含葡糖基酮洛芬乙烯醇酯共聚物的合成及其药物释放性能

分别利用化学法和酶促法合成了酮洛芬乙烯酯和葡萄糖丁二酸乙烯酯（6-O-乙烯丁二酰-D-葡萄糖）2种聚合单体,通过2种单体的自由基聚合反应制备了具有较高分子量的酮洛芬葡萄糖共聚物前药,通过IR、NMR对聚合物的结构进行了表征,用GPC方法测定共聚物分子量。 研究了聚合单体投料比例对共聚物分子量和载药量的影响。 结果表明,随着药物乙烯酯在投料中比例的增加,聚合物前药的分子量逐渐下降,聚合物中酮洛芬的载药量逐渐增加。 酮洛芬含糖聚合物前药的体外释放研究表明,酮洛芬的释放时间大大延长,达到了缓释的目的,释药速率随着聚合物前药中葡萄糖含量增加而加快。 聚合物前药的释放动力学模拟结果显示,共聚物释药更符合一级动力学释放模型。     

Long conjugated 2-nitrobenzyl derivative caged anticancer prodrugs with visible light regulated release: preparation and functionalizations

A series of anticancer prodrugs with different chemical functional groups were prepared, in which the styryl conjugated 2-nitrobenzyl derivatives were introduced as the phototrigger to regulate the drug (chlorambucil) release. Compared to the common 4,5-dimethoxy-2-nitrobenzyl caged compounds, most of the prodrugs exhibited large and redshifted one-photon absorption within the visible range. One-photon excitation for the drug release was studied by measuring UV-vis absorption, FT-IR, and HPLC spectra, which suggested that chlorambucil was released effectively and precisely by manipulating external light conditions. And the introduction of different functional groups made this type of prodrug a good platform to further react with some typical drug carriers and to further form excellent visible light responsive drug delivery systems. Moreover, the drug also could be effectively released under the excitation of two-photon at 800 nm with comparable photorelease efficiencies.     

Synthesis of potential prodrug systems for reductive activation. Prodrugs for anti-angiogenic isoflavones and VEGF receptor tyrosine kinase inhibitory oxindoles

A number of potential prodrug systems for reductive activation have been investigated. The prodrug systems chosen for the study were the 2-nitrophenylacetyl, 3-methyl-3-(3,6-dimethyl-1,4-benzoquinon-2-yl)butanoyl and 4-nitrobenzyl groups, readily attached to acidic OH or NH groups in drug molecules, and released upon bioreductive activation. The drug molecules studied were the naturally occurring isoflavone biochanin A, an inhibitor of VEGF-induced angiogenesis, and the pyrrolylmethylidenyl oxindole SU5416 (semaxanib) and its 6-hydroxy derivative, inhibitors of VEGF receptor tyrosine kinase. Following coupling the prodrug system to the drug, the compounds were evaluated chemically and biologically. Under chemical reducing conditions, the 3-methyl-3-(3,6-dimethyl-1,4-benzoquinon-2-yl)butanoic acid based prodrugs appear to fragment the most efficiently, followed by the 2-nitrophenylacetate esters with the 4-nitrobenzyl ethers being the least efficient. The potentially pro-anti-angiogenic compounds were also assayed for their ability to block VEGF-induced angiogenesis in HUVECS in comparison to the free agents. Control compounds that cannot be activated under bioreductive conditions are less potent than the free drug, whereas many of the potential prodrugs not only exhibit a dose response, but appear at least equipotent with the free drug.     

Controlled release of 5-fluoro-2'-deoxyuridine by the combination of prodrug and polymer matrix.

