibroin solutions in water or organic solvents are often water-soluble and require post-treatment to render them water-stable. Here, we present a strategy for fabrication of water-stable films from S. c. ricini silk gland fibroin (SGF) without post-treatment. Aqueous ethanol induced gelation of fibroin in the posterior silk glands (PSG), enabling its separation from the rest of the silk gland. When dissolved in 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP), the SGF-gel gave a solution from which a transparent, flexible, and water-insoluble film (SGFHFIP) was cast. Detailed structural characterization of the SGFHFIP as-cast film was carried out and compared to a conventional, water-soluble film cast from LFaq. FTIR and 13C solid-state NMR analyses revealed both cast films to be α-helix-rich. However, gelation of SGF induced by the 40%-EtOH-treatment resulted in an imperfect β-sheet structure. As a result, the SGF-gel was soluble in HFIP, but some β-sheet structural memory remains, and the SGFHFIP as-cast film obtained has some β-sheet content which renders it water-resistant. These results reveal a structure water-solubility relationship in S. c. ricini SF films that may offer useful insights towards tunable fabrication of novel biomaterials. A plausible model of the mechanism that leads to the difference in water resistance of the two kinds of α-helix-rich films is proposed.

Identification of Cinnamaldehyde as Most Effective Fatty Acid Uptake Reducing Cinnamon-Derived Compound in Differentiated Caco-2 Cells Compared to Its Structural Analogues Cinnamyl Alcohol, Cinnamic Acid, and Cinnamyl Isobutyrate

Naturally occurring cinnamon compounds such as cinnamaldehyde (CAL) and structurally related constituents have been associated with antiobesity activities, although studies regarding the impact on intestinal fatty acid uptake are scarce. Here, we demonstrate the effects of CAL and structural analogues cinnamyl alcohol (CALC), cinnamic acid (CAC), and cinnamyl isobutyrate on mechanisms regulating intestinal fatty acid uptake in differentiated Caco-2 cells. CAL, CALC, and CAC (3000 μM) were found to decrease fatty acid uptake by 58.0 ± 8.83, 19.4 ± 8.98, and 21.9 ± 6.55%, respectively. While CAL and CALC at a concentration of 300 μM increased serotonin release 14.9 ± 3.00- and 2.72 ± 0.69-fold, respectively, serotonin alone showed no effect on fatty acid uptake. However, CAL revealed transient receptor potential channel A1-dependency in the decrease of fatty acid uptake, as well as in CAL-induced serotonin release. Overall, CAL was identified as the most potent of the cinnamon constituents tested.

Solar light induced transformation mechanism of allyl alcohol to monocarbonyl and dicarbonyl compounds on different TiO2: A combined experimental and theoretical investigation

Enols are an important group of photochemical precursors of atmospheric carbonyl compounds. However, the transformation mechanism is not fully understood. In this study, the photo-induced transformation of a typical enol, allyl alcohol, to carbonyl compounds on TiO₂ (P25) and aluminum reduced TiO₂ (P25, rutile and anatase TiO₂) were investigated. Intermediate results confirmed that a total of seven carbonyl compounds, including four monocarbonyl compounds (acetone, glycolaldehyde, 1,3-dihydroxyacetone and acrolein) and three dicarbonyl compounds (glyoxal, methylglyoxal and dimethylglyoxal), were formed on studied TiO₂. This is the first time to report the transformation of allyl alcohol to dicarbonyl compounds on TiO₂. The same byproducts formation indicated negligible effects of reduction treatment and crystal phase to the composition of carbonyl intermediates. However, the relative content ratio of dicarbonyl compounds to monocarbonyl ones on reduced P25 is ca. 4.1 times higher than that on P25, suggesting reduction treatment significantly accelerated the transformation of allyl alcohol or monocarbonyl compounds to dicarbonyl ones. Furthermore, both rutile and anatase crystal phases were found beneficial for the dicarbonyl compounds generation within enough reaction time, especially for anatase. The enhanced ^•OH was responsible for all accelerations. Furthermore, the intermediate results together with quantum chemical calculations confirmed that ^•OH addition and O₂ oxidation preferred converting allyl alcohol to dicarbonyl compounds rather than monocarbonyl ones. The present work could provide a deep insight into the transformation of allyl alcohol to carbonyl compounds, and efficiently replenish atmospheric transformation fate of enols.

