Effects of the Blending Ratio on the Design of Keratin/Poly(butylene succinate) Nanofibers for Drug Delivery Applications.

In recent years there has been a growing interest in the use of proteins as biocompatible and environmentally friendly biomolecules for the design of wound healing and drug delivery systems. Keratin is a fascinating protein, obtainable from several keratinous biomasses such as wool, hair or nails, with intrinsic bioactive properties including stimulatory effects on wound repair and excellent carrier capability. In this work keratin/poly(butylene succinate) blend solutions with functional properties tunable by manipulating the polymer blending ratios were prepared by using 1,1,1,3,3,3-hexafluoroisopropanol as common solvent. Afterwards, these solutions doped with rhodamine B (RhB), were electrospun into blend mats and the drug release mechanism and kinetics as a function of blend composition was studied, in order to understand the potential of such membranes as drug delivery systems. The electrophoresis analysis carried out on keratin revealed that the solvent used does not degrade the protein. Moreover, all the blend solutions showed a non-Newtonian behavior, among which the Keratin/PBS 70/30 and 30/70 ones showed an amplified orientation ability of the polymer chains when subjected to a shear stress. Therefore, the resulting nanofibers showed thinner mean diameters and narrower diameter distributions compared to the Keratin/PBS 50/50 blend solution. The thermal stability and the mechanical properties of the blend electrospun mats improved by increasing the PBS content. Finally, the RhB release rate increased by increasing the keratin content of the mats and the drug diffused as drug-protein complex.

Bio-Based Solvents and Gasoline Components From Renewable 2,3-Butanediol and 1,2-Propanediol: Synthesis and Characterization.

In this study approaches for chemical conversions of the renewable compounds 1,2-propanediol (1,2-PD) and 2,3-butanediol (2,3-BD) that yield the corresponding cyclic ketals and glycol ethers have been investigated experimentally. The characterization of the obtained products as potential green solvents and gasoline components is discussed. Cyclic ketals have been obtained by the direct reaction of the diols with lower aliphatic ketones (1,2-PD + acetone → 2,2,4-trimethyl-1,3-dioxolane (TMD) and 2,3-BD + butanone-2 → 2-ethyl-2,4,5-trimethyl-1,3-dioxolane (ETMD)), for which the ΔH0r, ΔS0r and ΔG0r values have been estimated experimentally. The monoethers of diols could be obtained through either hydrogenolysis of the pure ketals or from the ketone and the diol via reductive alkylation. In the both reactions, the cyclic ketals (TMD and ETMD) have been hydrogenated in nearly quantitative yields to the corresponding isopropoxypropanols (IPP) and 3-sec-butoxy-2-butanol (SBB) under mild conditions (T = 120-140 °C, p(H2) = 40 bar) with high selectivity (>93%). Four products (TMD, ETMD, IPP and SBB) have been characterized as far as their physical properties are concerned (density, melting/boiling points, viscosity, calorific value, evaporation rate, Antoine equation coefficients), as well as their solvent ones (Kamlet-Taft solvatochromic parameters, miscibility, and polymer solubilization). In the investigation of gasoline blending properties, TMD, ETMD, IPP and SBB have shown remarkable antiknock performance with blending antiknock indices of 95.2, 92.7, 99.2 and 99.7 points, respectively.

Utilizing Furfural-Based Bifuran Diester as Monomer and Comonomer for High-Performance Bioplastics: Properties of Poly(butylene furanoate), Poly(butylene bifuranoate), and Their Copolyesters.

