Pharmacokinetics of a ternary conjugate based pH-responsive 10-HCPT prodrug nano-micelle delivery system

Research progress in nano-drug delivery systems based on the characteristics of the liver cancer microenvironment

The liver cancer has microenvironmental features such as low pH, M2 tumor-associated macrophage enrichment, low oxygen, rich blood supply and susceptibility to hematotropic metastasis, high chemokine expression, enzyme overexpression, high redox level, and strong immunosuppression, which not only promotes the progression of the disease, but also seriously affects the clinical effectiveness of traditional therapeutic approaches. However, nanotechnology, due to its unique advantages of size effect and functionalized modifiability, can be utilized to develop various responsive nano-drug delivery system (NDDS) by using these characteristic signals of the liver cancer microenvironment as a source of stimulation, which in turn can realize the intelligent release of the drug under the specific microenvironment, and significantly increase the concentration of the drug at the target site. Therefore, researchers have designed a series of stimuli-responsive NDDS based on the characteristics of the liver cancer microenvironment, such as hypoxia, weak acidity, and abnormal expression of proteases, and they have been widely investigated for improving anti-tumor therapeutic efficacy and reducing the related side effects. This paper provides a review of the current application and progress of NDDS developed based on the response and regulation of the microenvironment in the treatment of liver cancer, compares the effects of the microenvironment and the NDDS, and provides a reference for building more advanced NDDS.

Camptothecin-based prodrug nanomedicines for cancer therapy

Camptothecin (CPT) is a cytotoxic alkaloid that attenuates the replication of cancer cells via blocking DNA topoisomerase 1. Despite its encouraging and wide-spectrum antitumour activity, its application is significantly restricted owing to its instability, low solubility, significant toxicity, and acquired tumour cell resistance. This has resulted in the development of many CPT-based therapeutic agents, especially CPT-based nanomedicines, with improved pharmacokinetic and pharmacodynamic profiles. Specifically, smart CPT-based prodrug nanomedicines with stimuli-responsive release capacity have been extensively explored owing to the advantages such as high drug loading, improved stability, and decreased potential toxicity caused by the carrier materials in comparison with normal nanodrugs and traditional delivery systems. In this review, the potential strategies and applications of CPT-based nanoprodrugs for enhanced CPT delivery toward cancer cells are summarized. We appraise in detail the chemical structures and release mechanisms of these nanoprodrugs and guide materials chemists to develop more powerful nanomedicines that have real clinical therapeutic capacities.

Advances in Antitumor Nano-Drug Delivery Systems of 10-Hydroxycamptothecin

10-Hydroxycamptothecin (HCPT) is a natural plant alkaloid from Camptotheca that shows potent antitumor activity by targeting intracellular topoisomerase I. However, factors such as instability of the lactone ring and insolubility in water have limited the clinical application of this drug. In recent years, unprecedented advances in biomedical nanotechnology have facilitated the development of nano drug delivery systems. It has been found that nanomedicine can significantly improve the stability and water solubility of HCPT. NanoMedicines with different diagnostic and therapeutic functions have been developed to significantly improve the anticancer effect of HCPT. In this paper, we collected reports on HCPT nanomedicines against tumors in the past decade. Based on current research advances, we dissected the current status and limitations of HCPT nanomedicines development and looked forward to future research directions.

Elucidating inhaled liposome surface charge on its interaction with biological barriers in the lung

Liposome is the promising nanocarrier for pulmonary drug delivery and surface charge is its basic property. However, there is a lack of knowledge about relationship between the liposomal surface charge and its interaction with biological barriers in the lung. Therefore, the purpose of this research is to elucidate the influence of liposome surface charge on its in vivo fate. Firstly, liposomes with positive, negative and neutral surface charge were constructed and characterized, their compatibility towards pulmonary cells was studied. Then their interaction with different biological barriers in lung, including mucus, trachea, bronchoalveolar lavage fluid (BALF) and alveolar macrophage, were investigated. Their retention behavior in lung and systemic exposure were further explored. It was demonstrated that neutrally and negatively charged liposomes were safer than positively charged ones. In the conducting airway, liposome with positive surface charge could better enhance trachea distribution but only within 2 h. In the respiratory region, both neutrally and negatively charged liposomes presented improved mucus permeability, good stability in BALF containing pulmonary surfactant, decreased macrophage uptake, prolonged lung retention and decreased systemic exposure to other organs, with neutrally charged liposome showing superior performance than the negatively charged ones. While the positively charged liposome was not stable in lung microenvironment with aggregation observed, leading to increased alveolar macrophage uptake, thereby lower pulmonary retention and higher risk of systemic exposure. In conclusion, liposomal surface charge is a tunable formulation factor to modulate the interaction with biological barriers in the lung and thus in vivo fate of inhaled liposomes.

