Synthesis and biological application of glyco- and peptide derivatives of fullerene C₆₀

Fullerenes have attracted considerable attention for their possible use in human therapy. Pure C₆₀ is soluble only in some organic solvents, but this could be overcome by chemical modifications. This review investigates the derivatization strategies and biological applications of fullerene C₆₀ by using polar "active" molecules as sugars and amino acids/peptides that allow the increase of solubility in water. The effect of glycosylation on biological activity of fullerene can be divided in indirect and direct action. The "indirect action" of sugars correlates with their ability to make fullerene soluble in water but glycosylation can be also exploited for the target delivery; accordingly, glyco-derivatives of fullerenes have been investigated in PDT (photodynamic therapy), as inhibitors of in HIV-1 protease or against neurodegenerative diseases. The "direct action" involves fullerenes conjugated with sugars having a defined therapeutic role and the "multivalency" is the properties that ensures a good biological activity of glycofullerene derivatives. Increasing the sugars attached to fullerene intensifies the multivalency needed to efficiently use these glycosylated nanoparticles as potential ligands for receptors and enzymes that mediate the infection of viruses and bacteria (e.g. E. Coli, Ebola or Dengue viruses). Also, amino acids-derivatives of fullerenes have been studied as anti-infective agents (against viruses such as cytomegalovirus and HIV), thanks to their immunological properties; derivatives as fullerenol or by linking tuftsin on a C₆₀ core could be exploited as immunogenic nano-carriers. Alternatively fullerene conjugated with amino acids or peptides is investigated in the treatments of pathologies that request new approaches (Alzheimer, cancer, mixed connective tissue disease, lupus).