-Mei Li

Schinalactone A, a New Cytotoxic Triterpenoid from Schisandra sphenanthera

A new cytotoxic triterpenoid, schinalactone A (1), together with two new biogenetically related compounds, schinalactones B (2) and C (3), has been isolated from the roots and stems of Schisandra sphenanthera.Their structures were elucidated on the basis of extensive spectroscopic analysis. Compounds 1 and 2 showed significant cytotoxicity against PANC-1 cell lines with IC(50) values of 5.9 and 4.1 microM, respectively. A plausible biosynthetic pathway of 1 was also postulated.

ent-Kaurane and Cembrane Diterpenoids from Isodon sculponeatus and Their Cytotoxicity

Nine new ent-kauranoids, sculponins D-L (1-9), and 14 known diterpenoids (10-23) were isolated from the aerial parts of Isodon sculponeatus. The structures of the new diterpenoids were determined by detailed interpretation of their 1D and 2D NMR spectra and HRESIMS. The isolated compounds were evaluated for their cytotoxic activities against a small panel of human cancer cell lines.

Scopariusic Acid, a New Meroditerpenoid with a Unique Cyclobutane Ring Isolated from Isodon scoparius

Scopariusic acid (1), a new ent-clerodane-based meroditerpenoid with a unique cyclobutane ring and an unusual 1-octen-3-ol substituent, together with its biosynthetic related compound 2, were isolated from the aerial parts of Isodon scoparius. The structures of 1 and 2, including their absolute configurations, were determined by spectroscopic methods, single-crystal X-ray diffraction analysis, and chemical methods. Compound 1 showed weak cytotoxicity and moderate immunosuppressive activity.

Scopariusicides, Novel Unsymmetrical Cyclobutanes: Structural Elucidation and Concise Synthesis by a Combination of Intermolecular [2 + 2] Cycloaddition and C–H Functionalization

Scopariusicides A (1) and B (2), two novel immunosuppressive unsymmetrical cyclobutane derivatives, were isolated from the aerial parts of Isodon scoparius. Moreover, based on the results of phytochemical investigation, a concise stereocontrolled synthesis of scopariusicide A and its analogues with enhanced biological activities was efficiently achieved using the main diterpenoid (3) isolated from this plant as a readily available starting material. A crossed intermolecular [2 + 2] photocycloaddition and a Pd-catalyzed sp(3) C-H bond β-arylation were used synergistically to access the highly congested unsymmetrical cyclobutane core with four contiguous stereocenters.

Structure and Cytotoxicity of Diterpenoids from Isodon eriocalyx

A new ent-atisanoid, eriocatisin A (1), six new ent-abietanoids, eriocasins B-E (2-4, 7), 3-acetyleriocasin C (5), and 3β-acetoxyeriocasin D (6), and seven new ent-kauranoids, maoesins A-F (8, 10-14) and 3α-acetoxy-maoesin A (9), together with 21 known compounds, were isolated from the aerial parts of Isodon eriocalyx. The structures of 1-14 were determined by spectroscopic data interpretation. All compounds isolated were evaluated for their in vitro growth inhibitory activity against the HT-29, BEL-7402, and SK-OV-3 human cancer cell lines. Compounds 17, 18, and 20 showed inhibitory effects for all three tumor cell lines used, with IC(50) values in the range 2.1-7.3 μM.

Calophyline A, a New Rearranged Monoterpenoid Indole Alkaloid from Winchia calophylla

Calophyline A (1), a novel unprecedented rearranged monoterpenoid indole alkaloid, along with a new natural product N-methyl aspidodasycarpine (2) and six known analogues, was isolated from the trunk barks of Winchia calophylla. The structure of compound 1 was elucidated on the basis of spectroscopic data and then confirmed by a single-crystal X-ray crystallographic analysis. A hypothetical biogenetic pathway for compound 1 was proposed. All isolated compounds were evaluated for their in vitro cytotoxicity against a small panel of human cancer cell lines.

Chaetoconvosins A and B, Alkaloids with New Skeleton from Fungus Chaetomium convolutum

Chaetoconvosins A and B (1 and 2), two novel cytochalasan alkaloids with a new 6/6/5/5/7 pentacyclic ring system, were isolated from the solid-state fermented medium of the wheat rhizospheric fungus Chaetomium convolutum cib-100. Their structures were elucidated on the basis of spectroscopic data. The structure of chaetoconvosin A (1) was confirmed by X-ray crystallographic analysis. Chaetoconvosin B (2), the major metabolite, showed remarkable inhibitory ability on root elongation and moderate cytotoxicity against several cancer cell lines.

ent-Kaurane Diterpenoids from Isodon nervosus

A pentacyclic ent-kauranoid, nervonin A ( 1), with an unprecedented cyclobutane moiety in the structure, and nine other new ent-kaurane diterpenoids, nervonins B-J ( 2- 10), along with 10 known ones ( 11- 20), were isolated from Isodon nervosus. Their structures were elucidated by detailed spectroscopic analysis. All diterpenoids were assayed for their cytotoxicity against K562, A549, and HepG2 human cell lines. Compounds 2, 11, 16, 17, and 20 showed significant cytotoxicity.

19-Oxygenated ent-Kaurane Diterpenoids from Isodon pharicus

Eight new 19-oxygenated ENT-kaurane diterpenoids were isolated from the aerial parts of Isodon pharicus. Their structures were determined by means of extensive spectroscopic techniques including interpretation of 1D and 2D NMR spectra. Selected compounds were evaluated for their cytotoxicity against NB4, A549, PC-3, MCF-7, and SH-SY5Y cell lines.

ent-Kaurane Diterpenoids from Isodon japonicus

Two new 6,7-seco-ent-kaurane diterpenoids, isojaponins A (1) and B (2), together with 18 known ent-kaurane diterpenoids were isolated from the aerial parts of Isodon japonicus. The structures of the two new compounds were elucidated by extensive 1D- and 2D-NMR spectroscopic methods in combination with MS experiments.