Targeted conjugation of breast anticancer drug tamoxifen and its metabolites with synthetic polymers

Codelivery of Phytochemicals with Conventional Anticancer Drugs in Form of Nanocarriers

Anticancer drugs in monotherapy are ineffective to treat various kinds of cancer due to the heterogeneous nature of cancer. Moreover, available anticancer drugs possessed various hurdles, such as drug resistance, insensitivity of cancer cells to drugs, adverse effects and patient inconveniences. Hence, plant-based phytochemicals could be a better substitute for conventional chemotherapy for treatment of cancer due to various properties: lesser adverse effects, action via multiple pathways, economical, etc. Various preclinical studies have demonstrated that a combination of phytochemicals with conventional anticancer drugs is more efficacious than phytochemicals individually to treat cancer because plant-derived compounds have lower anticancer efficacy than conventional anticancer drugs. Moreover, phytochemicals suffer from poor aqueous solubility and reduced bioavailability, which must be resolved for efficacious treatment of cancer. Therefore, nanotechnology-based novel carriers are employed for codelivery of phytochemicals and conventional anticancer drugs for better treatment of cancer. These novel carriers include nanoemulsion, nanosuspension, nanostructured lipid carriers, solid lipid nanoparticles, polymeric nanoparticles, polymeric micelles, dendrimers, metallic nanoparticles, carbon nanotubes that provide various benefits of improved solubility, reduced adverse effects, higher efficacy, reduced dose, improved dosing frequency, reduced drug resistance, improved bioavailability and higher patient compliance. This review summarizes various phytochemicals employed in treatment of cancer, combination therapy of phytochemicals with anticancer drugs and various nanotechnology-based carriers to deliver the combination therapy in treatment of cancer.

A new firewall in the fight against breast cancer: in-vitro and in-silico studies correlating chemistry to apoptotic activity of Otostegia fruticosa

Breast cancer is the most devastating disease for women. There is a great demand for new sources to treat this disease. Medicinal plants are an indispensable source of bioactive compounds with wide range of pharmacological activities. In-vitro cytotoxic activity of Otostegia fruticosa methanolic extract against human breast cancer was studied using MCF-7 cell line. The extract showed mildly potent activity (IC₅₀ = 51 ± 9.836 µg/mL) in comparison to the standard anticancer doxorubicin (IC₅₀ = 7.467 ± 1.05 µg/mL). Potential compounds responsible for activity have been identified using Molecular Operating Environment (MOE) module on the major compounds detected by HPLC-MS/MS technique against estrogen alpha receptor (ERα+: PDB ID 2JF9). 3,5-di-O-dicaffeoylquinic acid, hyperoside and rutin showed similar binding and antagonistic interaction with the estrogen alpha receptor as tamoxifen in several poses. The retrieved results confirm that we can add this plant to a powerful arsenal that combats this insidious disease.

In Silico Screening of Marine Compounds as an Emerging and Promising Approach against Estrogen Receptor Alpha-Positive Breast Cancer

Presently, the majority of breast tumors are estrogen receptor (ER) positive. Breast cancer (BC) is defined by uncontrolled cell proliferation (CP) in breast tissue. BCs are caused by the overexpression of genes that promote CP in breast cells. The discovery of effective inhibitors is an excellent chemopreventive method. Our in silico approach analysis offers a pharmacoinformatics methodology for identifying lead molecules targeting cochaperone HSP90 and the epidermal growth factor receptors (EGFR) and human epidermal growth factor receptor 2 (HER2)/neu receptor. BC has been associated with the high expression of these targets. The use of drug-likeness filters aided in determining the therapeutic properties of possible lead compounds. In this study, docking-based virtual screening (VS) was performed. Database of about 450 cancer marine compounds was used. The X-ray-assisted structure of ERα with 4-OHT (PDB code: 3ERT) was chosen for 4-OHT. A docking-based virtual screening was performed on the dataset supplied using the molecular operating environment (MOE) dock application. The binding energy (BE) and explanation of the protein inhibitor interaction (PII) are crucial findings for future both in terms of dry or wet lab research. The GBVI/WAS binding-free energy assessment (in kcal/mol) scores were used to grade the compounds. Compounds with a BE of less than -9.500 kcal/mol were deemed to be the most effective inhibitors. For further analysis, the top seven structurally diverse scaffolds were selected. Seven marine compounds exhibited the best docking score, which validates them to be potent anti-BC compounds. These compounds' bioactive potential and prospective drug-likeness profile make them promising leads for further experimental research.

