Structure elucidation and conformational properties of a novel bioactive clerodane diterpene using a combination of high field NMR spectroscopy, computational analysis and X-ray diffraction

The structure of a novel CC clerodane type diterpenoid, namely (+)-19-aceto xy-cis-clerodan-3-ene-15-oic acid 1 was elucidated and its conformational p roperties were explored using a combination of high field NMR spectroscopy and computational analysis. The structural analysis provided results consis tent with those obtained by a single X-ray diffraction study of its dicyclo hexylammonium salt. The new clerodane type diterpene isolated in large quan tities from Cistus monspeliensis L. leaves was found to exhibit significant antibacterial activity against Staphyloccoci (MIC50 = 0.085 mM) and theref ore represents a promising lead compound. Interestingly the deacetylated de rivative 2 of compound 1 was inactive. (C) 2001 Elsevier Science Ltd. All r ights reserved.