Investigation of the host-guest complexation between 4-sulfocalix[4]arene and nedaplatin for potential use in drug delivery

Advancements in steroidal Pt(II) & Pt(IV) derivatives for targeted chemotherapy (2000-2023)

One of the key strategies in chemotherapy involves crosslinking the DNA strands of cancer cells to impede their replication, with platinum (Pt) coordination compounds being a prominent class and cisplatin being its major representative. Steroidal ligands tethered to DNA interactive Pt core act as drug carriers for targeted therapy. While crosslinking of nuclear or mitochondrial DNA strands using coordination complexes has been studied for years, there remains a lack of comprehensive reviews addressing the advancements made in steroidal-Pt derivatives. This review specifically focuses on advancements made in steroid-tethered structural derivatives of Pt(II) or prodrug Pt(IV) for targeted chemotherapy, synthesized between 2000 and 2023. This period was deliberately chosen due to the widespread use of computational techniques for more accurate structure-based drug-design in last two decades. This review discusses the strategy behind tethering steroidal ligands such as testosterone, estrogen, bile acids, and cholesterol to the central DNA interactive Pt core through specific linker groups. The steroidal ligands function as drug delivery vehicles of DNA interactive Pt core and bind with their respective target receptors or proteins that are often overexpressed in cancer cells, thus enabling targeted delivery of Pt moiety to interact with DNA. We discussed structural features such as the location of the linker group on the steroid, the mono, bi, and tridentate configuration of the chelating arm in coordination with Pt, and the rigidity and flexibility of the linker group. The comparative in vitro, in vivo activities, and relative binding affinities of the designed compounds against standard Pt drugs are also discussed. We also provided a critique of observed trends and shortcomings. Our review will provide insights into future molecular designing of targeted DNA crosslinkers and their structural optimization to achieve desired drug properties. From this analysis, we proposed further research directions leading to the future of targeted chemotherapy.

Membranes with Molecular Gatekeepers for Efficient CO2 Capture and H2 Purification

The urgent need for CO2 capture and hydrogen energy has attracted great attention owing to greenhouse gas emissions and global warming problems. Efficient CO2 capture and H2 purification with membrane technology will reduce greenhouse gas emissions and help reach a carbon-neutral society. Here, 4-sulfocalix[4]arene (SC), which has an intrinsic cavity, was embedded into the Matrimid membrane as a molecular gatekeeper for CO2 capture and H2 purification. The interactions between SC and the Matrimid polymer chains immobilize SC molecules into the interchain gaps of the Matrimid membrane, and the strong hydrogen and ionic bondings were able to form homogeneous mixed-matrix membranes. The incorporation of the SC molecular gatekeeper with exceptional molecular-sieving properties improved the gas separation performance of the mixed-matrix membranes. Compared with that of the Matrimid membrane, the CO2 permeability of the Matrimid-SC-3% membrane increased from 16.75 to 119.78 Barrer, the CO2/N2 selectivity increased from 29.39 to 106.95, and the CO2/CH4 selectivity increased from 29.91 to 140.92. Furthermore, when the permeability of H2 was increased to 172.20 Barrer, the H2/N2 and H2/CH4 selectivities reached approximately 153.75 and 202.59, respectively, which are far superior to those of most existing Matrimid-based materials. The mixed-matrix membranes also exhibited excellent long-term operation stability, with separation performance for several important gas pairs still overtaking the Robeson upper limit after aging for 400 days.

Least Absolute Shrinkage and Selection Operator-Based Prediction of the Binding Constant of p-Sulfonatocalix[6]/[8]arenes with Alkaloids

p-Sulfonatocalix[n]arenes (SCnA) have demonstrated great potential for drug encapsulation through host-guest complexation to improve solubility, stability, and bioavailability. In this study, the solubilization effect of SCnA (n = 4, 6, 8) on 95 active compounds derived from traditional Chinese medicine (TCM) was investigated. Based on the significant solubilization effect on alkaloids, SC6A/SC8A and 76 alkaloids were selected as the host and guest, respectively, to determine the binding constant by competitive fluorescence titration. LASSO regression was adopted to investigate the mechanism of the complex of SCnA with alkaloids. The binding constant of alkaloids-SC6A and alkaloids-SC8A was related to the alkaloid alkalinity. Also, the electronegativity, polarization, first ionization potential, hydrogen bond potential, the molecular size, and shape of alkaloids are critical properties to determine alkaloids-SC6A binding constant as well as electronegativity, polarization, hydrophobicity, and the molecular size and shape of alkaloids play an important role for the alkaloids-SC8A binding constant.

Promises of anionic calix[n]arenes in life science: State of the art in 2023

Because they hold together molecules by means of non-covalent interactions - relatively weak and thus, potentially reversible - the anionic calixarenes have become an interesting tool for efficiently binding a large range of ligands - from gases to large organic molecules. Being highly water soluble and conveniently biocompatible, they showed growing interest for many interdisciplinary fields, particularly in biology and medicine. Thanks to their intrinsic conical shape, they provide suitable platforms, from vesicles to bilayers. This is a valuable characteristic, as so they mimic the biologically functional architectures. The anionic calixarenes propose efficient alternatives for overcoming the limitations linked to drug delivery and bioavailability, as well as drug resistance along with limiting the undesirable side effects. Moreover, the dynamic non-covalent binding with the drugs enables predictable and on demand drug release, controlled by the stimuli present in the targeted environment. This particular feature instigated the use of these versatile, stimuli-responsive compounds for sensing biomarkers of diverse pathologies. The present review describes the recent achievements of the anionic calixarenes in the field of life science, from drug carriers to biomedical engineering, with a particular outlook on their applications for the diagnosis and treatment of different pathologies.

