New derivatives of vitamin B12 show preferential targeting of tumors.

Rapidly growing cells show an increased demand for nutrients and vitamins. The objective of our work is to exploit the supply route of vitamin B12 to deliver new derivatives of this vital vitamin to hyperproliferative cells. To date, radiolabeled ((57)Co and (111)In) vitamin B12 derivatives showed labeling of tumor tissue but also undesired high accumulation of radioactivity in normal tissue.

Microbiological ring expansion of penicillin N.

A mutant of Cephalosporium acremonium producing high amounts of penicillin N was isolated. This antibiotic was purified and characterized. It was possible to convert this penicillin N to deacetoxycephalosporin C enzymatically.