Combretastatin A4/poly(L-glutamic acid)-graft-PEG conjugates self-assembled to nanoparticles

Combretastatin A4(CA4) possesses varying ability to cause vascular disruption in tumors,while the short half-life, low water solubility and deactivation of many CA4 analogs during storage limited its antitumor efficacy and drug stability. A novel macromolecular conjugate of CA4(CA4-PL) was synthesized by covalent bonding of CA4 onto poly(L-glutamic acid)-graft-polyethylene glycol(PLG-g-PEG) via Yamaguchi reaction. The obtained CA4-PL was characterized by ~1H NMR, GPC, and UV methods, and the properties of the nanoparticles composed of CA4-PL, including critical aggregation concentration, size and size distribution, and morphology, were investigated. CA4-PL can self-assemble to form micelle-like nanoparticles of 80～120 nm in diameter, which may have potential to improve the blood circulation period as well as the targetability of CA4, and find applications to treat various tumors when combined with traditional chemotherapy or radio therapy.

Light-responsive Self-Immolative L-glutamic Acid-based Polyester Nanoparticles for Controlled Drug Release via Passerini Three-Component Polymerization

L-glutamic acid(LA)is a bio-based,non-toxic,environmentally friendly material derived from biomass.The present study reports the application of Passerini three-component polymerization(P-3CP)for the straightforward preparation of LA-based light-responsive polyesters(PLTDs)under mild conditions.PLTDs with molar masses up to 8500 g/mol and high yields exceeding 90%are obtained.The chemical structures and light-responsive self-immolative behavior of PLTDs are comprehensively characterized by employing ultraviolet-visible(UV-Vis)spectroscopy,size exclusion chromatography(SEC),nuclear magnetic resonance(NMR)spectroscopy,and liquid chromatography mass spectrometry(LC-MS).Meanwhile,monodisperse PLTD-based doxorubicin-loaded nanoparticles(PLTD-DOX-NP)(size=193 nm,PDI=0.018)are formulated by nanoprecipitation method.Upon light-induced depolymerization,the PLTD-DOX-NP undergoes rapid decomposition,resulting in a burst release of 80%cargo within 13 s.Furthermore,according to biological toxicity tests,the PLTD-NP possesses adequate biosafety,both before and after irradiation.Overall,the incorporation of P-3CP with biorenewable LA-based monomer adheres to the principles of green chemistry,significantly simplifying the synthetic pathway of light-responsive polymers.

Poly(L-glutamic acid)-cisplatin nanoformulations with detachable PEGylation for prolonged circulation half-life and enhanced cell internalization

PEGylation has been widely applied to prolong the circulation times of nanomedicines via the steric shielding effect,which consequently improves the intratumoral accumulation.However,cell uptake of PEGylated nanoformulations is always blocked by the steric repulsion of PEG,which limits their therapeutic effect.To this end,we designed and prepared two kinds of poly(L-glutamic acid)-cisplatin(PLG-CDDP)nanoformulations with detachable PEG,which is responsive to specific tumor tissue microenvironments for prolonged circulation time and enhanced cell internalization.The extracellular pH(pHe)-responsive cleavage 2-propionic-3-methylmaleic anhydride(CDM)-derived amide bond and matrix metalloproteinases-2/9(MMP-2/9)-sensitive degradable peptide PLGLAG were utilized to link PLG and PEG,yielding pHe-responsive PEG-pHe-PLG and MMP-sensitive PEG-MMP-PLG.The corresponding smart nanoformulations PEG-pHe-PLG-Pt and PEG-MMP-PLG-Pt were then prepared by the complexation of polypeptides and cisplatin(CDDP).The circulation half-lives of PEG-pHe-PLG-Pt and PEG-MMP-PLG-Pt were about 4.6 and 4.2 times higher than that of the control PLG-Pt,respectively.Upon reaching tumor tissue,PEG on the surface of nanomedicines was detached as triggered by pHe or MMP,which increased intratumoral CDDP retention,enhanced cell uptake,and improved antitumor efficacy toward a fatal high-grade serous ovarian cancer(HGSOC)mouse model,indicating the promising prospects for clinical application of detachable PEGylated nanoformulations.

