Studies on the Catalytic Properties of Crude Freeze-Dried Preparations of Yarrowia lipolytica Extracellular Lipases for Geranyl Ester Derivative Synthesis.

The study aimed to evaluate the impact of selected factors of the freeze-drying process on the hydrolytic and synthetic activity of the extracellular lipases of Y. lipolytica KKP 379 and to attempt the use of the crude enzyme preparation as a biocatalyst in the synthesis of geranyl 4-hydroxyphenylpropanoate. Antioxidant and antibacterial properties of the geranyl ester derivative were also investigated in order to evaluate their usefulness as a novel food additive. The studies confirmed that freeze-drying was an effective method of dehydrating yeast supernatant and allowed for obtaining lyophilizates with low water activity from 0.055 to 0.160. The type and concentration of the additive (2-6% whey protein hydrolyzate, 0.5% and 1% ammonium sulphate) had a significant effect on the hydrolytic activity of enzyme preparations, while the selected variants of drying temperature during the freeze-drying process were not significant (10 °C and 50 °C). Low yield of geranyl 4-hydroxyphenylopropionate was shown when the lyophilized supernatant was used (5.3%), but the yield of ester synthesis increased when the freeze-dried Y. lipolytica yeast biomass was applied (47.9%). The study confirmed the antioxidant properties of the synthesized ester by the DPPH• and CUPRAC methods, as well as higher antibacterial activity against tested bacteria than its precursor with 0.125 mM MIC (minimal inhibitory concentration) against L. monocytogenes.

Application of Lipase Purified from Aspergillus fumigatus in the Syntheses of Ethyl Acetate and Ethyl Lactate.

Microbial lipases are used for the synthesis of various short chain esters such as octyl acetate, methyl salicylate, ethyl acetate and ethyl lactate. In this study, a purified lipase of Aspergillus fumigatus was utilized for the synthesis of two esters i.e. ethyl acetate and ethyl lactate. The purified lipase from Aspergillus fumigatus performed esterification of ethanol and acetic acid (at a molar ratio of 1:1) when incubated at 40℃ under shaking (130 min-1) for 12 h resulting in the formation of ethyl acetate (89%). In case of ethyl lactate maximum esterification (87.32%) was achieved when ethanol and lactic acid (500:100 mM ) was used in heptane resulting in the synthesis of ethyl lactate at 40°C under shaking (120 rpm) after 12 h of reaction time. These esters of short chain carboxylic acid and alcohols belong to the highly important natural aroma compounds and are used as green solvents in food and pharmaceutical industry.

Tanshinol borneol ester, a novel synthetic small molecule angiogenesis stimulator inspired by botanical formulations for angina pectoris.

BACKGROUND AND PURPOSE: Tanshinol borneol ester (DBZ) is a novel synthetic compound derived from Dantonic® , a botanical drug approved in 26 countries outside the United States for angina pectoris and currently undergoing FDA Phase III clinical trial. Here, we investigated the angiogenic effects of (S)-DBZ and (R)-DBZ isomers in vitro and in vivo. EXPERIMENTAL APPROACH: A network pharmacology approach was used to predict molecular targets of DBZ. The effects of DBZ isomers on proliferation, migration, and tube formation of human endothelial cells were assessed. For in vivo approaches, the transgenic Tg (vegfr2:GFP) zebrafish and C57BL/6 mouse Matrigel plug models were used. ELISA and western blots were used to quantitate the release and expression of relevant target molecules and signalling pathways. KEY RESULTS: DBZ produced a biphasic modulation on proliferation and migration of three types of human endothelial cells. Both DBZ isomers induced tube formation in Matrigel assay and a 12-day co-culture model in vitro. Moreover, DBZ promoted Matrigel neovascularization in mice and partially reversed the vascular disruption in zebrafish induced by PTK787. Mechanistically, DBZ enhanced the cellular levels of VEGF, VEGFR2, and MMP-9, as well as activating Akt and MAPK signalling in endothelial cells. Selective inhibition of PI3K and MEK significantly attenuated its angiogenic effects. CONCLUSIONS AND IMPLICATIONS: These data reveal, for the first time, that DBZ promotes multiple key steps of angiogenesis, at least in part through Akt and MAPK signalling pathways, and suggest it may be potentially developed further for treating myocardial infarction and other cardiovascular diseases.

