Construction of multilayer films with bactericidal and long-term antitumor drug release properties as a non-vascular stent coating for therapy in obstruction.

The construction of antibacterial and antitumor coatings could offer effective routes to improve the therapeutic effects of non-vascular stents for unresectable obstructions caused by malignant tumours. Herein, polyelectrolyte multilayers have been explored as bactericidal coatings with controlled antitumor drug release. To solve the challenges of loading and controlled release of small-molecule chemotherapeutic drugs in polyelectrolyte multilayers, the antitumor drug doxorubicin (DOX) was chemically conjugated onto polyethylenimine via cis aconitic anhydride (pH-sensitive linker), thus obtaining the polycation prodrug PEI-CA-DOX. Alginate sodium was oxidized (O-Alg) and mixed with DOX to prepare the O-Alg-DOX complex as a polyanion. QCM-D and contact angle tests were used to monitor and verify the progressive build-up of the PEI-CA-DOX/O-Alg-DOX multilayer films, which show a linear growth. The in vitro antibacterial tests indicated that the PEI-CA-DOX-terminated PEI-CA-DOX/O-Alg-DOX multilayers could kill the bacteria effectively. As-such multilayers also presented a long-term sustained DOX release behaviour in PBS due to the combination of slow release in PEI-CA-DOX and fast release in the O-Alg-DOX complex. The as-designed PEI-CA-DOX/O-Alg-DOX multilayers with combined antibacterial and antitumor properties may have great potential for applications in non-vascular stent coatings for palliative treatment of obstruction caused by malignant tumours.

pH and redox dual responsive carrier-free anticancer drug nanoparticles for targeted delivery and synergistic therapy.

Advanced drug delivery systems often employ nanomaterials as carriers to deliver drugs to desirable disease sites for enhanced efficacy. However, most systems have low drug loading capacity and cause safety concerns. Therefore, many anticancer therapeutics have recently been assembled to NPs form without using any additional nanocarrier to achieve high drug loading. However, carrier-free nanomedicines are often constrained by limitations such as inadequate stability and lack of control in drug release. Therefore, we synthesize carrier-free drug NPs containing cis-aconitic anhydride-modified doxorubicin and paclitaxel (CAD-PTX) and coating with crosslinked (CL) surfactant based on hyaluronic acid (HA) segment. With this design, the pure drug NPs possess pH and redox dual responsive release characteristic and could target CD44 overexpressed cancer cells. Our studies demonstrate that these CAD-PTX-CLHA NPs display high stability, excellent active targeting effect and controllable intracellular drug release, and ultimately achieve significantly better anti-cancer efficiency than individual doxorubicin and paclitaxel.

Microenvironment-Induced In Situ Self-Assembly of Polymer-Peptide Conjugates That Attack Solid Tumors Deeply.

In cancer treatment, the unsatisfactory solid-tumor penetration of nanomaterials limits their therapeutic efficacy. We employed an in vivo self-assembly strategy and designed polymer-peptide conjugates (PPCs) that underwent an acid-induced hydrophobicity increase with a narrow pH-response range (from 7.4 to 6.5). In situ self-assembly in the tumor microenvironment at appropriate molecular concentrations (around the IC50 values of PPCs) enabled drug delivery deeper into the tumor. A cytotoxic peptide KLAK, decorated with the pH-sensitive moiety cis-aconitic anhydride (CAA), and a cell-penetrating peptide TAT were conjugated onto poly(ß-thioester) backbones to produce PT-K-CAA, which can penetrate deeply into solid tumors owing to its small size as a single chain. During penetration in vivo, CAA responds to the weak acid, leading to the self-assembly of PPCs and the recovery of therapeutic activity. Therefore, a deep-penetration ability for enhanced cancer therapy is provided by this in vivo assembly strategy.

Direct Macromolecular Drug Delivery to Cerebral Ischemia Area using Neutrophil-Mediated Nanoparticles.

