Isolation of four new monoterpenes from Ailanthus altissima (mill.) Swingle and their enzyme inhibitory effects.

A phytochemical study of the ethanol extract from Ailanthus altissima (Mill.) Swingle leaves resulted in the isolation of four new monoterpenoids (1-3, 5). The structures were elucidated using HRESIMS data, NMR spectroscopic data, quantum chemical calculations for NMR and ECD, and custom DP4+ probability analysis. Additionally, the absolute configuration of sugar was determined by acid hydrolysis. Compounds 1-4 are cyclogeraniane monocyclic monoterpenes, while compound 5 contains an acyclic mycrane monoterpenes skeleton. Anti-tyrosinase, anti-acetylcholinesterase, and anti-butyrylcholinesterase activities were tested. Compound 1 showed notable anti-acetylcholinesterase activity, and compound 3 exhibited significant inhibitory effects on anti-tyrosinase activity. Furthermore, the potential binding sites of compounds 1 and 3 were predicted by molecular docking.

Isolation and characterization of seven neovibsane-type diterpenoids from Viburnum odoratissimum and their neuroblastoma cell protective effects.

Seven undescribed neovibsane-type diterpenoids (1-7) were isolated from the leaves of Viburnum odoratissimum. Their planar structures and relative configurations were elucidated based on a combination of 1D and 2D NMR analysis. The absolute configurations were confirmed by Rh2(OCOCF3)4-induced ECD analysis and comparison of experimental and TDDFT-calculated ECD spectrum. Based on the empirical results of the ECD of in situ formed Rh-complexes, rapid determination of the absolute configuration of C-14 within vibsane-type diterpenoids was proposed. In addition, 3 exhibited a high neuroblastoma cell protective effect of 81.8 % at 50 µM (the control group showed a neuroblastoma cell protective effect of 56.2 % at 50 µM).

Four pairs of neolignan enantiomers with distinctive isochroman moiety from the fruits of Crataegus pinnatifida and their protective activities against H2O2-induced SH-SY5Y cells.

Four pairs of neolignan enantiomers (±)-1- (±)-4 with a distinctive isochroman moiety, including seven undescribed compounds, were isolated and identified from the fruits of Crataegus pinnatifida. Structural characterization of these compounds was established through comprehensive spectroscopic analyses, as well as quantum chemical calculations of ECD and NMR data. The preliminary bioassay displayed that compounds (+)-2 and (±)-3 exerted protective activities against H2O2-induced human neuroblastoma SH-SY5Y cells compared with the positive control. These bioactive compounds could be potential candidates for further pharmaceutical applications.

Structurally diverse terpenoids from Elephantopus scaber L. and their acetylcholinesterase inhibitory activities.

Three undescribed compounds elephantopuscabers A-C, along with one previously reported compound spirowallichiione, were isolated from Elephantopus scaber L. Their structures were determined via extensive NMR spectroscopic analysis, quantum chemical calculations, and single-crystal X-ray diffraction crystallography. A plausible biosynthetic pathway for spirowallichiione was proposed. All the isolated compounds were tested for their acetylcholinesterase inhibitory activities. Among them, elephantopuscaber B and C displayed promising inhibitory activities against AChE, and the binding sites were predicted by molecular docking.

Four Pairs of Neuroprotective Aryldihydronaphthalene-Type Lignanamide Enantiomers from the Herbs of Solanum lyratum.

Four pairs of aryldihydronaphthalene-type lignanamide enantiomers were isolated from Solanum lyratum (Solanaceae). The enantiomeric separation was accomplished by chiral-phase HPLC, and five undescribed compounds were elucidated. Analysis by various spectroscopy and ECD calculations, the structures of undescribed compounds were illuminated. The neuroprotective effects of all compounds were evaluated using H2 O2 -induced human neuroblastoma SH-SY5Y cells and AchE inhibition activity. Among them, compound 4 a exhibited remarkable neuroprotective effects at high concentrations of 25 and 50 µmol/L comparable to Trolox. Compound 1 a showed the highest AchE inhibition with the IC50 value of 3.06±2.40 µmol/L. Molecular docking of the three active compounds was performed and the linkage between the compounds and the active site of AchE was elucidated.