Heyneanol A induces apoptosis via cytochrome c release and caspase activation in human leukemic U937 cells

Resveratrol and the mitochondria: From triggering the intrinsic apoptotic pathway to inducing mitochondrial biogenesis, a mechanistic view

BACKGROUND

Mitochondria, the power plants of the cell, are known as a cross-road of different cellular signaling pathways. These cytoplasmic double-membraned organelles play a pivotal role in energy metabolism and regulate calcium flux in the cells. It is well known that mitochondrial dysfunction is associated with different diseases such as neurodegeneration and cancer. A growing body of literature has shown that polyphenolic compounds exert direct effects on mitochondrial ultra-structure and function. Resveratrol is known as one of the most common bioactive constituents of red wine, which improves mitochondrial functions under in vitro and in vivo conditions.

SCOPE OF REVIEW

This paper aims to review the molecular pathways underlying the beneficial effects of resveratrol on mitochondrial structure and functions. In addition, we discuss the chemistry and main sources of resveratrol.

MAJOR CONCLUSIONS

Resveratrol represents the promising effects on mitochondria in different experimental models. However, there are several reports on the detrimental effects elicited by resveratrol on mitochondria.

GENERAL SIGNIFICANCE

An understanding of the chemistry and source of resveratrol, its bioavailability and the promising effects on mitochondria brings a new hope to therapy of mitochondrial dysfunction-related diseases.

Vitis amurensis Ruprecht root inhibited α-melanocyte stimulating hormone-induced melanogenesis in B16F10 cells

BACKGROUND/OBJECTIVES

The root of Vitis amurensis Ruprecht, a sort of wild-growing grape, has been used in oriental medicine for treatment of skin ailments; however, its dermatological activity is not sufficiently understood. The aim of this study was to investigate tyrosinase inhibitory and anti-melanogenic activities of V. amurensis Ruprecht root methanol extract (VARM) in B16F10 mouse melanoma cells and to attempt to isolate and identify the active compound issued from VARM.

MATERIALS/METHODS

Anti-melanogenic activity of VARM was analyzed in α-melanocyte stimulating hormone (MSH)-stimulated B16F10 cells through evaluation of antioxidative activity as well as inhibited tyrosinase activity and melanin contents compared with those of kojic acid and arbutin. After anti-melanogenic analysis of VARM, serial fractionation, nuclear magnetic resonance (NMR), and thin layer chromatorgraphy (TLC) were applied for identification of active compounds contained in VARM.

RESULTS

VARM significantly inhibited oxidative stress and tyrosinase activity and attenuated α-MSH-induced melanin production in B16F10 cells. For isolation of active compounds, VARM was fractionated using a series of organic solvents, including dichloromethane (CH₂Cl₂), ethyl acetate (EtOAc), and n-butanol (n-BuOH). Among fractions showing anti-melanogenic activity, the CH₂Cl₂ fraction induced the most potent attenuation of melanogenesis without cytotoxicity and the major compound in the CH₂Cl₂ fraction was identified as betulinic acid. Betulinic acid isolated from the CH₂Cl₂ fraction of VARM significantly attenuated α-MSH-induced melanogenesis in a dose dependent manner, which was stronger than that of arbutin used as a positive control.

CONCLUSIONS

These results indicate that VARM inhibits oxidative stress, tyrosinase activity, and α-MSH-induced melanogenesis in B16F10 cells, due primarily to the active compound, betulinic acid, in the CH₂Cl₂ fraction.