Poly(L-lactic acid) (L-PLA) microspheres containing 5-fluoro-2'-deoxyuridine (FUdR) or its ester prodrugs with saturated aliphatic acids (FUdR-Cn, n = 2, 3, 4, 5, 6, 8, 10 and 12) were prepared. The physicochemical and biological properties and antitumor activity of the L-PLA microspheres were studied. The lipophilicity of FUdR-Cn was increased by prolonging its acyl-promoieties. FUdR-C5, FUdR-C6, FUdR-C8, FUdR-C10 and FUdR-C12 showed almost complete incorporation into the microspheres, while incorporation of hydrophilic FUdR and FUdR-C2 was poor. The sustained release of FUdR from the microspheres containing FUdR-C4, FUdR-C5 and FUdR-C6 was obtained in the presence of esterase, and higher antitumor activity against P388 leukemia was observed in vivo. On the other hand, the release rates of FUdR from the microspheres containing FUdR-C10 and FUdR-C12 were very small, and their antitumor activity was much smaller than that of the free prodrug suspension. Effects of the susceptibility to enzymatic hydrolysis and the physiocochemical properties of prodrugs on the release profiles of FUdR from spheres were discussed.     

Computational modeling and in-vitro/in-silico correlation of phospholipid-based prodrugs for targeted drug delivery in inflammatory bowel disease

Targeting drugs to the inflamed intestinal tissue(s) represents a major advancement in the treatment of inflammatory bowel disease (IBD). In this work we present a powerful in-silico modeling approach to guide the molecular design of novel prodrugs targeting the enzyme PLA₂, which is overexpressed in the inflamed tissues of IBD patients. The prodrug consists of the drug moiety bound to the sn-2 position of phospholipid (PL) through a carbonic linker, aiming to allow PLA₂ to release the free drug. The linker length dictates the affinity of the PL-drug conjugate to PLA₂, and the optimal linker will enable maximal PLA₂-mediated activation. Thermodynamic integration and Weighted Histogram Analysis Method (WHAM)/Umbrella Sampling method were used to compute the changes in PLA₂ transition state binding free energy of the prodrug molecule (??G^tr) associated with decreasing/increasing linker length. The simulations revealed that 6-carbons linker is the optimal one, whereas shorter or longer linkers resulted in decreased PLA₂-mediated activation. These in-silico results were shown to be in excellent correlation with experimental in-vitro data. Overall, this modern computational approach enables optimization of the molecular design of novel prodrugs, which may allow targeting the free drug specifically to the diseased intestinal tissue of IBD patients.     

Prodrugs in cardiovascular therapy

Prodrugs are biologically inactive derivatives of an active drug intended to solve certain problems of the parent drug such as toxicity, instability, minimal solubility and non-targeting capabilities. The majority of drugs for cardiovascular diseases undergo first-pass metabolism, resulting in drug inactivation and generation of toxic metabolites, which makes them appealing targets for prodrug design. Since prodrugs undergo a chemical reaction to form the parent drug once inside the body, this makes them very effective in controlling the release of a variety of compounds to the targeted site. This review will provide the reader with an insight on the latest developments of prodrugs that are available for treating a variety of cardiovascular diseases. In addition, we will focus on several drug delivery methodologies that have merged with the prodrug approach to provide enhanced target specificity and controlled drug release with minimal side effects.     

Photocaged prodrug under NIR light-triggering with dual-channel fluorescence: <Emphasis Type="Italic">in vivo</Emphasis> real-time tracking for precise drug delivery

Light-triggered drug delivery system is an effective strategy for precise diagnosis and therapy in cancer treatment. However, it suffers from difficultly balancing the dosimetry of drug with light dose and a lack of in vivo models for validating their clinical benefits. Here we report an unprecedented near-infrared (NIR) light photocaged cyanine-based prodrug Cy-CPT-Biotin with dual-channel fluorescence mode, enabling NIR light to precisely regulate where, when and how the intact and active prodrugs are delivered. The synergy of photochemical reaction and modulation in π-conjugated polyene backbone of cyanine can fully perform distinct dual-channel fluorescence changes in a NIR light-mediated manner. The prodrug has striking characteristics of excellent tumor-targeting ability, real-time monitoring of the in vivo behaviors by dual-channel mode and NIR-light triggering, especially for achieving fine regulation and on-demand drug release in the precise dosimetry of drug with light dose in living animals. This optical orthogonality strategy that conjuncts with NIR light-triggered and dual-channel fluorescence in vivo imaging provides a powerful tool for in vivo real-time tracking and finely tuning the prodrug release for precise drug delivery.     

