Improved Solubility and Bioactivity of Camptothecin Family Antitumor Drugs with Supramolecular Encapsulation by Water-Soluble Pillar[6]arene

Effect of the combined binding of topotecan and catechin/protocatechuic acid to a pH-sensitive DNA tetrahedron on release and cytotoxicity: Spectroscopic and calorimetric studies

The therapeutic efficacy of chemotherapy drugs can be effectively improved through the dual effects of their combination with natural polyphenols and the delivery of targeted DNA nanostructures. In this work, the interactions of topotecan (TPT), (+)-catechin (CAT), or protocatechuic acid (PCA) with a pH-sensitive DNA tetrahedron (MUC1-TD) in the binary and ternary systems at pHs 5.0 and 7.4 were investigated by fluorescence spectroscopy and calorimetry. The intercalative binding mode of TPT/CAT/PC to MUC1-TD was confirmed, and their affinity was ranked in the order of PCA > CAT > TPT. The effects of the pH-sensitivity of MUC1-TD and different molecular structures of CAT and PCA on the loading, release, and cytotoxicity of TPT were discussed. The weakened interaction under acidic conditions and the co-loading of CAT/PCA, especially PCA, improved the release of TPT loaded by MUC1-TD. The targeting of MUC1-TD and the synergistic effect with CAT/PCA, especially CAT, enhanced the cytotoxicity of TPT on A549 cells. For L02 cells, the protective effect of CAT/PCA reduced the damage caused by TPT. The single or combined TPT loaded by MUC1-TD was mainly concentrated in the nucleus of A549 cells. This work will provide key information for the combined application of TPT and CAT/PCA loaded by DNA nanostructures to improve chemotherapy efficacy and reduce side effects.

Aptamers for the Delivery of Plant-Based Compounds: A Review

Natural compounds have a high potential for the treatment of various conditions, including infections, inflammatory diseases, and cancer. However, they usually present poor pharmacokinetics, low specificity, and even toxicity, which limits their use. Therefore, targeted drug delivery systems, typically composed of a carrier and a targeting ligand, can enhance natural product selectivity and effectiveness. Notably, aptamers-short RNA or single-stranded DNA molecules-have gained attention as promising ligands in targeted drug delivery since they are simple to synthesize and modify, and they present high tissue permeability, stability, and a wide array of available targets. The combination of natural products, namely plant-based compounds, with a drug delivery system utilizing aptamers as targeting agents represents an emerging strategy that has the potential to broaden its applications. This review discusses the potential of aptamers as targeting agents in the delivery of natural compounds, as well as new trends and developments in their utilization in the field of medicine.

Electro-organic synthesis of C-5 sulfenylated amino uracils: Optimization and exploring topoisomerase-I based anti-cancer profile

Cancer is spreading worldwide and is one of the leading causes of death. The use of existing chemotherapeutic agents is frequently limited due to side effects. As a result, it is critical to investigate new agents for cancer treatment. In this context, we developed an electrochemical method for the synthesis of a series of thiol-linked pyrimidine derivatives (3a-3p) and explored their anti-cancer potential. The biological profile of the synthesized compounds was evaluated against breast (MDAMB-231 and MCF-7) and colorectal (HCT-116) cancer cell lines. 3b and 3d emerged to be the most potent agents, with IC50 values ranging between 0.98 to 2.45 µM. Target delineation studies followed by secondary anticancer parameters were evaluated for most potent compounds, 3b and 3d. The analysis revealed compounds possess DNA intercalation potential and selective inhibition towards human topoisomerase (hTopo1). The analysis was further corroborated by DNA binding studies and in silico-based molecular modeling studies that validated the intercalating binding mode between the compounds and the DNA.