Betulinic acid isolated from Vitis amurensis root inhibits 3-isobutyl-1-methylxanthine induced melanogenesis via the regulation of MEK/ERK and PI3K/Akt pathways in B16F10 cells

Previously, betulinic acid was identified as one of the main compounds responsible for the anti-melanogenic effect in Vitis amurensis root. In this study, we investigated the precise mechanism underlying the anti-melanogenic activity of betulinic acid in B16F10 cells. Betulinic acid significantly attenuated 3-isobutyl-1-methylxanthine (IBMX)-induced melanin production by inhibiting tyrosinase, tyrosinase related protein (TRP)-1, and TRP-2 expression through the modulation of their corresponding transcription factors, microphthalamia associated transcription factor (MITF) and cAMP response element binding protein (CREB), in B16F10 cells. In addition, phosphorylation of mitogen-activated protein kinase kinase (MEK)/extracellular regulated kinase (ERK) and phosphoinositide 3-kinase (PI3K)/Akt, involved in the melanogenic processes, were ameliorated by betulinic acid treatment. Role of MEK/ERK and PI3K/Akt signaling pathway in the melanogenesis was confirmed by using specific inhibitors, PD98059 (for MEK/ERK) and LY294002 (for PI3K/Akt), respectively. As a result, betulinic acid inhibited melanin production by tyrosinase, TRP-1, and TRP-2 inhibition through the regulation of CREB and MITF, which was accompanied with MEK/ERK and PI3K/Akt inactivation in IBMX-stimulated B16F10 cells. Consequently, these results demonstrate a novel molecular function of betulinic acid derived from V. amurensis root in melanogenesis, which in turn enhances our understanding on the application of cosmetic therapy for reducing skin hyperpigmentation.

Spectroscopic studies on the interaction between an anticancer drug ampelopsin and bovine serum albumin

The interaction between bovine serum albumin (BSA) and the anticancer drug molecule ampelopsin (AMP) was investigated using fluorescence spectroscopy, circular dichroism (CD) spectra, and time-resolved spectra under simulated physiological conditions. Fluorescence data showed that the intrinsic fluorescence of BSA was strongly quenched by AMP in terms of a dynamic quenching process. Binding constants and binding sites were calculated. The thermodynamic parameters indicated that the hydrogen bonding and weak van der Waals force played a major role in the interaction. The site marker competitive experiments suggested that the binding site of AMP and BSA was probably located on site III. Based on the Förster's theory, the average binding distance between AMP and BSA was obtained (r=5.47nm). The binding of AMP and BSA leaded to conformational changes of BSA according to synchronous fluorescence spectra, CD data and mean fluorescence lifetime values.

Biological and medicinal properties of grapes and their bioactive constituents: an update

The grape is one of the most valued conventional fruits, worldwide. Although most of the parts of the grapevine are useful, primarily, the grape is considered as a source of unique natural products not only for the development of valuable medicines against a number of diseases, but also for manufacturing various industrial products. Over the last few decades, apart from the chemistry of grape compounds, considerable progress has been made towards exploring the biological activities of various grape-derived constituents. Today, it is well established that in addition to serving as food, the grape is a major source of several phytochemicals. The main biologically active and well-characterized constituent from the grape is resveratrol, which is known for various medicinal properties in human diseases. This review discusses the roles of various grape-derived phytochemicals in relation to various diseases.

A novel resveratrol derivative, HS1793, overcomes the resistance conferred by Bcl-2 in human leukemic U937 cells

