Effects of mixed fertilizers formed by the compounding of two targeted controlled-release nitrogen fertilizers on yield,nitrogen use efficiency,and ammonia volatilization in double-cropping rice

One-time application of mixed fertilizer formed by the compounding of two controlled-release nitrogen fertilizers(CRUs)with targeted N supply during the periods from transplantation(TS)to panicle initiation(PI)and from PI to heading(HS)is expected to synchronize the double-peak N demand of rice.However,its effects on the yield and N use efficiency(NUE)of labor-intensive double-cropping rice were unknown.Two targeted CRU(CRU_(A)and CRU_(B))were compounded in five ratios(CRU_(A):CRU_(B)=10:0,7:3,5:5,3:7,and 0:10)to form five mixed fertilizers(BBFs):BBF1-5.A field experiment was performed to investigate the characteristics of N supply in early and late seasons under different BBFs and their effects on N uptake,yield,and ammonia volatilization(AV)loss from paddy fields of double-cropping rice.Conventional high-yield fertilization(CK,three split applications of urea)and zero-N treatments were established as controls.The N supply dropped significantly with the increased compound ratio of CRU_(B)during the period from TS to PI,but increased during the period from PI to HS.With the exception of the period from TS to PI in the late rice season,the N uptake of early and late rice maintained close synchronicity with the N supply of BBFs during the double-peak periods.Excessive N supply(BBF1 and BBF2)in the late rice season during the period from TS to PI increased N loss by AV.The effect of BBF on grain yield increase varied widely between seasons,irrespective of year.Among the BBFs,the BBF2 treatment of early rice not only stabilized the spikelets per panicle but also ensured a high number of effective panicles by promoting N uptake during the period from TS to PI and a high grain-filling percentage by appropriately reducing the N supply at the later PI stage,resulting in the highest rice yield.While stabilizing the effective panicle number,the BBF4 treatment of late rice increased the number of spikelets per panicle by promoting N uptake during the period from PI to HS,resulting in the highest rice yield.The two-year average yield and apparent N recovery efficiency of the BBF2 treatment during the early rice season were 9.6 t ha 1 and 45.3%,while those of late rice in BBF4 were 9.6 t ha 1 and 43.0%,respectively.The yield and NUE indexes of BBF2 in early rice and BBF4 in late rice showed no significant difference from those of CK.The AVs of BBF2 during the early rice season and of BBF4 during the late rice season were 50.0%and 76.8%lower,respectively,than those of CK.BBF2 and BBF4 could effectively replace conventional urea split fertilization in early and late rice seasons,ensuring rice yield and NUE and reducing AV loss in paddy fields.

Glucocorticoids-based prodrug design:Current strategies and research progress

Attributing to their broad pharmacological effects encompassing anti-inflammation,antitoxin,and immunosuppression,glucocorticoids(GCs)are extensively utilized in the clinic for the treatment of diverse diseases such as lupus erythematosus,nephritis,arthritis,ulcerative colitis,asthma,keratitis,macular edema,and leukemia.However,longterm use often causes undesirable side effects,including metabolic disorders-induced Cushing's syndrome(buffalo back,full moon face,hyperglycemia,etc.),osteoporosis,aggravated infection,psychosis,glaucoma,and cataract.These notorious side effects seriously compromise patients'quality of life,especially in patients with chronic diseases.Therefore,glucocorticoid-based advanced drug delivery systems for reducing adverse effects have received extensive attention.Among them,prodrugs have the advantages of low investment,low risk,and high success rate,making them a promising strategy.In this review,we propose the strategies for the design and summarize current research progress of glucocorticoid-based prodrugs in recent decades,including polymer-based prodrugs,dendrimer-based prodrugs,antibody-drug conjugates,peptide-drug conjugates,carbohydrate-based prodrugs,aliphatic acid-based prodrugs and so on.Besides,we also raise issues that need to be focused on during the development of glucocorticoid-based prodrugs.This review is expected to be helpful for the research and development of novel GCs and prodrugs.

