Calixarenes and Resorcinarenes: Supramolecular Solutions for Drug Delivery

Supramolecular chemistry, with its foundations in non-covalent interactions, is a transformative field with broad implications in drug discovery. Supramolecular structures like calixarenesand resorcinarenes(Fig. 1) have attracted significant interest due to their ability to form stable host-guest complexes and facilitate controlled drug delivery. These macrocyclic compounds serve as versatile platforms for developing innovative drug carriers, such as nanotubes and molecular transporters, providing enhanced drug stability, specificity, and release control.

Figure 1. Representative calixarene-based building blocks (a) and resorcinarenes (b) are offered for Custom Synthesis.

The fundamentals of supramolecular chemistry rely on the assembly of molecules through non-covalent forces, such as hydrogen bonding, van der Waals interactions, π-π stacking, and metal coordination [1-3]. These interactions create adaptable molecular structures (Fig. 2) suitable for encapsulating and stabilizing active pharmaceutical ingredients (APIs). In drug design, the ability to form reversible yet stable complexes enables precise control over drug release profiles, improving bioavailability. Thus, such host-guest interactions are central to drug delivery innovations, providing flexible encapsulation of diverse drug molecules to ensure controlled delivery at the target site.

Figure 2. Examples of supramolecular materials forming host/guest supramolecular systems, adopted from [4].

Calixarenes and resorcinarenes are prominent examples of supramolecular scaffolds due to their cyclic, bowl-like structures and their capacity to engage in versatile molecular interactions [5]. Calixarenes (Fig. 1a), composed of repeating phenolic units, possess a hydrophobic cavity and can be easily modified with functional groups to enhance selective binding. Resorcinarenes (Fig. 1b), derived from resorcinol, feature a more open structure, which enables them to form nanotubes and capsules. Their ability to form host-guest complexes with various pharmaceuticals has been extensively explored. Early developments in the 1990s [1,6] laid the groundwork for using these macrocycles in drug delivery applications, focusing on stability, encapsulation, and the versatility of functionalization.

Due to their unique structural adaptability, Calixarenes have proven highly effective as drug carriers. Recent research in calixarene-based drug delivery systems [7,8] has demonstrated the potential of calixarene nanocarriers in enhancing drug solubility and bioavailability. By adjusting the functional groups, calixarenes can be tailored to target specific cells or tissues, thereby increasing the precision of drug delivery.Various substituents at the upper or lower rim of calixarenes allow creation of task-specific carriers for chemotherapeutic drugs, anti-inflammatory agents, and antibiotics [9]. This adaptability makes calixarenes particularly valuable for developing personalized medicine applications.

Furthermore, calixarene nanotubes have emerged as effective transporters for therapeutic agents due to their ability to encapsulate molecules [7-10]. By adjusting the inner cavity size and adding functional groups, these nanotubes can be tailored to create specific drug transporters with enhanced stability and controlled release profiles. In particular, calixarene nanotubes improve the delivery efficiency of poorly soluble drugs and protect sensitive molecules, such as peptides and nucleotides, from enzymatic degradation.

Resorcinarenes, with their flexible yet stable architecture, are increasingly explored as drug carriers, particularly for encapsulating hydrophobic drugs [5,11-12]. These compounds form stable molecular capsules through hydrogen bonding and π-π stacking, offering a robust platform for host-guest chemistry. Recent advances in resorcinarene-based systems highlight their potential in delivering anti-cancer and anti-inflammatory drugs while protecting compounds from degradation and improving bioavailability [12-13]. The customizable nature of resorcinarenes makes them highly adaptable for different pharmaceutical applications, enhancing their role in modern drug design.

Similar to calixarene nanotubes, resorcinarene-based nanotubes have proven effective for encapsulating drugs with controlled release profiles. These nanotubes effectively deliver hydrophobic drugs, overcoming challenges related to solubility and stability. Resorcinarenes significantly enhance the pharmacokinetics of challenging APIs, resulting in prolonged circulation times and improved therapeutic outcomes. Moreover, resorcinarene transporters exhibit unique specificity in drug delivery, enabling targeted therapies. Supported by screening libraries and task-specific functionalization, resorcinarenes can be tailored for particular targets, thereby increasing drug delivery efficiency.

Despite these advancements, several challenges remain [2-5]. The stability and biocompatibility of calixarene and resorcinarene drug carriers can vary significantly depending on functionalization and environmental conditions. Potential toxicity and immunogenicity also pose concerns, demanding extensive testing before clinical application. Additionally, large-scale synthesis of these complex structures is rather complicated, as supramolecular chemistry often requires multi-step syntheses, which can be costly for mass production.

