Two inhibitors of CD45 tyrosine phosphatase, dihydrocarolic acid (1) and penitricin D (2), were isolated from a fermentation broth of the fungus Aspergillus niger and purified by HSCCC (high speed countercurrent chromatography) followed by HPLC. The structures were determined by NMR. The inhibitory activities of both compounds were specific to tyrosine phosphatases.
K. A. Alvi, Dr. Bipin G. Nair, J. Rabenstein, G. Davis, and D. B. Baker, “CD45 Tyrosine Phosphatase Inhibitory Components from Aspergillus niger”, J. Antibiotics, no. 53, pp. 110-113, 2000.