ent-Kauranoids isolated from Isodon eriocalyx var. laxiflora and their structure activity relationship analyses

• DOI: 10.1016/j.tet.2015.09.066
• Publication Date: 2015-10-01T22:29:18Z
• Authors: Wei-Guang Wang; Jin Yang; Hai-Yan Wu; Ling-Mei Kong; Jia Su; Xiao-Nian Li; Xue Du; Rui Zhan; Min Zhou; Yan Li; Jian-Xin Pu; Han-Dong Sun
• Keywords: IC50; MTT assay; Structure–activity relationship

In this report, a new cytotoxic group, a 15-oxo-16 alpha-H-17-methoxy (or ethoxy)- unit, was suggested from the structure-activity relationship analyses of 39 ent-kaurane diterpenoids, including 17 new compounds (neolaxiflorins I-Y, 1-17) isolated from the leaves of Isodon eriocalyx var. laxiflora using an in vitro cytotoxicity assay against HL-60, SMMC-7721, A-549, MCF-7, and SW-480 human cancer cell lines. This discovery is counter to the rule that the alpha,beta-unsaturated ketone (C-15-C-16-C-17) unit is indispensable for cytotoxicity of the ent-kauranoids. Furthermore, portions of the isolates exhibited inhibitory activity against nitric oxide (NO) production in LPS-activated RAW264.7 macrophages. The NF-kappa B inhibitory activity assay suggests a potential novel cytotoxic mechanism for compounds 9 and 22. (C) 2015 Elsevier Ltd. All rights reserved.