PEGylated Chitosan Nanoparticles Loaded with Betaine and Nedaplatin Hamper Breast Cancer: In Vitro and In Vivo Studies

The current study investigates the anticancer effects of PEGylated chitosan nanoparticles (CS NPs) coloaded with betaine (BT) and nedaplatin (ND) on breast adenocarcinoma (MCF-7) cells and breast cancer-bearing rats. Hereof, the ionotropic gelation approach was implemented for the synthesis of PEG-uncoated and PEG-coated CS NPs encompassing either BT, ND, or both (BT-ND). The sizes of the developed BT/CS NPs, ND/CS NPs, and BT-ND/CS NPs were 176.84 ± 7.45, 204.1 ± 13.6, and 201.1 ± 23.35 nm, respectively. Meanwhile, the sizes of the synthesized BT/PEG-CS NPs, ND/PEG-CS NPs, and BT-ND/PEG-CS NPs were 165.1 ± 32.40, 148.2 ± 20.98, and 143.7 ± 7.72 nm, respectively. The surface charges of the fabricated nanoparticles were considerably high. All of the synthesized nanoparticles displayed a spherical form and significant entrapment efficiency. Release experiments demonstrated that the PEGylated and non-PEGylated CS NPs could discharge their contents into the tumor cells' microenvironments (pH 5.5). In addition, the NPs demonstrated an outstanding ability to reduce the viability of the MCF-7 cell line. In addition, BT-ND/PEG-CS NPs were found to be the strongest among all NP preparations, where they caused around 90% decrease in the size of mammary gland tumors in rats compared to vehicle-treated animals.

Functionalized Calixarenes as Promising Antibacterial Drugs to Face Antimicrobial Resistance

Since the discovery of polyphenolic resins 150 years ago, the study of polymeric compounds named calix[n]arene has continued to progress, and those skilled in the art perfectly know now how to modulate this phenolic ring. Consequently, calix[n]arenes are now used in a large range of applications and notably in therapeutic fields. In particular, the calix[4]arene exhibits multiple possibilities for regioselective polyfunctionalization on both of its rims and offers researchers the possibility of precisely tuning the geometry of their structures. Thus, in the crucial research of new antibacterial active ingredients, the design of calixarenes finds its place perfectly. This review provides an overview of the work carried out in this aim towards the development of intrinsically active prodrogues or metallic calixarene complexes. Out of all the work of the community, there are some excellent activities emerging that could potentially place these original structures in a very good position for the development of new active ingredients.

Thermosensitive Liposomes Encapsulating Nedaplatin and Picoplatin Demonstrate Enhanced Cytotoxicity against Breast Cancer Cells

Thermosensitive liposomes (TSL) have been used for localized temperature-responsive release of chemotherapeutics into solid cancers, with a minimum of one invention currently in clinical trials (phase III). In this study, TSL was designed using a lipid blend comprising 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC), 1,2-distearoyl-sn-glycero-3-phosphocholine (DSPC), cholesterol, and 1,2-distearoyl-sn-glycero-3-phosphoethanolamine-N-[maleimide(polyethylene glycol)-2000] (DSPE-PEG-2000) (molar ratio of 88:9:2.8:0.2). Either nedaplatin (ND) or p-sulfonatocalix[4]arene-nedaplatin was encapsulated in the aqueous inner layer of TSL to form (ND-TSL) or p-SC4-ND-TSL, respectively. The hydrophobic platinum-based drug picoplatin (P) was loaded into the external lipid bilayer of the TSL to develop P-TSL. The three nanosystems were studied in terms of size, PDI, surface charge, and on-shelf stability. Moreover, the entrapment efficiency (EE%) and release % at 37 and 40 °C were evaluated. In a 30 min in vitro release study, the maximum release of ND, p-SC4-ND, and picoplatin at 40 °C reached 74, 79, and 75%, respectively, compared to approximately 10% at 37 °C. This demonstrated temperature-triggered drug release from the TSL in all three developed systems. The designed TSL exhibited significant in vitro anticancer activity at 40 °C when tested on human mammary gland/breast adenocarcinoma cells (MDA-MB-231). The cytotoxicity of ND-TSL, p-SC4-ND-TSL, and P-TSL at 40 °C was approximately twice those observed at 37 °C. This study suggests that TSL is a promising nanoplatform for the temperature-triggered release of platinum-based drugs into cancer cells.

An innovative extraction strategy for herbal medicine by adopting p-sulphonatocalix[6]/[8]arenes

INTRODUCTION

Alkaloids exist in various herbal medicine widely and exhibit diverse biological and pharmacological activities. p-Sulphonatocalix[6]arenes (SC6A) and p-sulphonatocalix[8]arenes (SC8A) are water-soluble supramolecular macrocycles and are applied to the extraction of alkaloids from herbal products.

OBJECTIVE

In this study, an innovative method of SC6A/SC8A assisted extraction of the alkaloids from herbs was established.

METHODS

SC6A and SC8A were designed to extract 27 alkaloids from seven herbal medicines. Based on the significant solubilisation and extraction effect, Stephaniae Tetrandrae Radix (Fangji, FJ) was selected to obtain the optimal extraction process by adopting single factor test and orthogonal experiment. Then, the alkaloids and SC6A/SC8A were separated by one-step alkalisation and SCnA were reused. The host-guest complexes between alkaloids and SCnA were determined by competitive fluorescence titration, differential scanning calorimetry (DSC), Fourier-transform infrared (FTIR) and proton nuclear magnetic resonance (¹ H-NMR) analysis.

