Paclitaxel-Loaded Magnetic Nanoparticles Based on Biotinylated N-Palmitoyl Chitosan: Synthesis,Characterization and Preliminary In Vitro Studies

A considerable interest in cancer research is represented by the development of magnetic nanoparticles based on biofunctionalized polymers for controlled-release systems of hydrophobic chemotherapeutic drugs targeted only to the tumor sites, without affecting normal cells. The objective of the paper is to present the synthesis and in vitro evaluation of the nanocomposites that include a magnetic core able to direct the systems to the target, a polymeric surface shell that provides stabilization and multi-functionality, a chemotherapeutic agent, Paclitaxel (PTX), and a biotin tumor recognition layer. To our best knowledge, there are no studies concerning development of magnetic nanoparticles obtained by partial oxidation, based on biotinylated N-palmitoyl chitosan loaded with PTX. The structure, external morphology, size distribution, colloidal and magnetic properties analyses confirmed the formation of well-defined crystalline magnetite conjugates, with broad distribution, relatively high saturation magnetization and irregular shape. Even if the ability of the nanoparticles to release the drug in 72 h was demonstrated, further complex in vitro and in vivo studies will be performed in order to validate the magnetic nanoparticles as PTX delivery system.     

pH敏感性叶酸修饰羧甲基壳聚糖纳米粒子作为紫杉醇载体的研究

将活化的叶酸分子连接到O-羧甲基壳聚糖(O-CMCS)上.以CaCl2为交联剂,通过离子交联法制备叶酸修饰的O-CMCS纳米粒子(FCC NPs),并开展了从FCC NPs作为抗癌药物紫杉醇(PTX)载体的研究.结果表明:FCC NPs呈球形,粒子大小约190 nm,对PTX的载药量和包封率均受PTX加入量的影响.该纳米粒子对药物的释放具有较好的pH敏感性,能够增强PTX在癌细胞处的富集.同时,该纳米粒子无细胞毒性,纳米粒子表面由于叶酸的存在使其具有较好的细胞靶向性,且载药纳米粒子对癌细胞生长具有良好的抑制作用.     

Hyperbranched poly (amine‐ester)‐poly (lactide‐co‐glycolide) copolymer and their nanoparticles as paclitaxel delivery system

A new hyperbranched poly (amine‐ester)‐poly (lactide‐co‐glycolide) copolymer (HPAE‐co‐PLGA) was synthesized by ring‐opening polymerization of D , L ‐lactide (DLLA) glycolid and branched poly (amine‐ester) (HPAE‐OHs) with Sn(Oct)₂ as catalyst. The chemical structures of copolymers were determined by FT‐IR, ¹H‐NMR(¹³C NMR), TGA and their molecular weights were determined by gel permeation chromatography (GPC). Paclitaxel‐loaded copolymer nanoparticles were prepared by the nanoprecipitation method. Their physicochemical characteristics, e.g. morphology and nanoparticles size distribution were then evaluated by means of fluorescence spectroscopy, environmental scanning electron microscopy (ESEM), and dynamic light scattering (DLS). Paclitaxel‐loaded nanoparticles assumed a spherical shape and have unimodal size distribution. It was found that the chemical composition of the nanoparticles was a key factor in controlling nanoparticles size, drug‐loading content, and drug release behavior. As the molar ratio of DL ‐lactide/glycolide to HPAE increased, the nanoparticles size and drug‐loading content increased, and the drug release rate decreased. The antitumor activity of the paclitaxel‐loaded HPAE‐co‐PLGA nanoparticles against human liver cancer H7402 cells was evaluated by 3‐(4, 5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyl tetrazolium bromide (MTT) method. The paclitaxel‐loaded HPAE‐co‐PLGA nanoparticles showed comparable anticancer efficacy with the free drug. Copyright © 2010 John Wiley & Sons, Ltd.     

键合紫杉醇纳米胶束对H22肝癌小鼠的体内疗效评估

以H22肝癌的balb/c荷瘤小鼠为动物模型,考察了紫杉醇纳米胶束、紫杉醇注射液和生理盐水对小鼠肿瘤的抑制效果。 紫杉醇注射液组、紫杉醇纳米胶束低剂量组和紫杉醇纳米胶束高剂量组在给药后10 d的肿瘤相对体积抑制率分别为22%、49%和67%,瘤重抑制率分别为29%、45%和47%;蛋白表达检测结果显示,紫杉醇纳米胶束组呈现p53的高表达和bcl-2的低表达,说明紫杉醇纳米胶束对小鼠H22肝癌的抑制作用强于紫杉醇注射液。     

Delaying Anticancer Drug Delivery by Self-Assembly and Branching Effects of Minimalist Dendron–Drug Conjugates

Self-assembly of a covalently-bound lipophilic drug to a dendronic scaffold for making organic nanoparticles is reported as a proof of concept in nanovectorization. A minimalist structural approach with a small PEG-dendron conjugated to paclitaxel (PTX), incorporating safe succinic and gallic acids, is efficient to provide the expected anticancer bioactivity, but also significantly retards and targets intracellular delivery of PTX in 2D and 3D lung cancer cell cultures. A branching effect of dendrons is crucial, when compared to linear PTX conjugates. Transmission electron microscopy (TEM) and dynamic light-scattering (DLS) studies indicate the formation of stable, low-disperse nanoparticles at 10⁻⁵ m in H₂0, which could also be responsible for the biological effects. An ultrasensitive LC-MS/MS method was used for the determination of intracellular PTX concentration over time, along with the survival rates of cancer cells. Similarly, cell survival assays were successfully correlated to a 3D cell culture with spheroids for mimicking tumors, when treated with PTX conjugates. Our work opens the way to a full evaluation program required for new chemical entities.     