New Benzofuranoids and Phenylpropanoids from the Mangrove Endophytic Fungus, Aspergillus sp. ZJ-68

Three new benzofuranoids, asperfuranoids A-C (1-3), two new phenylpropanoid derivatives (6 and 7), and nine known analogues (4, 5, and 8-14) were isolated from the liquid substrate fermentation cultures of the mangrove endopytic fungus Aspergillus sp. ZJ-68. The structures of the new compounds were determined by extensive spectroscopic data interpretation. The absolute configurations of 1-3 were assigned via the combination of Mosher's method, and experimental and calculated electronic circular dichroism (ECD) data. Compounds 4 and 5 were a pair of enantiomers and their absolute configurations were established for the first time on the basis of their ECD spectra aided with ECD calculations. All isolated compounds (1-14) were evaluated for their enzyme inhibitory activity against α-glucosidase and antibacterial activities against four pathogenic bacteria (Staphylococcus aureus, Escherichia coli, Bacillus subtilis, and Pseudomonas aeruginosa). Among them, compound 6 exhibited potent inhibitory activity against α-glucosidase in a standard in vitro assay, with an IC₅₀ value of 12.4 μM, while compounds 8 and 11 showed activities against S. aureus, E. coli, and B. subtilis, with MIC values in the range of 4.15 to 12.5 μg/mL.

HFIP-Functionalized Co3 O4 Micro-Nano-Octahedra/rGO as a Double-Layer Sensing Material for Chemical Warfare Agents

Semiconductor metal oxides (SMO)-based gas-sensing materials suffer from insufficient detection of a specific target gas. Reliable selectivity, high sensitivity, and rapid response-recovery times under various working conditions are the main requirements for optimal gas sensors. Chemical warfare agents (CWA) such as sarin are fatal inhibitors of acetylcholinesterase in the nerve system. So, sensing materials with high sensitivity and selectivity toward CWA are urgently needed. Herein, micro-nano octahedral Co₃ O₄ functionalized with hexafluoroisopropanol (HFIP) were deposited on a layer of reduced graphene oxide (rGO) as a double-layer sensing materials. The Co₃ O₄ micro-nano octahedra were synthesized by direct growth from electrospun fiber templates calcined in ambient air. The double-layer rGO/Co₃ O₄ -HFIP sensing materials presented high selectivity toward DMMP (sarin agent simulant, dimethyl methyl phosphonate) versus rGO/Co₃ O₄ and Co₃ O₄ sensors after the exposure to various gases owing to hydrogen bonding between the DMMP molecules and Co₃ O₄ -HFIP. The rGO/Co₃ O₄ -HFIP sensors showed high stability with a response signal around 11.8 toward 0.5 ppm DMMP at 125 °C, and more than 75 % of the initial response was maintained under a saturated humid environment (85 % relative humidity). These results prove that these double-layer inorganic-organic composite sensing materials are excellent candidates to serve as optimal gas-sensing materials.

Pd-Catalyzed Stereodivergent Allylic Amination of α-Tertiary Allylic Alcohols towards α,β-Unsaturated γ-Amino Acids

Tertiary allylic alcohols were conveniently converted into either (Z)- or (E)-configured α,β-unsaturated γ-amino acids by treatment with secondary amines under Pd catalysis at ambient conditions. The key to control the stereochemical course of these formal allylic aminations was the presence of a suitable diphosphine ligand, with dppp [1,3-bis(diphenylphosphino)propane, L12] providing high yields and selectivities for the (Z) isomers, whereas the bis[(2-diphenylphosphino)phenyl]ether (DPEPhos) derivative L1' allowed for selective formation of the corresponding (E) isomeric products. This ligand-controlled, stereodivergent protocol thus shows promise for the stereoselective preparation of allylic amine products from a common substrate precursor.