Crystalline Nanoparticles of Water-Soluble Covalent Basket Cages (CBCs) for Encapsulation of Anticancer Drugs

We herein describe the preparation, assembly, recognition characteristics, and biocompatibility of novel covalent basket cage CBC-11, composed of four molecular baskets linked to four trivalent aromatic amines through amide groups. The cage is tetrahedral in shape and similar in size to small proteins (Mw =8637 g/mol) with a spacious nonpolar interior for accommodating multiple guests. While 24 carboxylates at the outer surface of CBC-11 render it soluble in aqueous phosphate buffer (PBS) at pH=7.0, the amphiphilic nature prompts its assembly into nanoparticles (d=250 nm, DLS). Cryo-TEM examination of nanoparticles revealed their crystalline nature with wafer-like shapes and hexagonally arranged cages. Nanoparticulate CBC-11 traps anticancer drugs irinotecan and doxorubicin, with each cage binding up to four drug molecules in a non-cooperative manner. The inclusion complexation resulted in nanoparticles growing in size and precipitating. In media containing mammalian cells (HCT 116, human colon carcinoma), the IC50 value of CBC-11 was above 100 μM. While this work presents the first example of a large covalent organic cage operating in water at the physiological pH and forming crystalline nanoparticles, it also demonstrates its biocompatibility and potential to act as a polyvalent binder of drugs for their sequestration or delivery.

Green, Efficient Detection and Removal of Hg2+ by Water-Soluble Fluorescent Pillar[5]arene Supramolecular Self-Assembly

Developing a water-soluble supramolecular system for the detection and removal of Hg²⁺ is extremely needed but remains challenging. Herein, we reported the facile construction of a fluorescent supramolecular system (H⊃G) in 100% water through the self-assembly of carboxylatopillar[5]arene sodium salts (H) and diketopyrrolopyrrole-bridged bis(quaternary ammonium) guest (G) by host–guest interaction. With the addition of Hg²⁺, the fluorescence of H⊃G could be efficiently quenched. Since Hg²⁺ showed synergistic interactions (coordination and Hg²⁺- cavity interactions with G and H, respectively), crosslinked networks of H⊃G@Hg²⁺ were formed. A sensitive response to Hg²⁺ with excellent selectivity and a low limit of detection (LOD) of 7.17 × 10⁻⁷ M was obtained. Significantly, the quenching fluorescence of H⊃G@Hg²⁺ can be recovered after a simple treatment with Na₂S. The reusability of H⊃G for the detection of Hg²⁺ ions was retained for four cycles, indicating the H⊃G could be efficiently used in a reversible manner. In addition, the H⊃G could efficiently detect Hg²⁺ concentration in real samples (tap water and lake water). The developed supramolecular system in 100% water provides great potential in the treatment of Hg²⁺ detection and removal for environmental sustainability.

Prostate-Specific Membrane Antigen and Esterase Dual Responsive Camptothecin-Oligopeptide Self-Assembled Nanoparticles for Efficient Anticancer Drug Delivery

Background

The clinical utility of camptothecin (CPT) is restricted by poor aqueous solubility, high lipophilicity, active lactone ring instability, and off-targeted toxicities. We report here a prostate-specific membrane antigen (PSMA) and esterase dual responsive self-assembled nanoparticles (CPT-WT-H NPs) for highly efficient CPT delivery and effective cancer therapy.

Methods and Results

In this study, smart self-assembled nanoparticles CPT-WT-H NPs were elaborately designed and synthesized by combing hydrophobic CPT with hydrophilic PSMA-responsive penta-peptide via a cleavable ester bond. This dual responsive nanoparticle with negatively charged surface first respond to the extracellular PSMA and then to the intracellular esterase, achieving a programmable release of CPT at the tumor site and producing the byproducts of biocompatible glutamic acid and aspartic acid. Our data demonstrated that CPT-WT-H NPs exhibited greatly improved water solubility and stability. Results from MTT and flow cytometry showed CPT-WT-H NPs exhibited significantly higher cytotoxicity as well as apoptosis-inducing activity against PSMA-expressing LNCaP-FGC cells than the non-PSMA-expressing cancer cells, showing excellent cytotoxic selectivity. Moreover, the unique nanostructure provided the efficient transportation of CPT to tumor site, which resulted in the effective inhibition of tumor growth and low systemic toxicity in vivo.