RESULTS

The optimum condition for SC6A assisted extraction was 5:1:80 (g/g/mL) for herbs/SC6A/solution ratio, 355-250 μm particle size and ultrasonicate 0.5 h, whilst 10:1:40 (g/g/mL) for herbs/SC8A/solution ratio, 355-250 μm particle size and ultrasonicate 0.5 h for SC8A assisted extraction. The total yield of alkaloids (fangchinoline and tetrandrine) from FJ was increased by 4.87 times and 5.97 times with SC6A and SC8A. Moreover, a good reusability of SC6A/SC8A was achieved by alkalisation dissociation. Host-guest complexes were determined by competitive fluorescence titration at a molar ratio of 1:1 between most alkaloids (25/27, except evodiamine and rutaecarpine) and SC6A/SC8A. The complex structure was proved by DSC, FTIR and ¹ H-NMR analysis.

CONCLUSION

The study provided an effective eco-friendly and energy-saving extraction method of alkaloids from herbal medicine.

Synthesis, Characterization and Host-Guest Complexation of Asplatin: Improved In Vitro Cytotoxicity and Biocompatibility as Compared to Cisplatin

Para-sulfocalix[n]arenes are promising host molecules that can accommodate various chemotherapeutic drugs. Pt(IV)-based complexes, including satraplatin and asplatin, are promising alternatives that overcome the shortcomings of Pt(II) complexes. In this study, asplatin has been synthesized by fusing acetylsalicylic acid (aspirin) and cisplatin. Furthermore, it has been characterized using ¹H NMR, mass spectrometry, elemental analysis, and UHPLC. A host-guest complex of asplatin and p-sulfocalix[4]arene (PSC4) has been developed and characterized using UV, Job’s plot analysis, HPLC, and density functional theory (DFT) calculations. The experimental and computational investigations propose that a 1:1 complex between asplatin and PSC4 is formed. The stability constant of the designed complex has been determined using Job’s plot and UHPLC and computed to be 9.1 × 10⁴ M^–1 and 8.7 × 10⁴ M⁻¹, which corresponds to a free energy of complexation of −6.8 kcal mol^–1, while the calculated value for the inclusion free energy is −13.2 kcal mol⁻¹. Both experimentally and theoretically estimated complexation free energy show that a stable host-guest complex can be formed in solution. The in vitro drug release study displayed the ability of the complex to release its cargo at a cancerous pH (pH of 5.5). Additionally, the asplatin/PSC4 complex is shown to be biocompatible when tested on human skin fibroblast noncancerous cells, demonstrating the highest in vitro cytotoxic activity against (MCF-7), cervical (HeLa), and lung cancer cells (A-549), with IC₅₀ values of 0.75, 2.15, and 3.60 µg/mL, respectively. This is as compared to either cisplatin (IC₅₀ of 5.47, 5.94 and 9.61 µg/mL, respectively) or asplatin (IC₅₀ of 1.54, 5.05 and 3.91 µg/mL, respectively). On the other hand, the free asplatin exhibited higher cytotoxicity on cancerous cells and lower toxicity on noncancerous cells. The outcomes of the present joint theoretical and experimental investigation reinforce the interest in platinum-based anticancer therapeutics when they are protected from undesired interactions and suggest the use of the PSC4 macromolecule as a promising carrier for Pt(IV) anticancer drugs. The formed asplatin/PSC4 inclusion complex may represent an effective chemotherapeutic agent.

Enhanced Anticancer Activity of Nedaplatin Loaded onto Copper Nanoparticles Synthesized Using Red Algae

Marine algae are a rich source of biologically active compounds that can be utilized in various food and pharmaceutical applications. In this study, ultrasound-assisted extraction (UAE) was optimized to maximize yield and total carbohydrate content extracted from the red algae, Pterocladia capillacea. The extract was shown to possess potent antioxidant activity of up to ~70%, and was successfully used as a reducing and capping agent in the green synthesis of copper nanoparticles, which were characterized by UV-spectroscopy, Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), transmission electron microscopy (TEM), and dynamic light scattering (DLS). Primarily, CuO nanoparticles with an average size of 62 nm were produced. FTIR spectra for the extract and algal-mediated CuO nanoparticles showed characteristic polysaccharide peaks. The synthesized CuO nanoparticles were subsequently loaded with nedaplatin where UV data suggested a complex formation. Nedaplatin release profiles showed a sustained release that reached a maximum at 120 h. The formulation was shown to have greater cytotoxicity relative to nedaplatin on hepatocellular carcinoma, breast cancer and ovarian cancer cell lines with IC₅₀ values of 0.40 ± 0.08, 1.50 ± 0.12, and 0.70 ± 0.09 µg/mL, respectively. Loading nedaplatin onto CuO nanoparticles synthesized using red algae extract, greatly enhances its anticancer effect.

PEGylated Chitosan Nanoparticles Encapsulating Ascorbic Acid and Oxaliplatin Exhibit Dramatic Apoptotic Effects against Breast Cancer Cells