Stability of nitroxide biradical TOTAPOL in biological samples

We characterize chemical reduction of a nitroxide biradical, TOTAPOL, used in dynamic nuclear polarization (DNP) experiments, specifically probing the stability in whole-cell pellets and lysates, and present a few strategies to stabilize the biradicals for DNP studies. DNP solid-state NMR experiments use paramagnetic species such as nitroxide biradicals to dramatically increase NMR signals. Although there is considerable excitement about using nitroxide-based DNP for detecting the NMR spectra of proteins in whole cells, nitroxide radicals are reduced in minutes in bacterial cell pellets, which we confirm and quantify here. We show that addition of the covalent cysteine blocker N-ethylmaleimide to whole cells significantly slows the rate of reduction, suggesting that cysteine thiol radicals are important to in vivo radical reduction. The use of cell lysates rather than whole cells also slows TOTAPOL reduction, which suggests a possible role for the periplasm and oxidative phosphorylation metabolites in radical degradation. Reduced TOTAPOL in lysates can also be efficiently reoxidized with potassium ferricyanide. These results point to a practical and robust set of strategies for DNP of cellular preparations.

A Review: The Bioactivities and Pharmacological Applications of Phellinus linteus

Phellinus linteus is a popular medicinal mushroom that is widely used in China, Korea, Japan, and other Asian countries. P. linteus comprises various bioactive components, such as polysaccharides, triterpenoids, phenylpropanoids, and furans, and has proven to be an effective therapeutic agent in traditional Chinese medicine for the treatment and the prevention of various diseases. A number of studies have reported that P. linteus possesses many biological activities useful for pharmacological applications, including anticancer, anti-inflammatory, immunomodulatory, antioxidative, and antifungal activities, as well as antidiabetic, hepatoprotective, and neuroprotective effects. This review article briefly presents the recent progress made in understanding the bioactive components, biological activities, pharmacological applications, safety, and prospects of P. linteus, and provides helpful references and promising directions for further studies of P. linteus.

The role of fluoroalcohols as counter anions for ion-pairing reversed-phase liquid chromatography/high-resolution electrospray ionization mass spectrometry analysis of oligonucleotides

RATIONALE

Hexafluoroisopropanol (HFIP) has been widely used as a counter anion in the mobile phase for ion-pairing reversed-phase liquid chromatography/mass spectrometry (IP-RP-LC/MS) analysis of oligonucleotides. However, researchers are still searching for improvements to counter anions for LC/MS analysis of oligonucleotides. This study aimed to find alternatives to HFIP for analyzing oligonucleotides.

METHODS

The study was performed using an Agilent 1290 ultra-high-performance liquid chromatography (UHPLC) system coupled to an Agilent 6540 mass spectrometer by using an oligonucleotide BEH C18 column (100 × 2.1 mm, 1.7 μm). Buffer systems containing ion-pairing reagents (triethylamine, tripropylamine, hexylamine, dimethylbutylamine, diisopropylethylamine, N,N-dimethylcyclohexylamine, and octylamine) and fluoroalcohols (HFIP and hexafluoro-2-methyl-2-propanol (HFTP)) were compared chromatographically and mass spectrometrically.

RESULTS

Results showed that HFTP has better desalting ability than HFIP, but both HFIP and HFTP have comparable effects on the separation of oligonucleotides sized from 10mer to 40mer for most of ion-pairing reagents, with the exception of triethylamine and N,N-dimethylcyclohexylamine, where HFIP performed better than HFTP.

CONCLUSIONS

The choice of fluoroalcohols in IP-RP-LC/MS analysis of oligonucleotides depends on the type of ion-pairing reagents used in the mobile phase. As a guideline, we would recommend to use either HA-HFIP or HA-HFTP for small oligonucleotides, but TPA-HFTP for large oligonucleotides for IP-RP-LC/MS analysis of synthetic oligonucleotides.

Ruthenium-Catalyzed Redox Isomerizations inside Living Cells

Tailored ruthenium(IV) complexes can catalyze the isomerization of allylic alcohols into saturated carbonyl derivatives under physiologically relevant conditions, and even inside living mammalian cells. The reaction, which involves ruthenium-hydride intermediates, is bioorthogonal and biocompatible, and can be used for the "in cellulo" generation of fluorescent and bioactive probes. Overall, our research reveals a novel metal-based tool for cellular intervention, and comes to further demonstrate the compatibility of organometallic mechanisms with the complex environment of cells.