Conclusion

CPT-WT-H NPs exhibited excellent in vitro PSMA-response ability and in vivo antitumor activity and safety, holding the promise to become a new and potent anticancer drug. The current research presents a promising strategy for efficient drug delivery.

Camptothecin's journey from discovery to WHO Essential Medicine: Fifty years of promise

Nature represents a rich source of compounds used for the treatment of many diseases. Camptothecin (CPT), isolated from the bark of Camptotheca acuminata, is a cytotoxic alkaloid that attenuates cancer cell replication by inhibiting DNA topoisomerase 1. Despite its promising and wide spectrum antiproliferative activity, its use is limited due to low solubility, instability, acquired tumour cell resistance, and remarkable toxicity. This has led to the development of numerous CPT analogues with improved pharmacodynamic and pharmacokinetic profiles. Three natural product-inspired drugs, namely, topotecan, irinotecan, and belotecan, are clinically approved and prescribed drugs for the treatment of several types of cancer, whereas other derivatives are in clinical trials. In this review, which covers literature from 2015 to 2020, we aim to provide a comprehensive overview and describe efforts that led to the development of a variety of CPT analogues. These efforts have led to the discovery of potent, first-in-class chemotherapeutic agents inspired by CPT. In addition, the mechanism of action, SAR studies, and recent advances of novel CPT drug delivery systems and antibody drug conjugates are discussed.

Supramolecular cancer nanotheranostics

Among the many challenges in medicine, the treatment and cure of cancer remains an outstanding goal given the complexity and diversity of the disease. Nanotheranostics, the integration of therapy and diagnosis in nanoformulations, is the next generation of personalized medicine to meet the challenges in precise cancer diagnosis, rational management and effective therapy, aiming to significantly increase the survival rate and improve the life quality of cancer patients. Different from most conventional platforms with unsatisfactory theranostic capabilities, supramolecular cancer nanotheranostics have unparalleled advantages in early-stage diagnosis and personal therapy, showing promising potential in clinical translations and applications. In this review, we summarize the progress of supramolecular cancer nanotheranostics and provide guidance for designing new targeted supramolecular theranostic agents. Based on extensive state-of-the-art research, our review will provide the existing and new researchers a foundation from which to advance supramolecular cancer nanotheranostics and promote translationally clinical applications.

Evaluation the synergistic antitumor effect of methotrexate-camptothecin codelivery prodrug from self-assembly process to acid-catalyzed both drugs release: A comprehensive theoretical study

Therapeutic efficiency of amphiphilic methotrexate-camptothecin (MTX-CPT) prodrug compared to free drug mixture (MTX/CPT) has been investigated using all-atom molecular dynamics simulation and first principles density functional theory calculations. This comparison revealed that MTX-CPT prodrug tends to form spherical self-assembled nanoparticle (NP), while free MTX/CPT mixture forms rod-shape NP. These observations are attributed to a structural defect in the MTX-CPT prodrug and solvation free energies of MTX, CPT and MTX-CPT molecules. The results provided evidence that noncovalent interactions (NCIs) among the pharmaceutical drugs play a very important role in anticancer agents aggregation process, leading to enhanced stability of the self-assembled NPs. It is found that the stability of MTX-CPT self-assembled NP is greater than the MTX/CPT NP due to the synergistic effect of hydrogen bonding between monomers and solvent (water). Moreover, the noncatalyzed as well as catalyzed hydrolysis reactions of MTX-CPT prodrug are theoretically studied at the PCM(water)//M06-2X/6-31G(d,p) computational level to shed additional light on the role of acidic condition in tumor tissues. We found that the ester hydrolysis in mild acidic solutions is a concerted reaction. In an agreement between theory and experiment, we also confirmed that the activation energies of the catalyzed-hydrolysis steps are much lower than the activation energies of the corresponding steps in the noncatalyzed reaction. Thus, the MTX-CPT prodrug reveals very promising properties as a pH-controlled drug delivery system.

