Jun-Ting Fan

Rubiyunnanins C-H, cytotoxic cyclic hexapeptides from Rubia yunnanensis inhibiting nitric oxide production and NF-κB activation.

Six new (rubiyunnanins C-H, 1-6) and five known (7-11) cyclic hexapeptides were isolated from the roots of Rubiayunnanensis (Franch.) Diels. The structures and stereochemistry of 1-6 were established by extensive spectroscopic analyses and chemical methods. All compounds (1-11) not only exhibited cytotoxic activities against a panel of eleven cancer cell lines with IC₅₀ values ranging from 0.001 to 56.24 μM, but also exerted inhibitory activities against nitric oxide (NO) production in LPS and IFN-γ-induced RAW 264.7 murine macrophages with IC₅₀ values ranging from 0.05 to 12.68 μM. Furthermore, this is the first time it is being reported that compounds 2 and 7-10 significantly inhibited TNF-α-induced NF-κB activation in HEK-293-NF-κB luciferase stable cells with IC₅₀ values of 35.07, 0.03, 1.69, 12.64 and 1.18 μM, respectively.

Plant cyclopeptide RA-V kills human breast cancer cells by inducing mitochondria-mediated apoptosis through blocking PDK1-AKT interaction

In the present paper, we examined the effects of a natural cyclopeptide RA-V on human breast cancer cells and the underlying mechanisms. RA-V significantly inhibited the growth of human breast cancer MCF-7, MDA-MB-231 cells and murine breast cancer 4T1 cells. In addition, RA-V triggered mitochondrial apoptotic pathway which was indicated by the loss of mitochondrial membrane potential, the release of cytochrome c, and the activation of caspase cascade. Further study showed that RA-V dramatically inhibited phosphorylation of AKT and 3-phosphoinositide dependent protein kinase 1 (PDK1) in MCF-7 cells. Moreover, RA-V disrupted the interaction between PDK1 and AKT in MCF-7 cells. Furthermore, RA-V-induced apoptosis could be enhanced by phosphatidylinositol 3-kinase inhibitor or attenuated by over-expression of AKT in all the three kinds of breast cancer cells. Taken together, this study shows that RA-V, which can induce mitochondria-mediated apoptosis, exerts strong anti-tumor activity against human breast cancer. The underlying anti-cancer mechanism of RA-V is related to the blockage of the interaction between PDK1 and AKT.

Cyclopeptide RA-V inhibits angiogenesis by down-regulating ERK1/2 phosphorylation in HUVEC and HMEC-1 endothelial cells

BACKGROUND AND PURPOSE Anti‐angiogenic agents have recently become one of the major adjuvants for cancer therapy. A cyclopeptide, RA‐V, has been shown to have anti‐tumour activities. Its in vitro anti‐angiogenic activities were evaluated in the present study, and the underlying mechanisms were also assessed.

Apoptosis inducement of bigelovin from Inula helianthus‐aquatica on human Leukemia U937 cells

Inula helianthus‐aquatica C. Y. Wu is a traditional medicinal plant used to treat some cancers in folk herbal medicine of Yunnan, China. Bigelovin, a sesquiterpene lactone isolated from this herb, potently inhibits the growth of a panel of eight cancer cell lines, especially in human monoblastic leukemia U937 cells with an IC50 value of 0.47 µM. Characteristic morphological features of apoptosis were observed in U937 cells treated with bigelovin. Annexin V and nuclear DNA content distribution assays showed that the percentage of Annexin V positive cells increased to 8.86% (24 h) with 1 µM bigelovin treatment, and cells treated with bigelovin at this concentration apparently arrested at G0/G1 phase compared with the control. These data suggested that cytotoxic effect of bigelovin on U937 cells involves induction of apoptosis, and the cell cycle is arrested at G0/G1 phase. Copyright

Biologically Active Arborinane-Type Triterpenoids and Anthraquinones from Rubia yunnanensis

Twelve new arborinane-type triterpenoids (1-12) and four new anthraquinones (13-16), together with 50 known compounds, were isolated from the roots of Rubia yunnanensis. The structures of 1-16 were elucidated by spectroscopic data analysis and chemical methods. All compounds were evaluated for their cytotoxic, antibacterial, and antifungal activities. Rubiyunnanol C (5) is the first example of an arborinane-type triterpenoid with a double bond at C-8-C-9.

Natural Inhibitors of DNA Topoisomerase I with Cytotoxicities

DNA Topoisomerase I can cause DNA breaks and play a key role during cell proliferation and differentiation. It is an important target for anticancer agents. While screening for anticancer compounds, seven natural compounds, 1–7, showed potent cytotoxicities against a panel of ten cancer cell lines. Moreover, an inhibition assay demonstrated that they are also DNA topoisomerase I inhibitors, in which inhibitors 1–5 are new ones.

Cyclopeptide Alkaloids from Ziziphus apetala

Six novel Ia₃-type cyclopeptide alkaloids (1-6) were isolated from stems of Ziziphus apetala. Compound 5 and the known compounds mauritine A (7) and mauritine F (8) were isolated from the roots. Their structures were determined by spectroscopic analyses and chemical methods. The total alkaloids from the roots and the isolated cyclopeptide alkaloids were tested for antidepressant behavior on mice, cytotoxicity, and 11β-hydroxysteroid dehydrogenase (11β-HSD) inhibition in vitro. Only mauritine A (7) showed inhibitory activity on 11β-HSD1, with IC₅₀ values of 52.0 (human) and 31.2 μg/mL (mouse).

2D- and 3D-QSAR studies on 54 anti-tumor Rubiaceae-type cyclopeptides.

RA-VII, a bicyclic hexapeptide isolated from the roots of Rubia cordifolia, Rubia akane belongs to Rubiaceae-type cyclopeptides (RAs) and has attracted much attention for its potent anti-tumor activity and its bicyclic structure incorporating the isodityrosine moiety. In this work, hologram quantitative structure-activity relationship (HQSAR), comparative molecular field analysis (CoMFA), and comparative molecular similarity indices analysis (CoMSIA) methods were employed to develop 2D- and 3D-QSAR models for 54 anti-tumor RAs. The LOO cross-validated q(2) values of HQSAR, CoMFA and CoMSIA models are 0.701, 0.510 and 0.613, respectively. The predictive ability of these models was validated by the test set including 7 RAs, and the predicted IC(50) values were in good agreement with the experimental IC(50) values. HQSAR result showed that chirality descriptor plays an important role in anti-tumor activity of RAs and OMe at R(1) and R(2) is necessary for increasing their activity. CoMFA and CoMSIA results demonstrated that small bulky and electropositive side chains at R(3) position and hydrophobic groups at R(7) and R(8) positions will increase their activity, and intra-molecular hydrogen bonds between residues 1 and 4 are necessary to maintain the pharmacophoric conformation of RAs. These results may be helpful in designing novel and potential anti-tumor RAs.