Preparation, stability and pharmacokinetics evaluation of lipid microspheres loading a promising antitumor candidate, Timataxel

Timataxel(13-(N-Boc-3-i-butylisoserinoyl-4,10-β-diacetoxy-2-α-benzoyloxy-5-β-20-epoxy-1,13-α-dihydroxy-9-oxo-19-norcyclopropa[g]tax-11-ene)), used to be called TM-2, is a novel semi-synthetic promising candidate for cancer treatment. However the preformulation study showed that TM-2 was insoluble and chemically instable in water, which would limit its application. This study aimed at the preparation of Timataxel lipid microspheres(TM-2 LMs)and investigated the difference between TM-2 LMs and TM-2 solution in pharmacokinetics. In this work, the final formulation was as follows: 0.10%(w/v) TM-2;10.00%(w/v) oil phase(long chain triglyceride:media chain triglyceride = 2.50%:7.50%);1.40%(w/v) phospholipid;0.02%(w/v) NaH2 PO4;2.25%(w/v) glycerin and water to a total volume of 100 ml.The particle size distribution, content and entrapment efficacy were 205.0 ± 43.3 nm, 101.00% and 99.12%, respectively. TM-2 LMs were stable during storage at 25 °C for 3 months, even under the condition of 60 °C and 4500 lx for 10 d. Phosphatidylethanolamine(PE) in phospholipid may contribute to the stability of TM-2 LMs. The pharmacokinetic parameters for TM-2 LMs were as follows: AUC(0-∞) 3663.71 μg/l h and the clearance 2.26 l/h/kg. As for solution, these parameters were 1712.52 μg/l h and 4.77 l/h/kg, respectively. The t1/2 of TM-2 LMs was similar to TM-2 solution. The pharmacokinetic results indicated that the AUC of TM-2 LMs was larger, the clearance was smaller than that of TM-2 solution. In a word, lipid microspheres were a promising drug delivery system for TM-2.

Hot-melt sub-and outercoating combined with enteric aqueous coating to improve the stability of aspirin tablets

Aspirin is apt to hydrolyze. In order to improve its stability, a new method has been developed involving the application of hot-melt sub-and outercoating combined with enteric aqueous coating. The main aim was to investigate the influence of these factors on the stability of ASA and understand how they work. Satisfactory storage stability were obtained when the aspirin tablet core coated with Eudragit L30D55 film was combined with glycerin monostearate(GMS) as an outercoat. Hygroscopicity testing indicated that the moisture penetrating into the tablet may result in a significant change in the physical properties of the coating film observed by scanning electron microscopy. Investigation of the compatibility between the drug and film excipients shows that the talc and methacrylic acid had a significant catalytic effect on ASA. A hypothesis was proposed that the hydrolysis of ASA enteric coated tablets(ASA-ECT) was mostly concentrated in the internal film and the interfaces between the film and tablet core. In conclusion, hot-melt coating technology is an alternative to subcoating or outercoating. Also, GMS sub-coating was a better choice for forming a stable barrier between the tablet core and the polymer coating layer, and increases the structure and chemical stability.

Supersaturation induced by Itraconazole/Soluplus micelles provided high GI absorption in vivo

To investigate the effect of supersaturation induced by micelle formation during dissolution on the bioavailability of itraconazole(ITZ)/Soluplus~? solid dispersion. Solid dispersions prepared by hot melt extrusion (HME) were compressed into tablets directly with other excipients. Dissolution behavior of ITZ tablets was studied by dissolution testing and the morphology of micelles in dissolution media was studied using transmission electron microscopy (TEM). Drug transferring from stomach into intestine was simulated to obtain a supersaturated drug solution. Bioavailability studies were performed on the ITZ tablets and Sporanox~? in beagle dogs. The morphology of micelles in the dissolution media was observed to be spherical in shape, with an average size smaller than 100 nm. The supersaturated solutions formed by Soluplus~? micelles were stable and no precipitation took place over a period of 180 min. Compared with Sporanox~?, ITZ tablets exhibited a 2.50-fold increase in the AUC (0–96) of ITZ and a 1.95-fold increase in its active metabolite hydroxyitraconazole (OHITZ) in the plasma of beagle dogs. The results obtained provided clear evidence that not only the increase in the dissolution rate in the stomach, but also the supersaturation produced by micelles in the small intestine may be of great assistance in the successful development of poorly water-soluble drugs. The micelles formed by Soluplus~? enwrapped the molecular ITZ inside the core which promoted the amount of free drug in the intestinal cavity and carried ITZ through the aqueous boundary layer(ABL), resulting in high absorption by passive transportation across biological membranes. The uptake of intact micelles through pinocytosis together with the inhibition of P-glycoprotein-mediated drug efflux in intestinal epithelia contributed to the absorption of ITZ in the gastrointestinal tract. These results indicate that HME with Soluplus~?, which can induce supersaturation by micelleformation, may be of great assistance to the successful development of poorly watersoluble drugs.

