Solid dispersion in the development of a nimodipine delayed-release tablet formulation

Nimodipine(NMD)is a dihydropyridine calcium channel blocker with selectivity for cerebral blood vessels and the major therapeutic indication of NMD is for the prevention and treatment of delayed ischemic neurological disorders and other cerebrovascular disorders,such as stroke which is associated with biological rhythm.This study was mainly designed to solve the drawback of conventional NMD solid dosage form,low bioavailability and limited clinical efficacy,by preparing enteric solid dispersion(SD)and the SD was prepared via melting method.The physical state of the dispersed NMD in the polymer matrix was characterized by differential scanning calorimetry(DSC),powder X-ray diffraction(PXRD)and dissolution studies.Compared with pure drug and physical mixture,the dissolution of NMD-SD was enhanced dramatically(about 80%).Furthermore,in consideration of the biological rhythm of stroke,we first obtained a delayed-release tablet containing NMD-SD by a direct powder compression method.As shown in the dissolution studies,the tablet released less than 10%in the artificial gastric acid in the initial 2 h and released 32.1%,75%,more than 90%at 4,10 and 14 h respectively in the artificial intestinal fluid.This investigation has solved the problems of oral solid dosage forms of NMD,and it has the good industry prospect.

Prodrugs incorporated into nanotechnology-based drug delivery systems for possible improvement in bioavailability of ocular drugs delivery

Numerous systems have been designed during the past three decades to improve bioavailability of ophthalmic drug delivery,including:ocular prodrugs and nanotechnology-based drug delivery system.The former can improve the efficacy of ocular drug via enhancing corneal penetration of ocular drugs,prolonging their duration of action and/or reducing the systemic side-effects,unfortunately,some characteristics of the pro-drugs,such as poorly aqueous stability,poorly aqueous solubility and severe eye irritation probably,limit their clinical practice and cannot be ignored.As we all know,nanotech-nology for ocular drug delivery can carry poorly soluble drugs,protect the encapsulated molecules from hydrolysis,control the rate of drug delivery and prolong the precorneal retention of drugs.All of these merits may solve the problems in the utilization of ocular prodrugs and increase the bioavailability of ocular drug delivery.By reviewing recent ad-vances of prodrugs and nanostructures in ocular drug delivery,this paper focus specifically on the promising prospects of nanocarriers overcoming the drawbacks of prodrugs for ophthalmic drug delivery by precorneal routes.

Succinylated whey protein isolate as a sustained-release excipient of puerarin derivative oral tablets:Preparation,optimization and pharmacokinetics

This work was done to investigate succinylated commercial whey protein isolate(S-WPI)as an oral sustained-release delivery carrier for puerarin 5(PR-5). The succinylation condi-tions were established for S-WPIs by optimization of single factor study and Box–Beehnkendesign. The effect of succinylation degree on S-WPIs solubility was evaluated. Physicochem-ical properties of S-WPIs dried by different three methods on their flow ability, particle size,morphology and in vitro release behavior were studied. After preparing PR-5 sustained re-lease protein tablets with S-WPIs as the carrier by direct powder compression method, thedrug release were studied in vitro and the oral pharmacokinetics and bioavailability wasevaluated using in vivo dog model. It was observed that concentration of substrate has asignificant effect on succinylation. Release behavior in vitro showed spry dried S-WPIs with100% succinylation rate and 30% drug loading would be applied to the preparation of PR-5 sustained-release protein tablets based on the swelling mechanism(protein loss). Comparedwith PR-5 conventional tablet with oral administration, T max value of PR-5 sustained-releaseprotein tablets was approximately 1.58 fold greater than those of the conventional tablets asfurther evidenced by the significantly prolonged MRT and T 1/2. The findings demonstratedthat spray-dried S-WPIs has potential as a promising functional excipient for the design of PR-5 oral sustained-release tablets which can fully improve sustained-release effect and oral bioavailability.