Paclitaxel loaded poly (DL lactic acid co castor oil) 60:40 with poloxamer‐F68 rod shape cylindrical nanoparticle preparation and in vitro cytotoxicity studies

This research presents a thin‐film hydration‐solvent evaporation method to formulate the paclitaxel loaded poly (DL lactic acid co castor oil) 4:6 with poloxamer‐F68 cylindrical shape nanoparticles. The particles were less than 250 nanometers (nm) in size, with an average width of 60 nm and an average length of 100 nm. The percent yield, encapsulation efficiency (EE), and percent drug loading (DL) were detected. This approach produces drug loading values between 5% and 20% w/w. X‐ray powder diffraction (XRD) identified the physicochemical properties of nanoparticles differential scanning calorimetry (DSC) and Fourier‐transform infrared spectroscopy (FTIR). The investigation shows that the drug is molecularly dispersed in polymers or given in an amorphous or semicrystalline state. Horizontal water bath shaker technology considered the in vitro release of PTX loaded nanoparticles under sink conditions. Poly (DL lactic acid co castor oil) 4:6 nanoparticles exhibited a sustained release analysis. At the end of 30 hours, the percent cumulative drug release from the formulations was between 74.52% and 92.87% for F1 and F4. In vitro cytotoxicity assays indicate that PTX having p (DLLA:CO60:40) nanoparticles have a higher cytotoxic effect on MCF‐7/ADR.     

Toward ab initio potential energy surface for paclitaxel: a baccatin III conformational study

The ab initio conformational energy profile of baccatin III, the diterpene part of paclitaxel, a natural, taxoid anticancer agent, has been investigated using medium‐size basis sets including an electron correlation method (MP2/DFT). By exploiting the internal coordinates using random search methods, 39 conformers of baccatin III were found. The most stable conformer, competing with its 13‐C rotamers, was shown to have three intramolecular hydrogen bonds of 1, 7 and 13 hydroxyls to the carbonyl oxygen atoms of 2‐benzoate and 10‐ and 4‐acetate ester groups, respectively. The results of the polarizable continuum model (PCM) used to account for the dielectric effect of the environment show that in water, the delicate balances between intramolecular hydrogen bridges and general conformational preferences are conserved, at least in the absence of explicit solvent molecules. Copyright © 2016 John Wiley & Sons, Ltd.     

Preparative isolation of paclitaxel and related taxanes from cell cultures of Taxus chinensis using reversed-phase flash chromatography

In this study, paclitaxel, baccatin III, taxuyunnanine C and sinenxane C were successfully separated by reversed-phase flash chromatography on a manually packed C₁₈ column from Taxus chinensis cell culture extract. The crude cell culture extract was first treated with Al₂O₃ column chromatography and then divided into two parts: fraction 1 and fraction 2. Ten milligrams of baccatin III and 19 mg of paclitaxel were obtained from 100 mg dried fraction 1. Fifty-two milligrams of taxuyunnanine C and 11 mg sinenxane C were obtained from 100 mg dried fraction 2. The purities of the four compounds were 98.02%, 98.53%, 98.93% and 98.76%, respectively. Their structures were characterised by using UV, MS and NMR. These results indicate that paclitaxel and related taxanes including baccatin III can be obtained from cell culture in a highly pure state using reversed-phase flash chromatography.     

Synthesis and biological evaluation of novel A-seco-taxoids derived from 1-deoxybaccatin VI

Three novel nor-seco-taxoids 13, 15, 23 in which the A rings are cleaved but the B, C, and D rings are retained were prepared from 1-deoxybaccatin VI via its nor-dioxo derivative and their structures were confirmed by ¹H NMR, ¹³C NMR and high resolution MS. Oxidative introduction of C-1 hydroxyl to 1-deoxybaccatin VI with oxidising agent KBrO₃ and catalyst RuCl₃ led to the dioxo derivative 6 and its structure is determined by X-ray crystallographic analysis. A-seco taxoids 13, 15, 23 with a C-13 ester linkage were tested for cytotoxic activity and all compounds showed no measurable cytotoxic activity against HCT-116 cell line. However, 1-deoxy-9a-dihydrotaxane analogue 4 semi-synthesised from 1-deoxybaccatin VI is 10-fold less cytotoxic than paclitaxel, indicating the indispensible nature of the A ring double bond for the bioactivity of paclitaxel.