Weidong Zhang

(−) and (+)-Merrilliaquinone, a pair of new quinone enantiomers from Illicium merrillianum and their distinctive effect on human hepatoma and hepatic cells

Merrilliaquinone (1), a new racemic quinone was isolated from the branches and leaves of Illicium merrillianum. Chiral separation of 1 gave two enantiomers (−)-merrilliaquinone (1a) and (+)-merrilliaquinone (1b). The structure of 1 was established by comprehensive spectroscopic analysis, and the absolute configurations of 1a and 1b were determined by quantum mechanical calculation of ECD spectra. It is very interesting that 1b had a selective cytotoxicity against human hepatoma cell lines SMMC7721 and HuH7 with IC50 values of 0.91 μM and 1.29 μM, while its IC50 values on normal human hepatic cells QSG7701 and LO2 were 47.79 μM and 36.71 μM, respectively. Moreover, 1a and racemate 1 only exhibited very weak cytotoxicity against SMMC7721 and HuH7 cells with IC50 values of 27.01–37.82 μM. These results implied that the absolute configurations of 1a and 1b possess remarkable influences on their cytotoxicities. Further mechanism studies indicated that 1b dose-dependently induced SMMC7721 cell apoptosis and reduction of mitochondrial membrane potential (MMP) at 1–10 μM. Flow cytometry analysis showed that the 1b-induced SMMC7721 cell apoptosis was associated with cell cycle arrest during the G0/G1 phase.

Jacarelhyperol A induced apoptosis in leukaemia cancer cell through inhibition the activity of Bcl-2 proteins

BackgroundHypericum japonicum Thunb. ex Murray is widely used as an herbal medicine for the treatment of hepatitis and tumours in China. However, the molecular mechanisms of its effects are unclear. Our previous research showed that extracts of H. japonicum can induce apoptosis in leukaemia cells. We also previously systematically analysed and isolated the chemical composition of H. japonicum.MethodsThe fluorescence polarisation experiment was used to screen for inhibitors of Bcl-2 proteins which are proved as key proteins in apoptosis. The binding mode was modelled by molecular docking. We investigated the proliferation attenuating and apoptosis inducing effects of active compound on cancer cells by MTT assay and flow cytometry analysis. Activation of caspases were tested by Western blot. A broad-spectrum caspase inhibitor Z-VAD-FMK was used to investigate the caspases-dependence. In addition, co-immunoprecipitation was performed to analyse the inhibition of heterodimerization between anti-apoptotic Bcl-2 proteins with pro-apoptotic proteins. Moreover, in vivo activity was tested in a mouse xenograph tumour model.ResultJacarelhyperol A (Jac-A), a characteristic constituent of H. japonicum, was identified as a potential Bcl-2 inhibitor. Jac-A showed binding affinities to Bcl-xL, Bcl-2, and Mcl-1 with Ki values of 0.46 μM, 0.43 μM, and 1.69 μM, respectively. This is consistent with computational modelling results, which show that Jac-A presents a favorable binding mode with Bcl-xL in the BH3-binding pocket. In addition, Jac-A showed potential growth inhibitory activity in leukaemia cells with IC50 values from 1.52 to 6.92 μM and significantly induced apoptosis of K562 cells by promoting release of cytochrome c and activating the caspases. Jac-A also been proved that its effect is partly caspases-dependent and can disrupt the heterodimerization between anti-apoptotic Bcl-2 proteins with pro-apoptotic proteins. Moreover, Jac-A dose-dependently inhibited human K562 cell growth in a mouse xenograph tumour model with low toxicity.ConclusionIn this study, a characteristic constituent of H. japonicum, Jac-A, was shown to induce apoptosis in leukaemia cells by mediating the Bcl-2 proteins. Therefore, we propose a new lead compound for cancer therapy with a low toxicity, and have provided evidence for using H. japonicum as an anti-cancer herb.

Cytotoxic 2,4-linked sesquiterpene lactone dimers from Carpesium faberi exhibiting NF-κB inhibitory activity

Six new 2,4-linked exo/endo sesquiterpene lactone dimers, faberidilactones A–E (1–5) and endodischkuhriolin (6), were isolated from Carpesium faberi. The characteristic chemical shift of Ha-3′ and diagnostic negative/positive CE can be used to assign the exo/endo stereochemistry of those dimers. Compounds 1–3, 5 and 6 exhibited potent cytotoxicity with IC50 value in the range of 1.11–8.50 μM against the four human tumor cell lines (CCRF-CEM, K562, HL-60 and HCT116 cells). Moreover, 1, 3 and 5 (exo-SLDs) showed potent NF-κB inhibitory effect with inhibition ratio of 65.98, 53.27 and 71.45%, respectively.

Isochamaejasmin induces apoptosis in leukemia cells through inhibiting Bcl-2 family proteins

The biflavonoid isochamaejasmin is mainly distributed in the root of Stellera chamaejasme L. (Thymelaeaceae) that is used in traditional Chinese medicine (TCM) to treat tumors, tuberculosis, and psoriasis. Herein, isochamaejasmin was found to show similar bioactivity against Bcl-2 family proteins to the reference Bcl-2 ligand (-)-gossypol through 3D similarity search. It selectively bound to Bcl-xl and Mcl-1 with Ki values being 1.93 ± 0.13 μmol·L(-1) and 9.98 ± 0.21 μmol·L(-1), respectively. In addition, isochamaejasmin showed slight growth inhibitory activity against HL-60 with IC50 value being 50.40 ± 1.21 μmol·L(-1) and moderate growth inhibitory activity against K562 cells with IC50 value being 24.51 ± 1.62 μmol·L(-1). Furthermore, isochamaejasmin induced apoptosis of K562 cells by increasing the intracellular expression levels of proteins of the cleavage of caspase-9, caspase-3, and PARP which involved in the Bcl-2-induced apoptosis pathway. These results indicated that isochamaejasmin induces apoptosis in leukemia cells by inhibiting the activity of Bcl-2 family proteins, providing evidence for further studying the underlying anti-cancer mechanism of S. chamaejasme L.

