Abstract: Microbial transformation of imbricatolic acid (1) by Aspergillus niger afforded 1α-hydroxyimbricatolic acid (2), while transformation with Rhizopus nigricans yielded 15-hydroxy-8,17-epoxylabdan-19-oic acid (3). When the diterpene 1 was added to a Cunninghamella echinulata culture, the main products were the microbial metabolites mycophenolic acid (4) and its 3-hydroxy derivative 5. All the structures were elucidated by spectroscopic methods. The cytotoxicity of these compounds towards human lung fibroblasts and AGS cells was assessed. While 4 and 5 showed low cytotoxicity, with IC50 values > 1000 μM against AGS cells and fibroblasts, 1α-hydroxyimbricatolic acid (2) presented moderate toxicity towards these targets, with IC50 values of 307 and 631 μM, respectively. The structure of 2 is presented for the first time.
Keywords: Aspergillus niger; Rhizopus nigricans; imbricatolic acid; biotransformation; diterpene; Cunninghamella echinulata; mycophenolic acid
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Schmeda-Hirschmann, G.; Aranda, C.; Kurina, M.; Rodríguez, J.A.; Theoduloz, C. Biotransformations of Imbricatolic Acid by Aspergillus niger and Rhizopus nigricans Cultures. Molecules 2007, 12, 1092-1100.
Schmeda-Hirschmann G, Aranda C, Kurina M, Rodríguez JA, Theoduloz C. Biotransformations of Imbricatolic Acid by Aspergillus niger and Rhizopus nigricans Cultures. Molecules. 2007; 12(5):1092-1100.
Schmeda-Hirschmann, Guillermo; Aranda, Carlos; Kurina, Marcela; Rodríguez, Jaime A.; Theoduloz, Cristina. 2007. "Biotransformations of Imbricatolic Acid by Aspergillus niger and Rhizopus nigricans Cultures." Molecules 12, no. 5: 1092-1100.