Two homopolyesters and a series of novel random copolyesters were synthesized from two bio-based diacid esters, dimethyl 2,5-furandicarboxylate, a well-known renewable monomer, and dimethyl 2,2'-bifuran-5,5'-dicarboxylate, a more uncommon diacid based on biochemical furfural. Compared to homopolyesters poly(butylene furanoate) (PBF) and poly(butylene bifuranoate) (PBBf), their random copolyesters differed dramatically in that their melting temperatures were either lowered significantly or they showed no crystallinity at all. However, the thermal stabilities of the homopolyesters and the copolyesters were comparable. Based on tensile tests from amorphous film specimens, it was concluded that the elastic moduli, tensile strengths, and elongation at break values for all copolyesters were similar as well, irrespective of the furan:bifuran molar ratio. Tensile moduli of approximately 2 GPa and tensile strengths up to 66 MPa were observed for amorphous film specimens prepared from the copolyesters. However, copolymerizing bifuran units into PBF allowed the glass transition temperature to be increased by increasing the amount of bifuran units. Besides enhancing the glass transition temperatures, the bifuran units also conferred the copolyesters with significant UV absorbance. This combined with the highly amorphous nature of the copolyesters allowed them to be melt-pressed into highly transparent films with very low ultraviolet light transmission. It was also found that furan-bifuran copolyesters could be as effective, or better, oxygen barrier materials as neat PBF or PBBf, which themselves were found superior to common barrier polyesters such as PET.

Synthesis, characterization of phosphorus-containing copolyester and its application as flame retardants for poly(butylene succinate) (PBS).

Two novel phosphorus-containing copolyesters were synthesized by direct polycondensation reaction of phenyl dichlorophosphate, 1,4-succinic acid and 1,4-butanediol using stannous chloride (SnCl2) and 4-Methylbenzenesulfonic acid as catalyst, and its chemical structures were identified by 1H and 31P nuclear magnetic resonances (1H and 31P NMR). The resulting phosphorus-containing poly(butylene succinate) (PPBS) was characterized by X-ray diffraction (XRD), polarized optical microscope (POM), thermogravimetry analysis (TGA) and differential scanning calorimetry (DSC). PPBS can be as a flame retardant for commercial poly(butylene succinate) (PBS). A series of flame retardant composite materials were produced by melt-blending of PBS and PPBS. The comprehensive flame retardant property of composite materials was evaluated by limited oxygen index (LOI). While 20 wt % of PPBS was added into PBS resin, good flame retardant properties could be obtained. Composite materials can have much better flame retardancy (LOI = 30) than neat PBS resin. Thermogravimetric analysis (TGA) showed that the weight loss of PBS was decreased by the introduction of PPBS. In addition, possible flame retardancy mechanism of PPBS in composite materials was analyzed by SEM photos of char residue.

Formation of i-motifs from acyclic (l)-threoninol nucleic acids.

Acyclic (l)-threoninol nucleic acids ((l)-aTNA) containing poly-cytosines are prepared and investigated at various pH values, revealing the formation of a highly stable structure at lower pH that have the characteristics of an i-motif. Depending on the sequence, the aTNA forms inter-, bi- and intra-molecular i-motif structures. Pyrene was conjugated to aTNA sequences and both monomeric and excimer fluorescence were efficiently quenched by the i-motif structures and thus demonstrated that the aTNA i-motif can serve as a pH switch.

Chemically synthesized Secoisolariciresinol diglucoside (LGM2605) improves mitochondrial function in cardiac myocytes and alleviates septic cardiomyopathy.

Sepsis is the overwhelming systemic immune response to infection, which can result in multiple organ dysfunction and septic shock. Myocardial dysfunction during sepsis is associated with advanced disease and significantly increased in-hospital mortality. Our group has shown that energetic failure and excess reactive oxygen species (ROS) generation constitute major components of myocardial dysfunction in sepsis. Because ROS production is central to cellular metabolic health, we tested if the synthetic anti-oxidant lignan secoisolariciresinol diglucoside (SDG; LGM2605) would alleviate septic cardiac dysfunction and investigated the underlying mechanism. Using the cecal ligation and puncture (CLP) mouse model of peritonitis-induced sepsis, we observed impairment of cardiac function beginning at 4 h post-CLP surgery. Treatment of mice with LGM2605 (100 mg/kg body weight, i.p.) 6 h post-CLP surgery reduced cardiac ROS accumulation and restored cardiac function. Assessment of mitochondrial respiration (Seahorse XF) in primary cardiomyocytes obtained from adult C57BL/6 mice that had undergone CLP and treatment with LGM2605 showed restored basal and maximal respiration, as well as preserved oxygen consumption rate (OCR) associated with spare capacity. Further analyses aiming to identify the cellular mechanisms that may account for improved cardiac function showed that LGM2605 restored mitochondria abundance, increased mitochondrial calcium uptake and preserved mitochondrial membrane potential. In addition to protecting against cardiac dysfunction, daily treatment with LGM2605 and antibiotic ertapenem (70 mg/kg) protected against CLP-associated mortality and reversed hypothermia when compared against mice receiving ertapenem and saline. Therefore, treatment of septic mice with LGM2605 emerges as a novel pharmacological approach that reduces cardiac ROS accumulation, protects cardiac mitochondrial function, alleviates cardiac dysfunction, and improves survival.