Simultaneous regeneration of calcium lactate and cellulose into PCL nanofiber for biomedical application.

Synthetic polymers are easy to process and have excellent mechanical properties but low wettability and poor cell compatibility limit their applications in tissue scaffolding. In this study, a facile procedure was established to regenerate cellulose and calcium lactate (CaL) into a polycaprolactone (PCL) nanofibrous scaffold for tissue engineering applications. Briefly, varying amounts of lactic acid (LA) was mixed with the blend of PCL and cellulose acetate (CA) solutions and electrospun to fabricate an optimal composite PCL/CA/LA fibrous membrane. Later on, as-prepared membranes were treated with calcium hydroxide solution. This process simultaneously converted CA and LA contents into Cellulose and CaL, respectively. In situ regeneration of Cellulose and CaL into the composite fiber remarkably enhanced the biological and physicochemical properties of the composite fiber. This work provides a novel dual-channel strategy for simultaneous regeneration of biopolymer and bioactive molecule into the PCL nanofiber for regenerative medicine and tissue engineering applications.

Doxorubicin-loaded protease-activated near-infrared fluorescent polymeric nanoparticles for imaging and therapy of cancer.

INTRODUCTION: Despite significant progress in the field of oncology, cancer remains one of the leading causes of death. Chemotherapy is one of the most common treatment options for cancer patients but is well known to result in off-target toxicity. Theranostic nanomedicines that integrate diagnostic and therapeutic functions within an all-in-one platform can increase tumor selectivity for more effective chemotherapy and aid in diagnosis and monitoring of therapeutic responses. MATERIAL AND METHODS: In this work, theranostic nanoparticles were synthesized with commonly used biocompatible and biodegradable polymers and used as cancer contrast and therapeutic agents for optical imaging and treatment of breast cancer. These core-shell nanoparticles were prepared by nanoprecipitation of blends of the biodegradable and biocompatible amphiphilic copolymers poly(lactic-co-glycolic acid)-b-poly-l-lysine and poly(lactic acid)-b-poly(ethylene glycol). Poly-l-lysine in the first copolymer was covalently decorated with near-infrared fluorescent Alexa Fluor 750 molecules. RESULTS: The spherical nanoparticles had an average size of 60-80 nm. The chemotherapeutic drug doxorubicin was encapsulated in the core of nanoparticles at a loading of 3% (w:w) and controllably released over a period of 30 days. A 33-fold increase in near-infrared fluorescence, mediated by protease-mediated cleavage of the Alexa Fluor 750-labeled poly-l-lysine on the surface of the nanoparticles, was observed upon interaction with the model protease trypsin. The cytocompatibility of drug-free nanoparticles and growth inhibition of drug-loaded nanoparticles on MDA-MB-231 breast cancer cells were investigated with a luminescence cell-viability assay. Drug-free nanoparticles were found to cause minimal toxicity, even at high concentrations (0.2-2,000 µg/mL), while doxorubicin-loaded nanoparticles significantly reduced cell viability at drug concentrations >10 µM. Finally, the interaction of the nanoparticles with breast cancer cells was studied utilizing fluorescence microscopy, demonstrating the potential of the nanoparticles to act as near-infrared fluorescence optical imaging agents and drug-delivery carriers. CONCLUSION: Doxorubicin-loaded, enzymatically activatable nanoparticles of less than 100 nm were prepared successfully by nanoprecipitation of copolymer blends. These nanoparticles were found to be suitable as controlled drug delivery systems and contrast agents for imaging of cancer cells.

