Wenwei Fu

Prenylated benzoylphloroglucinols and xanthones from the leaves of Garcinia oblongifolia with antienteroviral activity.

An acetone extract of the leaves of Garcinia oblongifolia showed antiviral activity against enterovirus 71 (EV71) using a cytopathic effect inhibition assay. Bioassay-guided fractionation yielded 12 new prenylated benzoylphloroglucinols, oblongifolins J-U (1-12), and five known compounds. The structures of 1-12 were elucidated by spectroscopic analysis including 1D- and 2D-NMR and mass spectrometry methods. The absolute configurations were determined by a combination of a Mosher ester procedure carried out in NMR tubes and ECD calculations. Compared to ribavirin (IC50 253.1 μM), compounds 1, 4, and 13 exhibited significant anti-EV71 activity in vitro, with IC50 values of 31.1, 16.1, and 12.2 μM, respectively. In addition, the selectivity indices of these compounds were 1.5, 2.4, and 3.0 in African green monkey kidney (Vero) cells, respectively.

Cytotoxic and anti-inflammatory prenylated benzoylphloroglucinols and xanthones from the twigs of Garcinia esculenta.

Five new prenylated benzoylphloroglucinol derivatives, garciesculentones A-E (1-5), a new xanthone, garciesculenxanthone A (6), and 15 known compounds were isolated from the petroleum ether extract and the EtOAc-soluble fraction of a 80% (v/v) EtOH extract of Garcinia esculenta. The structures of the new compounds were elucidated by 1D- and 2D-NMR spectroscopic analysis and mass spectrometry. Experimental and calculated ECD and a convenient modified Moshers method were used to determine the absolute configurations. The cytotoxicity of these compounds were evaluated by MTT assay against three human cancer cell lines (HepG2, MCF-7, and MDA-MB-231) and against normal hepatic cells (HL-7702). In addition, these isolates were evaluated for their inhibitory effects on interferon-γ plus lipopolysaccharide-induced nitric oxide production in RAW264.7 cells.

Guttiferone K induces autophagy and sensitizes cancer cells to nutrient stress-induced cell death.

BACKGROUND Medicinal plants have long been an excellent source of pharmaceutical agents. Autophagy, a catabolic degradation process through lysosomes, plays an important role in tumorigenesis and cancer therapy. PURPOSE Through a screen designed to identify autophagic regulators from a library of natural compounds, we found that Guttiferone K (GUTK) can activate autophagy in several cancer cell lines. The objective of this study is to investigate the mechanism by which GUTK sensitizes cancer cells to cell death in nutrient starvation condition. METHODS Cell death analysis was performed by propidium iodide staining with flow cytometry or Annexin V-FITC/PI staining assay. DCFH-DA staining was used for intracellular ROS measurement. Protein levels were analyzed by western blot analysis. Cell viability was measured by MTT assay. RESULTS Exposure to GUTK was observed to markedly induce GFP-LC3 puncta formation and activate the accumulation of LC3-II and the degradation of p62 in HeLa cells, suggesting that GUTK is an autophagy inducer. Importantly, hydroxychloroquine, an autophagy inhibitor, was found to significantly prevent GUTK-induced cell death in nutrient starvation conditions, suggesting that the cell death observed is largely dependent on autophagy. We further provide evidence that GUTK inhibits Akt phosphorylation, thereby inhibiting the mTOR pathway in cancer cells during nutrient starvation. In addition, GUTK causes the accumulation of reactive oxygen species (ROS) and the phosphorylation of JNK in EBSS, which may mediate both autophagy and apoptosis. CONCLUSION These data indicate that GUTK sensitizes cancer cells to nutrient stress-induced cell death though Akt/mTOR dependent autophagy pathway.

Identification and characterization of anticancer compounds targeting apoptosis and autophagy from Chinese native Garcinia species.