Highly Loaded Cellulose/Poly (butylene succinate) Sustainable Composites for Woody-Like Advanced Materials Application.

We report the manufacturing and characterization of poly (butylene succinate) (PBS) and micro cellulose (MCC) woody-like composites. These composites can be applied as a sustainable woody-like composite alternative to conventional fossil polymer-based wood-plastic composites (WPC). The PBS/MCC composites were prepared by using a melt blending of 70 wt% of MCC processed from bleached softwood. MCC was modified to enhance dispersion and compatibility by way of carbodiimide (CDI), polyhydroxy amides (PHA), alkyl ester (EST), (3-Aminopropyl) trimethoxysilane (APTMS), maleic acid anhydride (MAH), and polymeric diphenylmethane diisocyanate (PMDI). The addition of filler into PBS led to a 4.5-fold improvement of Young's modulus E for the MCC composite, in comparison to neat PBS. The 1.6-fold increase of E was obtained for CDI modified composition in comparison to the unmodified MCC composite. At room temperature, the storage modulus E' was found to improve by almost 4-fold for the APTMS composite. The EST composite showed a pronounced enhancement in viscoelasticity properties due to the introduction of flexible long alkyl chains in comparison to other compositions. The glass transition temperature was directly affected by the composition and its value was -15 °C for PBS, -30 °C for EST, and -10 °C for MAH composites. FTIR indicated the generation of strong bonding between the polymer and cellulose components in the composite. Scanning electron microscopy analysis evidenced the agglomeration of the MCC in the PBS/MCC composites. PMDI, APTMS, and CDI composites were characterized by the uniform dispersion of MCC particles and a decrease of polymer crystallinity. MCC chemical modification induced the enhancement of the thermal stability of MCC composites.

Preparation of New Risperidone Depot Microspheres Based on Novel Biocompatible Poly(Alkylene Adipate) Polyesters as Long-Acting Injectable Formulations.

Risperidone (RIS)-loaded microspheres based on poly(alkylene adipate)s derived from dicarboxylic acids and different aliphatic diols were prepared by the oil in water emulsion and solvent evaporation method. Specifically, 3 polyesters, namely poly(ethylene adipate), poly(propylene adipate), and poly(butylene adipate), were prepared with the aid of a 2-stage melt-polycondensation method and characterized by gel permeation chromatography, proton nuclear magnetic resonance (1H NMR), differential scanning calorimetry, and X-ray diffraction analysis. Results showed that the molecular weight of the polyesters increased as the diol molecular weight increased, while all polymers were of semi-crystalline nature and the melting temperature was varying from 49.1°C to 51.8°C and 65.9°C for poly(propylene adipate), poly(ethylene adipate), and poly(butylene adipate), respectively. The particle size of the RIS-loaded microspheres varied from 10 to 100 µm depending on the polyester type and the drug loading, while X-ray diffraction analysis revealed amorphous active pharmaceutical ingredient in the cases of high drug-loaded microspheres. In vitro drug release studies along with scanning electron microscopy images of microspheres after the completion of dissolution process showed that in all cases RIS release was controlled by the glass transition temperature of polyesters and physical state of active pharmaceutical ingredients via diffusion.

Enhanced production of 2,3-butanediol in pyruvate decarboxylase-deficient Saccharomyces cerevisiae through optimizing ratio of glucose/galactose.