Oral genistein-loaded phytosomes with enhanced hepatic uptake, residence and improved therapeutic efficacy against hepatocellular carcinoma

Genistein (Gen) is one of the most potent soy isoflavones used for hepatocellular carcinoma (HCC) treatment. Low aqueous solubility and first-pass metabolism are the main obstacles resulting in low Gen oral bioavailability. The current study aims to introduce phytosomes as an approach to improve Gen solubility, protect it from metabolism by complexation with phospholipids (PL), and get used to PL in Gen lymphatic delivery. Different forms of PL namely: Lipiod® S100, Phosal® 53 MCT, and Phosal®75 SA were used in phytosomes preparation GP, GPM, and GPL respectively. The effect of formulation components on Gen absorption, metabolism, and liver accumulation was evaluated following oral administration to rats. Cytotoxicity and cellular uptake studies were applied on HepG2 cells and in-vivo anti-tumor studies were applied to the DEN-mice model. Results revealed that GP and GPL remarkably accumulated Gen aglycone in hepatic cells and minimized the metabolic effect on Gen. They significantly increased the intracellular accumulation of Gen in its complex form in HepG2 cells. Their cytotoxicity is time-dependent according to the complex stability. The enhanced in-vivo anti-tumor effect was observed for GP and GPL compared to Gen suspension on DEN-induced HCC in mice. In conclusion, Gen-phytosomes can represent a promising approach for liver cancer treatment.

Synthesis, characterization and in vivo evaluation of honokiol bisphosphate prodrugs protects against rats' brain ischemia-reperfusion injury

Honokiol (HK) usage is greatly restricted by its poor aqueous solubility and limited oral bioavailability. We synthesized and characterized a novel phosphate prodrug of honokiol (HKP) for in vitro and in vivo use. HKP greatly enhanced the aqueous solubility of HK (127.54 ± 15.53 mg/ml) and the stability in buffer solution was sufficient for intravenous administration. The enzymatic hydrolysis of HKP to HK was extremely rapid in vitro (T1/ 2  = 8.9 ± 2.11 s). Pharmacokinetics studies demonstrated that after intravenous administration of HKP (32 mg/kg), HKP was converted rapidly to HK with a time to reach the maximum plasma concentration of ∼5 min. The prodrug HKP achieved an improved T1/2 (7.97 ± 1.30 h) and terminal volume of distribution (26.02 ± 6.04 ml/kg) compared with direct injection of the equimolar parent drug (0.66 ± 0.01 h) and (2.90 ± 0.342 ml/kg), respectively. Furthermore, oral administration of HKP showed rapid and improved absorption compared with the parent drug. HKP was confirmed to maintain the bioactivity of the parent drug for ameliorating ischemia-reperfusion injury by decreasing brain infarction and improving neurologic function. Taken together, HKP is a potentially useful aqueous-soluble prodrug with improved pharmacokinetic properties which may merit further development as a potential drug candidate.

A novel oral prodrug-targeting transporter MCT 1: 5-fluorouracil-dicarboxylate monoester conjugates