TPGS-1000 exhibits potent anticancer activity for hepatocellular carcinoma in vitro and in vivo

D-alpha-tocopheryl polyethylene glycol 1000 succinate (TPGS1000) is the most active water-soluble derivative of vitamin E and has been widely used as a carrier of solvents, plasticizers, emulsifiers, absorbent agents and refractory drug delivery systems. However, its anti-hepatocellular carcinoma (HCC) properties have not been explored. HCC cells were treated with different concentrations of TPGS1000. Cell survival was tested by CCK8 assay, and cell migration was tested by wound healing and Transwell assay. EdU staining verified cell proliferation, and signalling pathway was assayed by Western blot analysis. The BALB/c-nu mouse xenograft model was established to test HCC cell growth in vivo. In vitro TPGS1000 significantly inhibited the viability and mobility of HCC cells (HepG2, Hep3B and Huh7) in a dose-dependent manner. Cell cycle analysis indicated that TPGS1000 treatment arrested the HCC cell cycle in the G0/G1 phase, and induction of cell apoptosis was confirmed by TUNEL and Annexin V-7-AAD staining. Further pharmacological analysis indicated that collapse of the transmembrane potential of mitochondria, increased ROS generation, PARP-induced cell apoptosis and FoxM1-p21-mediated cell cycle arresting, were involved in the anti-HCC activity of TPGS1000. Moreover, treatment in vivo with TPGS1000 effectively impaired the growth of HCC xenografts in nude mice.

Preparation and Characterization of Cationic Water-Soluble Pillar[5]arene-Modified Zeolite for Adsorption of Methyl Orange

A novel quaternary cationic pillar[5]arene-modified zeolite (WPA5/zeolite) was prepared via charge interaction between the cationic WPA5 and natural zeolite and characterized by scanning electron microscopy (SEM), Fourier transform infrared absorption spectroscopy, X-ray diffraction, solid-state nuclear magnetic resonance, and thermogravimetric (TG) analysis. The effects of zeolite particle size, WPA5 concentration, adsorption time, initial concentration, and pH on the removal of methyl orange (MO) were studied. The SEM and XRD results revealed a strong interaction between WPA5 and natural zeolite, and the modified composites showed novel microscopic morphology and structural properties. TG analysis indicated excellent thermal stability of the composite. MO was removed via electrostatic adsorption, and the removal efficiency was 84% at an initial concentration of 100 mg/L. Increase in the initial dye concentration enhanced the adsorption capacity of WPA5/zeolite and decreased the removal of MO. Based on the adsorption kinetics, the pseudo-second-order model (R ² = 0.998) described the kinetic behavior of MO on WPA5/zeolite. In addition, UV and fluorescence spectra revealed that MO and WPA5 are complexed by a 1:1 complex ratio, and the binding constant between them was 12 595 L·mol^-1. NMR and molecular docking also verified their interaction. Therefore, the potential application of the prepared composite includes removal of organic anionic dyes.

Formulation of injectable glycyrrhizic acid-hydroxycamptothecin micelles as new generation of DNA topoisomerase I inhibitor for enhanced antitumor activity

To develop a new drug delivery system is one of the useful approaches to break through the limitation of hydroxycamptothecin (HCPT), a typical DNA topoisomerase I (Topo I) inhibitor in clinical appliance. Injectable glycyrrhizic acid-hydroxycamptothecin (GL-HCPT) micelles that were able to dramatically improve the solubility and stability of HCPT were prepared through self-assembly process and evaluated both in vitro and in vivo. With a mean particle size (PS) of 105.7 ± 9.7 nm and a drug loading (DL) of 9.0 ± 1.5%, GL-HCPT micelles were rapidly internalized by HepG2 cells after 1 h, significantly increasing the intracellular accumulation of HCPT. Compared with the current used HCPT injection and HCPT/GL physical mixture, GL-HCPT micelles showed enhanced antitumor activity against liver cancer cells (HepG2 and Huh7) as well as a superior suppression on the tumor growth of HepG2 tumor bearing mice. Interestingly, GL-HCPT micelles gathered in liver and simultaneously reduced the drug accumulation in normal tissues, thereby exhibiting minimal cytotoxicity to human normal liver cells (LO2). Therefore, we offered a convenient and cost-effective strategy to construct an intravenous drug delivery system (GL-HCPT micelles) as new generation of DNA Topo I inhibitor for enhanced cancer chemotherapy.

