Yushan Li

Bioactive myrsinol diterpenoids from the roots of Euphorbia prolifera.

Ten myrsinol diterpenes, euphorbiaproliferins A-J (1-10), along with nine known analogues (11-19) were isolated from the roots of Euphorbia prolifera. Their structures were elucidated by spectroscopic data analysis (IR, ESIMS, HRESIMS, 1D and 2D NMR), and the structure of 1 was confirmed by X-ray crystallography. The diterpenes showed neuroprotective effects against MPP+-induced neuronal cell death in SH-SY5Y cells.

Bioactive neo-clerodane diterpenoids from the whole plants of Ajuga ciliata Bunge.

Ten new neo-clerodane diterpenes, ajugaciliatins A-J (1-5, 8-12), along with 17 known analogues (6, 7, 13-27) were isolated from the whole plants of Ajuga ciliata Bunge. Their structures were elucidated by spectroscopic data analysis (IR, ESIMS, HRESIMS, 1D and 2D NMR), and the configuration of 1 was confirmed by X-ray crystallography. All of the compounds were assessed for neuroprotective effects against MPP(+)-induced neuronal cell death in dopaminergic neuroblastoma SH-SY5Y cells. Compounds 2, 6, 7, 9, 10, 15-17, 19, and 20 exhibited moderate neuroprotective effects.

Prenylated xanthones with NGF-potentiating activity from Garcinia xanthochymus.

Two prenylated xanthones, 1,4,5,6-tetrahydroxy-7,8-di(3-methylbut-2-enyl)xanthone (1) and 1,2,6-trihydroxy-5-methoxy-7-(3-methylbut-2-enyl)xanthone (2), were isolated from the wood of Garcinia xanthochymus along with a known xanthone, 12b-hydroxy-des-D-garcigerrin A (3). Their structures were elucidated by spectroscopic analysis. Compound 1 (10 muM), 2 (10-30 muM) and 3 (10 muM) showed a markedly enchancing activity of nerve growth factor (NGF)-mediated neurite outgrowth on PC12D cells.

Potentiation of nerve growth factor‐induced elongation of neurites by gelsemiol and 9‐hydroxysemperoside aglucone in PC12D cells

In PC12D cells, nerve growth factor (NGF) increased the proportion of neurite‐bearing cells and made neurites longer. A methanol extract of Verbena littoralis H. B. K. collected in Paraguay only slightly potentiated the proportion of PC12D cells with neurites but markedly increased the length of neurites in the presence of NGF (2 ng mL−1). The methanol extract was partitioned between ethyl acetate and water followed by further extraction of water fraction with n‐butanol. The potentiating activity of NGF‐action was observed in the ethyl acetate and n‐butanol fractions. The n‐butanol fraction was separated by silica gel chromatography, monitoring the NGF‐potentiating activity to give gelsemiol and 9‐hydroxysemperoside aglucone (9‐OHSA). Neither compound (30–300 μM) exhibited neurite‐inducing activity alone. Gelsemiol (100–300 μM) markedly enhanced an increase in the proportion of neurite‐bearing cells and an extension of the neurite length in the presence of NGF (2 ng mL−1). Interestingly, in the presence of NGF (2 ng mL−1), 9‐OHSA (100–300 μM) enhanced the elongation of neurites without affecting the increase in the proportion of cells with neurites. These results suggested that gelsemiol and 9‐OHSA were major active components of V. littoralis in the NGF‐potentiating action. It was possible that the mechanism of neurite elongation by NGF was different from that of the increase in the proportion of neurite‐bearing cells, and that 9‐OHSA selectively affected the neurite elongation mechanism.

Sesquiterpenoids from the resinous exudates of Commiphora myrrha and their neuroprotective effects.

Ten new furanosesquiterpenoids, myrrhterpenoids A-J (1- 10), together with eight known analogues (11- 18), were isolated from the resinous exudates of COMMIPHORA MYRRHA. Their structures and relative configurations were elucidated by spectroscopic methods (IR, ESIMS, HRESIMS, 1D and 2D NMR) and by the ChemDraw 3D modeling using MM2. All isolated furanosesquiterpenes showed neuroprotective effects against MPP (+)-induced neuronal cell death in SH-SY5Y cells.

neo-Clerodane diterpenes from Ajuga decumbens and their inhibitory activities on LPS-induced NO production.

A phytochemical investigation of the whole plants of Ajuga decumbens led to the isolation of three new (1, 2a, and 2b) and three known (3a-3c) neo-clerodane diterpenes. Their structures were elucidated by spectroscopic data analysis (IR, ESIMS, HR-ESIMS, 1D and 2D NMR), and the structure of 1 was confirmed by X-ray crystallography. The inhibitory activities on LPS-induced NO production of the six diterpenes were evaluated and compounds 2a, 2b, and 3a showed inhibitory effects.

Iridoids from the roots of Valeriana jatamansi

Two new iridoids, jatamanvaltrates N (1) and O (2), together with four known compounds (3–6), were isolated from the roots of Valeriana jatamansi. Their structures and relative configurations were elucidated by spectroscopic methods (IR, ESI-MS, HR-ESI-MS, 1D, and 2D NMR) and by comparison of their NMR spectral data with those of related compounds. All the isolated compounds were evaluated for their neuroprotective effects, and only compound 1 showed weak neuroprotective activities.

Iridoids from the roots of Valeriana jatamansi and their biological activities

A new iridoid, jatamandoid A (1), and four known analogues (2–5) were isolated from the roots of Valeriana jatamansi. Their structures were elucidated on the basis of extensive spectroscopic analysis (IR, ESI–MS, HR–ESI–MS, 1-D and 2-D NMR). Five compounds were evaluated and compounds 1, 2 and 5 showed moderate neuroprotective effects against MPP+-induced neuronal SH-SY5Y cell death.

A new triterpenoid saponin from the roots of Silene viscidula.

A new triterpenoid saponin, silenoviscoside F (1), was isolated from the roots of Silene viscidula, together with three known saponins, dianchinenoside D (2), sinocrassuloside I (3) and sinocrassuloside II (4). The structure of compound 1 was elucidated by spectroscopic data, GC–MS and chemical methods. The structures of compounds 2–4 were determined on the basis of spectroscopic data comparison with the literature values, which were isolated from the genus Silene for the first time.