[60]Fullerene for Medicinal Purposes, A Purity Criterion towards Regulatory Considerations

Since the early nineties countless publications have reported promising medicinal applications for [60]fullerene (C₆₀) related to its unparalleled affinity towards free radicals. Yet, until now no officially approved C₆₀-based drug has reached the market, notably because of the alleged dangers of C₆₀. Nevertheless, since the publication of the effects of C₆₀ on the lifespan of rodents, a myriad of companies started selling C₆₀ worldwide for human consumption without any approved clinical trial. Nowadays, several independent teams have confirmed the safety of pure C₆₀ while demonstrating that previously observed toxicity was due to impurities present in the used samples. However, a purity criterion for C₆₀ samples is still lacking and there are no regulatory recommendations on this subject. In order to avoid a public health issue and for regulatory considerations, a quality-testing strategy is urgently needed. Here we have evaluated several analytical tools to verify the purity of commercially available C₆₀ samples. Our data clearly show that differential scanning calorimetry is the best candidate to establish a purity criterion based on the sc-fcc transition of a C₆₀ sample (T_onset ≥ 258 K, ∆_sc-fccH ≥ 8 J g^-1).