The chemopreventive and chemotherapeutic properties associated with resveratrol offer promise for the design of new chemotherapeutic agents. However, resveratrol is not a potent cytotoxic compound when compared with other chemotherapeutic drugs. Thus, several studies were undertaken to obtain synthetic analogues of resveratrol with potent activity. The present study was undertaken to examine whether four resveratrol analogues (HS-1784, -1792, -1791 and -1793) that we had designed and synthesized show antitumor activity. Here, we observed that all of these resveratrol analogues displayed stronger antitumor effects than resveratrol in most cancer cells tested. We further examined whether HS-1793, showing potent antitumor effects in most cancer cells tested, overcomes the resistance conferred by Bcl-2, since overcoming the resistance conferred by Bcl-2 represents an attractive therapeutic strategy against cancer. Our viability assay showed that HS-1793 overcomes the resistance conferred by Bcl-2 in human leukemic U937 cells. Various apoptosis assessment assays demonstrated that HS-1793 overcomes the resistance conferred by Bcl-2 in human leukemic U937 cells by inducing apoptosis. Noticeably, we elucidated the marked downregulation of 14-3-3 protein by HS-1793, indicating that HS-1793 overcomes the resistance conferred by Bcl-2 in U937 cells via 14-3-3. We also observed that HS-1793 exerts its antitumor activity via Bad. However, overall data obtained from methylation specific PCR, RT-PCR and real-time PCR suggest that HS-1793 plays a role in the downregulation of 14-3-3 at a post-transcriptional level. Further understanding exactly how HS-1793 overcomes the resistance conferred by Bcl-2 via 14-3-3 may guide the development of future anticancer agents.

Inhibition of cholinesterase and amyloid-beta aggregation by resveratrol oligomers from Vitis amurensis

In the course of screening for acetylcholinesterase and butyrylcholinesterase inhibitors from natural products by an in vitro Ellman method, the extract of the roots of Vitis amurensis Rupr. (Vitaceae) showed significant cholinesterase inhibitory activity. Employing a bioassay-linked HPLC method, followed by a semi-preparative HPLC method, two compounds of interest were isolated and characterized as vitisin A and heyneanol A. They inhibited effectively both acetylcholinesterase and butyrylcholinesterase in a dose-dependent manner and exhibited higher activity against butyrylcholinesterase compared with that of galantamine, a positive control. Furthermore, the aggregation of beta-amyloid was evaluated in vitro based on a thioflavine T fluorescence assay to expand their activity profile, with the result that both compounds showed the ability to block beta-amyloid aggregation.

Induction of apoptosis in human leukemia K562 cells by cyclic lipopeptide from Bacillus subtilis natto T-2

A new cyclic lipopeptide (CLP) purified from Bacillus subtilis natto T-2 dose dependently inhibited growth in human leukemia K562 cells. The results of fluorescent staining indicated that CLP brought about apoptosis in K562 cells. Flow cytometric analysis also demonstrated that CLP caused dose-dependent apoptosis of K562 cells through cell arrest at G1 phase. Western blotting revealed that CLP-induced apoptosis in K562 cells was associated with caspase-3 and poly(ADP-ribose)polymerase (PARP) protein. It is estimated that CLP inhibited proliferation in K562 cells by inducing apoptosis.

γ-Glutamyltranspeptidase of Helicobacter pylori induces mitochondria-mediated apoptosis in AGS cells

Gamma-glutamyltranspeptidase (GGT) is a novel protein involved in the induction of Helicobacter pylori-mediated apoptosis; however, the signal pathway involved in GGT-induced apoptosis remains unclear. Using DNA recombination techniques, ggt was cloned into pET117b and transformed into Escherichia coli. Recombinant GGT was purified using nickel-affinity resin and was digested by thrombin. Recombinant GGT induced apoptosis in AGS cells in a time-dependent manner, which was confirmed by TUNEL staining, the MTT assay and immunoblot analysis for caspases-9, -3, Bax, Bcl-2, Bcl-xL and cytochrome c release. Activation of caspase-3 and -9 following exposure to GGT increased in a time-dependent manner and upregulation of proapoptotic Bax and a downregulation of antiapoptotic Bcl-2 and Bcl-xL was detected. Apoptotic signals also trigger changes in mitochondria, which lead to a release of cytochrome c into the cytosolic space. The GGT-deficient mutant was not as able to induce apoptosis as the wild-type strain. These results indicate that GGT of H. pylori induces apoptosis via a mitochondria-mediated pathway.