Understanding the Pharmaceutical Aspects of Dendrimers for the Delivery of Anticancer Drugs

Dendrimers are emerging class of nanoparticles used in targeted drug delivery systems. These are radially symmetric molecules with well-defined, homogeneous, and monodisperse structures. Due to the nano size, they can easily cross the biological membrane and increase bioavailability. The surface functionalization facilitates targeting of the particular site of action, assists the high drug loading and improves the therapeutic efficiency of the drug. These properties make dendrimers advantageous over conventional drug delivery systems. This article explains the features of dendrimers along with their method of synthesis, such as divergent growth method, convergent growth method, double exponential and mixed method, hyper-core and branched method. Dendrimers are effectively used in anticancer delivery and can be targeted at the site of tumor either by active or passive targeting. There are three mechanisms by which drugs interact with dendrimers, and they are physical encapsulation, electrostatic interaction, chemical conjugation of drug molecules. Drug releases from dendrimer either by in vivo cleavage of the covalent bond between drugdendrimer complexes or by physical changes or stimulus like pH, temperature, etc.

Applications and Limitations of Dendrimers in Biomedicine

Biomedicine represents one of the main study areas for dendrimers, which have proven to be valuable both in diagnostics and therapy, due to their capacity for improving solubility, absorption, bioavailability and targeted distribution. Molecular cytotoxicity constitutes a limiting characteristic, especially for cationic and higher-generation dendrimers. Antineoplastic research of dendrimers has been widely developed, and several types of poly(amidoamine) and poly(propylene imine) dendrimer complexes with doxorubicin, paclitaxel, imatinib, sunitinib, cisplatin, melphalan and methotrexate have shown an improvement in comparison with the drug molecule alone. The anti-inflammatory therapy focused on dendrimer complexes of ibuprofen, indomethacin, piroxicam, ketoprofen and diflunisal. In the context of the development of antibiotic-resistant bacterial strains, dendrimer complexes of fluoroquinolones, macrolides, beta-lactamines and aminoglycosides have shown promising effects. Regarding antiviral therapy, studies have been performed to develop dendrimer conjugates with tenofovir, maraviroc, zidovudine, oseltamivir and acyclovir, among others. Furthermore, cardiovascular therapy has strongly addressed dendrimers. Employed in imaging diagnostics, dendrimers reduce the dosage required to obtain images, thus improving the efficiency of radioisotopes. Dendrimers are macromolecular structures with multiple advantages that can suffer modifications depending on the chemical nature of the drug that has to be transported. The results obtained so far encourage the pursuit of new studies.

Protein modification by thiolactone homocysteine chemistry: a multifunctionalized human serum albumin theranostic

As the most abundant protein with a variety of physiological functions, albumin has been used extensively for the delivery of therapeutic molecules. Thiolactone chemistry provides a powerful tool to prepare spin-labeled albumin-based multimodal imaging probes and therapeutic agents. We report the synthesis of a tamoxifen homocysteine thiolactone derivative and its use in thiol-'click' chemistry to prepare multi-functionalized serum albumin. The released sulfhydryl group of the homocysteine functional handle was labeled with a nitroxide reagent to prepare a spin-labeled albumin-tamoxifen conjugate confirmed by MALDI-TOF-MS, EPR spectroscopy, UV-vis and fluorescent emission spectra. This is the basis for a novel multimodal tamoxifen-albumin theranostic with a significant (dose-dependent) inhibitory effect on the proliferation of malignant cells. The response of human glioblastoma multiforme T98G cells and breast cancer MCF-7 cells to tamoxifen and its albumin conjugates was different in tumor cells with different expression level of ERα in our experiments. These results provide further impetus to develop a serum protein for delivery of tamoxifen to cancer cells.

Nanotechnology-Based Biopolymeric Oral Delivery Platforms for Advanced Cancer Treatment

Routes of drug administration and their corresponding physiochemical characteristics play major roles in drug therapeutic efficiency and biological effects. Each route of delivery has favourable aspects and limitations. The oral route of delivery is the most convenient, widely accepted and safe route. However, the oral route of chemotherapeutics to date have displayed high gastric degradation, low aqueous solubility, poor formulation stability and minimum intestinal absorption. Thus, mainstream anti-cancer drugs in current formulations are not suitable as oral chemotherapeutic formulations. The use of biopolymers such as chitosan, gelatin, hyaluronic acid and polyglutamic acid, for the synthesis of oral delivery platforms, have potential to help overcome problems associated with oral delivery of chemotherapeutics. Biopolymers have favourable stimuli-responsive properties, and thus can be used to improve oral bioavailability of anti-cancer drugs. These biopolymeric formulations can protect gastric-sensitive drugs from pH degradation, target specific binding sites for targeted absorption and consequently control drug release. In this review, the use of various biopolymers as oral drug delivery systems for chemotherapeutics will be discussed.

