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In a continuing search for potential inhibitors against human carboxylesterases 1A1 and 2A1 (hCES1A1 and hCES2A1), an EtOAc extract of the roots of Paeonia lactiflorashowed strong hCES inhibition activity. Bioassay-guided fractionation led to the isolation of 26 terpenoids including 12 new ones (1–5, 7–12, and 26). Among these, sesquiterpenoids 1and 6, monoterpenoids 10, 11, and 13–15, and triterpenoids 18–20, 22, and 24–26contributed to the hCES2A1 inhibition, in the IC50range of 1.9–14.5 μM, while the pentacyclic triterpenoids 18–26were responsible for the potent inhibitory activity against hCES1A1, with IC50values less than 5.0 μM. The structures of all the compounds were elucidated using MS and 1D and 2D NMR data, and the absolute configurations of the new compounds were resolved via specific rotation, experimental and calculated ECD spectra, and single-crystal X-ray diffraction analysis. The structure–activity relationship analysis highlighted that the free HO-3 group in the pentacyclic triterpenoids is crucial for their potent inhibitory activity against hCES1A1.

Six new pairs of isoquinoline alkaloid enantiomers, designated as yanhusanines A–F (1–6), were isolated from an aqueous extract of Corydalis yanhusuotubers. The structures of these enantiomers were elucidated via physicochemical analysis and a variety of spectroscopic methods. All compounds were resolved into their enantiomers via chiral-phase HPLC, and their configurations were determined by DP4+ NMR calculation methods, specific rotations, and comparison of experimental and calculated ECD spectra. Compounds 1–6bear a rare 9-methyl moiety, and compound 1possesses a rare 1-oxa-6-azaspiro[4.5]decane core containing an N-CHO group. Compounds (+)-2, (−)-2, (+)-4, (−)-4, (+)-5, (−)-5, (+)-6, and (−)-6exhibited selective inhibitory activities against human carboxylesterase (hCE2), in the IC50value range of 2.0–13.2 μM.

Purpurolide A (1), an unprecedent sesquiterpene lactone with a rarely encountered 5/5/5 spirocyclic skeleton, along with two new 6/4/5/5 tetracyclic sesquiterpene lactones (2and 3), were isolated from the cultures of the endophytic fungus Penicillium purpurogenumIMM003. The structures and absolute configurations of 1–3were established by spectroscopic analysis, single-crystal X-ray diffraction, and calculations of the 13C NMR and ECD data. Compounds 1–3showed significant inhibitory activity against pancreatic lipase.

Fractionation of an aqueous extract of the air-dried roots of a traditional Chinese medicinal plant, Paeonia lactiflora, yielded the new monoterpenoid glycosides 1–10. Their structures were assigned via spectroscopic techniques, and the absolute configurations of 1, 4–6, and 8were verified via chemical methods, specific rotation, and electronic circular dichroism data. Compounds 1–4are rare compared to the reported cage-like paeoniflorin derivatives; that is, they comprised two monoterpenoidal moieties. In the in vitro assay, compounds 5, 8, and 9showed weak inhibitions against lipopolysaccharide-induced nitric oxide production in RAW264.7 macrophages, with IC50values of 64.8, 60.1, and 97.5 μM, respectively.

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