This study aims to design a pH-responsive dual-loaded nanosystem based on PEGylated chitosan nanoparticles loaded with ascorbic acid (AA) and oxaliplatin (OX) for the effective treatment of breast cancer. In this regard, non-PEGylated and PEGylated chitosan nanoparticles (CS NPs) loaded with either ascorbic acid (AA), oxaliplatin (OX), or dual-loaded with AA-OX were fabricated using the ionotropic gelation method. The hydrodynamic diameters of the fabricated AA/CS NPs, OX/CS NPs, and AA-OX/CS NPs were 157.20 ± 2.40, 188.10 ± 9.70, and 261.10 ± 9.19 nm, respectively. While the hydrodynamic diameters of the designed AA/PEG-CS NPs, OX/PEG-CS NPs, and AA-OX/PEG-CS NPs were 152.20 ± 2.40, 156.60 ± 4.82, and 176.00 ± 4.21 nm, respectively. The ζ-potential of the prepared nanoparticles demonstrated high positive surface charges of +22.02 ± 1.50, +22.58 ± 1.85 and +40.4 ± 2.71 mV for AA/CS NPs, OX/CS NPs, and AA-OX/CS NPs, respectively. The ζ-potential of the PEGylated CS NPs was reduced owing to the shielding of the positive charges by the PEG chains. Additionally, all the prepared nanoparticles exhibited high entrapment efficiencies (EE%) and spherical-shaped morphology. The chemical features of the prepared nanoparticles were investigated using Fourier transform infrared (FTIR) spectroscopy. Release studies showed the capability of the prepared non-PEGylated and PEGylated chitosan NPs to release their cargo in the acidic environment of cancer tissue (pH 5.5). Furthermore, the AA/CS NPs, AA/PEG-CS NPs, OX/CS NPs, OX/PEG-CS NPs, AA-OX/CS NPs and AA-OX/PEG-CS NPs exhibited remarkable cytotoxic activities against breast adenocarcinoma (MCF-7) cells with IC₅₀ values of 44.87 ± 11.49, 23.3 ± 3.73, 23.88 ± 6.29, 17.98 ± 3.99, 18.69 ± 2.22, and 7.5 ± 0.69 µg/mL, respectively; as compared to free AA and OX (IC₅₀ of 150.80 ± 26.50 and 147.70 ± 63.91 µg/mL, respectively). Additionally, treatment of MCF-7 cells with IC₅₀ concentrations of AA, AA/CS NPs, AA/PEG-CS NPs, OX, OX/CS NPs, OX/PEG-CS NPs, AA-OX/CS NPs or AA-OX/PEG-CS NPs increased the percentages of early apoptotic cells to 5.28%, 9.53%, 11.20%, 5.27%, 13.80%, 8.43%, 2.32%, and 10.10%, respectively, and increased the percentages of late apoptotic cells to 0.98%, 0.37%, 2.41%, 2.06%, 0.97%, 9.66%, 56%, and 81.50%, respectively. These results clearly indicate that PEGylation enhances the apoptotic effect of AA and OX alone, in addition to potentiating the apoptotic effect of AA and OX when combined on MCF-7 cells. In conclusion, PEGylated chitosan nanoparticles encapsulating AA, OX, or AA and OX represent an effective formula for induction of apoptosis in MCF-7 cells.

PLGA/PEG Nanoparticles Loaded with Cyclodextrin-Peganum harmala Alkaloid Complex and Ascorbic Acid with Promising Antimicrobial Activities

Antimicrobial drugs face numerous challenges, including drug resistance, systemic toxic effects, and poor bioavailability. To date, treatment choices are limited, which warrants the search for novel potent antivirals, including those extracted from natural products. The seeds of Peganum harmala L. (Zygophyllaceae family) have been reported to have antimicrobial, antifungal, and anticancer activities. In the present study, a 2-hydroxy propyl-β-cyclodextrin (HPβCD)/harmala alkaloid-rich fraction (HARF) host-guest complex was prepared using a thin-film hydration method to improve the water solubility and bioavailability of HARF. The designed complex was then co-encapsulated with ascorbic acid into PLGA nanoparticles coated with polyethylene glycol (HARF-HPßCD/AA@PLGA-PEG NPs) using the W/O/W multiple emulsion-solvent evaporation method. The average particle size, PDI, and zeta potential were 207.90 ± 2.60 nm, 0.17 ± 0.01, and 31.6 ± 0.20 mV, respectively. The entrapment efficiency for HARF was 81.60 ± 1.20% and for ascorbic acid was 88 ± 2.20%. HARF-HPßCD/AA@PLGA-PEG NPs had the highest antibacterial activity against Staphylococcus aureus and Escherichia coli (MIC of 0.025 mg/mL). They also exhibited high selective antiviral activity against the H1N1 influenza virus (IC50 2.7 μg/mL) without affecting the host (MDCK cells). In conclusion, the co-encapsulation of HPCD-HARF complex and ascorbic acid into PLGA-PEG nanoparticles significantly increased the selective H1N1 killing activity with minimum host toxic effects.

Stimuli-Responsive Amphiphilic Pillar[n]arene Nanovesicles for Targeted Delivery of Cancer Drugs

Cancer chemotherapeutics face several challenges, including uncontrollable drug release, off-target toxic effects, and poor bioavailability. Recently, supramolecular nanovesicles, such as calix[n]arenes (CXs), cyclodextrins (CDs), cucurbiturils (CBs), and pillar[n]arenes (PRs), have attracted attention as potential smart nanocarriers for chemotherapeutics because of their exceptional cavities that can achieve high encapsulation capacity and accommodate both hydrophilic and hydrophobic drugs. In addition, they can be functionalized with different stimuli-responsive groups, which facilitate controlled drug release. Supramolecular nanovesicles, loaded with drugs and decorated with stimuli-responsive targeting moieties, are designed by either host-guest complexation or self-assembly of amphiphilic cavitands. Pillar[n]arenes, in particular, are novel supramolecular host molecules that have recently been employed in cancer targeted drug delivery because of their symmetric pillar-shaped structure, simplicity of functionalization, and biocompatibility. This review summarizes state-of-the-art strategies for developing single or multiple stimuli-responsive pillar[n]arene nanovesicles for effective cancer treatment.