Monocarboxylate transporter 1 (MCT1) is responsible for oral absorption of short-chain monocarboxylic acids from small intestine, hence, it's likely to serve as an ideal design target for the development of oral prodrugs. However, potential application of MCT1 to facilitate the oral delivery is still unclear. Irregular oral absorption, poor permeability and bioavailability greatly limit the oral delivery efficiency of 5-fluorouracil (5-FU). Herein, we design three 5-FU-fatty acid conjugates targeting intestinal MCT1 with different lipophilic linkages. Interestingly, due to high MCT1 affinity and good gastrointestinal stability, 5-FU-octanedioic acid monoester prodrug exhibited significant improvement in membrane permeability (13.1-fold) and oral bioavailability (4.1-fold) compared to 5-FU. More surprisingly, stability experiment in intestinal homogenates showed that 5-FU prodrugs could be properly activated to release 5-FU within intestinal cells, which provides an ideal foundation for the improvement of oral bioavailability. In summary, good gastrointestinal stability, high membrane permeability and appropriate intestinal cell bioactivation are the important factors for high-efficiency 5-FU oral prodrugs, and such work provides a good platform for the development of novel oral prodrugs targeting intestinal transporters.

Tissue Distribution and Anti-Lung Cancer Effect of 10-Hydroxycamptothecin Combined with Platycodonis Radix and Glycyrrhizae Radix ET Rhizoma

10-Hydroxycamptothecin (HCPT) is a broad-spectrum chemotherapeutic drug, although its side effects and multidrug resistance (MDR) limit its clinical application. A range of drug delivery systems have been utilized to overcome its shortcomings and maintain its therapeutic efficacy, however the use of the transport effect of traditional Chinese medicines (TCMs) to improve the distribution of chemotherapeutic drugs has not been widely reported. Platycodonis Radix (JG) and Glycyrrhizae Radix ET Rhizoma (GC) are common TCMs in clinics and are often combined as drug pairs to act as "transport agents". In the present study, the effect of JG and GC (JGGC) on the distribution of HCPT in tissues and its antitumor efficacy after being combined as a therapy were investigated, for which ultrahigh-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) was used. Furthermore, the effect on the protein expression of multidrug resistance proteins (P-gp and LRP), and the immunomodulatory and synergistic antiapoptotic effect on Lewis lung cancer-bearing C57BL/6J mice were also evaluated. The results demonstrate that JGGC significantly increased the area under the concentration time curve (AUC) and mean residence time (MRT) and reduced the clearance rate (CL) of HCPT. In addition, the combined use of JGGC decreased the levels of LRP, P-gp and Bcl-2/Bax when treated with HCPT. JGGC also significantly elevated the levels of RBCs, PLTs, HGB, IL-2, and IFN-γ, and decreased IL-10 levels. In summary, an increased concentration of HCPT in tissues was observed when it was combined with JGGC through inhibition of efflux protein, with a synergistic enhancement of the anticancer effect observed through promotion of apoptosis and immunity due to a reversion of the Th1/Th2 shift. Our findings provide a reference for the feasibility of combining JGGC with chemotherapy drugs in clinical applications.

Probing a dipeptide-based supramolecular assembly as an efficient camptothecin delivering carrier for cancer therapy: computational simulations and experimental validations

Short peptide-based supramolecular assemblies have drawn much attention in the field of drug delivery. However, the progress still remains limited owing to the inefficient drug loading capacity of conventional short peptide-based materials. In this study, based on coordinated intramolecular π-π stacking, we customize a dipeptide-based rhein derivative (rhein-diphenylalanine peptide, RDP), which could spontaneously form spherical nanoassemblies for drug delivery. A structure-based virtual screening of a library of small molecules is conducted to identify the suitable compounds which could be effectively delivered by this nanocarrier. Sorted by binding energy results, fifteen superior and five inferior molecules are found. Subsequently, the co-assembly capacity of high-affinity molecules (camptothecin, CPT) and low-affinity molecules (norcantharidin, NCTD) with the dipeptide-based carrier is predicted via dissipative particle dynamics (DPD) simulation. Consistent with computational results, the in vitro experimental results show that CPT-encapsulated nanoassemblies have significant advantages in the particle size distribution and recrystallization-inhibitory effect compared with NCTD. Furthermore, in vivo experiments were conducted to determine whether CPT is precisely delivered to tumor sites by using the dipeptide-based nanoassemblies. The CPT-loaded nanoassemblies show better effects in terms of drug biodistribution and in vivo anti-tumor efficacy compared to free CPT. The cooperative computational and experimental strategies (in vitro and in vivo) used in this work lay a good foundation to systematically understand short peptide-based assemblies for precise drug delivery.