Mechanochemical solid-state polymerization (XI): effect of water-insoluble pharmaceutical aids on drug release from mechanically synthesized polymeric prodrugs

We discuss here the effect of water-insoluble pharmaceutical aids on the nature of drug release from composite polymeric prodrugs synthesized by mechanochemical solid-state polymerization. Magnesium stearate (Mgst) and hydrogen castor oil (HCO) were used as water-insoluble pharmaceutical aids. Composite polymeric prodrugs were synthesized by the mechanochemical solid-state polymerization of a vinyl monomer of 5-fluorouracil (I) in the presence of Mgst or HCO. The molecular weight of the resulting polymeric prodrugs increased with increasing the content of Mgst or HCO. Prodrug hydrolysis was carried out in a heterogeneous system in phosphate buffer at pH 6.8 and 37 degrees C. The rate of drug release from the composite polymeric prodrug containing Mgst (Poly-Mgst) was faster than that from polymeric prodrug containing no pharmaceutical aids (Poly-Non), while hydrolysis of the composite polymeric prodrug containing HCO (Poly-HCO) was slower than Poly-Non. Scanning electron microscope (SEM) photos showed the surface of Poly-HCO was smoother than that of Poly-Non and Poly-Mgst. It was suggested that the slower drug release from Poly-HCO may be responsible for the smaller specific surface area than that of Poly-Non. It was also shown that the rate of drug release from the composite polymeric prodrugs decreases with increasing the content of Mgst or HCO. Hence, novel composite polymeric prodrugs with a variety of drug release rates can be prepared by mechanochemical solid-state polymerization in a totally dry process.     

Facile preparation of pH-responsive PEGylated prodrugs for activated intracellular drug delivery

The acid-cleavable amphiphilic prodrug DOX-PEG-DOX self-assemble to form nanoparticles and enter the cell by endocytosis for the pH-triggered intracellular delivery of DOX.     

Polymeric prodrugs of mitomycin C

Poly-[N-(2-hydroxyethyl)-L-glutamine] (PHEG) prodrugs of the cytotoxic agent Mitomycin C were synthesized using peptidyl spacers to link the drug to the polymeric carrier. The influence on the length and detailed structure of the oligopeptide on the rate of drug release was investigated in buffer, in the presence of lysosomal enzymes (tritosomes, cathepsin B and D) and metalloprotease type IV collagenase. It was observed that tetra- and hexapeptide based conjugates generally release Mitomycin C (MMC) more effectively than tripeptide derivatives. The gly-phe-ala-leu conjugate released MMC very rapidly both in presence of lysosomal enzymes and collagenase IV. Only in the presence of the aspartic protease cathepsin D, the gly-phe-leu-gly-phe-leu derivative turned out to be a better substrate. In vivo studies against C26 solid tumour bearing mice suggest that PHEG-spacer-MMC conjugates act as prodrugs of MMC: antitumour efficacy of the macromolecular prodrugs was better than free MMC both in inhibition of tumour growth and increasing survival.     

Mechanochemical solid-state polymerization (X): the influence of copolymer structure in copolymeric prodrugs on the nature of drug release

From the standpoint of the mechanism of mechanochemical polymerization, two kinds of copolymeric prodrug, whose monomer sequence distribution (MSD) is different from each other, can be prepared by this polymerization under appropriate operational conditions: one is a random copolymer abundant in the longer block consisting of the same repeating units (multi-block copolymer), and the other is a block copolymer. To confirm the difference of MSD, the 13C-NMR spectra of poly(acrylamide-co-sodium acrylate) prepared by mechanochemical polymerization were measured and compared with the spectrum of that synthesized by a conventional radical-initiated solution polymerization, which produces the random copolymer normally. The results show that MSD in copolymers depends on the polymerization method (operational condition). We prepared three kinds of copolymeric prodrug consisting of acrylamide and vinyl monomer of 5-fluorouracil, whose MSD is different from one another. These copolymeric prodrugs had almost the same number average molecular weight, particle diameter and composition, and differed only in MSD. We compared the rate of drug release of these copolymeric prodrugs. The rate of drug release was the highest with the random copolymer, followed by the mechanochemically produced multi-block copolymer and the block copolymer. This result suggests that the rate of drug release depends on MSD of copolymeric prodrugs. These results are useful as they give a fundamental insight into the synthesis of copolymeric prodrugs having the desired rate of drug release.     

