Emerones A–C: three novel merosesquiterpenoids with unprecedented skeletons from Emericella sp. XL029

Abstract

Three novel highly oxygenated α-pyrone merosesquiterpenoids, emerones A–C (1–3), have been obtained from the fungus, Emericella sp. XL029, which was isolated from the leaves of the traditional Chinese medicinal plant, Panax notoginseng. The structures and absolute configurations of 1–3 were determined by NMR experiments, X-ray diffraction analysis, and computational methods. Structurally, compound 1 possessed an unprecedented 5/7 bicyclic ring architecture, compound 2 had an unusual substituted 10-membered ring, and compound 3 had an undescribed norsesquiterpene skeleton. In addition, compounds 1 and 2 showed moderate activity towards several types of bacteria and fungi, exhibiting MIC values ranging from 12.5 to 50 μg mL⁻¹, whereas compound 3 showed no antimicrobial activity.