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Four undescribed regular rosane-type diterpenoids euphominoids M−P and three undescribed rearranged rosane-type diterpenoids euphomilones C-E were isolated from the whole plants of Euphorbia milii Des Moul., along with nine known compounds. Their structures were elucidated by detailed interpretation of the NMR and mass spectroscopy. The absolute configurations were established by single-crystal X-ray diffraction experiments, as well as comparative analyses of calculated and experimental ECD spectra. Euphominoid M featured a highly oxygenated ring A and a rare four-membered oxygen ring while euphomilones C-E possessed 7/5/6 or 5/7/6 fused ring systems, which were rarely occurring in rosane-type diterpenoids. In the in-vitro bioassays, 19-norrosa-1,3,5(10),15-tetraene-2,3-diol and antiquorin showed more potent α -glucosidase inhibitory activity than the positive control acarbose while euphominoid C exhibited significant inhibitory activity against both α -glucosidase and β -glucuronidase. To the best of our knowledge, it was the first time that rosane-type diterpenoids were reported as β -glucuronidase inhibitors. [Display omitted] • Seven underscribed rosane-type diterpenoids were isolated from Euphorbia milii. • Euphominoid M featured a highly oxygenated six-membered ring. • Euphomilones C−E possessed rare 7/5/6 or 5/7/6 fused ring systems. • 19-Norrosa-1,3,5(10),15-tetraene-2,3-diol, euphominoid C and antiquorin showed obvious α -glucosidase inhibitory activity. • Euphominoid C was the first rosane-type diterpenoid with β -glucuronidase inhibitory activity. [ABSTRACT FROM AUTHOR]

Abstract: Extraction of Petalostigma pubescens heartwood followed by chromatographic purifications and crystallizations afforded five tricyclic diterpenes: 5,9-syn-rosanes petalostigmones A and B (1 and 2), the erythroxylane petalostigmone C (3), the norditerpene lactone pubescenone (4), and the known ent-cleistanthane diterpene (−)-sonderianol (5). The structures and relative stereochemistry were elucidated by means of spectroscopic methods, chemical correlations, and, in the cases of 1 and 4, by X-ray crystallographic analyses. The new isolates 1–4 are assumed to belong to the same absolute configurational family (9αCH3) of ent-pimarane-derived diterpenes as the known co-occurring (−)-5 (10αCH3). Biogenetic schemes originating from a common ent-copalyl diphosphate intermediate are presented to rationalize the structures of these natural products. A novel ring contraction–ring expansion mechanism is suggested to account for the 7-membered B ring of pubescenone. Compounds 1–5 were evaluated for their cytotoxicity; sonderianol (5) showed the highest activity against mouse leukemia cell lines L1210, P388 and mouse liver cancer cells HEPA1c1c7. [Copyright &y& Elsevier]

Two new herbertane sesquiterpenoids, (−)-herbertene-1,12-diol and (−)-γ-herbertenol, a new aromadendrane, 9-acetoxy-10-hydroxyaromadendrane, a new rosane diterpenoid, 5,15-rosadiene-3,11-dione and a new phytane, 2Z-phytene-1,15,20-triol, along with the known (−)-α-herbertenol have been isolated from the liverwort Tylimanthus renifolius. Several flavones and flavanones with an unsubstituted ring B were also identified. This is the first report of this class of flavonoids from the Hepaticae. All structures were elucidated by NMR spectroscopy. [Copyright &y& Elsevier]