Stereoselective synthesis of (5R,6S)-6-acetoxy hexadecanolide——The major component of the oviposition attractant pheromone of the mosquito Culex pipens fatigans and its enantiomer from L-glutamic acid

A concise synthesis of the mosquito oviposition attractant pheromone, (-)-(5R, 6S)- and (+)-(5S 6R)-6-acetoxy hexadecanolide from L-glutamic acid is described. The key steps are the inversion of the configuration at C-4 of 7, and the formation of δ-lactone from the γ-lactone through ring enlargement.

POLYMERIZATION OF γ-STEARYL-α,l-GLUTAMATE N-CARBOXYANHYDRIDE USING RARE EARTH COORDINATION CATALYSTS

A rare earth coordination system was first investigated as a new type of catalyst for the ring-openingpolymerization of α-amino acid N-carboxyanhydrides (NCAs). The results for the polymerization of γ-stearyl-α,L-glutamate(SLG) NCA using neodymium acetylacetonate (Nd(acac)_3)- or neodymium tris(2-ethylhexylphosphonate) (Nd(P_(204))_3)-triethylaluminum-water as catalysts were compared with those using conventional catalysts. It was found that the helicalpoly(γ-stearyl-L-glutamate) with high molecular weight as well as narrow molecular weight distribution can be obtained inthe presence of Nd(acac)_3/AlEt_3-1/2H_2O. The polymer obtained was characterized by IR and NMR spectroscopy.

银杏内酯B对大鼠海马CA1区神经元自发放电的影响(英文)

为了研究银杏内酯B(Ginkgolide B,BN52021)对静息状态下的海马脑片神经元活动的影响。本研究应用细胞外记录单位放电技术观察了银杏内酯B对海马神经元电活动的影响,并分析了相关机制。结果显示:(1)在43个CA1区神经元放电单位给予银杏内酯B(0.1,1,10μmol/L)2min,有42个放电单位(97.67%)放电频率明显降低,且呈剂量依赖性;(2)预先用0.2mmol/L的L-glutamate(L-Glu)灌流海马脑片,10个放电单位放电频率明显增加,表现为癫痫样放电,在此基础上灌流银杏内酯B(1μmol/L)2min,其癫痫样放电全部被抑制;(3)预先用L型钙通道开放剂BayK8644灌流8个海马脑片神经元,8个单位(100%)放电全部增加,在此基础上灌流银杏内酯B(1μmol/L)2min,7个放电单位(87.5%)放电频率明显减低;(4)在8个CA1区神经元,银杏内酯B(1μmol/L)对单位放电的抑制效应可被1mmol/L广泛钾通道阻断剂(tetraethylammonium,TEA)完全阻断。上述结果提示,银杏内酯B可抑制海马CA1区神经元的自发放电,这种作用可能与银杏内酯B抑制L型钙通道有关,而且可能与延迟整流型钾通道(delayed rectifier potassium channel,KDR)有关。银杏内酯B通过降低神经元的活动而发挥对中枢神经元的保护作用。

On-line near-infrared spectroscopy optimizing and monitoring biotransformation process of γ-aminobutyric acid

Near-infrared spectroscopy （NIRS） with its fast and nondestructive advantages can be qualified for the real-time quantitative analysis. This paper demonstrates that NIRS combined with partial least squares （PLS） regression can be used as a rapid analytical method to simultaneously quantify L-glutamic acid （L- GIu） and γ-aminobutyric acid （GABA） in a biotransformation process and to guide the optimization of production conditions when the merits of NIRS are combined with response surface methodology. The high performance liquid chromatography （HPLC） reference analysis was performed by the o-phthaldialdehyde pre-column derivatization. NIRS measurements of two batches of 141 samples were firstly analyzed by PLS with several spectral pre-processing methods. Compared with those of the HPLC reference analysis, the resulting determination coefficients （R2）, root mean square error of prediction （RMSEP） and residual predictive deviation （RPD） of the external validation for the L-GIu concentration were 99.5%, 1.62 g/L, and 11.3, respectively. For the GABA concentration, R2, RMSEP, and RPD were 99.8%, 4.00 g/L, and 16.4, respectively. This NIRS model was then used to optimize the biotransformation process through a Box- Behnken experimental design. Under the optimal conditions without pH adjustment, 200 gjL L-GIu could be catalyzed by 7148 U/L glutamate decarboxylase （GAD） to GABA, reaching 99% conversion at the fifth hour. NIRS analysis provided timely information on the conversion from L-GIu to GABA. The results suggest that the NIRS model can not only be used for the routine profiling of enzymatic conversion, providing a simple and effective method of monitoring the biotransformation process of GABA, but also be considered to be an optimal tool to guide the optimization of production conditions.