Galactose and glucose are two of the most abundant monomeric sugars in hydrolysates of marine biomasses. While Saccharomyces cerevisiae can ferment galactose, its uptake is tightly controlled in the presence of glucose by catabolite repression. It is desirable to construct engineered strains capable of simultaneous utilization of glucose and galactose for producing biofuels and chemicals from marine biomass. The MTH1 gene coding for transcription factor in glucose signaling was mutated in a pyruvate decarboxylase (Pdc)-deficient S. cerevisiae expressing heterologous 2,3-butanediol (2,3-BD) biosynthetic genes. The engineered S. cerevisiae strain consumed glucose and galactose simultaneously and produced 2,3-BD as a major product. Total sugar consumption rates increased with a low ratio of glucose/galactose, though, occurrence of the glucose depletion in a fed-batch fermentation decreased 2,3-BD production substantially. Through optimizing the profiles of sugar concentrations in a fed-batch cultivation with the engineered strain, 99.1 ± 1.7 g/L 2,3-BD was produced in 143 hours with a yield of 0.353 ± 0.022 g 2,3-BD/g sugars. This result suggests that simultaneous and efficient utilization of glucose and galactose by the engineered yeast might be applicable to the economical production of not only 2,3-BD, but also other biofuels and chemicals from marine biomass.

Regio- and Enantioselective Sequential Dehalogenation of rac-1,3-Dibromobutane by Haloalkane Dehalogenase LinB.

The hydrolytic dehalogenation of rac-1,3-dibromobutane catalyzed by the haloalkane dehalogenase LinB from Sphingobium japonicum UT26 proceeds in a sequential fashion: initial formation of intermediate haloalcohols followed by a second hydrolytic step to produce the final diol. Detailed investigation of the course of the reaction revealed favored nucleophilic displacement of the sec-halogen in the first hydrolytic event with pronounced R enantioselectivity. The second hydrolysis step proceeded with a regioselectivity switch at the primary position, with preference for the S enantiomer. Because of complex competition between all eight possible reactions, intermediate haloalcohols formed with moderate to good ee ((S)-4-bromobutan-2-ol: up to 87 %). Similarly, (S)-butane-1,3-diol was formed at a maximum ee of 35 % before full hydrolysis furnished the racemic diol product.

A Direct, Concise, and Enantioselective Synthesis of 2-Substituted 4,4,4-Trifluorobutane-1,3-diols Based on the Organocatalytic In Situ Generation of Unstable Trifluoroacetaldehyde.

A direct, concise, and enantioselective synthesis of 2-substituted 4,4,4-trifluorobutane-1,3-diols based on the organocatalytic asymmetric direct aldol reaction of an ethyl hemiacetal of trifluoroacetaldehyde with various aldehydes was examined. A catalytic amount (30 mol %) of commercially available and inexpensive l-prolinamide is quite effective as an organocatalyst for the catalytic in situ generation of gaseous and unstable trifluoroacetaldehyde from its hemiacetal, and a successive asymmetric direct aldol reaction with various aldehydes in dichloromethane at 0 °C, followed by reduction with sodium borohydride, gives 2-substituted 4,4,4-trifluorobutane-1,3-diols in moderate to good yields (31-84%) with low diastereoselectivities and good to excellent enantioselectivities (64-97% ee).

Highly stable triple helix formation by homopyrimidine (L)-acyclic threoninol nucleic acids with single stranded DNA and RNA.

Acyclic (L)-threoninol nucleic acid (aTNA) containing thymine, cytosine and adenine nucleobases were synthesized and shown to form surprisingly stable triplexes with complementary single stranded homopurine DNA or RNA targets. The triplex structures consist of two (L)-aTNA strands and one DNA or RNA, and these triplexes are significantly stronger than the corresponding DNA or RNA duplexes as shown in competition experiments. As a unique property the (L)-aTNAs exclusively form triplex structures with DNA and RNA and no duplex structures are observed by gel electrophoresis. The results were compared to the known enantiomer (D)-aTNA, which forms much weaker triplexes depending upon temperature and time. It was demonstrated that (L)-aTNA triplexes are able to stop primer extension on a DNA template, showing the potential of (L)-aTNA for antisense applications.