αVβ3-Targeted Delivery of Camptothecin-Encapsulated Carbon Nanotube-Cyclic RGD in 2D and 3D Cancer Cell Culture

Integrin αvβ3 is widely expressed in various types of human cancer lines and plays a key role in angiogenesis for tumor growth and metastasis. Delivery of therapeutics to αvβ3-expressing tumors can thus be a promising approach for treating cancer. For targeted delivery of anticancer therapeutics to αvβ3-expressing tumor cells, cyclic arginylglycylaspartic acid (RGD) peptide was covalently conjugated to the surface of carboxylic acid-functionalized carbon nanotubes (fCNTs), and the topoisomerase I inhibitor camptothecin (CPT) was encapsulated in the fCNTs (CPT@fCNT-RGD). CPT@fCNT-RGD was successfully delivered to αvβ3-expressing A375 cells, and compared with nontargeted CPT@fCNT, it provided 3.78- and 3.02-fold increases in the anticancer effect in 2D and 3D culture. Analysis of apoptosis-related gene expression shows that the expression levels of Bax, cleaved caspase-3, and nuclear factor kappa-light-chain-enhancer of activated B cells were significantly increased in A375 cells incubated with CPT@fCNT-RGD compared with those incubated with CPT@fCNT. These results suggest that cyclic RGD-conjugated CNTs encapsulating an anticancer therapeutic can be a promising platform for treating cancer.

Carboxylated pillar[n]arene (n = 5-7) host molecules: high affinity and selective binding in water

Water-soluble carboxylated pillar[n]arenes (n = 5-7) or WPns were discovered to be high affinity host molecules with selective binding for different guests based on a systematic investigation. We chose 22 dyes or guests and determined the value of K_a for 51 supramolecular complexes. It was discovered that the electrostatic interactions, π-π stacking and hydrophobic effect were the driving force for high affinity supramolecular encapsulation. WPns had selective binding toward suitable guests based on their sizes and molecular structures. Based on the above discovery, a guest (guest 21) was designed, which bound with WP7 3.3-fold tighter compared to methyl viologen.

Mitochondria and nucleus delivery of active form of 10-hydroxycamptothecin with dual shell to precisely treat colorectal cancer

AIM

The objective of this study was to deliver a ring-closed form of 10-hydroxycamptothecin (HCPT) to the mitochondria and nucleus to treat colorectal cancer.

MATERIALS & METHODS

HCPT-loaded nanoparticle HCPT@PLGA-PEG_2k-triphenylphosphonium/PLGA-hyd-PEG_4k-folic acid (PT/PHF) and HCPT@PT/PLGA-SS-PEG_4k-folic acid (PSF) were prepared by using emulsion-solvent evaporation method.

RESULTS

In vitro experimental results indicated HCPT@PT/PHF and HCPT@PT/PSF maintained a large amount of HCPT in active form, and delivered more HCPT to the nucleus and mitochondria of the tumor cell, which resulted in the enhancement of cytotoxicity of HCPT. In vivo experimental results indicated that HCPT@PT/PHF and HCPT@PT/PSF delivered more ring-closed form of HCPT to tumor tissue, which led to strong antitumor activity.

CONCLUSION

HCPT@PT/PHF and HCPT@PT/PSF could enhance therapeutic efficacy of HCPT to colorectal cancer.

Supramolecular delivery systems based on pillararenes

Supramolecular delivery systems (SDSs) fabricated via molecular assembly, which conveniently allow integration of multiple functions in a single system and structural diversity of systems, are a very active research area due to their enormous potential in biomedical applications, including drug delivery, cell imaging, diagnosis, and release monitoring. Pillararenes, a novel type of macrocyclic molecule, are gaining increasing interest as an important component in the construction of SDSs due to their unique structural and chemical properties. This feature article summarizes pillararene-based SDSs constructed via host-guest interactions via four strategies: (1) supramolecular host-guest complexation; (2) self-assembly of supramolecular amphiphiles; (3) self-assembly of amphiphilic supramolecular polymer conjugates; (4) hybridization with other porous materials, such as inorganic materials and metal-organic frameworks (MOFs). The various SDSs based on pillararenes for the delivery of different cargoes from anti-cancer drugs, fluorescent molecules, siRNAs, and insulin to antibiotics are reviewed. Furthermore, future challenges for advanced SDSs based on pillararenes and their broader applications are outlined.