Experimental Study on Modified Treatment andEndothelialization of Bovine Pericardial Valves

The purpose of this study were to confirm whether the modified treatment with L-glutamic acid could attenuate the calcification of the GA-fixed valves and improve its biocompatibility. Pericardial valves were routinely treated with GA and valves were treated with GA and 8% L-glutamic acid. The valves treated with these methods were implanted subcutaneously in rats. Calcium deposits of the valves collected at the 7th, 21st, 60th, 90th day were assessed by atomic absorption spectroscopy, and the pathologic changes were examined by light and electron microscopy. Cultured endothelial cells (ECs ) were seeded onto the valves. The cell counts were determined at the 1st. 4th, 7th, 10th day after seeding. PGI2 in culture medium was tested at the 10th day. Transmission and scanning electron microscopy were used to observe the growth of ECs on the valves.Results showed that subsequent treatment with L-glutamic acid could significantly mitigate calcification of bovine pericardial valves as compared with simple GAfixed valves (P<0. 01). ECs seeded on the GA treated valves died within 4 days.On the valves treated by modified method, ECs could proliferate and release PGI2. It is concluded that treatment with L- glutamic acid can markedly inhibit the calcification and improve the biocompatibility of bioprosthetical valves.

三羟异黄酮对大鼠海马CA1区神经元自发放电的影响(英文)

目的研究三羟异黄酮(GENISTEIN,GST)对静息状态下的海马脑片神经元活动的影响。方法应用细胞外记录单位放电技术。结果 (1)在48个CA1区神经元放电单位给予GST(10,50,100 ΜMOL／L)2 MIN,有46个放电单位(95．83％)放电频率明显降低,且呈剂量依赖性;(2)在9个CA1区神经元放电单位上,GST(50ΜMOL／ L)的抑制效应可被G蛋白激活的内向整流型钾通道(G PROTEIN-COUPLED INWARDLY RECTIFYING K+ CHANNELS,GIRK)阻断剂(TETRAETHYLAMMONIUM,TEA)1 MMOL／L完全阻断;(3)10个放电单位灌流一氧化氮合酶抑制剂(NG-NITRO-L-ARGININE METHYL ESTER,L-NAME)50ΜMOL／L,有9个单位(90．0％)放电明显增加,在此基础上灌流GST(50 ΜMOL／L)2 MIN,放电被抑制;(4)预先用0．2 MMOL／L的L-GLUTAMATE(L-GLU)灌流海马脑片,11个放电单位放电频率明显增加,表现为癫痫样放电,在此基础上灌流GST(50ΜMOL／L)2 MIN,其癫痫样放电被抑制。结论 GST可抑制海马神经元自发放电,并可抑制由L-NAME和L-GLUTAMATE诱发的神经元放电。提示GST对中枢神经元通过降低其活动而具有一定程度的保护作用,这种作用与钾电流有关,似与其激动GIRK促进K+外流引起细胞膜超极化以及NO 产生增加有关。

Effect of Dietary Supplementation of Fu-libao and Glutamic Acid on Finishing and Slaughter Performance and Meat Quality of Pigs

