Amygdalin is a controversial anti-tumor natural product that has been used as an alternative cancer drug for many years. The anti-tumor mechanism and metabolism of amygdalin have been the focus of many studies. However, previous studies by our group demonstrated that amygdalin itself has no anti-tumor activity, but rather the active ingredients were determined to be amygdalin degradation products. To screen novel drugs with anti-tumor activity, the extracellular enzymes from Aspergillus niger were used to degrade amygdalin. Within 4h of the catalytic reaction at 37 degrees, amygdalin was rapidly degraded into four products. The products were then extracted and purified by column chromatography. By comparing the H PLC chromatograms, H-1 NMR, C-13 NMR and MS data, the products were identified as mandelonitrile, prunasin, benzaldehyde and phenyl-(3.4,5-trihydroxy-6-methyl-tetrahydro-pyran-2-yloxy)-acetonitrile (PTMT), a novel hydroxyl derivative of prunasin. Furthermore, pharmacology studies of these compounds demonstrated that 10 mg/kg of PTMT significantly suppressed the growth of S-18 tumor cells within 11 days in a concentration-dependent manner. (C) 2011 Elsevier Ltd. All rights reserved.