PSMA-Oriented Target Delivery of Novel Anticancer Prodrugs: Design, Synthesis, and Biological Evaluations of Oligopeptide-Camptothecin Conjugates

Clinical applications of camptothecin (CPT) have been heavily hindered due to its non-targeted toxicity, active lactone ring instability, and poor water solubility. Targeted drug delivery systems may offer the possibility to overcome the above issues as reported. In this research, a series of prostate-specific membrane antigen (PSMA)-activated CPT prodrugs were designed and synthesized by coupling water-soluble pentapeptide, a PSMA hydrolyzing substrate, to CPT through an appropriate linker. The cytotoxicity of CPT prodrugs was masked temporarily until they were hydrolyzed by the PSMA present within the tumor sites, which restored cytotoxicity. The in vitro selective cytotoxic activities of the prodrugs were evaluated against PSMA-expressing human prostate cancer cells LNCaP-FGC and non-PSMA-expressing cancer cells HepG2, Hela, MCF-7, DU145, PC-3 and normal cells MDCK, LO2 by standard methylthiazol tetrazolium (MTT) assay. Most of the newly synthesized CPT prodrugs showed excellent selective toxicity to PSMA-producing prostate cancer cells LNCaP-FGC with improved water solubility. From among the library, CPT-HT-J-ZL₁₂ showed the best cytotoxic selectivity between the PSMA-expressing and the non-PSMA-expressing cancer cells. For example, the cytotoxicity of CPT-HT-J-ZL₁₂ (IC₅₀ = 1.00 ± 0.20 µM) against LNCaP-FGC (PSMA⁺) was 40-fold, 40-fold, 21-fold, 5-fold and 40-fold, respectively, higher than that against the non-PSMA-expressing cells HepG2 (IC₅₀ > 40.00 µM), Hela (IC₅₀ > 40.00 µM), MCF-7 (IC₅₀ = 21.68 ± 4.96 µM), DU145 (IC₅₀ = 5.40 ± 1.22 µM), PC-3 (IC₅₀ = 42.96 ± 3.69 µM) cells. Moreover, CPT-HT-J-ZL₁₂ exhibited low cytotoxicity (IC₅₀ > 40 μM) towards MDCK and LO2 cells. The cellular uptake experiment demonstrated the superior PSMA-targeting ability of the CPT-HT-J-ZL₁₂, which was significantly accumulated in LNCaP-FGC (PSMA⁺), while it was minimized in HepG2 (PSMA⁻) cells. Further cell apoptosis analyses indicated that it showed a dramatically higher apoptosis-inducing activity in LNCaP-FGC (PSMA⁺) cells than in HepG2 (PSMA⁻) cells. Cell cycle analysis indicated that CPT-HT-J-ZL₁₂ could induce cell cycle arrest at the S phase.

Structure-Based Drug Design and Identification of H2O-Soluble and Low Toxic Hexacyclic Camptothecin Derivatives with Improved Efficacy in Cancer and Lethal Inflammation Models in Vivo

Camptothecin (CPT) has been shown to block disassembly of the topoisomerase I (Topo I)/DNA cleavable complex. However, the poor aqueous solubility, intrinsic instability, and severe toxicity of CPTs have limited their clinical applications. Herein, we report the design and synthesis of H₂O-soluble and orally bioavailable hexacyclic CPT derivatives. By analysis of a virtual chemical library and cytotoxicity screening in vitro, 9 and 11 were identified as potential prodrugs and chosen for further characterization in vivo. Both compounds exhibited remarkable anticancer and anti-inflammation efficacies in animals and improved drug-like profiles.