Delivery of macromolecular drugs to the brain is impeded by the blood brain barrier. The recruitment of leukocytes to lesions in the brain, a typical feature of neuroinflammation response which occurs in cerebral ischemia, offers a unique opportunity to deliver drugs to inflammation sites in the brain. In the present study, cross-linked dendrigraft poly-L-lysine (DGL) nanoparticles containing cis-aconitic anhydride-modified catalase and modified with PGP, an endogenous tripeptide that acts as a ligand with high affinity to neutrophils, were developed to form the cl PGP-PEG-DGL/CAT-Aco system. Significant binding efficiency to neutrophils, efficient protection of catalase enzymatic activity from degradation and effective transport to receiver cells were revealed in the delivery system. Delivery of catalase to ischemic subregions and cerebral neurocytes in MCAO mice was significantly enhanced, which obviously reducing infarct volume in MCAO mice. Thus, the therapeutic outcome of cerebral ischemia was greatly improved. The underlying mechanism was found to be related to the inhibition of ROS-mediated apoptosis. Considering that neuroinflammation occurs in many neurological disorders, the strategy developed here is not only promising for treatment of cerebral ischemia but also an effective approach for various CNS diseases related to inflammation.

A dihydrochalcone derivative and further steroidal saponins from Sansevieria trifasciata Prain.

Phytochemical investigation of the aerial parts of Sansevieria trifasciata, one of the most common Dracaenaceae plants, has resulted in the isolation of a new dihydrochalcone derivative named trifasciatine C (1), four previously unreported steroidal saponins as two pairs of inseparable regioisomers: trifasciatosides K/L (2/3), M/N (4/5), together with the known 1,2-(dipalmitoyl)-3-O-ß-D-galactopyranosylglycerol (6), aconitic acid (7), and 1-methyl aconitic acid (8). Their structures were elucidated mainly by extensive spectroscopic analysis (1D and 2D nuclear magnetic resonance) and high-resolution electronspray ionization-mass spectrometry, as well as chemical methods and comparison of their spectral data with those of related compounds. Compounds 2/3 and 4/5 were evaluated for their antiproliferative activity on Hela cells, and no significant effect was observed.

Co-delivery of docetaxel and curcumin prodrug via dual-targeted nanoparticles with synergistic antitumor activity against prostate cancer.

PURPOSE: Combination therapy is increasingly used as a primary cancer treatment regimen. In this report, we designed EGFR peptide decorated nanoparticles (NPs) to co-deliver docetaxel (DTX) and pH sensitive curcumin (CUR) prodrug for the treatment of prostate cancer. RESULTS: EGFR peptide (GE11) targeted, pH sensitive, DTX and CUR prodrug NPs (GE11-DTX-CUR NPs) had an average diameter of 167nm and a zeta potential of -37.5mV. The particle size of the NPs was adequately maintained in serum and a sustained drug release pattern was observed. Improved inhibition of cancer cell and tumor tissue growth was shown in the GE11-DTX-CUR NPs group compared to the other groups. CONCLUSION: It can be summarized that DTX and CUR prodrug could be delivered into tumor cells simultaneously by the GE 11 targeting and the EPR effect of NPs. The resulting GE11-DTX-CUR NPs is a promising system for the synergistic antitumor treatment of prostate cancer.

Graphene oxide-incorporated pH-responsive folate-albumin-photosensitizer nanocomplex as image-guided dual therapeutics.

The objective of this study was to develop an active-targeted, pH-responsive albumin-photosensitizer-incorporated graphene oxide nanocomplex as an image-guided theranostic agent for dual therapies. Herein, bovine serum albumin (BSA)-cis-aconityl pheophorbide-a (c-PheoA) conjugate was complexed with graphene oxide (GO) at ratios of 1:1, 1:0.5, and 1:0.1 with the mean hydrodynamic diameter of the resulting complex being 100-200nm. Further, with the 1:0.5 ratio, we developed a folate-BSA-c-PheoA conjugate:GO complex incorporated free PheoA (PheoA+GO:FA-BSA-c-PheoA NC) with a mean hydrodynamic diameter of 182.0±33.2nm. The release study showed that the photosensitizer from the nanocomplex was released rapidly at pH5.5 compared to that at pH7.4 when incubated for 24h. Cellular uptake results showed that the PheoA+GO:FA-BSA-c-PheoA NCs was readily taken up by B16F10 and MCF7 cancer cells. In vitro phototoxicity results showed that PheoA+GO:FA-BSA-c-PheoA NC has a higher efficacy against cancer cells than free PheoA, thereby demonstrating the synergistic effect of PS and GO in response to a single laser of 670nm. In vivo and ex vivo bioimaging results showed that fluorescence signals of higher intensity were observed in the tumor area of mice treated with PheoA+GO:FA-BSA-c-PheoA NC than those in the tumor of mice treated with free PheoA, thereby suggesting that the targeted nanocomplex selectively accumulated in the tumor area compared to free PheoA. Through antitumor study, PheoA+GO:FA-BSA-c-PheoA NC showed a synergistic effect in tumor-bearing mice by a single 671nm laser treatment. These results demonstrate that our prepared PheoA+GO:FA-BSA-c-PheoA NC can be used as a theranostic agent in phototherapies and for the photodiagnosis of cancer.