Transesterification of Lactic Acid Oligomers with Ethanol, a Way to Anhydrous Ethyl Lactate: A Kinetic Study.

A new method for the preparation of anhydrous ethyl ester of lactic acid was studied. The selected method is based on catalytic transesterification of lactic acid oligomers, which were prepared for this purpose by autocatalytic oligomerization of lactic acid. In this work, a kinetic model for the case of catalytic alcoholysis of oligoesters was derived assuming a first-order reaction and equimolar content of reactants in the reaction mixture. The model makes it possible to obtain the values of the reaction rate and equilibrium constants and the equilibrium alcohol concentration by regression analysis at one time. The model was verified by measuring the rate of consumption of ethanol over the time at various reaction temperatures with anhydrous FeCl3 as the catalyst. The reaction was studied at overpressure under autogenous conditions in the temperature range of 100⁻180 °C. For the catalyst concentration of 1 mol %, the activation energy value was 64.35 kJ·mol-1. The dependence of equilibrium composition and rate constant on the temperature was obtained. The derived model is generally applicable to all first-order equilibrium reactions. The presumption is that the forward and reverse reactions are of the same order and have the same stoichiometry and equivalent amounts of reactants at the beginning of the reaction.

Synthesis of Functionalized N-Acetyl Muramic Acids To Probe Bacterial Cell Wall Recycling and Biosynthesis.

Uridine diphosphate N-acetyl muramic acid (UDP NAM) is a critical intermediate in bacterial peptidoglycan (PG) biosynthesis. As the primary source of muramic acid that shapes the PG backbone, modifications installed at the UDP NAM intermediate can be used to selectively tag and manipulate this polymer via metabolic incorporation. However, synthetic and purification strategies to access large quantities of these PG building blocks, as well as their derivatives, are challenging. A robust chemoenzymatic synthesis was developed using an expanded NAM library to produce a variety of 2 -N-functionalized UDP NAMs. In addition, a synthetic strategy to access bio-orthogonal 3-lactic acid NAM derivatives was developed. The chemoenzymatic UDP synthesis revealed that the bacterial cell wall recycling enzymes MurNAc/GlcNAc anomeric kinase (AmgK) and NAM α-1 phosphate uridylyl transferase (MurU) were permissive to permutations at the two and three positions of the sugar donor. We further explored the utility of these derivatives in the fluorescent labeling of both Gram (-) and Gram (+) PG in whole cells using a variety of bio-orthogonal chemistries including the tetrazine ligation. This report allows for rapid and scalable access to a variety of functionalized NAMs and UDP NAMs, which now can be used in tandem with other complementary bio-orthogonal labeling strategies to address fundamental questions surrounding PG's role in immunology and microbiology.

Fabrication of dopamine modified polylactide-poly(ethylene glycol) scaffolds with adjustable properties.

Bio-based polymers have been widely used to be as scaffolds for repairing the bone defects. However, the polymer scaffolds are generally lack of bioactivity and cell recognition site. Seeking effective ways to improve the bioactivity and interaction between materials and tissue or cells is clinically important for long-term performance of bone repair materials. In this work, polylactide-b-poly(ethylene glycol)-b-polylactide (PLA-PEG-PLA, PLEL) tri-block copolymers were firstly synthesized by ring-opening polymerization of lactide using PEG with various molecular weights. Inspired by excellent adhesion of dopamine (DA), a facile and effective method was developed to fabricate polydopamine (PDA) and polydopamine/nano-hydroxyapatite (PDA/n-HA) modified PLEL scaffolds by deposition of PDA and PDA/n-HA coating. The surface structure, degradation rates and mineralization of the modified PLEL scaffolds were investigated, and obviously improved after immobilization of PDA and PDA/n-HA coatings. Moreover, the biocompatible results showed a significant increase in cells viability and adhesion. Therefore, the surface modification with PDA and PDA/n-HA could not only adjust the properties of scaffolds, but also reinforce the interfacial adhesion between the PLEL and cells.