An intravenous clarithromycin lipid emulsion with a high drug loading, H-bonding and a hydrogen-bonded ion pair complex exhibiting excellent antibacterial activity

The aim of this study was to develop an intravenous clarithromycin lipid emulsion(CLE)with good stability and excellent antibacterial activity. The CLE was prepared by the thinfilm dispersed homogenization method. The interaction between clarithromycin(CLA) and cholesteryl hemisuccinate(CHEMS) was confirmed by DSC, FT-IR and^1H NMR analysis. The interfacial drug loading, thermal sterilization, freeze–thaw stability, and in vitro and in vivo antibacterial activity were investigated systematically. DSC, FT-IR and^1H NMR spectra showed that CHEMS(CLA: CHEMS, M ratio 1:2) could interact with CLA through H-bonding and a hydrogen-bonded ion pair. The CHEMS was found necessary to maintain the stability of CLE.Ultracentrifugation showed that almost 88% CLA could be loaded into the interfacial layer.The optimized CLE formulation could withstand autoclaving at 121 °C for 10 min and remain stable after three freeze–thaw cycles. The in vitro susceptibility test revealed that the CLA–CHEMS ion-pair and CLE have similar activity to the parent drug against many different bacterial strains. The in vivo antibacterial activity showed that the ED50 of intravenous CLE was markedly lower than that of CLA solution administrated orally. CLE exhibited pronounced antibacterial activity and might be a candidate for a new nanocarrier for CLA with potential advantages over the current commercial formulation.

Tablets of paliperidone using compression-coated technology for controlled ascending release

The aim of this work was to prepare ascending release compression-coated(CC) tablets with paliperidone(PAL) using a simple manufacturing technique and short manufacturing process.The release behavior and mechanisms in vitro of the final tablets was investigated and evaluated. The PAL CC tablets were comprised of a core layer of high viscosity hydroxypropyl cellulose(HPC-H) and a coating layer of high viscosity hydroxypropyl methylcellulose(HPMCK100 M). Several factors such as materials and core tablet compositions were studied for their influence in the formulation procedure. The drug release mechanism was studied using gravimetric analysis. The data could be fitted to the Peppas model. The ascending drug release results were expressed in terms of the slope of the release curve at different time points.Results showed that the formulation could achieve a good ascending drug release when the weight ratio of PAL was 5:1(core:layer). The fraction of HPC and HPMC was 33 %, and the combination of Eudragit RL-PO was 10%. The ascending release mechanism was due to solvent penetration into the PAL CC tablets, and subsequent drug dissolution from the gelatinous HPC and HPMC matrix erosion. The release mechanism was therefore a combination of diffusion and erosion. This work demonstrated that the compression-coated tablets could achieve controlled ascending release over 24 h for the oral administration systems.