However, the integration of calixarene and resorcinarene drug carriers with other nanotechnologies, such as multifunctional nanoparticles, presents a promising direction for enhancing drug delivery precision and efficiency [14]. Furthermore, the adoption of artificial intelligence and machine learning in supramolecular chemistry can expedite the screening and design process, allowing researchers to identify optimal host-guest pairs and functionalization strategies more efficiently [4,15-16]. These advances will likely lead to breakthroughs in using supramolecular chemistry in personalized medicine, as supramolecular systems offer versatile, efficient, and safe drug delivery solutions adaptable to individual therapeutic needs.

With these demanding needs in mind, Life Chemicals is happy to provide efficient Custom Synthesis solutions based on its screening libraries to facilitate the discovery of new drug carriers tailored to specific applications. These libraries enable the exploration of a vast range of various macrocyclic compounds, including functionalized calixarenes and resorcinarenes, supporting the optimization process for specific therapeutic targets:

• Task-Specific Calixarenes
• Resorcinarenes

Order your custom compound selections and enjoy the most convenient terms and competitive pricing.

Please, contact us at marketing@lifechemicals.com for any additional information and price quotations.

Download SD files with compound structures directly from our Downloads section

 References

1. Lehn, J. M. (1995). Supramolecular chemistry (Vol. 1). New York: Vch, Weinheim.
2. Steed, J. W., & Atwood, J. L. (2022). Supramolecular chemistry. John Wiley & Sons.
3. Kolesnichenko, I. V., & Anslyn, E. V. (2017). Practical applications of supramolecular chemistry. Chem. Soc. Rev. 46(9), 2385-2390. DOI: 10.1039/C7CS00078B 
4. Jelfs, K. E. (2022). Computational modeling to assist in the discovery of supramolecular materials. Annals of the New York Academy of Sciences, 1518(1), 106-119. DOI: 10.1111/nyas.14913
5. Sliwa, W., & Kozlowski, C. (2009). Calixarenes and resorcinarenes: synthesis, properties and applications. John Wiley & Sons.
6. Cram, D. J., & Cram, J. M. (2007). Container molecules and their guests. Royal Society of Chemistry.
7. Fan, X., & Guo, X. (2021). Development of calixarene-based drug nanocarriers. Journal of Molecular Liquids, 325, 115246. DOI: 10.1016/j.molliq.2020.115246 
8. Saji, V. S. (2022). Recent updates on supramolecular‐based drug delivery–macrocycles and supramolecular gels. The Chemical Record, 22(7), e202200053. DOI: 10.1002/tcr.202200053
9. Hussain, M.A., Ashraf, M.U., Muhammad, G., Tahir, M.N., & Bukhari, S.N.A. (2017). Calixarene: a versatile material for drug design and applications. Curr. Pharm. Des. 23(16), 2377-2388. DOI: 10.2174/1381612822666160928143328
10. Rafiee, Z., Kakanejadifard, A., Hosseinzadeh, R., Nemati, M., & Adeli, M. (2016). Synthesis of calixarene–polyglycerol conjugates and their self-assembly toward nano and microtubes. RSC advances, 6(21), 17470-17473. DOI: 10.1039/C5RA24941D
11. Timmerman, P., Verboom, W., & Reinhoudt, D. N. (1996). Resorcinarenes. Tetrahedron, 52(8), 2663-2704. DOI: 10.1016/0040-4020(95)00984-1
12. Galindres, D. M., Cifuentes, D., Tinoco, L. E., Murillo-Acevedo, Y., Rodrigo, M. M., Ribeiro, A. C., & Esteso, M. A. (2022). A Review of the Application of Resorcinarenes and SBA-15 in Drug Delivery. Processes, 10(4), 684. DOI: 10.3390/pr10040684
13. Mendoza-Cardozo, S., Pedro-Hernández, L. D., Organista-Mateos, U., Allende-Alarcón, L. I., Martínez-Klimova, E., Ramírez-Ápan, T., & Martínez-García, M. (2019). In vitro activity of resorcinarene–chlorambucil conjugates for therapy in human chronic myelogenous leukemia cells. Drug Dev. Ind. Pharm. 45(4), 683-688. DOI: 10.1080/03639045.2019.1569036
14. Montes-García, V., Pérez-Juste, J., Pastoriza-Santos, I., & Liz-Marzán, L. M. (2020). Metal nanoparticles and supramolecular macrocycles: a tale of synergy. Colloidal Synthesis of Plasmonic Nanometals, 537-561. DOI: 10.1201/9780429295188
15. Ollerton, K., Greenaway, R. L., & Slater, A. G. (2021). Enabling technology for supramolecular chemistry. Frontiers in Chemistry, 9, 774987. DOI: 10.3389/fchem.2021.774987
16. Ramakrishnan, M., van Teijlingen, A., Tuttle, T., & Ulijn, R. V. (2023). Integrating Computation, Experiment, and Machine Learning in the Design of Peptide‐Based Supramolecular Materials and Systems. Angewandte Chemie International Edition, 62(18), e202218067. DOI: 10.1002/anie.202218067