Design, synthesis, and characterization of fullerene–peptide–steroid covalent hybrids

A Comprehensive Review on Steroidal Bioconjugates as Promising Leads in Drug Discovery

Ever increasing unmet medical requirements of the human race and the continuous fight for survival against variety of diseases give birth to novel molecules through research. As diseases evolve, different strategies are employed to counter the new challenges and to discover safer, more effective, and target-specific therapeutic agents. Among several novel approaches, bioconjugation, in which two chemical moieties are joined together to achieve noticeable results, has emerged as a simple and convenient technique for a medicinal chemist to obtain potent molecules. The steroid system has been extensively used as a privileged scaffold gifted with significantly diversified medicinal properties in the drug discovery and development process. Steroidal molecules are preferred for their rigidness and good ability to penetrate biological membranes. Slight alteration in the basic ring structure results in the formation of steroidal derivatives with a wide range of therapeutic activities. Steroids are not only active as such, conjugating them with various biologically active moieties results in increased lipophilicity, stability, and target specificity with decreased adverse effects. Thus, the steroid nucleus prominently behaves as a biological carrier for small molecules. The steroid bioconjugates offer several advantages such as synergistic activity with fewer side effects due to reduced dose and selective therapy. The steroidal bioconjugates have been widely explored for their usefulness against various disorders and have shown significant utility as anticancer, anti-inflammatory, anticoagulant, antimicrobial, insecticidal/pesticidal, antioxidant, and antiviral agents along with several other miscellaneous activities. This work provides a comprehensive review on the therapeutic progression of steroidal bioconjugates as medicinally active molecules. The review covers potential biological applications of steroidal bioconjugates and would benefit the wider scientific community in their drug discovery endeavors.

Self-assembly of amphiphilic amino acid derivatives for biomedical applications

Amino acids are one of the simplest biomolecules and they play an essential role in many biological processes. They have been extensively used as building blocks for the synthesis of functional nanomaterials, thanks to their self-assembly capacity. In particular, amphiphilic amino acid derivatives can be designed to enrich the diversity of amino acid-based building blocks, endowing them with specific properties and/or promoting self-assembly through hydrophobic interactions, hydrogen bonding, and/or π-stacking. In this review, we focus on the design of various amphiphilic amino acid derivatives able to self-assemble into different types of nanostructures that were exploited for biomedical applications, thanks to their excellent biocompatibility and biodegradability.

Molecular Interpretation of Pharmaceuticals’ Adsorption on Carbon Nanomaterials: Theory Meets Experiments

The ability of carbon-based nanomaterials (CNM) to interact with a variety of pharmaceutical drugs can be exploited in many applications. In particular, they have been studied both as carriers for in vivo drug delivery and as sorbents for the treatment of water polluted by pharmaceuticals. In recent years, the large number of experimental studies was also assisted by computational work as a tool to provide understanding at molecular level of structural and thermodynamic aspects of adsorption processes. Quantum mechanical methods, especially based on density functional theory (DFT) and classical molecular dynamics (MD) simulations were mainly applied to study adsorption/release of various drugs. This review aims to compare results obtained by theory and experiments, focusing on the adsorption of three classes of compounds: (i) simple organic model molecules; (ii) antimicrobials; (iii) cytostatics. Generally, a good agreement between experimental data (e.g. energies of adsorption, spectroscopic properties, adsorption isotherms, type of interactions, emerged from this review) and theoretical results can be reached, provided that a selection of the correct level of theory is performed. Computational studies are shown to be a valuable tool for investigating such systems and ultimately provide useful insights to guide CNMs materials development and design.

[60]Fullerene-peptides: bio-nano conjugates with structural and chemical diversity

[60]Fullerene-peptides represent a simple yet chemically diverse example of a bio-nano conjugate. The C₆₀ moiety provides the following attributes to the conjugate: (a) precise three-dimensional architecture, (b) a large hydrophobic mass and (c) unique electronic properties. Conversely, the peptide component provides: (a) structural diversity depending on the overall length and amino acids composition, (b) charge flexibility and (c) secondary structure and recognition. Recent advances in the synthetic strategy for [60]fullerene-peptide synthesis from both pre-formed peptides and using solid phase peptide synthesis (SPPS) are described. The effects of the hydrophobic C₆₀ on the secondary structure of the peptide depend on the sequence of the latter, but in general the relative stability of particular structures is greatly enhanced. The ability of the [60]fullerene substituent to dramatically modify both cellular uptake and transdermal transport is discussed as is the effects on cell viability and antimicrobial activity.

Diamide-based fullerosteroidal and disteroidal [2]rotaxanes: solvent-induced macrocycle translocation and/or unthreading

Two hydrogen bonded rotaxanes: a template directed synthesis, detailed characterization and shuttling/unthreading processes.

Fulleropeptide esters as potential self-assembled antioxidants

The potential use of amphiphilic fullerene derivatives as a bionanomaterial was investigated by cyclic voltammetry (CV), scanning electron microscopy (SEM), and the ferrous ion oxidation-xylenol orange (FOX) method. Despite the disrupted delocalization of the π-electronic system over the C60 sphere, its antioxidant capacity remained high for all twelve derivatives. The compounds expressed up to two-fold and 5-12-fold better peroxide quenching capacity as compared to pristine C60 and standard antioxidant vitamin C, respectively. During precipitation and slow evaporation of the solvent, all compounds underwent spontaneous self-assembly giving ordered structures. The size and morphology of the resulting particles depend primarily on the sample concentration, and somewhat on the side chain structure.