同轴静电喷涂法制备核壳靶向示踪重组人白细胞介素Ⅱ微球

重组人白细胞介素-2(rh IL-2)具有促进免疫细胞增殖和分化的潜能,可用于治疗肺癌。然而,rh IL-2半衰期短,生物活性不稳定,需要将其载入微球中进行缓释给药。本研究采用同轴静电喷涂技术制备了载rh IL-2的核壳微球。以量子点为示踪材料,核层用壳聚糖做载体包裹rh IL-2和量子点偶联物,壳层采用透明质酸做载体制备核壳复合微球。采用单因素法对载体浓度、电压、针孔内径、喷雾流量等因素进行了研究。优化了同轴静电喷雾法制备核壳微球的工艺参数。结果表明,制备的核壳微球粒径在1.2–2.0μm,包封率和载药量分别为78.39%±1.96%和19.58±2.76μg/mg。体外释放实验显示微球释放效果较好,无突释现象。该制剂的生物学活性实验表明,核壳微球中的rh IL-2与游离蛋白药物具有相同的作用。体内成像分析也显示微球具有主动靶向性。本研究为rh IL-2靶向缓释微球的研制提供了理论依据。

Total Synthesis of Three Families of Natural Antibiotics:Anthrabenzoxocinones,Fasamycins/Naphthacemycins,and Benastatins

Due to the critical bacterial resistance and antibiotic crisis,the discovery of new antibiotics is an urgent need in the clinic than ever.Naturally occurring antibiotics have proven to be an indispensable source of the development of new antibacterial agents.Herein,we report the total synthesis of three families of biogenetically related natural antibiotics,including anthrabenzoxocinones(ABXs),fasamycins/naphthacemycins,and benastatins.The synthesis featured divergent and convergent approaches,which enabled efficient construction of the basic polycyclic skeletons in 6–10 steps on a large-scale,followed by a collective synthesis of 14 natural products and their corresponding analogs.The core scaffold of gemdimethyl-anthracenone,a naturally occurring type II fatty acid-specific condensation enzyme(FabFspecific)antibiotic pharmacophore,was forged via a Ti(Oi-Pr)4-mediated photoenolization/Diels–Alder(PEDA)reaction between 2-isopropyl benzaldehyde and a variety of enones.A scale-up of the PEDA reaction was facilitated in an assembled continuous-flow reactor,which allowed us to overcome the issues associated with batch photochemistry.Subsequently,the synthetic natural antibiotics and their analogs would be utilized in structure–activity relationships(SAR)and mechanism studies,which should enable the discovery of new and leading antibiotic compounds.

Titanium-promoted Intramolecular Photoenolization/Diels-Alder Reaction to Construct Polycyclic Terpenoids: Formal Synthesis of Mycoleptodiscin A

Summary of main observation and conclusion A titanium-promoted intramolecular photoenolization/Diels-Alder (PEDA) reaction was developed to construct the core skeleton of aromatic polycyclic terpenoids bearing an all-carbon quaternary center on the benzylic position. Titanium(Ⅳ) isopropoxide [Ti(Oi-Pr)4] plays a key role during the photo cycloaddition, which may help to accelerate the in teraction between dienophile and the stereo-hi ndered diene species as well as control the diastereoselectivity. This photolysis provides a new solution for the stereospecific formation core structures of aromatic abietane diterpenoids and sesquiterpenoids, which have multiple functional groups for the further transformations. As a synthetic application, it was successfully used in the synthesis of indolosesquiterpenoid mycoleptodiscin A.

Oral delivery of polyester nanoparticles for brain-targeting: Challenges and opportunities

Efficient oral delivery of drugs treating brain diseases has long been a challenging topic faced by the drug delivery community. Fortunately, polyester nanoparticles offer certain solutions to this problem. This review article firstly describes the main obstacles faced by oral administered brain targeting, including:(1)instability in the gastrointestinal tract;(2) poor penetration of the intestinal mucosa and epithelium;(3)blood clearance;and(4) restriction by the BBB. Then the key factors influencing brain-targeting efficiency of orally administered polyester nanoparticles are also discussed, such as size, shape and surface properties. Finally, recent brain-targeting delivery strategies using oral polyester nanoparticles as carriers and their effects on brain drugs transport are reviewed, and the delivery ‘as a whole’ strategy of polyester nanoparticles will provide new insight for oral brain-targeting delivery. And by combination of multiple strategies, both the stability and permeability of polyester nanoparticles can be greatly improved for oral brain drug delivery.