Chitosan-Coated PLGA Nanoparticles Loaded with Peganum harmala Alkaloids with Promising Antibacterial and Wound Healing Activities

Wound healing is a major healthcare concern, and complicated wounds may lead to severe outcomes such as septicemia and amputations. To date, management choices are limited, which warrants the search for new potent wound healing agents. Natural products loaded in poly (lactic-co-glycolic acid) (PLGA) coated with chitosan (CS) constitute a promising antibacterial wound healing formulation. In this work, harmala alkaloid-rich fraction (HARF) loaded into PLGA nanoparticles coated with chitosan (H/CS/PLGA NPs) were designed using the emulsion-solvent evaporation method. Optimization of the formulation variables (HARF: PLGA and CS: PLGA weight ratios, sonication time) was performed using the 33 Box-Behnken design (BBD). The optimal NPs were characterized using transmission electron microscopy (TEM) and Attenuated Total Reflection Fourier-Transformed Infrared Spectroscopy (ATR-FTIR). The prepared NPs had an average particle size of 202.27 ± 2.44 nm, a PDI of 0.23 ± 0.01, a zeta potential of 9.22 ± 0.94 mV, and an entrapment efficiency of 86.77 ± 4.18%. In vitro drug release experiments showed a biphasic pattern where an initial burst of 82.50 ± 0.20% took place in the first 2 h, which increased to 87.50 ± 0.50% over 72 h. The designed optimal H/CS/PLGA NPs exerted high antibacterial activity against Staphylococcus aureus and Escherichia coli (MIC of 0.125 and 0.06 mg/mL, respectively) compared to unloaded HARF (MIC of 0.50 mg/mL). The prepared nanoparticles were found to be biocompatible when tested on human skin fibroblasts. Moreover, the wound closure percentage after 24 h of applying H/CS/PLGA NPs was found to be 94.4 ± 8.0%, compared to free HARF and blank NPs (68.20 ± 5.10 and 50.50 ± 9.40%, respectively). In conclusion, the three components of the developed nanoformulation (PLGA, chitosan, and HARF) have synergistic antibacterial and wound healing properties for the management of infected wounds.

Betaine host-guest complexation with a calixarene receptor: enhanced in vitro anticancer effect

p-Sulfonatocalix[n]arenes have shown excellent potential for accommodating chemotherapeutic drugs through host-guest complexation and enhancing their anticancer activity. Betaine has been reported to exert an anticancer effect at high concentrations. In order to increase its concentration in cancer cells, we have complexed it with p-SC4, which releases its content in an acidic environment typical of cancer tissue. In this work, a host-guest complex of the chemically stable, natural, and safe active methyl donor (betaine) and p-sulfonatocalix[4]arenes (p-SC4) was designed and characterized using 1H NMR, UV, Job's plot analysis, DFT calculations, and molecular modeling for use in cancer therapeutics. The peak amplitude of the prepared host-guest complexes was linearly proportional to the concentration of betaine in the range of 1.0 × 10-5 M-1 to 2.5 × 10-4 M-1. The reaction stoichiometry between p-SC4 and betaine in the formed complex was 1 : 1. The stability constant for the complex is 8.9 × 104 M-1 which corresponds to a complexation free energy of -6.74 kcal mol-1. Complexation between betaine and p-SC4 was found to involve the insertion of the trimethylammonium group of betaine into the p-SC4 cavity, as supported by the experimental data. The complex displayed enhanced cytotoxic activities against breast adenocarcinoma cells (MCF-7) and cervical cancer cells (HeLa) compared to free betaine. In conclusion, the host-guest complexation of betaine with p-SC4 increases its concentration in cancer cells, which warrants further investigation for cancer therapy.

The supramolecularly complexes of calix[4]arene derivatives toward favipiravir antiviral drug (used to treatment of COVID-19): a DFT study on the geometry optimization, electronic structure and infrared spectroscopy of adsorption and sensing

While the world is in search of a vaccine that can cure COVID-19 disease, favipiravir is the most commonly used antiviral drug in the treatment of patients during the pandemic process. In this study, we investigated the host-guest interaction between the popular supramolecule calix[4]arene derivatives and the favipiravir drug by using the DFT (Density Functional Theory) method. The B3LYP hybrid method and 6-31G (d,p) basis set were utilized to determine the optimized structures of the host and guest molecules and their complexes. The negative adsorption energy (∆E) and adsorption enthalpy (∆H) calculated for the complexes formed between calix[4]arene compounds and favipiravir drug molecule mentioned that adsorption of favipiravir molecule was an exothermic process on calix[4]arene structures. On the other hand, among the calixarene derivatives in the study, Gibbs free energy change (∆G) value for the adsorption was only negative on calix[4]arene4 molecule. The infrared spectroscopy (IR) calculations were performed by examining the C=O, O-H and NH2 vibrational frequencies to see the adsorption behavior in the favipiravir-calix[4]arene complex. After adsorption of the favipiravir molecule, HOMO-LUMO gap values decreased significantly for the structures and therefore electrical conductivity increased proportionally. In addition, sensor response factors, Fermi energy levels and workfunction changes of calix[4]arene derivatives were calculated and examined. Charge transfer between the four calix[4]arene compounds and the favipiravir molecule has occurred after adsorption. This attributes that calix[4]arene derivatives can be used as a well-suited favipiravir sensor (electronic and workfunction) and adsorbent at room temperature. Based on the calculations made to see the solvent effect on the adsorption of favipiravir it was determined that it did not affect the interaction between the drug molecule and the calix[4]arene compound too much and the adsorption energy turned into a slightly less negative value.