Efficient production of enantiomerically pure D-phenyllactate from phenylpyruvate by structure-guided design of an engineered D-lactate dehydrogenase.

3-Phenyllactic acid (PLA) is an antimicrobial compound with broad-spectrum activity against bacteria and fungi that could be widely used in the food industry and livestock feeds. Notably, D-PLA exhibits higher antibacterial activity, which gains more attention than L-PLA. In this report, the D-lactate dehydrogenase DLDH744 from Sporolactobacillus inulinus CASD was engineered to increase the enzymatic activities toward phenylpyruvate by protein structure-guided modeling analysis. The phenylpyruvate molecule was first docked in the active center of DLDH744. The residues that might tightly pack around the benzene ring of phenylpyruvate were all selected for mutation. The single site mutant M307L showed the highest increased activity toward bulkier substrate phenylpyruvate than the wild type. By using the engineered D-lactate dehydrogenase M307L expressed in Escherichia coli strains, without coexpression of the cofactor regeneration system, 21.43 g/L D-PLA was produced from phenylpyruvate with a productivity of 1.58 g/L/h in the fed-batch biotransformation process, which ranked in the list as the highest production titer of D-PLA by D-lactate dehydrogenase. The enantiomeric excess value of produced D-PLA in the broth was higher than 99.7 %. Additionally, the structure-guided design of this enzyme will also provide referential information for further engineering other 2-hydroxyacid dehydrogenases, which are useful for a wide range of fine chemical synthesis.

Block Copolymer-Encapsulated CaWO4 Nanoparticles: Synthesis, Formulation, and Characterization.

We envision that CaWO4 (CWO) nanocrystals have the potential for use in biomedical imaging and therapy because of the unique ways this material interacts with high-energy radiation. These applications, however, require development of nanoparticle (NP) formulations that are suitable for in vivo applications; primarily, the formulated nanoparticles should be sufficiently small, chemically and biologically inert, and stable against aggregation under physiological conditions. The present study demonstrates one such method of formulation, in which CWO nanoparticles are encapsulated in bioinert block copolymer (BCP) micelles. For this demonstration, we prepared three different CWO nanocrystal samples having different sizes (3, 10, and 70 nm in diameter) and shapes (elongated vs truncated rhombic). Depending on the specific synthesis method used, the as-synthesized CWO NPs contain different surfactant materials (citric acid or cetyltrimethylammonium bromide or a mixture of oleic acid and oleylamine) in the coating layers. Regardless of the type of surfactant, the original surfactant coating can be replaced with a new enclosure formed by BCP materials using a solvent-exchange method. Two types of BCPs have been tested: poly(ethylene glycol-block-n-butyl acrylate) (PEG-PnBA) and poly(ethylene glycol-block-D,L-lactic acid) (PEG-PLA). Both BCPs are able to produce fully PEGylated CWO NPs that are stable against aggregation under physiological salt conditions for very long periods of time (at least three months). The optical and radio luminescence properties of both BCP-encapsulated and surfactant-coated CWO NPs were extensively characterized. The study confirms that the BCP coating structure does not influence the luminescence properties of CWO NPs.

Relaxation effect of a novel Danshensu/tetramethylpyrazine derivative on rat mesenteric arteries.