[Objective]The paper was to investigate the effect of dietary supplementation of Fu-libao and L-glutamic acid on finishing and slaughter performances and meat quality trait of"L(Large Yorkshire)×L(Landrace)"crossbred pigs.[Method]Twelve individuals of L×L crossbred pigs with similar body weight of about 51 kg were selected.The pigs were randomly divided into two groups,three replicates each group,two piglets each replicate.The pigs in control group were fed with conventional diet(control diet),and pigs in treatment group were fed with the control diet added with 0.1%Fu-libao(mainly contained soybean phospholipid)and 0.6%L-glutamic acid.All the pigs were under the same feeding conditions except for different diets during the trial.At the end of the trial,one pig with similar body weight was selected from each replicate for slaughter and determination of meat quality.[Result]Dietary supplementation of Fu-libao and L-glutamic acid had no significant impact on finishing performance of pigs between the two groups(P>0.05),but the back fat thickness of pigs in treatment group was increased(P<0.05).On the contrary,the longissimus muscle(LM)area,meat color and water-holding capacity(WHC)were reduced significantly compared with the control group(P<0.05).However,the contents of glutamic acid,glysine,alanine,threonine,proline,valine and arginine in LM were increased significantly compared with the control group(P<0.05);moreover,the total amino acid and total flavor amino acid contents in LM were increased by 5.85%(P<0.05)and 6.87%(P<0.05)respectively.In addition,the content of intramuscular fat(IMF)in LM was improved from 5.11±0.24(control group)to 8.86±0.52(treatment group)(P<0.05).[Conclusion]Although dietary supplementation of Fu-libao and L-glutamic acid did not increase the finishing and slaughter performances of L×L crossbred pigs,it significantly enhanced the contents of total amino acid,total flavor amino acid and IMF,and significantly improved meat quality.

Effects of “Bioactive” amino acids leucine, glutamate, arginine and tryptophan on feed intake and mRNA expression of relative neuropeptides in broiler chicks

Feed intake control is vital to ensuring optimal nutrition and achieving full potential for growth and development in poultry. The aim of the present study was to investigate the effects of L-leucine, L-glutamate, L-tryptophan and L-arginine on feed intake and the mRNA expression levels of hypothalamic Neuropeptide involved in feed intake regulation in broiler chicks. Leucine, glutamate, tryptophan or arginine was intra-cerebroventricularly （ICV） administrated to 4d-old broiler chicks respectively and the feed intake were recorded at various time points. Quantitative PCR was performed to determine the hypothalamic mRNA expression levels of Neuropeptide Y （NPY）, agouti related protein （AgRP）, pro-opiomelanocortin （POMC）, melanocortin receptor 4 （MC4R） and corticotrophin releasing factor （CRF）. Our results showed that ICV administration of L-leucine （0.15 or 1.5 μmol） significantly （P〈0.05） increased feed intake up to 2 h post-administration period and elevated both hypothalamic NPY and AgRP mRNA expression levels. In contrast, ICV administration of L-glutamate （1.6 μmol） significantly （P 〈 0.05） decreased feed intake 0.25, 0.5 and 2 h post-injection, and increased hypothalamic CRF and MC4R mRNA expression levels. Meanwhile, both L-tryptophan （10 or 100 μg） and L-arginine （20 or 200 μg） had no significant effect on feed intake. These findings suggested that L-leucine and L-glutamate could act within the hypothalamus to influence food intake, and that both orexigenic and anorexigenic Neuropeptide genes might contribute directly to these effects.

Effects and mechanisms of L-glutamate microinjected into nucleus ambiguus on gastric motility in rats

Background L-glutamate （L-GLU） is a major neurotransmitter in the nucleus ambiguus （NA）, which can modulate respiration, arterial pressure, heart rate, etc. This study investigated the effects and mechanisms of L-GLU microinjected into NA on gastric motility in rats. Methods A latex balloon connected with a pressure transducer was inserted into the pylorus through the forestomach for continuous recording of the gastric motility. The total amplitude, total duration, and motility index of gastric contraction waves within 5 minutes before microinjection and after microinjection were measured. Results L-GLU （5 nmol, 10 nmol and 20 nmol in 50 nl normal saline （PS） respectively） microinjected into the right NA significantly inhibited gastric motility, while microinjection of physiological saline at the same position and the same volume did not change the gastric motility. The inhibitory effect was blocked by D-2-amino-5-phophonovalerate （D-AP5, 5 nmol, in 50 nl PS）, the specific N-methyI-D-aspartic acid （NMDA） receptor antagonist, but was not influenced by 6-cyaon-7-nitroquinoxaline-2,3-（1H,4H）-dione （CNQX） （5 nmol, in 50 nl PS）, the non-NMDA ionotropic receptor antagonist. Bilateral subdiaphragmatic vagotomy abolished the inhibitory effect by microinjection of L-GLU into NA. Conclusions Microinjection of L-GLU into NA inhibits the gastric motility through specific NMDA receptor activity, not non-NMDA receptor activity, and the efferent pathway is the vagal nerves.

