Professor Casu and Cyclodextrins

Abstract

Three years ago, Professor Benito Casu, G. Ronzoni Institute for Chemical and Biochemical Research, passed away on November 11, 2016, shortly before his 90th birthday. Professor Casu was an eminent scientist in the area of chemistry and biochemistry of polysaccharides and glycosaminoglycans. Casu’s scientific career started in the 1950s with the study of carbohydrates by innovative spectrometric techniques. Professor Casu was on the list of prestigious researchers who contributed in the 1960s to the development of cyclodextrins. At that time, there was a lack of sufficient knowledge about these molecules. Few researchers believed in the potential that these new molecules had. In the mid-1960s, Professor Casu was the first to demonstrate that infrared spectroscopy and proton nuclear magnetic resonance were powerful methods to study the structure and conformations of cyclodextrins. He suggested a common shape of the glucopyranose rings in the chair C-1 and the presence of hydrogen bonds between the hydroxyl groups. These conclusions greatly advanced the understanding of the structure and chemistry of cyclodextrins and their properties. In 1967, Professor Casu published the first perspective view of 2,6-di-O-methylated cyclodextrin and, 1 year later, prepared cyclodextrin derivatives such as methylated and acetylated products. At the end of the 1960s, Professor Casu was among the first to verify the idea that if the guest molecule is accommodated in the cyclodextrin cavity, then the hydrogen atoms located in the interior of the cavity would be significantly shielded by the guest, whereas the hydrogen atoms on the outer surface would not be affected by the formation of the inclusion complex. In 1969, his interest extended to biological active substances such as heparin with a visit to Department of Chemistry of McGill University of Montreal, Canada, guest of Professor Arthur S. Perlin. Nevertheless, Professor Casu has continued to work on cyclodextrin, publishing important contributions on the use of methylated cyclodextrins as versatile complexing agents for the complexation of some n-alkanes and dyes, and on the interactions of cyclodextrins with glycolipids. He also studied inclusion properties of methylated cycloamyloses, demonstrating that the inclusion complexes of methylated derivatives were more stable than the corresponding complexes with the parent cyclodextrins. Professor Casu was among the first to publish general notes and reviews on cyclodextrins for a broader public. He was a prolific publisher on topics related to cyclodextrin and heparin, an enthusiastic teacher of many doctoral students and postdoctoral fellows, a genial host to visitors, and a truly caring person. In this chapter, we would like to pay a posthumous tribute to Professor Casu, one of the pioneers in the dissemination of the knowledge of cyclodextrins in the 1960–1970s and later of heparin.