Danshen (Radix Salviae miltiorrhizae) and ChuanXiong (Ligusticum wallichii) are two traditional herbal medicines commonly used in China for the treatment of cardiovascular diseases. The active components in Danshen and ChuanXiong are Danshensu (DSS, (R)-3, 4-dihydroxyphenyllactic acid) and tetramethylpyrazine (TMP), respectively. In the present study, a new compound named ADTM, which is a conjugation of DSS and TMP, was synthesized and its effect on the contractility of rat mesenteric arteries was examined. The relaxation effect of ADTM on rat mesenteric arteries was studied using myography. The effects of ADTM on Ca(2+) channels were measured by Ca(2+) imaging and patch-clamp techniques. The results showed that ADTM caused a concentration-dependent relaxation of rat mesenteric arteries. This relaxation effect was not affected by the removal of endothelium or inhibitors of nitric oxide synthase, cyclooxygenase, guanylyl cyclase and adenylyl cyclase. Potassium channel blockers including tetraethylammonium, iberiotoxin, apamin, 4-aminopyridine, BaCl2 and glibenclamide also failed to inhibit the relaxation response to ADTM. ADTM inhibited CaCl2-induced contractions and reduced the Ca(2+) influx in isolated mesenteric arterial muscle cells. Our results suggest that ADTM may be a novel relaxing agent. Its mechanism of action involves the direct blockade of voltage-gated Ca(2+) channels in vascular smooth muscle cells, resulting in a decrease in Ca(2+) influx into the cells.

Development of a quantitative GC-FID method for the determination of stearoyl-lactylates (E481/482) in foods.

Sodium and calcium salts of stearoyl-lactylates (SLs) are food emulsifiers especially used in bread and bakery products to improve texture. They should be used at the lowest level at which the desired technological effect is achieved in a specific food category and at amounts not exceeding the maximums set by European Commission Regulation No. 1129/2011. In order to be able to evaluate whether these emulsifiers are used correctly but also to evaluate whether the commercial additive formulations comply with legislation, a quantitative GC-FID method was developed. An internal standard (nonadecanoyl-1-lactylate) was synthesized in-house and pure ester standards were isolated from commercial additive formulations. The method showed a limit of detection of 0.04 and a limit of quantification of 0.12 mg esters ml⁻¹. The commercial additive formulations analysed proved to be complex mixtures of free lactic and fatty acids together with only 50-60% esters. Besides SLs important amounts of palmitoyl-lactylates were present. Different food matrices (with low- and high-fat contents) were spiked with commercial SL formulations and recoveries ranged between 85% and 109%. Determination of SLs in commercial foods (such as bakery and bread) indicated that pre-treatment with amylase was essential to determine accurately the SL content due to the interaction of SL with the amylose.

Dephosphorylation and biodistribution of 1-¹³C-phospholactate in vivo.

Here, we present a new approach for the delivery of a metabolic contrast agent for in vivo molecular imaging. The use of a phosphate-protecting group that facilitates parahydrogen-induced polarization of 1-(13)C-phospholactate potentially enables the in vivo administration of a hydrogenated hyperpolarized adduct. When injected, nonhyperpolarized 1-(13)C-phospholactate is retained in the vasculature during its metabolic conversion to 1-(13)C-lactate by blood phosphatases as demonstrated here using a mucin 1 mouse model of breast cancer and ex vivo high-resolution (13)C NMR. This multisecond process is a suitable mechanism for the delivery of relatively short-lived (13)C and potentially (15)N hyperpolarized contrast agents using -OH phosphorylated small molecules, which is demonstrated here for the first time as an example of 1-(13)C-phospholactate. Through this approach, DL-1-(13)C-lactate is taken up by tissues and organs including the liver, kidneys, brain, heart, and tumors according to a timescale amenable to hyperpolarized magnetic resonance imaging.

Impact of core-forming segment structure on drug loading in biodegradable polymeric micelles using PEG-b-poly(lactide-co-depsipeptide) block copolymers.