Effect of dietary L-glutamate levels on growth,digestive and absorptive capability,and intestinal physical barrier function in Jian carp(Cyprinus carpio var.Jian)

The present study explored effects of L-glutamate(Glu)levels on growth,digestive and absorptive capability,and intestinal physical barrier functions of Jian carp(Cyprinus carpio).A total of 600 Jian carp(126.40±0.21 g)were randomly distributed into 5 groups with 3 replicates each,fed diets containing graded levels of Glu(53.4[control],57.2,60.6,68.4,and 83.4 g/kg)for 63 d.Results showed compared with control diet,feed intake and percent weight gain(PWG)in fish fed 83.4 g of Glu/kg diet were increased and feed conversion ratio in fish fed 68.4 g of Glu/kg diet was decreased(P<0.05).Similarly,body crude protein and lipid contents in fish fed 68.4 g of Glu/kg diet were higher(P<0.05).The activities of trypsin and chymotrypsin in the hepatopancreas and intestine,and amylase,alkaline phosphatase(AKP),Na^+,K^+-ATPase(NKA),and creatine kinase(CK)in intestine were higher in fish fed 68.4 g of Glu/kg diet(P<0.05).Dietary Glu(57.2 to 83.4 g/kg diet)decreased malondialdehyde(MDA)and protein carbonyl(PCO)contents in the intestine(P<0.05).The activities of catalase(CAT),glutathione peroxidase(GPx),and glutathione S-transferase(GST)in the hepatopancreas and intestine were higher in fish fed 60.6 and 68.4 g of Glu/kg diets(P<0.05).Intestinal the glutathione reductase(GR)activity and glutathione(GSH)content in fish fed 60.6,68.4,and 83.4 g of Glu/kg diet were increased(P<0.05).The GPx1 a,GST,and nuclear factor erythroid 2-related factor 2(Nrf2)mRNA expressions in the intestine were up-regulated in fish fed 60.6 and 68.4 g of Glu/kg diet(P<0.05).The zonula occludens protein-1(ZO-1),occludin1,and claudin3 mRNA expressions were also up-regulated in fish fed 83.4 g of Glu/kg diet(P<0.05).Fish fed 68.4 g of Glu/kg diet had higher levels of claudin 2,claudin7,and protein kinase C(PKC)mRNA(P<0.05).These results indicated that Glu improved frsh growth,digestive and absorptive ability,and intestinal physical barrier functions.Based on the quadratic regression analysis of PWG,and MDA of the hepatopancreas and intestine,the optimal dietary Glu levels were estimated to be 81.97,71.06,and 71.36 g/kg diet,respectively.

Production of L-glutamate family amino acids in Corynebacterium glutamicum:Physiological mechanism,genetic modulation,and prospects

L-glutamate family amino acids(GFAAs),consisting of L-glutamate,L-arginine,L-citrulline,L-ornithine,L-proline,L-hydroxyproline,γ-aminobutyric acid,and 5-aminolevulinic acid,are widely applied in the food,pharmaceutical,cosmetic,and animal feed industries,accounting for billions of dollars of market activity.These GFAAs have many functions,including being protein constituents,maintaining the urea cycle,and providing precursors for the biosynthesis of pharmaceuticals.Currently,the production of GFAAs mainly depends on microbial fermentation using Corynebacterium glutamicum(including its related subspecies Corynebacterium crenatum),which is substantially engineered through multistep metabolic engineering strategies.This review systematically summarizes recent advances in the metabolic pathways,regulatory mechanisms,and metabolic engineering strategies for GFAA accumulation in C.glutamicum and C.crenatum,which provides insights into the recent progress in L-glutamate-derived chemical production.