A Natural CCR2 Antagonist Relieves Tumor-associated Macrophage-mediated Immunosuppression to Produce a Therapeutic Effect for Liver Cancer

Hepatocellular carcinoma (HCC) is a common malignant tumor in the digestive tract with limited therapeutic choices. Although sorafenib, an orally administered multikinase inhibitor, has produced survival benefits for patients with advanced HCC, favorable clinical outcomes are limited due to individual differences and resistance. The application of immunotherapy, a promising approach for HCC is urgently needed. Macrophage infiltration, mediated by the CCL2/CCR2 axis, is a potential immunotherapeutic target. Here, we report that a natural product from Abies georgei, named 747 and related in structure to kaempferol, exhibits sensitivity and selectivity as a CCR2 antagonist. The specificity of 747 on CCR2 was demonstrated via calcium flux, the binding domain of CCR2 was identified in an extracellular loop by chimera binding assay, and in vivo antagonistic activity of 747 was confirmed through a thioglycollate-induced peritonitis model. In animals, 747 elevated the number of CD8 + T cells in tumors via blocking tumor-infiltrating macrophage-mediated immunosuppression and inhibited orthotopic and subcutaneous tumor growth in a CD8 + T cell-dependent manner. Further, 747 enhanced the therapeutic efficacy of low-dose sorafenib without obvious toxicity, through elevating the numbers of intra-tumoral CD8 + T cells and increasing death of tumor cells. Thus, we have discovered a natural CCR2 antagonist and have provided a new perspective on development of this antagonist for treatment of HCC. In mouse models of HCC, 747 enhanced the tumor immunosuppressive microenvironment and potentiated the therapeutic effect of sorafenib, indicating that the combination of an immunomodulator with a chemotherapeutic drug could be a new approach for treating HCC.

Synthesis, cytotoxicity and inhibition of NO production of ivangustin enantiomer analogues

The eight novel ivangustin enantiomer analogues possessing α-methylene-γ-butyrolactone moiety have been synthesized using (4S6R, 4S6S)-4-tert-butyldimethylsilyloxy-6-methylcyclohex-2-en-1-one (1) as starting material. These transformations were mainly carried out by aldol condensation reaction and one-pot annelation procedure. The stereochemistry of these synthesized analogues was determined by NOE analysis. Their cytoxicity was evaluated against the human cancer cell lines HCT-116 (colon), HL-60 (leukemia), QGY-7701 (liver), SMMC-7721 (liver), A549 (lung), MCF-7 (breast). The results showed that these analogues were more selective against the cell lines HL-60 and QGY-7701. Analogue 17 exhibited potent cytotoxicity and high selectivity toward HL-60 cell line with IC50 value of 1.02 μM, which suggested that it might be a promising anti-cancer lead compound. The inhibitory activities against NO production and the cytotoxicities in RAW 264.7 macrophages were determined at the same time. All of the analogues significantly inhibited the NO production with IC50 value in the range of 3.44-6.99 μM. Analogues 17, 22, 23 and 7 showed higher cytotoxicities, indicated their inhibitory activities against NO production may be influenced by the cytotoxicities.

Delavatine A, a structurally unusual cyclopenta[de]isoquinoline alkaloid from Incarvillea delavayi

Natural products have long been an important source for the discovery of biologically active compounds, in particular, drug leads. Delavatine A (1), a structurally unusual cyclopenta[de]isoquinoline alkaloid, was isolated from Incarvillea delavayi. Extensive spectroscopic analysis, in combination with biogenetic speculation, established the structure of 1. Delavatine A (1) exhibited considerable cytotoxicity against a number of cancer cell lines with IC50 values in the range of 4.28 to 6.61 μg mL−1.

Pseudolarenone, an unusual nortriterpenoid lactone with a fused 5/11/5/6/5 ring system featuring an unprecedented bicyclo[8.2.1]tridecane core from Pseudolarix amabilis

A phytochemical investigation of the cone of Pseudolarix amabilis led to the isolation of pseudolarenone (), a structurally novel pentacyclic (5/11/5/6/5) nortriterpenoid lactone with an unprecedented carbon skeleton featuring a unique bicyclo[8.2.1]tridecane core. Its structure and absolute configurations were elucidated by spectroscopic analysis and single crystal X-ray diffraction (CuK(α)).

Argutalactone, an unprecedented sesquiterpenoid lactone with a 6/5/7 tricyclic system from Incarvillea arguta

Argutalactone (1), a novel sesquiterpenoid lactone featuring an unprecedented 6/5/7 rigid skeleton, was isolated from the roots of Incarvillea arguta. The structure and relative configuration of 1 were established by extensive analysis of spectroscopic data. The absolute configuration of 1 was determined as 2R,5S,10R,12S based on the analysis of biogenetical transformation, comparison of the optical rotation with literature data, and comparison of the experimental circular dichroism spectrum with the calculated electronic circular dichroism spectra.

A concise asymmetric total synthesis for structure elucidation of 5,6-secoiridoid from Incarvillea argute

A phytochemical investigation of the roots of Incarvillea arguta led to the isolation of secoarguterin (1), which is the first example of 5,6-secoiridoid. Its structure and absolute configuration was elucidated by extensive spectral analysis and total synthesis. Compound 1 showed moderate inhibition against human colon cancer cells HCT116 with an IC50 value of 28.72 μM.