Peganum harmala Alkaloids Self-Assembled Supramolecular Nanocapsules with Enhanced Antioxidant and Cytotoxic Activities

Amphiphilic macrocycles, such as p-sulfonatocalix[6]arenes (p-SC6), have demonstrated great potential in designing synthetic nanovesicles based on self-assembly approaches. These supramolecular nanovesicles are capable of improving the solubility, stability, and biological activity of various drugs. In the present study, the biologically active harmala alkaloid-rich fraction (HARF) was extracted from Peganum harmala L. seeds. Ultraperformance liquid chromatography-electrospray ionization-tandem mass spectrometry (UPLC/ESI-MS) analysis of HARF revealed 15 alkaloids. The reversed-phase high-performance liquid chromatography (RP-HPLC) analysis revealed three peaks: peganine, harmol, and harmine. The HARF was then encapsulated in p-SC6 nanocapsules employing a thin-film hydration approach. The designed nanocapsules had an average particle size of 264.8 ± 10.6 nm, and a surface charge of -30.3 ± 2.2 mV. They were able to encapsulate 89.3 ± 1.4, 74.4 ± 1.3, and 76.1 ± 1.7% of the three harmala alkaloids; harmine, harmol, and peganine; respectively. The in vitro drug release experiments showed the potential of the designed nanocapsules to release their cargo at a pH of 5.5 (typical of cancerous tissue). The IC₅₀ values of HARF encapsulated in p-SC6 (H/p-SC6 nanocapsules) were 5 and 2.7 μg/mL against ovarian cancer cells (SKOV-3) and breast adenocarcinoma cells (MCF-7), respectively. The prepared nanocapsules were found to be biocompatible when tested on human skin fibroblasts. Additionally, the antioxidant activity of the designed nanocapsules was 5 times that of the free powder fraction; the IC₅₀ of the H/p-SC6 nanocapsules was 30.1 ± 1.3 μg/mL, and that of the HARF was 169.3 ± 7.2 μg/mL. In conclusion, encapsulation of P. harmala alkaloid-rich fraction into self-assembled p-SC6 significantly increases its antioxidant and cytotoxic activities.

Green Synthesis of Platinum and Palladium Nanoparticles Using Peganum harmala L. Seed Alkaloids: Biological and Computational Studies

This study reports a facile and eco-friendly method for the green synthesis of platinum and palladium nanoparticles (Pt NPs and Pd NPs) using Peganum harmala seed alkaloid fraction. The ζ-potential of the synthesized Pt NPs, Pd NPs and Pt–Pd NPs were −11.2 ± 0.5, −9.7 ±1.2, and −12.7 ± 2.1 mV; respectively. Transmission electron microscopy (TEM) revealed the formation of spherical-shaped nanoparticles with smooth margins. The mean diameters of the synthesized Pt NPs, Pd NPs, and Pt–Pd NPs were determined using TEM analysis and were found to be 20.3 ± 1.9, 22.5 ± 5.7, and 33.5 ± 5.4 nm, respectively. The nanoparticles’ bioreduction was confirmed by ultraviolet–visible (UV–vis) spectroscopy, X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy, and their organic contents were determined by thermal gravimetric analysis (TGA). The Pt–Pd NPs mixture showed more pronounced antioxidant activity of 843.0 ± 60 μM Trolox equivalent (TE)/mg NPs compared to the individual Pt NPs (277.3 ± 13.5 μM TE/mg NPs) and Pd NPs (167.6 ± 4.8 μM TE/mg NPs). Furthermore, the Pt–Pd NPs exhibited significant cytotoxic activities against lung cancer (A549) and breast adenocarcinoma (MCF-7) cells, IC₅₀ of 8.8 and 3.6 µg/mL, respectively; as compared to Pt NPs (IC₅₀ of 10.9 and 6.7 µg/mL, respectively) and Pd NPs (IC₅₀ of 31 and 10.8 µg/mL, respectively and compared to carboplatin (IC₅₀ of 23 and 9.5 µg/mL, respectively). Moreover, molecular docking studies were conducted to explore the possible anticancer and antioxidant mechanisms of the biogenic nanoparticles. Pt NPs, Pd NPs, and their mixture showed inhibitory activity against cysteine proteinase, which supports their high antitumor activity, but moderate antioxidant activity. In conclusion, Pd-Pt NPs mixture prepared using harmala seed alkaloid fraction showed potential as effective antineoplastic agents.

Host-Guest Complexation of Oxaliplatin and Para-Sulfonatocalix[n]Arenes for Potential Use in Cancer Therapy

P-sulfonatocalix[n]arenes have demonstrated a great potential for encapsulation of therapeutic drugs via host-guest complexation to improve solubility, stability, and bioavailability of encapsulated drugs. In this work, guest-host complexes of a third-generation anticancer drug (oxaliplatin) and p-4-sulfocalix[n]arenes (n = 4 and 6; p-SC4 and p-SC6, respectively) were prepared and investigated, using 1H NMR, UV, Job's plot analysis, and DFT calculations, for use as cancer therapeutics. The peak amplitude of the prepared host-guest complexes was linearly proportional to the concentration of oxaliplatin in the range of 1.0 × 10-5 M-1 to 2.1 × 10-4 M-1. The reaction stoichiometry between either p-SC4 or p-SC6 and oxaliplatin in the formed complexes was 1:1. The stability constants for the complexes were 5.07 × 104 M-1 and 6.3 × 104 M-1. These correspond to complexation free energy of -6.39 and -6.52 kcal/mol for p-SC4 and p-SC6, respectively. Complexation between oxaliplatin and p-SC4 or p-SC6 was found to involve hydrogen bonds. Both complexes exhibited enhanced biological and high cytotoxic activities against HT-29 colorectal cells and MCF-7 breast adenocarcinoma compared to free oxaliplatin, which warrants further investigation for cancer therapy.