Targeted delivery of docetaxel to the metastatic lymph nodes:A comparison study between nanoliposomes and activated carbon nanoparticles

The objective of this study is to compare the targeting ability of activated carbon nanoparticles and nanoliposomes,which are used as carriers for delivering docetaxel(DTX)to the metastatic lymph nodes.In this study,we first prepared the DTX-loaded activated carbon nanoparticles(DTX-AC-NPs)by modifying the activated carbon with nitric acid oxidation and absorbing DTX in the concentrated nitro-oxide nanocarbon.We then prepared DTX-loaded nanoliposomes(DTX-LPs)by the proliposome method.The physiochemical properties of DTX-AC-NPs and DTX-LPs were carefully evaluated in vitro.The metastatic lymph node uptake and the injection site retention were investigated by analyzing the DTX concentration in metastatic lymph nodes and injection sites.The result showed that DTX-AC-NPs and DTX-LPs with suitable and stable physicochemical properties could be used for in vivo lymph node targeting studies.DTX-AC-NPs significantly increased DTX-AUC_((0-24)) and prolonged DTX-retention in metastatic lymph nodes compared to DTX-LPs and non-modified activate carbon in vivo.This study demonstrated activated carbon nanoparticles may be potential intralymphatic drug delivery system to preferentially target regional metastatic lymph nodes.

Hydrogen sulfide regulates abiotic stress tolerance and biotic stress resistance in Arabidopsis

Hydrogen sulfide （H2S） is an important gaseous molecule in various plant developmental processes and plant stress responses. In this study, the transgenic Arabidopsis thaliana plants with modulated expressions of two cysteine desulfhydrases, and exogenous H2S donor （sodium hydrosulfide, NariS） and H2S scavenger （hypotaurine, HT） pre-treated plants were used to dissect the involvement of H2S in plant stress responses. The cysteine desulfhydrases overexpressing plants and NariS pre-treated plants exhibited higher endogenous H2S level and improved abiotic stress tolerance and biotic stress resistance, while cysteine desulfhydrases knockdown plants and HT pre-treated plants displayed lower endogenous H2S level and decreased stress resistance. Moreover, H2S upregulated the transcripts of multiple abiotic and biotic stress-related genes, and inhibited reactive oxygen species （ROS） accumulation. Interest- ingly, MlR393-mediated auxin signaling including MIR393a/b and their target genes （TIR1, AFB1, AFB2, and AFB3） was transcrip-tionally regulated by H2S, and was related with H2S-induced antibacterial resistance. Moreover, H2S regulated 50 carbon metabolites including amino acids, organic acids, sugars, sugar alcohols, and aromatic amines. Taken together, these results indicated that cysteine desulfhydrase and H2S conferred abiotic stress tolerance and biotic stress resistance, via affecting the stress-related gene expressions, ROS metabolism, metabolic homeostasis, and MIR393-targeted auxin receptors.

Comparative proteomic and metabolomic analyses reveal mechanisms of improved cold stress tolerance in bermudagrass (Cynodon dactylon(L.) Pers.) by exogenous calcium

As an important second messenger, calcium is involved in plant cold stress response, including chilling（〈20 °C） and freezing（〈0 °C）. In this study, exogenous application of calcium chloride（CaCl2） improved both chilling and freezing stress tolerances, while ethylene glycol‐bis‐（b‐aminoethyl） ether‐N,N,N,N‐tetraacetic acid（EGTA） reversed CaCl2 effects in bermudagrass（Cynodon dactylon（L.） Pers.）.Pysiological analyses showed that CaCl2 treatment alleviated the reactive oxygen species（ROS） burst and cell damage triggered by chilling stress, via activating antioxidant enzymes,non‐enzymatic glutathione antioxidant pool, while EGTA treatment had the opposite effects. Additionally, comparative proteomic analysis identified 51 differentially expressed proteins that were enriched in redox, tricarboxylicacid cycle,glycolysis, photosynthesis, oxidative pentose phosphate pathway, and amino acid metabolisms. Consistently, 42 metabolites including amino acids, organic acids, sugars, and sugar alcohols were regulated by CaCl2 treatment under control and cold stress conditions, further confirming the Researchcommon modulation of CaCl2 treatment in carbon metabolites and amino acid metabolism. Taken together, this study reported first evidence of the essential and protective roles of endogenous and exogenous calcium in bermudagrass response to cold stress, partially via activation of the antioxidants and modulation of several differentially expressed proteins and metabolic homeostasis in the process of cold acclimation.