Poly(2-methyl-2-oxazoline)-b-poly(tetrahydrofuran)-b-poly(2-methyl-2-oxazoline) amphiphilic triblock copolymers: synthesis, physicochemical characterizations, and hydrosolubilizing properties.

Block copolymers assembled into micelles have gained a lot of attention to improve drug delivery. The recent drawbacks of the poly(ethylene oxide) blocks (PEO) contained in amphiphilic pluronics derivatives made of a central poly(propylene oxide) block surrounded by two PEO blocks were recently revealed, opening the way to the design of new amphiphilic block copolymers able to self-assemble in water and to entrap molecules of interest. Here, a family of p(methyloxazoline)-b-p(tetrahydrofuran)-b-p(methyloxazoline) triblock copolymers (called TBCP) is synthesized using cationic ring opening polymerization. Studies of micelle formation using dynamic light scattering, isothermal titration calorimetry (ITC), NMR diffusion-ordered spectroscopy (DOSY), and fluorescence experiments lead us to draw a relationship between copolymer structure and the physicochemical properties of the block copolymers (critical micellar concentration (CMC), Nagg, core diameter, shell thickness, etc.). The packing parameter of the block copolymers indicates the formation of a core-corona structure. Hydrosolubilizing properties of TBCPs were exemplified with curcumin selected as a highly insoluble drug model. Curcumin, a natural polyphenolic compound, has shown a large spectrum of biological and pharmacological activity, including anti-inflammatory, antimicrobial, antioxidant, and anticarcinogenic activities. An optimized formulation process reveals that the aggregation number is the parameter affecting drug encapsulation. Patch clamp experiments carried out to study the interaction of TBCP with the cell membrane demonstrate their permeation property suitable to promote the cellular internalization of curcumin.

Novel synthetic (S,S) and (R,R)-secoisolariciresinol diglucosides (SDGs) protect naked plasmid and genomic DNA From gamma radiation damage.

Secoisolariciresinol diglucoside (SDG) is the major lignan in wholegrain flaxseed. However, extraction methods are complex and are associated with low yield and high costs. Using a novel synthetic pathway, our group succeeded in chemically synthesizing SDG (S,S and R,R enantiomers), which faithfully recapitulates the properties of their natural counterparts, possessing strong antioxidant and free radical scavenging properties. This study further extends initial findings by now investigating the DNA-radioprotective properties of the synthetic SDG enantiomers compared to the commercial SDG. DNA radioprotection was assessed by cell-free systems such as: (a) plasmid relaxation assay to determine the extent of the supercoiled (SC) converted to open-circular (OC) plasmid DNA (pBR322) after exposure of the plasmid to gamma radiation; and (b) determining the extent of genomic DNA fragmentation. Exposure of plasmid DNA to 25 Gy of γ radiation resulted in decreased supercoiled form and increased open-circular form, indicating radiation-induced DNA damage. Synthetic SDG (S,S) and SDG (R,R), and commercial SDG at concentrations of 25-250 µM significantly and equipotently reduced the radiation-induced supercoiled to open-circular plasmid DNA in a dose-dependent conversion. In addition, exposure of calf thymus DNA to 50 Gy of gamma radiation resulted in DNA fragments of low-molecular weight (<6,000 bps), which was prevented in a dose-dependence manner by all synthetic and natural SDG enantomers, at concentrations as low as 0.5 µM. These novel results demonstrated that synthetic SDG (S,S) and SDG (R,R) isomers and commercial SDG possess DNA-radioprotective properties. Such properties along with their antioxidant and free radical scavenging activity, reported earlier, suggest that SDGs are promising candidates for radioprotection for normal tissue damage as a result of accidental exposure during radiation therapy for cancer treatment.

Enhanced production of 2,3-butanediol by overexpressing acetolactate synthase and acetoin reductase in Klebsiella pneumoniae.