Experimental and Computational Investigations of Carboplatin Supramolecular Complexes

Supramolecular systems (macromolecules), such as calix[n]arenes (SCn), cyclodextrins (CDs), and cucurbiturils (CBs), are promising vehicles for anticancer drugs. In this work, guest-host complexes of carboplatin, a second-generation platinum-based anticancer drug, and p-4-sulfocalix[n]arenes (n = 4 and 6; PS4 and PS6, respectively) were prepared and studied using ¹H NMR, UV, Job's plot analysis, HPLC, and density-functional theory calculations. The experimental and the computational studies suggest the formation of 1:1 complexes between carboplatin and each of PS4 and PS6. The stability constants of the formed complexes were estimated to be 5.3 × 10⁴ M^-1 and 9.8 × 10⁴ M^-1, which correspond to free energy of complexation of -6.40 and -6.81 kcal mol^-1, in the case of PS4 and PS6, respectively. The interaction free energy depends on the different inclusion modes of carboplatin in the host cavities. UV-vis findings and atoms in molecules analysis showed that hydrogen bond interactions stabilize the host-guest complexes without the full inclusion in the host cavity. The in vitro anticancer study revealed that both complexes exhibited stronger anticancer activities against breast adenocarcinoma cells (MCF-7) and lung cancer cells (A-549) compared to free carboplatin, preluding to their potential use in cancer therapy.

Supraamphiphilic Systems Based on Metallosurfactant and Calix[4]resorcinol: Self-Assembly and Drug Delivery Potential

Metallic amphiphiles are used as building blocks in the construction of nanoscale superstructures, where the hydrophobic effects induce the self-assembly of the nanoparticles of interest. However, the influence of synergizing multiple chemical interactions on an effective design of these structures mostly remains an open question. In this regard, supraamphiphilic systems based on flexible surfactant molecules and rigid macrocycles are being actively developed, but there are few works on the interaction between metallosurfactants and macrocycles. In the present work, the self-assembly and biological properties of a metallosurfactant with calixarene were studied for the first time. The metallosurfactant, a complex between lanthanum nitrate and two 4-aza-1-hexadecylazoniabicyclo[2.2.2]octane bromide units, and calix[4]resorcinol containing sulfonate groups on the upper rim were used to form a novel supraamphiphilic composition. The system formed was studied using a variety of physicochemical methods, including spectrophotometry, NMR, XRF, and dynamic and electrophoretic light scattering. It was found that the most optimal tetraanionic calix[4]resorcinol to dicationic metallosurfactant molar ratio, leading to mixed aggregation upon ion pair complexation, is 2:3. The mixed aggregates formed in the pentamolar concentration range were able to encapsulate hydrophilic substrates, including the anticancer drug cisplatin, the pure form of which is more cytotoxic toward healthy cells than toward diseased cells. Interestingly, the drug loaded into the macrocycle-metallosurfactant particles was less cytotoxic to a healthy Chang liver cell line and more cytotoxic to tumor M-HeLa cells. This selectivity depends on the amount of cisplatin added. The more drug is added to the macrocycle-metallosurfactant composition, the greater the biological activity against cancer cells. Taking into account that the appearance of resistance of cancer cells to drugs, especially to cisplatin, is one of the most important problems in treatment, the results of this work envisage the potential application of a mixed macrocycle-metallosurfactant system for the design of therapeutic cisplatin compositions.

Palladium Nanoparticles Fabricated by Green Chemistry: Promising Chemotherapeutic, Antioxidant and Antimicrobial Agents

Palladium nanoparticles (Pd NPs) showed great potential in biomedical applications because of their unique physicochemical properties. Various conventional physical and chemical methods have been used for the synthesis of Pd NPs. However, these methods include the use of hazardous reagents and reaction conditions, which may be toxic to health and to the environment. Thus, eco-friendly, rapid, and economic approaches for the synthesis of Pd NPs have been developed. Bacteria, fungi, yeast, seaweeds, plants, and plant extracts were used to prepare Pd NPs. This review highlights the most recent studies for the biosynthesis of Pd NPs, factors controlling their synthesis, and their potential biomedical applications.

A theoretical study of the global and local electrophilicity, nucleophilicity, polarizability and QTAIM theory for calix[4]arene-gas interaction

The calix[4]arene molecule, abbreviated as CX[4], is known by the four phenolic groups and a hydrophobic cavity able to enclose small molecules. The interactions between CX[4] and NO3, NO2, CO2, and N2 gas molecules have been studied. These guest species are placed inside and outside the cavity of the host molecule CX[4]. The formation of H-bonding has been deeply discussed based on the infrared spectrum and the polarizability analysis. Global and local indices have been calculated for a series of gas (NO3, NO2, CO2 and N2) in interaction with the CX[4] molecule to explain the electrophilic or nucleophilic activations in endo-vs. exo-cavity interaction zone. As expected, there is a correlation between the proposed global electrophilicity and global nucleophilicity together for an explanation of the chemo-selectivity region. Finally, the topological parameter analyses of the host-guests interactions have been estimated by using DFT calculations.

Host-guest complexation studies of NO3, NO2, CO2, and N2 gas with the calix[4]arene molecule

Calix[n]arenes (abbreviated as CX[n]) are the macro-molecules based on phenol groups with a hydrophobic cavity to encapsulate a gas or small molecules. They are used as molecular vehicles. For instance, these molecules are used in the activation of the solubility of monomers in the specific media and in pharmaceutical drug delivery. The limit of the development of gaseous pollutants will be a vital subject in the future. The polluting gases NO₃, NO₂, CO₂, N₂, etc., need cage molecules, such as CX[4], to be encapsulated. In this report, the red shift of the H-bonding interactions of the CX[4]-gas (by adding the gas inside or outside the cavity) is clearly explained by the vibrational analysis. The electronic spectra of the complexes of CX[4] with NO₃, NO₂, CO₂, and N₂) exhibit a blue-shift pick in comparison with the ones observed for the CX[4] molecule. The electrophilic and nucleophilic sites of the stable host-guest have been investigated. Additionally, the non-covalent interactions have been calculated based on the reduced density gradient RDG and QTAIM theory.