Starch composites with aconitic acid.

The aim of this project is to examine the effectiveness of using aconitic acid (AcA), a tricarboxylic acid which contains a carbon/carbon double bond (CC), to enhance the properties of starch-based films. Starch/glycerol cast films were prepared with 0, 2, 5, 10 and 15wt% AcA (starch wt% basis) and the properties analysed. It was shown that AcA acted as both a cross-linking agent and also a strong plasticising agent. The 5wt% AcA derived starch films were the most effectively cross-linked having the lowest solubility (28wt%) and decreased swelling coefficient (35vol.%) by approximately 3 times and 2.4 times respectively compared to the control film submerged in water (23°C). There was also a significant increase in the film elongation at break by approximately 35 times (compared to the control) with the addition of 15wt% AcA, emphasising the plasticising effect of AcA. However, generally there was a reduced tensile strength, softening of the film, and reduced thermal stability with increased amounts of AcA.

Preclinical evaluation of antitumor activity of acid-sensitive PEGylated doxorubicin.

The acid-sensitive PEGylated doxorubicin (DOX) with exact chemical structure was designed and prepared as a potential tumor intracellular microenvironment-responsive drug delivery system. First, the insensitive succinic anhydride-functionalized DOX (i.e., SAD) and acid-sensitive cis-aconitic anhydride-modified DOX (i.e., CAD) were synthesized through the ring-opening reaction. Subsequently, the insensitive and acid-sensitive PEGylated DOX (i.e., mPEG-SAD and mPEG-CAD) was prepared by the condensation reaction between the terminal hydroxyl group of mPEG and the carboxyl group in SAD and CAD, respectively. The obtained mPEG-SAD and mPEG-CAD could spontaneously self-assemble into micelles in phosphate-buffered saline at pH 7.4 with diameters of about 100 nm. The DOX release of mPEG-CAD micelle could be accelerated by the decrease of pH from 7.4, 6.8, to 5.5 in relation to that of mPEG-SAD micelle. On the other hand, the result of the cellular proliferation inhibition test indicated that mPEG-CAD micelle exhibited favorable antiproliferative activity in vitro. In addition, the selective intratumoral accumulation and antitumor efficacy of mPEG-CAD micelle were significantly better than those of free DOX and mPEG-SAD. More importantly, the prodrug micelles exhibited upregulated security in vivo as compared to free DOX. Overall, the mPEG-CAD micelle with enhanced antitumor efficacy and decreased side effects was a fascinating prospect for the clinical chemotherapy of malignancy.

Combinatorially designed lipid-like nanoparticles for intracellular delivery of cytotoxic protein for cancer therapy.

An efficient and safe method to deliver active proteins into the cytosol of targeted cells is highly desirable to advance protein-based therapeutics. A novel protein delivery platform has been created by combinatorial design of cationic lipid-like materials (termed "lipidoids"), coupled with a reversible chemical protein engineering approach. Using ribonuclease A (RNase A) and saporin as two representative cytotoxic proteins, the combinatorial lipidoids efficiently deliver proteins into cancer cells and inhibit cell proliferation. A study of the structure-function relationship reveals that the electrostatic and hydrophobic interactions between the lipidoids and the protein play a vital role in the formation of protein-lipidoid nanocomplexes and intracellular delivery. A representative lipidoid (EC16-1) protein nanoparticle formulation inhibits cell proliferation in vitro and suppresses tumor growth in a murine breast cancer model.

Antifungal activity of homoaconitate and homoisocitrate analogs.

Thirteen structural analogs of two initial intermediates of the L-α-aminoadipate pathway of L-lysine biosynthesis in fungi have been designed and synthesized, including fluoro- and epoxy-derivatives of homoaconitate and homoisocitrate. Some of the obtained compounds exhibited at milimolar range moderate enzyme inhibitory properties against homoaconitase and/or homoisocitrate dehydrogenase of Candida albicans. The structural basis for homoisocitrate dehydrogenase inhibition was revealed by molecular modeling of the enzyme-inhibitor complex. On the other hand, the trimethyl ester forms of some of the novel compounds exhibited antifungal effects. The highest antifungal activity was found for trimethyl trans-homoaconitate, which inhibited growth of some human pathogenic yeasts with minimal inhibitory concentration (MIC) values of 16-32 mg/mL.