Application and biomolecular study of functionalized folic acid-dendrimer nanoparticles in drug delivery

We determined the loading efficacy of folic acid - PAMAM - G3 and folic acid - PAMAM - G4 nanoparticles with doxorubicin (Dox), tamoxifen (Tam) and tetracycline (Tet) in aqueous solution at pH 7.2. Thermodynamic parameters ΔH⁰ -16 to -4 (kJ mol^-1), ΔS⁰ 31 to -0.3 (J mol^-1K^-1) and ΔG⁰ -14 to -11 (kJ mol^-1) showed drug folic acid-PAMAM bindings are via ionic, H-bonding and van der Waals interactions. As acid - PAMAM size increased the stability and loading efficacy of drug-polymer conjugates were increased. The order of stability for drug-nanoparticles was doxorubicin > tetracycline > tamoxifen. TEM analysis showed major polymer morphological changes, upon drug encapsulation. Folic acid-PAMAM conjugates are effective drug delivery tools in vitro. Communicated by Ramaswamy H. Sarma.

Soft and Condensed Nanoparticles and Nanoformulations for Cancer Drug Delivery and Repurpose

Drug repurpose or reposition is recently recognized as a high-performance strategy for developing therapeutic agents for cancer treatment. This approach can significantly reduce the risk of failure, shorten R&D time, and minimize cost and regulatory obstacles. On the other hand, nanotechnology-based delivery systems are extensively investigated in cancer therapy due to their remarkable ability to overcome drug delivery challenges, enhance tumor specific targeting, and reduce toxic side effects. With increasing knowledge accumulated over the past decades, nanoparticle formulation and delivery have opened up a new avenue for repurposing drugs and demonstrated promising results in advanced cancer therapy. In this review, recent developments in nano-delivery and formulation systems based on soft (i.e., DNA nanocages, nanogels, and dendrimers) and condensed (i.e., noble metal nanoparticles and metal-organic frameworks) nanomaterials, as well as their theranostic applications in drug repurpose against cancer are summarized.

Interaction of Tamoxifen Analogs With the Pocket Site of Some Hormone Receptors. A Molecular Docking and Density Functional Theory Study

In this paper, the antiestrogenic properties of Tamoxifen analogs have been investigated and a theoretical report of its analogs interaction with the pocket site of some hormone receptors are presented. Analogs were generated by modification of the hydrophilic functional group of Tamoxifen by hydroxyl, amide, carboxyl, and sulfhydryl functional groups, in an attempt to improve their activity and selectivity. The analogs exhibit a negative binding energy in the estrogen and progesterone receptors, which indicates a spontaneous interaction between the analogs and the pocket site in the hormone receptors. The values of the molecular polar surface area indicate that the analogs have good permeability and are strong electrophiles. The couplings showed electrostatic interactions such as hydrogen bond and π-π interactions. According with the Lipinsky Rule of Five, the four analogs presented a good biodistribution, permeability, and pharmacological action on the hormone receptors. The analysis of the charge transfer suggests a limited enhanced oxidative damage in the estrogen receptor that not takes place with the progesterone receptor.

Binding analysis of antioxidant polyphenols with PAMAM nanoparticles

Dietary polyphenols are abundant micronutrients in our diet and paly major role in prevention of degenerative diseases. The binding efficacy of antioxidant polyphenols resveratrol, genistein, and curcumin with PAMAM-G3 and PAMAM-G4 nanoparticles was investigated in aqueous solution at physiological conditions, using multiple spectroscopic methods, TEM images, and docking studies. The polyphenol bindings are via hydrophilic, hydrophobic, and H-bonding contacts with resveratrol forming more stable conjugates. As PAMAM size increased the loading efficacy and the stability of polyphenol-polymer conjugates were increased. Polyphenol binding induced major alterations of dendrimer morphology. PAMAM nanoparticles are capable of delivery of polyphenols in vitro.