Para-sulfonatocalix[n]arene-based biomaterials: Recent progress in pharmaceutical and biological applications

The history, properties, and characteristics of para-sulfonato-calixarenes are described. On the one hand, the inherent antibacterial and antifungal properties against microorganisms, and on the other hand non-toxicity of these supramolecules toward human organs are analyzed. The resulting biocompatibility of para-sulfonato-calixarenes makes them potential candidates for diverse life sciences and pharmaceutical applications without significant side effects. The interactions with different drugs, the capability of drug encapsulation, delivery, and release, the formation of host-quest assemblies and inclusion complexation between para-sulfonato-calixarenes and drugs were also investigated in detail. Besides, their function in cancer treatment and their toxicity against different cancer cell lines were fully reviewed and summarized. Afterward, the capability of these macrocyclic compounds for biosensing of organic compounds, peptides and enzymes activity was highlighted. In this review, we also take a brief look at recent reports on the applications of para-sulfonato-calixarenes in fluorescence imaging and their usage as highly stable and bright probes for in vivo and in vitro imaging and sensing.

Design, Preparation, and Characterization of Novel Calix[4]arene Bioactive Carrier for Antitumor Drug Delivery

An amphiphilic and bioactive calix[4]arene derivative 8 (CA) is designed and successfully synthesized from tert-butyl calix[4] arene 1 by sequential inverse F-C alkylation, nitration, O-alkylation, esterification, aminolysis, reduction, and acylation reaction. The blank micelles of FA-CA and doxorubicin (DOX) loaded micelles FA-CA-DOX are prepared subsequently undergoing self-assembly and dialysis of CA and DSPE-PEG₂₀₀₀-FA. The drug release kinetics curve of the encapsulated-DOX micelle demonstrates a rapid release under mild conditions, indicating the good pH-responsive ability. Furthermore, the cytotoxicity of DOX-loaded micelle respect to the blank micelle against seven different human carcinoma (A549, HeLa, HepG2, HCT116, MCF-7, MDA-MB231, and SW480) cells has been also investigated. The results confirm the more significant inhibitory effect of DOX-loaded micelle than those of DOX and the blank micelles. The CDI calculations show a synergistic effect between blank micelles and DOX in inducing tumor cell death. In conclusion, FA-CA micelles reported in this work was a promising drug delivery vehicle for tumor targeting therapy.

DFT and TD-DFT investigation of calix[4]arene interactions with TFSI- ion

Understanding the interactions of the calix[n]arene molecules with a variety of invited chemicals entities is getting very important. In this context, we have studied a new host-guest such as the interaction of the calix[4]arenes with the bis (trifluoromethylsulfonyl) imide TFSI- ion. The energy gap has decreased from 3.53 eV to 2.11 eV indicating the reliability of the electrochemical evaluation of HOMO and LUMO energy levels. In a predominant number of cases, we obtain the spatial accumulation of HOMO and LUMO at the interface of phenol groups. Then, according to the QNBO charge distribution of these host-guests interactions, we have demonstrated the direction of charge transfer between the CX[4] molecule and the TFSI- ion. More importantly, the non covalent interactions (NCI) have been investigated that the endo-cavity position of the TFSI-4 is the most stable position between all these host-guests. By using DFT quantum methods, we have identified as a suitable host for TFSI- which can be used in the electronic technology.

Chemotherapy Based on Supramolecular Chemistry: A Promising Strategy in Cancer Therapy

Chemotherapeutic agents are considered one of the strategies in treating cancer. However, their use is faced by many challenges, such as poor water solubility leading to poor bioavailability and non-selective targeting of cancerous cells leading to diminished therapeutic actions and systemic adverse effects. Many approaches were adopted to overcome these drawbacks and to achieve the targeted delivery of the chemotherapeutic agents to the cancerous cells while minimizing adverse effects. Recently, supramolecular systems such as macrocycles have gained attention in the field of cancer therapy for being able to encapsulate different anticancer drugs via either host-guest complexation or self-assembly leading to a myriad of advantages. This review highlights the most recent studies concerned with the design of such novel systems for cancer therapy.

Calixarenes: Generalities and Their Role in Improving the Solubility, Biocompatibility, Stability, Bioavailability, Detection, and Transport of Biomolecules

The properties and characteristics of calix[n]arenes are described, as well as their capacity to form amphiphilic assemblies by means of the design of synthetic macrocycles with a hydrophilic head and a hydrophobic tail. Their interaction with various substances of interest in pharmacy, engineering, and medicine is also described. In particular, the role of the calix[n]arenes in the detection of dopamine, the design of vesicles and liposomes employed in the manufacture of systems of controlled release drugs used in the treatment of cancer, and their role in improving the solubility of testosterone and anthelmintic drugs and the biocompatibility of biomaterials useful for the manufacture of synthetic organs is emphasized. The versatility of these macrocycles, able to vary in size, shape, functional groups, and hydrophobicity and to recognize various biomolecules and molecules with biological activity without causing cytotoxicity is highlighted.

Host-Guest Recognition of Pesticides by Calixarenes

This article is based on a review of the literature and our own experience with toxicological molecules. We explain the nature of calix[n]arenes and as their recognized properties are used to detect compounds of toxicological interest, mainly the most important pesticide families such as organophosphorated, organochlorine compounds, pyrethroid insecticides, carbamate fungicides, and herbicides, using different techniques. In addition, we show the role of the macrocycle and its interactions, and the advantage of using this type of compound for improving conventional techniques, where the phenomenon of recognition is very important, such as chromatography, solid-phased extraction, and the development of specific sensors, among others and Even we also show the use of this macrocycle for detoxication procedures in vivo. In this way, we display as the multiple possibilities of functionalization of the calix[n]arenes makes these versatile molecules in the phenomena of specific recognition. Finally, This review highlights the main analytical methods reported in the literature for determination of plaguicides by host-guest interaction with calixarenes. In this way, among the available analytical tools, chromatographic, and electrochemical-based methods are the most used techniques for the detection and to quantify plaguicides using calixarenes.