Cis-aconitic anhydride ethyl ester and phenolic compounds from the seeds of Alisma orientale.

From the seeds of Alisma orientale, cis-aconitic anhydride ethyl ester and cis-2,4,5-trihydroxycinnamic acid were isolated, together with nine known phenolic compounds and a megastigmane sesquiterpene. All compounds are reported for the first time from Alisma species.

A surface transporter family conveys the trypanosome differentiation signal.

Microbial pathogens use environmental cues to trigger the developmental events needed to infect mammalian hosts or transmit to disease vectors. The parasites causing African sleeping sickness respond to citrate or cis-aconitate (CCA) to initiate life-cycle development when transmitted to their tsetse fly vector. This requires hypersensitization of the parasites to CCA by exposure to low temperature, conditions encountered after tsetse fly feeding at dusk or dawn. Here we identify a carboxylate-transporter family, PAD (proteins associated with differentiation), required for perception of this differentiation signal. Consistent with predictions for the response of trypanosomes to CCA, PAD proteins are expressed on the surface of the transmission-competent 'stumpy-form' parasites in the bloodstream, and at least one member is thermoregulated, showing elevated expression and surface access at low temperature. Moreover, RNA-interference-mediated ablation of PAD expression diminishes CCA-induced differentiation and eliminates CCA hypersensitivity under cold-shock conditions. As well as being molecular transducers of the differentiation signal in these parasites, PAD proteins provide the first example of a surface marker able to discriminate the transmission stage of trypanosomes in their mammalian host.

High-speed counter-current chromatography for the study of defense metabolites in wheat. Characterization of 5,6-O-methyl trans-aconitic acid.

High-speed counter-current chromatography (HSCCC) methods were developed for the study of induced defense metabolites in wheat (Triticum aestivum) against powdery mildew (Blumeria graminis f. sp. tritici). A single HSCCC purification step afforded extraction of mg-quantities of an induced compound with antifungal activity. Subsequent LC-MS and NMR analyses have led to the characterization of 5,6-O-methyl trans-aconitic acid, the first such report of this compound in a plant species. The inducible nature of aconitic acid was evidenced by comparing the metabolite profiles of leaf extracts from plants treated or not with soluble silicon and infected or not with powdery mildew. In a second step, dual-mode HSCCC was used to enhance the separation of other forms of aconitic acid in wheat. Based on these results, it was concluded that 5,6-O-methyl trans-aconitic acid plays an important role as a defense molecule in wheat plants and that HSCCC is a powerful separation method for purifying such compounds from complex plant-pathogen interactions.

Antiproliferative properties of chemically modified recombinant IFN-alpha2b.

The antiproliferative activity of aconitylated (AIFN) and succinylated (SIFN) derivatives of recombinant interferon- alpha2b (IFN-alpha2b) was examined. Acylation of IFN-alpha2b was performed by succinic and cis-aconitic anhydrides. Antiproliferative properties of AIFN and SIFN were studied in vitro on the CaOv cell line, highly sensitive to IFN, and on the SW-480 cell line, with low sensitivity to IFN-alpha2b. Acylation of one lysine in the IFN-alpha2b molecule with cis-aconitic or succinic anhydride resulted in a 3-3.5-fold increase of its antiproliferative activity on CaOv cells. The highest antiproliferative activity of acylated IFN-alpha2b on SW-480 cells was observed for both AIFNs and SIFNs with three modified lysine residues. In conclusion, aconitylated and succinylated IFNs may be useful antiproliferative agents for cancer treatment.

Massive and selective delivery of lipid-coated cationic lipoplexes of oligonucleotides targeted in vivo to hepatic endothelial cells.

PURPOSE: Previously we reported on massive uptake of liposomes surface-modified with negatively charged aconitylated albumin (AcoHSA) by liver sinusoidal endothelial cells (EC) in vivo. In the present work we applied this principle for the in vivo delivery of antisense oligonucleotides (ODN) to these cells. METHODS: Anti ICAM-1 ODN was complexed with the cationic lipid DOTAP and the complex was coated by an excess of neutral lipids including a lipid-anchored poly(ethylene glycol). Aco-HSA was coupled to the coated cationic lipoplexes (CCLs). Plasma disappearance, organ and intrahepatic distribution of Aco-HSA modified CCLs were determined in rats, using [3H]-cholesteryl oleyl ether and 32P-labeled ODN as markers. RESULTS: The Aco-HSA coupled CCLs were <160 nm in size, contained 1.03+/-0.35 nmol ODN and 54+/-18 microg Aco-HSA per micromol total lipid. These CCLs were rapidly eliminated from plasma, about 60% the injected dose of 3H- or 32P-label being recovered in the liver after 30 min. Within the liver, the EC accounted for two thirds of total liver uptake. Control non-targeted CCLs were eliminated very slowly: after 30 min still >90% of the particles was in the blood. CONCLUSIONS: Our results demonstrate efficient targeting of antisense ODN to EC in vivo, employing plasma-stable coated cationic lipoplexes, surface modified with negatively charged albumin. 40% of the injected ODN was delivered to the target cells within 30 min.