Identification of minor lignans, alkaloids, and phenylpropanoid glycosides in Magnolia officinalis by HPLC‒DAD‒QTOF-MS/MS

An effective strategy based on high-speed counter-current chromatography (HSCCC) knockout combination with HPLC-DAD-QTOF-MS/MS analysis were developed to identify minor lignans, alkaloids, and phenylpropanoid glycosides in M. officinalis. Petroleum ether/ethyl acetate/methanol/water (8:4:7:5, v/v/v/v) as solvent system was firstly selected to separate the crude extract of M. officinalis. Two major lignans, honokiol and magnolol were knocked out, and minor components were enriched. Then, five standards (honokiol, magnolol, magnocurarine, magnoflorine and acteoside) were used as examples to discuss their fragmentation patterns for structural identification. By comprehensive screening, sixteen lignans, nine alkaloids, six phenylpropanoid glycosides were unambiguously or tentatively identified by comparing their retention time, UV spectra, accurate mass and fragmentation patterns with standards or reported components. Eight of them, as far as was known, were discovered from M. officinalis for the first time. The proposed method might provide a model for the effective identification of minor components from complex herbs. Additionally, this study laid a foundation for the study of quality control, and clinical applications of M. officinalis.

A Complementary Process to Pauson-Khand-Type Annulation Reactions for the Construction of Fully Substituted Cyclopentenones

A complementary process to the Pauson-Khand annulation is described that is well suited to forging densely substituted/oxygenated cyclopentenone products (including fully substituted variants). The reaction is thought to proceed through a sequence of metallacycle-mediated bond-forming events that engages an internal alkyne and a β-keto ester in an annulation process that forges two C-C bonds. A variant of this annulation process has also been established that delivers deoxygenated cyclopentenones that lack the allylic tertiary alcohol.

Hexafluoroisopropanol/Brij-35 based supramolecular solvent for liquid-phase microextraction of parabens in different matrix samples

A novel supramolecular solvent (SUPRAS) based on hexafluoroisopropanol (HFIP)/Brij-35 was proposed for liquid-phase microextraction (LPME) of parabens in water samples, pharmaceuticals and personal care products. Brij-35 is a cost-effective and non-toxic non-ionic surfactant, but it has a high cloud point (>100 °C). HFIP, with the features of strong hydrogen-bond donor, high density and powerful hydrophobicity, was used as the cloud point-reducing agent and self-assembling and density-regulating solvent of Brij-35. Upon adding HFIP into the Brij-35 aqueous solution, the cloud point of Brij-35 was decreased to below room temperature, and the SUPRAS was formed in the bottom over a wide range of HFIP and Brij-35 concentrations at room temperature. The SUPRAS was composed of Brij-35, HFIP and water, having a density larger than water, and it showed a large spherical structure of positive micellar aggregates (2-8 μm). The HFIP/ Brij-35 SUPRAS-based LPME procedure was non-thermodependent and could be performed at room temperature with centrifugation using normal centrifuge tubes, being very simple. In the extraction of six parabens, the HFIP/ Brij-35 SUPRAS-based LPME method showed short extraction time (3.3 min), low solvent consumption (0.3 mL), and large enrichment factor (26-193). The method of HFIP/ Brij-35 SUPRAS-based LPME with HPLC-DAD gave good linearity for the quantification of parabens with correlation coefficients larger than 0.9990. The limits of detection based on a signal-to-noise ratio of 3 were from 0.042 to 0.167 μg L^-1. The recoveries for the spiked real samples were in the range of 90.2-112.4% with relative standard deviation less than 8.9%. Except for tap water, one or several paraben (s) were detected in all the other real samples.

Photoredox/Nickel-Catalyzed Single-Electron Tsuji-Trost Reaction: Development and Mechanistic Insights

A regioselective, nickel-catalyzed photoredox allylation of secondary, benzyl, and α-alkoxy radical precursors is disclosed. Through this manifold, a variety of linear allylic alcohols and allylated monosaccharides are accessible in high yields under mild reaction conditions. Quantum mechanical calculations [DFT and DLPNO-CCSD(T)] support the mechanistic hypothesis of a Ni0 to NiII oxidative addition pathway followed by radical addition and inner-sphere allylation.

