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Euphorhelipanes A (1) and B (2), two Euphorbia diterpenoids with a new 4-(5,5-dimethylheptan-2-yl)-2,7-dimethylbicyclo­[4.3.0]­nonane skeleton, were isolated from a 95% ethanol extract of the whole plants of Euphorbia helioscopia. Their structures were elucidated by spectroscopic data analysis, quantum chemical calculations, and single-crystal X-ray diffraction data. Compounds 1 and 2 represent the first examples of Euphorbia diterpenoids with a 5/6 fused carbon ring system, and their plausible biosynthetic pathways originating from jatrophanes are proposed. Compounds 1 and 2 showed a triglyceride-lowering effect in oleic-acid-stimulated HuH7 cells at concentrations of 1–50 μM.

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Jatrofolianes A (1) and B (2), which are two highly modified lathyrane diterpenoids, were isolated from Jatropha gossypiifolia. 1 incorporates an unusual transannular 1,3-dioxolane moiety, forming a unique 5/6/5/8/3 ring system, while 2 possesses a new 10,11:13,14-diseco-lathyrane skeleton with a 12-membered macrocyclic lactone ring. Their structures were determined by spectroscopic analysis, quantum chemical calculations, and single-crystal X-ray diffraction. 2 showed significant multidrug resistance (MDR) reversal activity to cancer cells HepG2/ADR and HCT-15/5-FU at 10 μM.

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Two polyprenylated acylcyclopentanone racemates, evodialones A (1) and B (2), featuring a 3-ethyl-1,1-diisopentyl-4-methylcyclopentane skeleton, were isolated from an extract of the aerial parts of Evodia lepta. Evodialone A (1) was resolved by chiral-phase HPLC to afford a pair of enantiomers, (+)- and (-)-evodialones A (1b/1a), while evodialone B (2) could not be resolved. Their structures were elucidated by spectroscopic analysis and a combination of computational techniques including gauge-independent atomic orbital calculation of 1D NMR data and experimental and TDDFT-calculated ECD spectra. A putative biosynthetic pathway of 1 and 2 starting from the monocyclic polyprenylated acylphloroglucinols is proposed. All the isolates were screened for the antimicrobial activity in vitro, and 1a and 1b showed moderate inhibitory activities against several pathogenic fungi with MICs values of 17.1-68.3 μM.

Phytochemical investigation of Strychnos nitida has led to the isolation of three new racemic pyridocarbazole alkaloids, (±)-stritidas A-C (1-3) and three known monoterpenoid indole alkaloids (4-6). Compounds 2 and 3 represent the first examples of pyridocarbazole alkaloids featuring an N-2-hydroxyethyl moiety. Their structures were determined by combined spectroscopic data (MS, UV, IR and NMR) and chemical methods.