The influence of charge clustering on the anti-HIV-1 activity and in vivo distribution of negatively charged albumins.

The substitution of human serum albumin with negatively charged molecules, such as succinic acid (Suc-HSA) or aconitic acid (Aco-HSA), resulted in proteins with potent anti-HIV activities, by binding to viral gp120 (V3 loop). The aim of the present study was to investigate whether the distribution of negative charges on the albumin backbone influences the anti-HIV activity. Therefore, we prepared albumins with clusters of negatively charged groups by coupling of heparin. The effects of this substitution on anti-HIV activity, in vivo distribution and the protein structure as compared to random succinylation were assessed. In vitro studies indicated that HSA-modified with heparin 6 or 13 kD displayed anti-HIV activity (IC50=660 and 37 nM, respectively) and exhibited affinity for gp120-V3 loop, although the activity was lower than that of Suc-HSA. Combined derivatization of HSA with heparin 13 kD and aconitic acid groups resulted in significantly increased inhibitory actions (IC50=2.8 nM). Structural analysis showed that modification of HSA with heparin did not lead to extensive unfolding of the protein, meaning that these modified proteins were still globular in structure. In contrast, succinylation of HSA resulted in a highly randomly coiled conformation. Dynamic light scattering experiments revealed that, at neutral pH, the heparin fragments attached to the protein were wrapped around the molecule rather than sticking out into the solution. In conclusion, coupling of sufficient clustered negative charges, by coupling of Hep-fragments, on HSA resulted in a clear anti-HIV activity of the protein. Yet, random distribution of anionic groups in the albumin seemed more optimal for in vitro anti-HIV activity. The higher plasma and lymphatic concentrations of Hep-HSA compared to Suc-HSA seemed more favorable for an anti-HIV activity in vivo.

The applicability of rat and human liver slices to the study of mechanisms of hepatic drug uptake.

In the present study we investigated the applicability of the liver slice model to study mechanisms of drug uptake. Four model compounds were investigated that enter hepatocytes via entirely different membrane transport mechanisms. Rhodamine B (RB), which enters hepatocytes by passive diffusion, was homogeneously distributed throughout the rat liver slice (250 microm thickness) within 5 min, indicating that the penetration rate into the slice and the diffusion rate into the cells are rapid. In contrast, lucigenin (LU), which is taken up by hepatocytes through adsorptive endocytosis, was detected in the inner cell layers after 15 min. Digoxin uptake into the slice showed a temperature-dependent component and was stereoselectively inhibited by quinine, which is compatible with the involvement of a carrier-mediated uptake mechanism. The neo-glycoalbumin Lactose(27)-Human Serum Albumin (Lact(27)-HSA) and the negatively charged Succinylated-Human Serum Albumin (Suc-HSA) entered the slices and were taken up temperature-dependently into hepatocytes and endothelial cells, respectively. The liver slice preparation is a valuable tool to investigate the mechanisms of cellular uptake of drugs. Moreover, the precision-cut liver slices offer the unique possibility to study both hepatocyte and endothelial cell function in human and rat liver.

[The use of liposomal form of phenylimide of cis-aconitic acid in herpes therapy]. / Primenenie fenilimida tsisakonitovoi kisloty v liposomal'noi forme dlia terapii gerpesa.

The results of study of the antiviral activity and pharmacokinetics of phenylimide of cis-aconitic acid (PCAA) is presented. The 20% increase of the antiviral activity of PCAA incorporated into liposomes in comparison with the antiviral activity of the pure substance was shown. Liposomes with PCAA were tropic to lymphocytes and macrophages with maximum fluorescence being observed in the spleen, while empty liposomes were accumulated mainly in the liver. After the treatment with liposomal PCAA the symptoms of herpetic meningoencephalitis became less severe with 100% survival of the experimental animals. In the control group of rabbits 50% of the animals died, and in the surviving animals blindness or paralysis developed.