TfOH-Promoted Reaction of 2,4-Diaryl-1,1,1-Trifluorobut-3-yn-2-oles with Arenes: Synthesis of 1,3-Diaryl-1-CF₃-Indenes and Versatility of the Reaction Mechanisms

The TfOH-mediated reactions of 2,4-diaryl-1,1,1-trifluorobut-3-yn-2-oles (CF₃-substituted diaryl propargyl alcohols) with arenes in CH₂Cl₂ afford 1,3-diaryl-1-CF₃-indenes in yields up to 84%. This new process for synthesis of such CF₃-indenes is complete at room temperature within one hour. The synthetic potential, scope, and limitations of this reaction were illustrated by more than 70 examples. The proposed reaction mechanism invokes the formation of highly reactive CF₃-propargyl cation intermediates that can be trapped at the two mesomeric positions by the intermolecular nucleophilic attack of an arene partner with a subsequent intramolecular ring closure.

Ionic Liquid-Promoted Three-Component Domino Reaction of Propargyl Alcohols, Carbon Dioxide and 2-Aminoethanols: A Thermodynamically Favorable Synthesis of 2-Oxazolidinones

To circumvent the thermodynamic limitation of the synthesis of oxazolidinones starting from 2-aminoethanols and CO₂ and realize incorporation CO₂ under atmospheric pressure, a protic ionic liquid-facilitated three-component reaction of propargyl alcohols, CO₂ and 2-aminoethanols was developed to produce 2-oxazolidinones along with equal amount of α-hydroxyl ketones. The ionic liquid structure, reaction temperature and reaction time were in detail investigated. And 15 mol% 1,5,7-triazabicylo[4.4.0]dec-5-ene ([TBDH][TFE]) trifluoroethanol was found to be able to synergistically activate the substrate and CO₂, thus catalyzing this cascade reaction under atmospheric CO₂ pressure. By employing this task-specific ionic liquid as sustainable catalyst, 2-aminoethanols with different substituents were successfully transformed to 2-oxazolidinones with moderate to excellent yield after 12 h at 80 °C.

Two pairs of phenylpropanoid enantiomers from the leaves of Eucommia ulmoides

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.

Alkylamine ion-pairing reagents and the chromatographic separation of oligonucleotides

Alkylamines are commonly used to improve both chromatographic and mass spectral performance of electrospray ionization liquid chromatography mass spectrometry based methods for the analysis of oligonucleotides. Recently several new alkylamines have been introduced to enhance the electrospray mass spectral response for oligonucleotides; however, the chromatographic properties of these new alkylamines have not been rigorously assessed. We have investigated the retention, peak width, resolution and general chromatographic performance of fifteen different alkylamines for the separation of a model DNA, RNA and an antisense therapeutic oligonucleotide. Eleven of the fifteen alkylamines were shown to provide similar chromatographic performance across all three classes of oligonucleotides. Based on these findings, a model for the mechanism of retention of oligonucleotides using alkylamines and hexafluoroisopropanol mobile phases is proposed. Depending on the concentrations of alkylamines and pH adjustment, oligonucleotides can be retained by micellar chromatography and not the generally held ion-pairing mechanism. This conclusion is supported by light scattering, transmission electron microscopy and ion mobility experiments detecting three micron aggregates in the mobile phase at concentrations that are routinely used for LC-MS analysis of oligonucleotides. These aggregates are not detected at lower alkylamine concentrations where the retention mechanism follows an ion-pairing mechanism. The formation of these aggregates appears to be dependent on the pH of the mobile phase.

Heck Transformations of Biological Compounds Catalyzed by Phosphine-Free Palladium

The development and optimization of synthetic methods leading to functionalized biologically active compounds is described. Two alternative pathways based on Heck-type reactions, employing iodobenzene or phenylboronic acid, were elaborated for the arylation of eugenol and estragole. Cinnamyl alcohol was efficiently transformed to saturated arylated aldehydes in reaction with iodobenzene using the tandem arylation/isomerization sequential process. The arylation of cinnamyl alcohol with phenylboronic acid mainly gave unsaturated alcohol, while the yield of saturated aldehyde was much lower. Catalytic reactions were carried out using simple, phosphine-free palladium precursors and water as a cosolvent, following green chemistry rules as much as possible.