Molecular Docking and 3D-Pharmacophore Modeling to Study the Interactions of Chalcone Derivatives with Estrogen Receptor Alpha

Tamoxifen is the most frequently used anti-estrogen adjuvant treatment for estrogen receptor-positive breast cancer. However, it is associated with an increased risk of several serious side-effects, such as uterine cancer, stroke, and pulmonary embolism. The 2',4'-dihydroxy-6-methoxy-3,5-dimethylchalcone (ChalcEA) from plant leaves of Eugenia aquea, has been found to inhibit the proliferation of MCF-7 human breast cancer cells in a dose-dependent manner, with an IC₅₀ of 74.5 μg/mL (250 μM). The aim of this work was to study the molecular interactions of new ChalcEA derivatives formed with the Estrogen Receptor α (ERα) using computer aided drug design approaches. Molecular docking using Autodock 4.2 was employed to explore the modes of binding of ChalcEA derivatives with ERα. The 3D structure-based pharmacophore model was derived using LigandScout 4.1 Advanced to investigate the important chemical interactions of the ERα-tamoxifen complex structure. The binding energy and the tamoxifen-pharmacophore fit score of the best ChalcEA derivative (HNS10) were -12.33 kcal/mol and 67.07 kcal/mol, respectively. The HNS10 interacted with Leu346, Thr347, Leu349, Ala350, Glu353, Leu387, Met388, Leu391, Arg394, Met421, and Leu525. These results suggest that the new ChalcEA derivatives could serve as the lead compound for potent ERα inhibitor in the fight against breast cancer.

PAMAM dendrimers in drug delivery: loading efficacy and polymer morphology

The binding efficacy of anticancer drugs doxorubicin and tamoxifen with polyamidoamine (PAMAM-G4) dendrimers was studied in aqueous solution at physiological pH. The results of multiple spectroscopic methods, transmission electron microscopy (TEM), and molecular modeling of conjugated drug–polymer were examined. Structural analysis showed that drug–polymer conjugation occurs mainly via H-bonding and hydrophilic and hydrophobic contacts. Doxorubicin forms a more stable conjugate with PAMAM-G4 than tamoxifen. The drug loading efficacy was 40%–50%. The TEM images showed major changes in the PAMAM morphology upon drug encapsulation. Modeling showed that drug is located in the polymer surface and in the internal cavities. PAMAM nanoparticles are capable of transporting doxorubicin and tamoxifen in vitro. This minireview presents the most recent work performed with the dendrimers demonstrating their usefulness for drug delivery in cancer therapy.

Dendrimers as Nanocarriers for Nucleic Acid and Drug Delivery in Cancer Therapy

Dendrimers are highly branched polymers with easily modifiable surfaces. This makes them promising structures for functionalization and also for conjugation with drugs and DNA/RNA. Their architecture, which can be controlled by different synthesis processes, allows the control of characteristics such as shape, size, charge, and solubility. Dendrimers have the ability to increase the solubility and bioavailability of hydrophobic drugs. The drugs can be entrapped in the intramolecular cavity of the dendrimers or conjugated to their functional groups at their surface. Nucleic acids usually form complexes with the positively charged surface of most cationic dendrimers and this approach has been extensively employed. The presence of functional groups in the dendrimer's exterior also permits the addition of other moieties that can actively target certain diseases and improve delivery, for instance, with folate and antibodies, now widely used as tumor targeting strategies. Dendrimers have been investigated extensively in the medical field, and cancer treatment is one of the greatest areas where they have been most used. This review will consider the main types of dendrimer currently being explored and how they can be utilized as drug and gene carriers and functionalized to improve the delivery of cancer therapy.

Protein conjugation with PAMAM nanoparticles: Microscopic and thermodynamic analysis

PAMAM dendrimers form strong protein conjugates that are used in drug delivery systems. We report the thermodynamic and binding analysis of polyamidoamine (PAMAM-G4) conjugation with human serum albumin (HSA), bovine serum albumin (BSA) and milk beta-lactoglobulin (b-LG) in aqueous solution at physiological pH. Hydrophobicity played a major role in PAMAM-protein interactions with more hydrophobic b-LG forming stronger polymer-protein conjugates. Thermodynamic parameters showed PAMAM-protein bindings occur via hydrophobic and H-bonding contacts for b-LG, while van der waals and H-bonding interactions prevail in HSA and BSA-polymer conjugates. The protein loading efficacy was 45-55%. PAMAM complexation induced major alterations of protein conformation. TEM images show major polymer morphological changes upon protein conjugation.