Microbial transformation of (+)-nootkatone and the antiproliferative activity of its metabolites Anna Gliszczyn ´ ska a , Agnieszka Lysek a , Tomasz Janeczko a , Marta S ´ witalska b Joanna Wietrzyk b , Czesław Wawrzen ´ czyk a,⇑ a Department of Chemistry, Wroclaw University of Environmental and Life Sciences, Norwida 25, 50-375 Wroclaw, Poland b Ludwik Hirszfeld Institute of Immunology and Experimental Therapy, Polish Academy of Sciences, Department of Experimental Oncology, Weigla 12, 53-114 Wrocław, Poland article info Article history: Received 6 October 2010 Revised 28 October 2010 Accepted 28 January 2011 Available online 4 March 2011 Keywords: Biotransformation Sesquiterpenes (+)-Nootkatone Botrytis cinerea Didymosphaeria igniaria Aspergillus ochraceus Aspergillus niger MB Chaetomium sp. Fusarium culmorum Cancer cell lines: A549 (human lung adenocarcinoma) and HL-60 (human promyelocytic leukemia) Antiproliferative activity abstract Six metabolites were obtained as a result of microbial transformation of (+)-nootkatone (1) by the fungal strains: Botrytis, Didymosphaeria, Aspergillus, Chaetomium and Fusarium. Their structure were estab- lished as (+)-(4R,5S,7R,9R)-9a-hydroxynootkatone (2), (+)-(4R,5S,7R)-13-hydroxynootkatone (3) and (+)- (4R,5S,7R,9R,11S)-11,12-epoxy-9a-hydroxynootkatone (4), (+)-(4R,5S,7R,11S)-11,12-epoksynootkatone (5), (+)-(4R,5S,7R)-11,12-dihydroxynootkatone (6) and (+)-(4R,5S,7R)-7,11,12-trihydroxynootkatone (7) on the basis of their spectral data. Two products: (4) and (7) were not previously reported in the literature. The antiproliferative activity of (+)-nootkatone (1) and isolated metabolites (2–7) of its biotransformation has been evaluated. Ó 2011 Elsevier Ltd. All rights reserved. 1. Introduction Bicyclic sesquiterpene (+)-nootkatone is a natural compound which was first isolated from the heartwood of Alaska yellow cedar (Chamaecyparis nootkatensis) and was found in trace amount in grapefruit (Citrus paradise). 1,2 This sesquiterpene ketone possesses pleasant grapefruit flavor and occurs in orange and grapefruit juice and in peel oils obtained from orange, grapefruit, lemon, mandarin and lime. 3 The literature presents wide range of biological activity of nootkatone and describes potential fields of its application. Nootkatone inhibits the gastric ulcer formation in rats as well as the activity of acetylcholinesterases and of human cytochrome P450 monooxygenases CYP450. 4–7 It is known as the potential insecticide against larvae of Drosophila melanogaster and a strong repellent to termites (Coptotermes formosanus). 8,9 As the carries of specific odor with interesting activity, (+)-nootkatone (1), is industrially valuable product in the fragrance, food, cosmetics and pharmaceutical applications. The objective of our research project is the synthesis of new ac- tive derivatives of natural compounds with enhanced biological activity. Recently we have published the synthesis of oxideriva- tives of farnesol by fungal strains. 10 Here we report results of func- tionalization of (+)-nootkatone (1) with the fungal cultures: Botrytis cinerea, Didymosphaeria igniaria, Aspergillus ochraceus, Aspergillus niger MB, Chaetomium sp. and Fusarium culmorum. Nootkatone and products of its microbial transformations were subjected to the biological tests. The antiproliferative activity to- wards the cancer cell lines: A549 (human lung adenocarcinoma) and HL-60 (human promyelocytic leukemia) was investigated. 2. Results and discussion Biotransformation of (+)-nootkatone (1) was carried out by fun- gal cultures: B. cinerea AM235 and D. igniaria KCh6670, A. ochraceus AM456, A. niger MB, Chaetomium sp. KCh6651 and F. culmorum AM10 which were selected in the screening procedure of 20 fungal strains. 0968-0896/$ - see front matter Ó 2011 Elsevier Ltd. All rights reserved. doi:10.1016/j.bmc.2011.01.062 ⇑ Corresponding author. Tel.: +48 71 320 52 57. E-mail addresses: anna.gliszczynska@wp.pl, czeslaw.wawrzenczyk@up.wroc.pl (C. Wawrzen ´ czyk). Bioorganic & Medicinal Chemistry 19 (2011) 2464–2469 Contents lists available at ScienceDirect Bioorganic & Medicinal Chemistry journal homepage: www.elsevier.com/locate/bmc