Facile preparation of pH-responsive PEGylated prodrugs for activated intracellular drug delivery

PEGylated prodrug, covalent attaching polyethylene glycol (PEG) polymer chains to therapeutic drugs, is one of the most promising techniques to improve the water-solubility, stability, and therapeutic effect of drugs. In this study, three PEGylated acid-sensitive prodrugs DOX-PEG-DOX with different molecular weights, were prepared via Schiff-base reaction between aldehyde-modified PEG and the amino groups of doxorubicin (DOX). This kind of amphiphilic polymeric prodrug could be self-assemble into nanoparticles in aqueous solution. The average particle size and morphologies of the prodrug nanoparticles under different pH conditions were observed by dynamic light scattering (DLS) and transmission electron microscopy (TEM), respectively. It turned out that the nanoparticles could be kept stable in the physiological environment, but degraded in acidic medium. Subsequently, we also investigated in vitro drug release behavior and found that the prodrug had acid-sensitive property. The cytotoxicity and intracellular uptake assays revealed that the prodrugs could rapidly internalized by HeLa or HepG2 cells to release DOX and effectively inhibited the proliferation of the tumor cells, which have the potential for use in cancer therapy.     

Monochalcoplatin: An Actively Transported,Quickly Reducible,and Highly Potent PtIV Anticancer Prodrug

Recently, Pt^IV prodrugs have attracted much attention as the next generation of platinum‐based antineoplastic drug candidates. Here we report the discovery and evaluation of monochalcoplatin, a monocarboxylated Pt^IV prodrug that is among the most cytotoxic Pt^IV prodrugs to date. Compared with its dicarboxylated counterpart chalcoplatin, monochalcoplatin accumulates astonishingly effectively and rapidly in cancer cells, which is not ascribed to its lipophilicity. The prodrug is quickly reduced, causes DNA damage, and induces apoptosis, resulting in superior cytotoxicity with IC₅₀ values in the nanomolar range in both cisplatin‐sensitive and ‐resistant cells; these IC₅₀ values are up to 422‐fold higher than that of cisplatin. A detailed mechanistic study reveals that monochalcoplatin actively enters cells through a transporter‐mediated process. Moreover, monochalcoplatin shows significant antitumor activity in an in vivo colorectal tumor model. Our study implies a practical strategy for the design of more effective Pt^IV prodrugs to conquer drug resistance by tuning both cellular uptake pathways and activation processes.     

A self-assembling prodrug nanosystem to enhance metabolic stability and anticancer activity of gemcitabine

Self-assembly is a powerful approach in molecular engineering for biomedical applications, in particular for creating self-assembling prodrugs. Here, we report a self-assembling prodrug of the anticancer drug gemcitabine(Gem) based on amphiphilic dendrimer approach. The prodrug reported in this study demonstrates high drug loading(40%) and robust ability to self-assemble into small nanomicelles, which increase the metabolic stability of Gem and enable entry into cells via endocytosis, hence bypa...     

Monochalcoplatin: An Actively Transported,Quickly Reducible,and Highly Potent PtIV Anticancer Prodrug

Recently, Pt^IV prodrugs have attracted much attention as the next generation of platinum‐based antineoplastic drug candidates. Here we report the discovery and evaluation of monochalcoplatin, a monocarboxylated Pt^IV prodrug that is among the most cytotoxic Pt^IV prodrugs to date. Compared with its dicarboxylated counterpart chalcoplatin, monochalcoplatin accumulates astonishingly effectively and rapidly in cancer cells, which is not ascribed to its lipophilicity. The prodrug is quickly reduced, causes DNA damage, and induces apoptosis, resulting in superior cytotoxicity with IC₅₀ values in the nanomolar range in both cisplatin‐sensitive and ‐resistant cells; these IC₅₀ values are up to 422‐fold higher than that of cisplatin. A detailed mechanistic study reveals that monochalcoplatin actively enters cells through a transporter‐mediated process. Moreover, monochalcoplatin shows significant antitumor activity in an in vivo colorectal tumor model. Our study implies a practical strategy for the design of more effective Pt^IV prodrugs to conquer drug resistance by tuning both cellular uptake pathways and activation processes.     