Resveratrol Oligomers from Vitis amurensis Attenuate .BETA.-Amyloid-Induced Oxidative Stress in PC12 Cells

Oxidative damage induced by beta-amyloid (Abeta) is closely associated with the hallmark pathologies of Alzheimer's disease (AD) and may play a critical role in the development of AD. In this study, the protective effects of vitisin A and heyneanol A, resveratrol oligomers isolated from Vitis amurensis Rupr. (Vitaceae), against Abeta-induced oxidative cell death were investigated using rat pheochromocytoma (PC12) cells. Exposure of PC12 cells to the Abeta (20 microM) for 24 h resulted in neuronal cell death, whereas pretreatment with vitisin A or heyneanol A at the concentration range of 5-50 microM reduced Abeta-induced cell death. In addition, Abeta-induced elevation of reactive oxygen species generation, the primary cause of Abeta-induced oxidative stress, was attenuated by treatment of vitisin A or heyneanol A (10, 25, 50 microM). Abeta-treated cells also displayed characteristic features of apoptosis such as induction of DNA fragmentation and caspase-3 activation, but vitisin A and heyneanol A (10, 50 microM) significantly suppressed these events. These results suggest that vitisin A and heyneanol A prevent Abeta-induced neurotoxicity through attenuating oxidative stress induced by Abeta, and may be useful as potential preventive or therapeutic agents for AD.

The Methylene Chloride Fraction of Trichosanthis Fructus Induces Apoptosis in U937 Cells through the Mitochondrial Pathway

Trichosanthis kirilowii MAXIM has been used as a folk remedy to treat diabetes, leukemia, and breast cancer. In the present study, the apoptotic mechanism of the methylene chloride fraction of Trichosanthis Fructus (MCTF) was investigated in human leukemic U937 cells. MCTF exhibited antiproliferative effectsagainst U937 cells (IC50=ca. 8 microg/ml). Apoptotic bodies were observed in MCTF-treated U937 cells in the TUNEL assay. We also confirmed that MCTF significantly increases annexin V(+)/propidium iodide-cells using FACS analysis. MCTF treatment activated caspase-8, -9 and -3, and led to cleaved poly (ADP-ribose) polymerase and release of cytochrome c into cytosol in a concentration-dependent manner, while MCTF did not affect Bax or Bcl-2 protein levels as shown by Western blot analysis. Taken together, these results indicate that MCTF can induce apoptosis in U937 cells chiefly via a mitochondrial-mediated pathway and suggest that Trichosanthis Fructus can be used in cancer treatment as a chemopreventive agent.

Induction of apoptosis by a novel indirubin-5-nitro-3′-monoxime, a CDK inhibitor, in human lung cancer cells

A novel indirubin analog, indirubin-5-nitro-3'-monoxime, inhibited cell proliferation against various human cancer cells. Additional studies indicate that the mechanism of action of this analog against human lung cancer cells might be to arrest cell cycle progression at the G2/M phase and induce apoptosis via p53- and mitochondria-dependent pathways. These data suggest that indirubin-5-nitro-3'-monoxime might be a novel candidate for development of anticancer agents.

Shiquandabutangjiaweibang inhibits tumor metastasis and angiogenesis via regulation of topoisomerase-1

Shiquandabutangjiaweibang (SDJ) is a traditional medicine prescription used for increasing body resistance against cancer. In the present study, the effect of SDJ extract on tumor metastasis and angiogenesis was evaluated. SDJ showed cytotoxicity against P388 (leukemia cells) and B16-F10 (murine melanoma cells) to 60% of control at 1 mg. SDJ significantly inhibited lung metastasis and also restored the number of platelets in C57BL/6 mice with thrombocytopenia induced by intravenous injection of B16-F10 cells. SDJ significantly disrupted chick embryonic angiogenesis in the chorioallantoic membrane (CAM). Interestingly, SDJ suppressed DNA topoisomerase I in a concentration-dependent manner. These results suggest that SDJ can be a potent inhibitor of metastasis and angiogenesis, at least in part, via regulation of topoisomerase I.