Mutants with overexpression of α-acetolactate synthase (ALS), α-acetolactate decarboxylase, and acetoin reductase (AR), either individually or in combination, were constructed to improve 2,3-butanediol (2,3-BD) production in Klebsiella pneumoniae. The recombinant strains were characterized in terms of the enzyme activity, 2,3-BD yield, and expression levels. The recombinant K. pneumoniae strain (KG-rs) that overexpressed both ALS and AR showed an improved 2,3-BD yield. When cultured in the media with five different carbon sources (glucose, galactose, fructose, sucrose, and lactose), the mutant exhibited higher 2,3-BD productivity and production than the parental strain in all the tested carbon sources except for lactose. The 2,3-BD production of KG-rs in a batch fermentation with glucose as the carbon source was 12% higher than that of the parental strain.

Gas phase production and loss of isoprene epoxydiols.

Isoprene epoxydiols (IEPOX) form in high yields from the OH-initiated oxidation of isoprene under low-NO conditions. These compounds contribute significantly to secondary organic aerosol formation. Their gas-phase chemistry has, however, remained largely unexplored. In this study, we characterize the formation of IEPOX isomers from the oxidation of isoprene by OH. We find that cis-ß- and trans-ß-IEPOX are the dominant isomers produced, and that they are created in an approximate ratio of 1:2 from the low-NO oxidation of isoprene. Three isomers of IEPOX, including cis-ß- and trans-ß, were synthesized and oxidized by OH in environmental chambers under high- and low-NO conditions. We find that IEPOX reacts with OH at 299 K with rate coefficients of (0.84 ± 0.07) × 10(-11), (1.52 ± 0.07) × 10(-11), and (0.98 ± 0.05) × 10(-11) cm(3) molecule(-1) s(-1) for the δ1, cis-ß, and trans-ß isomers. Finally, yields of the first-generation products of IEPOX + OH oxidation were measured, and a new mechanism of IEPOX oxidation is proposed here to account for the observed products. The substantial yield of glyoxal and methylglyoxal from IEPOX oxidation may help explain elevated levels of those compounds observed in low-NO environments with high isoprene emissions.

Novel membrane-based biotechnological alternative process for succinic acid production and chemical synthesis of bio-based poly (butylene succinate).

Succinic acid was produced in a novel membrane-based fermentation and separation integrated system. With this integrated system, product inhibition was alleviated by removing acids and replenishing fresh broth. High cell density maintain for a longer time from 75 to 130h and succinic acid concentration increased from 53 to 73g/L. In the developed separation process, succinic acid was crystallized at a recovery of 85-90%. The purity of the obtained succinic acid crystals reached 99.4% as found by HPLC and (1)H NMR analysis. A crystallization experiment indicated that among by-products glucose had a negative effect on succinic acid crystallization. Poly (butylene succinate) (PBS) was synthesized using the purified succinic acid and (1)H NMR analysis confirmed that the composition of the synthesized PBS is in agreement with that from petro-based succinic acid.

Observation of 2,3-butanediol biosynthesis in Lys regulator mutated Klebsiella pneumoniae at gene transcription level.

Microorganisms that produce 2,3-butanediol (2,3-BDO) are mostly mixed acid fermentation microorganisms, and they synthesize 2,3-BDO in order to suppress medium acidification. The 2,3-BDO operon (budBAC) is activated by the LysR regulator protein derived from the budR. In this study, the effect of the budR on 2,3-BDO-biosynthesis was observed at gene transcription level. The Klebsiella pneumoniae strains (wabG-deleted strain (SGSB100), budR over-expressed strain (SGSB101), and the budR-deleted strain (SGSB102)) were constructed. The resulting strains were cultivated in unified conditions. Samples were obtained at the lag-, log-, and stationary-phase of cell growth, and gene transcription levels of the budR, 2,3-BDO-biosynthesis-related (budB, budA, and budC), and acid-biosynthesis-related (ldhA and ack) genes were observed. During the lag-phase of cell growth in SGSB101, the budR transcription level increased approximately 8-fold, and 2,3-BDO production increased approximately 2-fold, when compared to SGSB100. Also in SGSB101 the transcription level of the acid-biosynthesis-related genes (ldhA and ack) increased approximately up to 11-fold during the lag-phase of cell growth compared to SGSB100. On contrast, in SGSB102 budR transcription was not detected, and the transcription level of the acid-biosynthesis-related genes (ldhA and ack) decreased approximately 70-fold during the lag-phase of cell growth compared to SGSB100. This is by far the first observation of 2,3-BDO regulation mechanism at gene transcription level in K. pneumoniae, and therefore may be useful for understanding and improving 2,3-BDO biosynthesis metabolic network.