Toxic and Repellent Effects of Volatile Phenylpropenes from Asarum heterotropoides on Lasioderma serricorne and Liposcelis bostrychophila

Toxic and repellent effects of the essential oil from Asarum heterotropoides Fr. Schmidt var. mandshuricum (Maxim.) Kitag. were evaluated against Lasioderma serricorne and Liposcelis bostrychophila. The essential oils (EOs) from roots (ER) and leaves (EL) of A. heterotropoides were obtained separately by hydrodistillation and characterized by gas chromatography-mass spectrometry (GC-MS) analysis. Major components of ER and EL included methyleugenol, safrole, and 3,5-dimethoxytoluene. Both ER and EL of A. heterotropoides showed certain toxicity and repellency against L. serricorne and L. bostrychophila. 3,5-Dimethoxytoluene, methyleugenol, and safrole were strongly toxic via fumigation to L. serricorne (LC50 = 4.99, 10.82, and 18.93 mg/L air, respectively). Safrole and 3,5-dimethoxytoluene possessed significant fumigant toxicity against L. bostrychophila (LC50 = 0.83 and 0.91 mg/L air, respectively). The three compounds all exhibited potent contact toxicity against the two insect species. Here, the EL of A. heterotropoides was confirmed to have certain toxicity and repellency against stored product insects, providing a novel idea for the comprehensive use of plant resources.

Rhodium(iii)-catalyzed C-H allylation of indoles with allyl alcohols via β-hydroxide elimination

An efficient Rh(iii)-catalyzed dehydrative C-H allylation of indoles with allyl alcohols via β-hydroxide elimination under oxidant-free conditions has been developed. This method features very mild reaction conditions, excellent regioselectivity and stereoselectivity, and compatibility with various functional groups. In addition, the directing group can be removed under mild reaction conditions, which further underscores the synthetic utility of this method.

Catalytic Dehydration of Fructose to 5-Hydroxymethylfurfural (HMF) in Low-Boiling Solvent Hexafluoroisopropanol (HFIP)

A mixture of hexafluoroisopropanol (HFIP) and water was used as a new and unknown monophasic reaction solvent for fructose dehydration in order to produce HMF. HFIP is a low-boiling fluorous alcohol (b.p. 58 °C). Hence, HFIP can be recovered cost efficiently by distillation. Different ion-exchange resins were screened for the HFIP/water system in batch experiments. The best results were obtained for acidic macroporous ion-exchange resins, and high HMF yields up to 70% were achieved. The effects of various reaction conditions like initial fructose concentration, catalyst concentration, water content in HFIP, temperature and influence of the catalyst particle size were evaluated. Up to 76% HMF yield was attained at optimized reaction conditions for high initial fructose concentration of 0.5 M (90 g/L). The ion-exchange resin can simply be recovered by filtration and reused several times. This reaction system with HFIP/water as solvent and the ion-exchange resin Lewatit K2420 as catalyst shows excellent performance for HMF synthesis.

Novel Method for l-Methionine Production Catalyzed by the Aminotransferase ARO8 from Saccharomyces cerevisiae

The aminotransferase ARO8 was proved to play an efficient role in conversion of l-methionine into methionol via the Ehrlich pathway in Saccharomyces cerevisiae in our previous work. In this work, the reversible transamination activity of ARO8 for conversion of α-keto-γ-(methylthio) butyric acid (KMBA) into l-methionine was confirmed in vitro. ARO8 was cloned from S. cerevisiae S288c and overexpressed in Escherichia coli BL21. A 2-fold higher aminotransferase activity was detected in the recombinant strain ARO8-BL21, and ARO8 was detected in the supernatant of ARO8-BL21 lysate with IPTG induction by SDS-PAGE analysis. The recombinant ARO8 was then purified and used for transforming KMBA into l-methionine. An approximately 100% conversion rate of KMBA into l-methionine was achieved by optimized enzymatic reaction catalyzed by ARO8. This work fulfilled l-methionine biosynthesis catalyzed by the aminotransferase ARO8 using glutamate and KMBA, which provided a novel method for l-methionine production by enzymatic catalysis with the potential application prospect in industry.