Natural compounds from medicinal plants are important resources for drug development. Active compounds targeting apoptosis and autophagy are candidates for anti-cancer drugs. In this study, we collected Garcinia species from China and extracted them into water or ethanol fractions. Then, we performed a functional screen in search of novel apoptosis and autophagy regulators. We first characterized the anti-proliferation activity of the crude extracts on multiple cell lines. HeLa cells expressing GFP-LC3 were used to examine the effects of the crude extracts on autophagy. Their activities were confirmed by Western blots of A549 and HeLa cells. By using bioassay guided fractionation, we found that two caged prenylxanthones from Garcinia bracteata, neobractatin and isobractatin, can significantly induce apoptosis and inhibit autophagy. Our results suggest that different Garcinia species displayed various degrees of toxicity on different cancer cell lines. Furthermore, the use of a high content screening assay to screen natural products was an essential method to identify novel autophagy regulators.

Chemical comparison of two dosage forms of Hemp Seed Pills by UHPLC-Q-ToF–MS/MS and multivariate statistical techniques

Hemp seed soft gel capsule (HSSGC) is a modernised dosage form that is derived from a traditional Chinese patent medicine, Hemp Seed Pills (HSP). Two dosage forms claim the same therapeutic effects; however, their chemical components and chemical equivalency are unclear. In the present study, an ultra performance liquid chromatography coupled with time-of-flight mass spectrometry (UHPLC-ToF-MS)-based chemical profiling approach was proposed to rapidly evaluate the chemical differences between HSP and HSSGC as model dosage forms. Samples of the two dosage forms were subjected to UHPLC-ToF-MS analysis. The datasets of retention time (TR) and mass-to-charge ratio (m/z) pairs, ion intensities and sample codes were processed with principal component analysis (PCA) and partial least squares discriminate analysis (PLS-DA) to holistically compare the difference between these two dosage form samples. A clear classification trend was observed in the score plot, and a loading bi-plot was generated in which the variables are correlated with the group and the samples that were observed. The important chemical components that caused differences among the samples were explored with a Variables Importance Projection (VIP) index. Using the proposed approach, global chemical differences were found between the two dosage forms and among samples of the same dosage form. The most important components that are related to the differences were identified and most of them were attributed to Fructus Aurantii Immaturus. It is suggested that this newly established approach could be used for pre-clinical trial chemical equivalence study or the quality evaluation of the traditional medicinal products with large variations in quality.

Bioassay-Guided Isolation of Prenylated Xanthone Derivatives from the Leaves of Garcinia oligantha.

Four new dihydroxanthone derivatives (1-4), four new tetrahydroxanthone derivatives (5-8), two new xanthone derivatives (9 and 10), and two known caged tetrahydroxanthones were isolated from extracts of the leaves of Garcinia oligantha by bioassay-guided fractionation. These structures of the new compounds were elucidated by NMR and MS spectroscopic data analysis, and the absolute configurations of compounds 1 and 5-7 were determined by electronic circular dichroism and/or single-crystal X-ray diffraction analysis. Compounds 6-9 were shown to be unusual xanthone derivatives with an isopropyl group, which was confirmed by the X-ray crystallographic structure of compound 8. The inhibitory activities of these isolates against four human tumor cell lines (A549, HepG2, HT-29, and PC-3) were assayed, and compounds 1, 2, 5, 11, and 12 showed inhibitory effects on tumor cell growth, with IC50 values ranging from 2.1 to 8.6 μM.

The natural compound nujiangexanthone A suppresses mast cell activation and allergic asthma

Mast cells play an important role in allergic diseases such as asthma, allergic rhinitis and atopic dermatitis. The genus Garcinia of the family Guttiferae is well known as a prolific source of polycyclic polyprenylated acylphloroglucinols and bioactive prenylated xanthones, which exhibit various biological activities including antibacterial, antifungal, anti-inflammatory, antioxidant, and cytotoxic effects. Nujiangexanthone A (N7) is a novel compound isolated from the leaves of Garcinia nujiangensis. In this paper, we sought to determine the anti-allergic and anti-inflammation activity of N7 in vivo and its mechanism in vitro. We found N7 suppressed IgE/Ag induced mast cell activiation, including degranulation and production of cytokines and eicosanoids, through inhibiting Src kinase activity and Syk dependent pathways. N7 inhibited histamine release, prostaglandin D2 and leukotriene C4 generation in mast cell dependent passive cutaneous anaphylaxis animal model. We also found N7 inhibited the IL-4, IL-5, IL-13 and IgE levels in ovalbumin-induced asthma model. Histological studies demonstrated that N7 substantially inhibited OVA-induced cellular infiltration and increased mucus production in the lung tissue. Our study reveals the anti-allergic function of N7, thereby suggesting the utility of this compound as a possible novel agent for preventing mast cell-related immediate and delayed allergic diseases.