Synthesis and antioxidant evaluation of (S,S)- and (R,R)-secoisolariciresinol diglucosides (SDGs).

Secoisolariciresinol diglucosides (SDGs) (S,S)-SDG-1 (major isomer in flaxseed) and (R,R)-SDG-2 (minor isomer in flaxseed) were synthesized from vanillin via secoisolariciresinol (6) and glucosyl donor 7 through a concise route that involved chromatographic separation of diastereomeric diglucoside derivatives (S,S)-8 and (R,R)-9. Synthetic (S,S)-SDG-1 and (R,R)-SDG-2 exhibited potent antioxidant properties (EC50=292.17±27.71 µM and 331.94±21.21 µM, respectively), which compared well with that of natural (S,S)-SDG-1 (EC50=275.24±13.15 µM). These values are significantly lower than those of ascorbic acid (EC50=1129.32±88.79 µM) and α-tocopherol (EC50=944.62±148.00 µM). Compounds (S,S)-SDG-1 and (R,R)-SDG-2 also demonstrated powerful scavenging activities against hydroxyl [natural (S,S)-SDG-1: 3.68±0.27; synthetic (S,S)-SDG-1: 2.09±0.16; synthetic (R,R)-SDG-2: 1.96±0.27], peroxyl [natural (S,S)-SDG-1: 2.55±0.11; synthetic (S,S)-SDG-1: 2.20±0.10; synthetic (R,R)-SDG-2: 3.03±0.04] and DPPH [natural (S,S)-SDG-1: EC50=83.94±2.80 µM; synthetic (S,S)-SDG-1: EC50=157.54±21.30 µM; synthetic (R,R)-SDG-2: EC50=123.63±8.67 µM] radicals. These results confirm previous studies with naturally occurring (S,S)-SDG-1 and establish both (S,S)-SDG-1 and (R,R)-SDG-2 as potent antioxidants and free radical scavengers for potential in vivo use.

Heterogeneous ceria catalyst with water-tolerant Lewis acidic sites for one-pot synthesis of 1,3-diols via Prins condensation and hydrolysis reactions.

The use of a heterogeneous Lewis acid catalyst, which is insoluble and easily separable during the reaction, is a promising option for hydrolysis reactions from both environmental and practical viewpoints. In this study, ceria showed excellent catalytic activity in the hydrolysis of 4-methyl-1,3-dioxane to 1,3-butanediol in 95% yield and in the one-pot synthesis of 1,3-butanediol from propylene and formaldehyde via Prins condensation and hydrolysis reactions in an overall yield of 60%. In-depth investigations revealed that ceria is a water-tolerant Lewis acid catalyst, which has seldom been reported previously. The ceria catalysts showed rather unusual high activity in hydrolysis, with a turnover number (TON) of 260, which is rather high for bulk oxide catalysts, whose TONs are usually less than 100. Our conclusion that ceria functions as a Lewis acid catalyst in hydrolysis reactions is firmly supported by thorough characterizations with IR and Raman spectroscopy, acidity measurements with IR and (31)P magic-angle-spinning NMR spectroscopy, Na(+)/H(+) exchange tests, analyses using the in situ active-site capping method, and isotope-labeling studies. A relationship between surface vacancy sites and catalytic activity has been established. CeO(2)(111) has been confirmed to be the catalytically active crystalline facet for hydrolysis. Water has been found to be associatively adsorbed on oxygen vacancy sites with medium strength, which does not lead to water dissociation to form stable hydroxides. This explains why the ceria catalyst is water-tolerant.