Prodrugs of HIV protease inhibitors-saquinavir, indinavir and nelfinavir-derived from diglycerides or amino acids: synthesis, stability and anti-HIV activity

With the aim of improving the pharmacological properties of current protease inhibitors (PIs), the synthesis of various acyl and carbamate amino acid- or diglyceride-containing prodrugs derived from saquinavir, indinavir and nelfinavir, their in vitro stability with respect to hydrolysis and their anti-HIV activity in CEM-SS and MT4 cells have been investigated. l-Leucine (Leu) and l-phenylalanine (Phe) were connected through their carboxyl to the PIs while l-tyrosine (Tyr) was conjugated through its aromatic hydroxyl via various spacer units. Hydrolysis of the prodrug with liberation of the active free drug was crucial for antiviral activity. The Leu- and Phe-PI prodrugs released the active free drug very rapidly (half-lives of hydrolysis in buffer at 37 degree C of 3-4 h). The Tyr-PI conjugates with a -C(O)(CH(2))(4)- linker exhibited half-lives in the 40-70 h range and antiviral activities in the 21-325 nM range (from 2 to 22 nM for the free PIs). The chemically very stable carbamate "peptidomimetic" Tyr-PI prodrugs (no hydrolysis detected after 7 days in buffer) displayed a very low anti-HIV activity or were even inactive (EC(50) from 2300 nM to >10 microM). A very low antiviral activity was measured for the diglyceride-substituted saquinavir and for all of the disubstituted indinavir and nelfinavir prodrugs. All these prodrugs probably released the active parent PI too slowly under the antiviral assay conditions. These results combined with those from transepithelial transport studies (Rouquayrol et al., Pharm. Res., 2002, 19, 1704-1712) indicate that conjugation of amino acids (through their carboxyl) to the PIs constitutes a most appealing alternative which could improve the intestinal absorption of the PIs and reduce their recognition by efflux carriers.     

Albumin-targeting of an oxaliplatin-releasing platinum(iv) prodrug results in pronounced anticancer activity due to endocytotic drug uptake in vivo

Oxaliplatin is a very potent platinum(ii) drug which is frequently used in poly-chemotherapy schemes against advanced colorectal cancer. However, its benefit is limited by severe adverse effects as well as resistance development. Based on their higher tolerability, platinum(iv) prodrugs came into focus of interest. However, comparable to their platinum(ii) counterparts they lack tumor specificity and are frequently prematurely activated in the blood circulation. With the aim to exploit the enhanced albumin consumption and accumulation in the malignant tissue, we have recently developed a new albumin-targeted prodrug, which supposed to release oxaliplatin in a highly tumor-specific manner. In more detail, we designed a platinum(iv) complex containing two maleimide moieties in the axial position (KP2156), which allows selective binding to the cysteine 34. In the present study, diverse cell biological and analytical tools such as laser ablation inductively-coupled plasma mass spectrometry (LA-ICP-MS), isotope labeling, and nano-scale secondary ion mass spectrometry (NanoSIMS) were employed to better understand the in vivo distribution and activation process of KP2156 (in comparison to free oxaliplatin and a non-albumin-binding succinimide analogue). KP2156 forms very stable albumin adducts in the bloodstream resulting in a superior pharmacological profile, such as distinctly prolonged terminal excretion half-life and enhanced effective platinum dose (measured by ICP-MS). The albumin-bound drug is accumulating in the malignant tissue, where it enters the cancer cells via clathrin- and caveolin-dependent endocytosis, and is activated by reduction to release oxaliplatin. This results in profound, long-lasting anticancer activity of KP2156 against CT26 colon cancer tumors in vivo based on cell cycle arrest and apoptotic cell death. Summarizing, albumin-binding of platinum(iv) complexes potently enhances the efficacy of oxaliplatin therapy and should be further developed towards clinical phase I trials.