Griffipavixanthone, a dimeric xanthone extracted from edible plants, inhibits tumor metastasis and proliferation via downregulation of the RAF pathway in esophageal cancer.

Metastasis causes a large number of deaths among esophageal cancer patients. The activation of RAF family proteins elevates tumor metastasis and proliferation. In screen targeting the RAF protein, we identified that Griffipavixanthone (GPX), a dimeric xanthone isolated from Garcinia esculenta, is a B-RAF and C-RAF inhibitor against esophageal cancer cells. Using wound healing, transwell migration and matrigel invasion assays, we confirmed that GPX significantly inhibited cell migration and invasion. Furthermore, exposure to GPX rendered cell proliferation and induced G2/M cell cycle arrest. Our mechanistic study showed that GPX suppressed cancer metastasis and proliferation through downregulation of RAF-MEK-ERK cascades proteins as well as RAF mRNA levels. In a pulmonary metastasis model, the intraperitoneal injection of GPX significantly suppressed esophageal tumor metastasis and ERK protein level in vivo. In conclusion, our present study suggested that GPX could inhibit tumor migration, invasion and proliferation in vitro and in vivo, which indicated the potential of GPX for preventing and treating esophageal cancer.

Xanthones from the Leaves of Garcinia cowa Induce Cell Cycle Arrest, Apoptosis, and Autophagy in Cancer Cells

Two new xanthones, cowaxanthones G (1) and H (2), and 23 known analogues were isolated from an acetone extract of the leaves of Garcinia cowa. The isolated compounds were evaluated for cytotoxicity against three cancer cell lines and immortalized HL7702 normal liver cells, whereby compounds 1, 5, 8, and 15–17 exhibited significant cytotoxicity. Cell cycle analysis using flow cytometry showed that 5 induced cell cycle arrest at the S phase in a dose-dependent manner, 1 and 16 at the G2/M phase, and 17 at the G1 phase, while 16 and 17 induced apoptosis. Moreover, autophagy analysis by GFP-LC3 puncta formation and western blotting suggested that 17 induced autophagy. Taken together, our results suggest that these xanthones possess anticancer activities targeting cell cycle, apoptosis, and autophagy signaling pathways.

Inhibitory effect of oblongifolin C on allergic inflammation through the suppression of mast cell activation

Oblongifolin C (OC), a natural small molecule compound extracted from Garcinia yunnanensis Hu, has been previously shown to have anti-cancer effect, but the anti-allergic effect of OC has not yet been investigated. The aim of the present study is to determine the anti-allergic effect of OC on IgE/Ag-induced mouse bone marrow-derived mast cells (BMMCs) and on the passive systemic anaphylaxis (PSA) reaction in mice. OC clearly suppressed cyclooxygenase-2 (COX-2)-dependent prostaglandin D2 (PGD2) generation as well as leukotriene C4 (LTC4) generation and the degranulation reaction in IgE/Ag-stimulated BMMCs. Biochemical analyses of the IgE/Ag-mediated signaling pathways showed that OC suppressed the phosphorylation of phospholipase Cγ1 (PLCγ1)-mediated intracellular Ca2+ influx and the nuclear factor-κB (NF-κB) pathway, as well as the phosphorylation of mitogen-activated protein (MAP) kinases. Although OC did not inhibit the phosphorylation of Fyn, Lyn, and Syk, it directly inhibited the tyrosine kinase activity in vitro. Moreover, oral administration of OC inhibited the IgE-induced PSA reaction in a dose-dependent manner. Taken together, the present study provides new insights into the anti-allergic activity of OC, which could be a promising candidate for allergic therapy.