Neophaseic acid catabolism in the 90 -hydroxylation pathway of abscisic acid in Arabidopsis thaliana

Abscisic acid(ABA)hydroxylation is an important pathway for ABA inactivation and homeostasis maintenance.Here,we discover a new downstream catabolite of neophaseic acid(neoPA)in the ABA 90-hydroxyl pathway and identify it as epi-neodihydrophaseic acid(epi-neoDPA)by comparing its accurate mass,retention time,and MSn spectra with those of our chemically synthesized epi-neoDPA.Analyses of Arabidopsis seed germination and ABA-related gene expression reveal that neoPA rather than epi-neoDPA possesses ABA-like hormonal activity.In vitro enzyme activity tests of prokaryotic recombinant protein reveal that NeoPAR1(neoPA reductase 1)identified from Arabidopsis converts neoPA into epi-neoDPA.Sitedirected mutation at Tyr163 in the conserved motif of NeoPAR1 abolishes the catalytic activity of NeoPAR1.Accelerated seed germination was observed in NeoPAR1 knockdown and knockout mutants,whereas retarded seed germination and the accumulation of epi-neoDPA and ABA were observed in NeoPAR1 overexpression lines,suggesting that NeoPAR1 is involved in seed germination and maintenance of ABA homeostasis.

Arabidopsis PED_2 positively modulates plant drought stress resistance

Abscisic acid (ABA) is an important phytohormone that functions in seed germination, plant development, and multiple stress responses. Arabidopsis Peroxisome defective 2 (AtPED2) (also known as AtPEXOXIN14, AtPEX14), is involved in the intracellular transport of thiolase from the cytosol to glyoxysomes, and perosisomal matrix protein import in plants. In this study, we assigned a new role for AtPED2 in drought stress resistance. The transcript level of AtPED2 was downregulated by ABA and abiotic stress treatments. AtPED2 knockout mutants were insensitive to ABA-mediated seed germination, primary root elongation, and stomatal response, while AtPED2 over-expressing plants were sensitive to ABA in comparison to wide type (WT). AtPED2 also positively regulated drought stress resistance, as evidenced by the changes of water loss rate, electrolyte leakage, and survival rate. Notably, AtPED2 positively modulated expression of several stress-responsive genes (RAB18, RD22, RD29A, and RD29B), positively affected underlying antioxidant enzyme activities and negatively regulated reactive oxygen species (ROS) level under drought stress conditions. Moreover, multiple carbon metabolites including amino acids, organic acids, sugars, sugar alcohols, and aromatic amines were also positively regulated by AtPED2. Taken together, these results indicated a positive role for AtPED2 in drought resistance, through modulation of stress-responsive genes expression, ROS metabolism, and metabolic homeostasis, at least partially.

The dioxygenase GIM_2 functions in seed germination by altering gibberellin production in Arabidopsis

The phytohormones gibberellic acid （GA） and abscisic acid （ABA） antagonistically control seed germina- tion. High levels of GA favor seed germination, whereas high levels of ABA hinder this process. The direct relationship between GA biosynthesis and seed germina- tion ability need further investigation. Here, we identified the ABA-insensitive gain-of-function mutant germination insensitive to ABA mutant 2 （gim2） by screening a population of XVE T-DNA-tagged mutant lines. Based on two loss-of-function gim2-ko mutant lines, the disruption of GIM2 function caused a delay in seed germination. By contrast, upregulation of GIM2 accelerated seed germina- tion, as observed in transgenic lines overexpressing GIM2 （OE）. We detected a reduction in endogenous bioactive GA levels and an increase in endogenous ABA levels in the gim2-ko mutants compared to wild type. Conversely, the OE lines had increased endogenous bioactive GA levels and decreased endogenous ABA levels. The expression levels of a set of GA- and]or ABA-related genes were altered in both the gim2-ko mutants and the OE lines. We confirmed that GIM2 has dioxygenase activity using an in vitro enzyme assay, observing that GIM2 can oxidize GA^2. Hence, our characterization of GIM2 demonstrates that it plays a role in seed germination by affecting the GA metabolic pathway in Arabidopsis.