Albumin-targeting of a maleimide-containing oxaliplatin-releasing platinum(iv) prodrug results in tumor-specific drug delivery and activity as shown by LA-ICP-MS, isotope-labeling and NanoSIMS in cell culture and in vivo.     

Preparation of pH- and reductive-responsive prodrug nanoparticles via polymerization-induced self-assembly

pH- and reductive-responsive prodrug nanoparticles are constructed via a highly efficient strategy, polymerization-induced selfassembly (PISA). First, reversible addition-fragmentation chain transfer (RAFT) polymerization of 2-(diisopropylamino) ethyl methacrylate (DIPEMA) and camptothecin prodrug monomer (CPTM) using biocompatible poly(N-(2-hydroxypropyl) methacrylamide) (PHPMA-CPDB) as the macro RAFT agent is carried out, forming prodrug diblock copolymer PHPMA-P (DIPEMA-co-CPTM). Then, simultaneous fulfillment of polymerization, self-assembly, and drug encapsulation are achieved via RAFT dispersion polymerization of benzyl methacrylate (BzMA) using the PHPMA-P(DIPEMA-co-CPTM) as the macro RAFT agent. The prodrug nanoparticles have three layers, the biocompatible shell (PHPMA), the drug-conjugated middle layer (P(DIPEMA-co-CPTM)) and the PBzMA core, and relatively high concentration (250 mg/g). The prodrug nanoparticles can respond to two stimuli (reductive and acidic conditions). Due to reductive microenvironment of cytosol, the cleavage of the conjugated camptothecin (CPT) within the prodrug nanoparticles could be effectively triggered. pH-Induced hydrophobic/ hydrophilic transition of the PDIPEMA chains results in faster diffusion of GSH into the CPTM units, thus accelerated release of CPT is observed in mild acidic and reductive conditions. Cell viability assays show that the prodrug nanoparticles exhibit well performance of intracellular drug delivery and good anticancer activity.     

Microenvironment-responsive chemotherapeutic nanogels for enhancing tumor therapy via DNA damage and glutathione consumption

Although targeted therapy and immunotherapy are now shining in the treatment of some cancers, chemotherapy is still the cornerstone of drug treatment for many cancer patients. The emergence of chemotherapy prodrugs can improve the drug activity and reduce the side effects of chemotherapy. When used, the tumor microenvironment has characteristics different from normal tissues, and the existence of the microenvironment provided a more convenient way to design responsive nanodrugs. Herein, we designed a glutathione (GSH)-responsive prodrug nanogels for enhancing tumor chemotherapy. In the nanogels of HHNP, 10-hydroxycamptothecin (HCPT) played an essential role in killing cancer cells. HCPT was jointed with a cross-linker agent with disulfide bond and was further coated with polyethylene glycol, which not only prolonged the half-life of the drug, but also made HCPT accurate transport to the tumor fractions and achieved precise and controllable release. The proposal of HHNP effectively retained the biological activity of the drug, and introduced functions such as targeting, selective release and biodegradation, which greatly improved the medical efficiency of the drug and effectively reduced the toxic and side effects. This chemotherapeutic prodrug nanogel offers a new window for constructing efficient drug delivery platform.     

Acid-sensitive PEGylated cabazitaxel prodrugs for antitumor therapy

Although the antitumor drug cabazitaxel shows great therapeutic potential, its high toxicity and poor water solubility limit its utility. However, the use of stimuli-responsive prodrugs is a promising strategy for overcoming these limitations. Herein, we report the synthesis of two highly water soluble, acid-sensitive PEGylated acyclic-ketal-linked cabazitaxel prodrugs (PKCs) with improved antitumor efficacy. In an acidic tumor microenvironment, the PKCs hydrolyzed rapidly to release the native drug, whereas they were stable in the normal physiological environment. Compared with cabazitaxel injection, the PKCs had much higher maximum tolerated doses; and in an MDA-MB-231 subcutaneous xenograft nude mouse model, the PKCs showed better antitumor efficacy and safety than cabazitaxel injection. The prodrug strategy reported herein could be useful for the development of other water soluble, acid-sensitive prodrugs with improved efficacy.