We synthesized series of amphiphilic AB-type block copolymers having systematic variation in the core-forming segments using poly(lactide-co-depsipeptide)s as a hydrophobic segment and prepared polymeric micelles using the block copolymers, PEG-b-poly(lactide-co-depsipeptide). We then discussed the relationship between the core-forming segment structure and drug loading efficiency for the polymeric micelles. PEG-b-poly(lactide-co-depsipeptide)s, PEG-b-PLGL containing L-leucine (Leu), and PEG-b-PLGF containing L-phenylalanine (Phe), with similar molecular weights and various mole fractions of depsipeptide units, were synthesized. Polymeric micelles entrapping model drug (fluorescein, FL) were prepared using these copolymers. As a result, PEG-b-poly(lactide-co-depsipeptide) micelles showed higher drug loading compared with PEG-b-PLLA and PEG-b-PDLLA as controls. The drug loading increased with increase in the mole fraction of depsipeptide unit in the hydrophobic segments. The introduction of aliphatic and aromatic depsipeptide units was effective to achieve higher FL loading into the micelles. PEG-b-PLGL micelle showed higher drug loading than PEG-b-PLGF micelle when the amount of FL in feed was high. These results obtained in this study should be useful for strategic design of polymeric micelle-type drug delivery carrier with high drug loading efficiency.

Unexpected and successful "one-step" formation of porous polymeric particles only by mixing organic solvent and water under "low-energy-input" conditions.

We found that porous particles were unexpectedly obtained in a "one-step" manner only by mixing an organic solvent and water under "low-energy-input" (i.e., low-homogenization-rate) conditions. This phenomenon was attributable to the unexpected formation of the spontaneously formed water-in-oil (w/o) emulsions in the droplets of o/w emulsions. The unexpected formation resulted in the successful formation of water-in-oil-in-water (w/o/w) emulsions instead of o/w emulsions, although the mixed solution containing both an organic solvent and water were simply emulsified in the presence of block copolymers. The present study clarifies the effects of the various preparation conditions on the morphology of unexpected w/o/w emulsions and resulting particles. The porous particles are expected to be suitable drug carriers for pulmonary delivery. The results obtained in the present study show that a newly developed one-step emulsification can be a powerful and facile technique for preparing porous polymeric particles.

Conversion of salvianolic acid B into salvianolic acid A in tissues of Radix Salviae Miltiorrhizae using high temperature, high pressure and high humidity.

Salvianolic acid A (Sal A), an important constituent of Radix Salviae Miltiorrhizae (RSM), is effective for the treatment of myocardial infarction (MI) and coronary heart disease due to its potential in the improvement of acute myocardial ischemia. However, its content is very low in RSM. So it is obvious to find a rich source of Sal A or to improve its content by conversion of other related components into Sal A modifying reaction conditions. In this research we focused on the conversion of Sal B into Sal A in aqueous solutions of RSM by using different reaction conditions including pH, temperature, pressure and humidity. During the reactions, the contents of Sal A, Sal B and danshensu in the RSM were analyzed by high-performance liquid chromatography (HPLC) and liquid chromatography-mass spectrometry (LCMS). The results indicated that the conversion of Sal B into Sal A in RSM tissues under the conditions of a high temperature, high pressure and high humidity was efficient and thereby, was readily utilized to prepare rich Sal A materials in practice.

Asymmetric synthesis and evaluation of danshensu-cysteine conjugates as novel potential anti-apoptotic drug candidates.

We have previously reported that the danshensu-cysteine conjugate N-((R)-3-benzylthio-1-methoxy-1-oxo-2-propanyl)-2-acetoxy-3-(3,4-diacetoxyphenyl) propanamide (DSC) is a potent anti-oxidative and anti-apoptotic agent. Herein, we further design and asymmetrically synthesize two diastereoisomers of DSC and explore their potential bioactivities. Our results show that DSC and its two diastereoisomers exert similar protective effects in hydrogen peroxide (H2O2)-induced cellular injury in SH-SY5Y cells, as evidenced by the increase of cell viability, superoxide dismutase (SOD), and reduced glutathione (GSH) activity, and glutathione peroxidase (GPx) expression, and the decrease of cellular morphological changes and nuclear condensation, lactate dehydrogenase (LDH) release, and malondialdehyde (MDA) production. In H2O2-stimulated human umbilical vein endothelial cells (HUVEC), DSC concentration-dependently attenuates H2O2-induced cell death, LDH release, mitochondrial membrane potential collapse, and modulates the expression of apoptosis-related proteins (Bcl-2, Bax, caspase-3, and caspase-9). Our results provide strong evidence that DSC and its two diastereoisomers have similar anti-oxidative activity and that DSC exerts significant vascular-protective effects, at least in part, through inhibition of apoptosis and modulation of endogenous antioxidant enzymes.