E-p-Methoxycinnamoyl-α-l-rhamnopyranosyl Ester, a Phenylpropanoid Isolated from Scrophularia buergeriana, Increases Nuclear Factor Erythroid-Derived 2-Related Factor 2 Stability by Inhibiting Ubiquitination in Human Keratinocytes

The nuclear factor erythroid-derived 2-related factor 2 (Nrf2) is a key regulator of gene expression during oxidative stress and drug detoxification. Thus, identifying Nrf2 activators to protect from possible cell damage is necessary. In this study, we investigated whether E-p-methoxycinnamoyl-α-l-rhamnopyranosyl ester (MCR), a phenylpropanoid isolated from Scrophularia buergeriana, can activate Nrf2 signaling in human keratinocytes (HaCaT). First, we determined the dose- and time-dependent effects of MCR on the expression and activity of Nrf2. The antioxidant response element-luciferase reporter assay and western blot analysis results showed that MCR markedly induced Nrf2 activity and its protein expression, respectively. Further, MCR increased both the mRNA and protein levels of heme-oxygenase-1, one of the Nrf2 target genes, in the cells. Interestingly, we found that Nrf2 stability was remarkably enhanced by MCR. Furthermore, ubiquitin-dependent proteasomal degradation of Nrf2 was significantly reduced by MCR. Thus, MCR might afford skin protection by enhancing Nrf2 stability or by blocking its proteasomal degradation.

Recent developments for introducing a hexafluoroisopropanol unit into the Vitamin D side chain

Among numerous studies on synthetic approaches to and the biological activities of vitamin D analogues, we herein focused on falecalcitriol, an analogue of calcitriol (1α,25-dihydroxyvitamin D₃), in which a 26,26,26,27,27,27-hexafluoroisopropanol unit has been introduced into the side chain. Falecalcitriol was designed to escape from the metabolism of CYP24A1 and has been used as a drug to treat secondary hyperparathyroidism since 2001. Its metabolite, the 23-hydroxy form, retains biological activity and resistants to further metabolism. Recent developments in synthetic methodologies for introducing the hexafluoroisopropanol unit into the vitamin D CD-ring side chain were described herein.

Anti-Inflammatory Prenylated Phenylpropenols and Coumarin Derivatives from Murraya exotica

Three new prenylated phenylpropenols, exotiacetals A-C (1-3), 10 new coumarin derivatives, exotimarins A-I (4-13), and 35 known analogues (14-48) were isolated from the roots of Murraya exotica. The absolute configurations of the new compounds were assigned via comparison of their specific rotations, single-crystal X-ray diffraction data, Mosher's method, the ECD exciton coupling method, comparison of experimental and calculated ECD data, and the ECD data of the in situ formed transition metal complexes. Compounds 1-3, which possess an unprecedented hexahydro-1H-isochromen-1-ol system, are presumably biosynthesized from two prenylated p-coumaryl alcohol moieties via Diels-Alder [4+2] cycloaddition and cyclic hemiacetal formation reactions. Compounds 1, 28, 33, and 35 demonstrated inhibition against LPS-induced NO production in BV-2 microglial cells with IC₅₀ values of 8.6 ± 0.3, 11.8 ± 0.9, 15.5 ± 0.9, and 16.9 ± 1.0 μM, respectively.

Identification of bicyclic hexafluoroisopropyl alcohol sulfonamides as retinoic acid receptor-related orphan receptor gamma (RORγ/RORc) inverse agonists. Employing structure-based drug design to improve pregnane X receptor (PXR) selectivity

We disclose the optimization of a high throughput screening hit to yield benzothiazine and tetrahydroquinoline sulfonamides as potent RORγt inverse agonists. However, a majority of these compounds showed potent activity against pregnane X receptor (PXR) and modest activity against liver X receptor α (LXRα). Structure-based drug design (SBDD) led to the identification of benzothiazine and tetrahydroquinoline sulfonamide analogs which completely dialed out LXRα activity and were less potent at PXR. Pharmacodynamic (PD) data for compound 35 in an IL-23 induced IL-17 mouse model is discussed along with the implications of a high Ymax in the PXR assay for long term preclinical pharmacokinetic (PK) studies.

Phenylpropanoid profiling reveals a class of hydroxycinnamoyl glucaric acid conjugates in Isatis tinctoria leaves