Microbial chassis design and engineering for production of amino acids used in food industry

Rational microbial chassis design and engineering for improving production of amino acids have attracted a considerable attention.l-glutamate,l-lysine,l-threonine and l-tryptophan are the main amino acids demanded in the food industry.Systems metabolic engineering and synthetic biology engineering generally are believed as the comprehensive engineering approaches to obtain rationally designed strains and construct high-performance platforms for amino acids.The strate-gies focus on microbial chassis characterization optimization,precise metabolic engineering such as promoter engineer-ing,modular pathway engineering,transporter engineering,and dynamic switch systems application,and global genome streamline engineering to reduce cell burden.In this review,we summarized the efficient engineering strategies to optimize Corynebacterium glutamicum and Escherichia coli cell factories for improving the production of l-glutamate,l-lysine,l-threonine,and l-tryptophan.

Preparation and Characterization of Attractive Poly(amino acid)Hydrogels Based on 2-Ureido-4[1H]-pyrimidinone

Self-healing hydrogels with the shear-thinning property are novel injectable materials and are superior to traditional injectable hydrogels.The self-healing hydrogels based on 2-ureido-4[1 H]-pyrimidinone(UPy)have recently received extensive attention due to their dynamic reversibility of UPy dimerization.However,generally,UPy-based self-healing hydrogels exhibit poor stability,cannot degrade in vivo and can hardly be excreted from the body,which considerably limit their bio-application.Here,using poly(l-glutamic acid)(PLGA)as biodegradable matrix,branchingα-hydroxy-ω-amino poly(ethylene oxide)(HAPEO)as bridging molecule to introduce UPy,and ethyl acrylate polyethylene glycol(MAPEG)to introduce double bond,the hydrogel precursors(PMHU)are prepared.A library of the self-healing hydrogels has been achieved with well self-healable and shear-thinning properties.With the increase of MAPEG grafting ratio,the storage modulus of the self-healing hydrogels decreases.The self-healing hydrogels are stable in solution only for 6 h,hard to meet the requirements of tissue regeneration.Consequently,ultraviolet(UV)photo-crosslinking is involved to obtain the dual crosslinking hydrogels with enhanced mechanical properties and stability.When MAPEG grafting ratio is 35.5%,the dual crosslinking hydrogels can maintain the shape in phosphate-buffered saline solution(PBS)for at least 8 days.Loading with adipose-derived stem cell spheroids,the self-healing hydrogels are injected and self-heal to a whole,and then they are crosslinked in situ via UV-irradiation,obtaining the dual crosslinking hydrogels/cell spheroids complex with cell viability of 86.7%±6.0%,which demonstrates excellent injectability,subcutaneous gelatinization,and biocompatibility of hydrogels as cell carriers.The novel PMHU hydrogels crosslinked by quadruple hydrogen bonding and then dual photo-crosslinking of double bond are expected to be applied for minimal invasive surgery or therapies in tissue engineering.

Design and evaluation of chitosan-amino acid thermosensitive hydrogel

Chitosan/glycerophosphate thermosensitive hydrogel crosslinked physically was a potential drug delivery carrier;however, long gelation time limits its application. Here, chitosan-amino acid (AA) thermosensitive hydrogels were prepared from chitosan (CS), αβ-glycerophosphate (GP), and L-lysine (Lys) or L-glutamic acid (Glu). The prepared CS-Lys/GP and CS-Glu/GP hydrogel showed good thermosensitivity and could form gels in a short time. The optimal parameters of CS-Lys/GP hydrogel were that the concentration of CS-Lys was 2.5%, the ratio of CS/Lys was 3.5/1.0, the ratio of CS-Lys/GP was 4.5/1.0. The optimal parameters of CS-Glu/GP hydrogel were that the concentration of CS-Glu was 3.0%, the ratio of CS/Glu was 2.0/1.0, and the ratio of CS-Glu/GP was 4.0/1.5. Chitosan-amino acid (CS-AA) thermosensitive hydrogel had a three-dimensional network structure. The addition of model drug tinidazole (TNZ) had no obvious effect on the structure of hydrogel. The results of infrared spectroscopy showed that there were hydrogen bonds between amino acids and chitosan. In vitro release results showed that CS-Lys/GP and CS-Glu/GP thermosensitive hydrogels had sustained release effects. Thus, the chitosan-amino acid thermosensitive hydrogels hold great potential as a sustained release drug delivery system.