Tacticity-induced changes in the micellization and degradation properties of poly(lactic acid)-block-poly(ethylene glycol) copolymers.

Poly(lactic acid)-block-poly(ethylene glycol) copolymers (PLA-b-PEG) featuring varying tacticities (atactic, heterotactic, isotactic) in the PLA block were synthesized and investigated for their micellar stability, degradation, and thermal properties. Utilizing tin(II) bis(2-ethylhexanoate), aluminum salan, and aluminum salen catalysts, the copolymers were synthesized through the ring-opening polymerization of d-, l-, rac-, or a blend of l- and rac-lactide using monomethoxy-poly(ethylene glycol) as a macroinitiator. The critical micelle concentration, which reflects the micellar stability, was probed using a fluorescence spectroscopic method with pyrene as the probe. The copolymers were degraded in a methanolic solution of 1,5,7-triaza-bicyclo[4.4.0]dec-5-ene and the degradation was measured by (1)H NMR spectroscopic and gel permeation chromatographic analyses. Differential scanning calorimetry and thermogravimetric analysis provided information on the thermal properties of the copolymers. Atactic and heterotactic microstructures in the PLA block resulted in lower micellar stability, as well as faster degradation and shorter erosion time compared to polymers with high isotactic enchainment (Pm). By modification of the Pm, micellar stability, degradation, and erosion rates of the copolymers can be tuned to specific biomedical applications. Interestingly, while tin(II) bis(2-ethylhexanoate) and aluminum salan-catalyzed PLA-b-PEG copolymers exhibited similar micellization behavior, the aluminum salen-catalyzed PLA-b-PEG exhibited unique behavior at high micelle concentration in the presence of the pyrene probe. This unique behavior can be attributed to the disintegration of the micelles through the interactions of long isotactic stereoblock segments.

Controlled drug release system based on cyclodextrin-conjugated poly(lactic acid)-b-poly(ethylene glycol) micelles.

Cyclodextrin-conjugated poly(lactic acid)-b-poly(ethylene glycol) (ß-CD-PLA-mPEG), a well-defined amphiphilic copolymer, was synthesized by controlled ring-open copolymerization and click coupling reaction, in order to obtain a biocompatible drug delivery system with controlled release profiles. The ß-CD-PLA-mPEG copolymer could self-assemble in aqueous solution to form micelles with a mean particle size of 173.4 nm, which will decrease to 159.2 nm after loaded with a kind of hydrophobic drug (indomethacin, IND). The IND-loaded ß-CD-PLA-mPEG micelles show spherical shape within the nano-size scale under TEM imaging. Compared with that formed by PLA-mPEG, the micelles formed by ß-CD-PLA-mPEG copolymer present higher drug loading efficiency and controlled release profile of IND, especially in the control of its initial burst release. Meanwhile, ß-CD-PLA-mPEG copolymer exhibits low toxicity to cells. The micelles formed by ß-CD-PLA-mPEG copolymer could be a promising controlled release system for various hydrophobic drugs.

Total synthesis of (-)-orthodiffenes A and C.

The efficient and concise synthesis of (-)-orthodiffenes A and C has been accomplished for the first time in eight steps from readily available chiral synthons, D-mannose and D-ethyl lactate. Our work confirmed the complete structure of orthodiffenes A and C, including their absolute stereochemistry. The key steps of our total synthesis involved cis-fused tetrahydrofuran cyclization, one-pot deprotection-lactonization, and intramolecular benzoyl migration according to a biosynthetic hypothesis of orthodiffenes.