The brassicaceous herb, Isatis tinctoria, is an ancient medicinal plant whose rosette leaf extracts have anti-inflammatory and anti-allergic activity. Brassicaceae are known to accumulate a variety of phenylpropanoids in their rosette leaves acting as antioxidants and a UV-B shield, and these compounds often have pharmacological potential. Nevertheless, knowledge about the phenylpropanoid content of I. tinctoria leaves remains limited to the characterization of a number of flavonoids. In this research, we profiled the methanol extracts of I. tinctoria fresh leaf extracts by liquid chromatography - mass spectrometry (LC-MS) and focused on the phenylpropanoid derivatives. We report the structural characterization of 99 compounds including 18 flavonoids, 21 mono- or oligolignols, 2 benzenoids, and a wide spectrum of 58 hydroxycinnamic acid esters. Besides the sinapate esters of malate, glucose and gentiobiose, which are typical of brassicaceous plants, these conjugates comprised a large variety of glucaric acid esters that have not previously been reported in plants. Feeding with ¹³C₆-glucaric acid showed that glucaric acid is an acyl acceptor of an as yet unknown acyltransferase activity in I. tinctoria rosette leaves. The large amount of hydroxycinnamic acid derivatives changes radically our view of the woad metabolite profile and potentially contributes to the pharmacological activity of I. tinctoria leaf extracts.

Terpenoids and Phenylpropanoids in Ligularia duciformis, L. kongkalingensis, L. nelumbifolia, and L. limprichtii

The diversity in root chemicals and evolutionally neutral DNA regions in the complex of Ligularia duciformis, L. kongkalingensis, and L. nelumbifolia (the d/k/n complex) was studied using eight samples collected in central and northern Sichuan Province of China. Cacalol (14) and epicacalone (15), rearranged eremophilanes, were isolated from the complex for the first time. Two new phenylpropanoids were also obtained. Seven of the eight samples produced phenylpropanoids and the other produced lupeol alone. Two of the seven samples also produced furanoeremophilanes or their derivatives and one produced oplopanes. The geographical distribution of the sesquiterpene-producing populations suggests that the production of sesquiterpenes evolved independently in separate regions. L. limprichtii collected in northern Sichuan was also analyzed and its chemical composition and the sequence of internal transcribed spacers (ITSs) in the ribosomal RNA gene cluster were found to be similar to that in the d/k/n complex and L. yunnanensis, which are morphologically similar.

The Conjugated Double Bond of Coniferyl Aldehyde Is Essential for Heat Shock Factor 1 Mediated Cytotoprotection

Coniferyl aldehyde (1) is previously reported as a potent inducer of heat shock factor 1 (HSF1). Here, we further examined the active pharmacophore of 1 for activation of HSF1 using the derivatives coniferyl alcohol (2), 4-hydroxy-3-methoxyphenylpropanal (3), and 4-hydroxy-3-methoxyphenylpropanol (4). Both 1 and 2 resulted in increased survival days after a lethal radiation (IR) dose. The decrease in bone marrow (BM) cellularity and Ki67-positive BM cells by IR was also significantly restored by 1 or 2 in mice. These results suggested that the vinyl moiety of 1 and 2 is necessary for inducing HSF1, which may be useful for developing small molecules for cytoprotection of normal cells against damage by cytotoxic drugs and radiation.

Total Synthesis of Tedarene A

Tedarene A is a macrocyclic diaryl ether heptanoid isolated from the marine sponge Tedania ignis showing an inhibitory effect against nitric oxide production. The first total synthesis of tedarene A was achieved starting from the commercially available 3-(4-methoxyphenyl)propan-1-ol in nine steps and 15.3% overall yield. The synthetic sequence featured an E,Z-dienic bond introduction and a macrocyclization under Ullman conditions. During the synthesis, the E,E-isomer of tedarene A was also obtained and fully characterized.

Glycidol, a Valuable Substrate for the Synthesis of Monoalkyl Glyceryl Ethers: A Simplified Life Cycle Approach

The disposal of any waste by recovering it within the production plant represents the ultimate goal of every biorefinery. In this scenario, the selective preparation of monoalkyl glyceryl ethers (MAGEs) starting from glycidol, obtained as byproduct in the epichlorohydrin production plant, represents a very promising strategy. Here, we report the synthesis of MAGEs through the reaction of glycidol with alcohols catalyzed by a green homogeneous Lewis acids catalyst, such as Bi^III triflate, under very mild reaction conditions. To evaluate the green potential of the proposed alternative, a simplified life cycle assessment (LCA) approach was followed by comparing the environmental performance of the proposed innovative route to prepare MAGEs with that of the most investigated pathway from glycerol. A considerable reduction of all impact categories considered was observed in our experimental conditions, suggesting that the glycidol-to-MAGEs route can be a valuable integration to the glycerol-to-MAGEs chain. Thanks to the use of primary data within the LCA model, the results achieved are a very good approximation of the real case.