Investigation on the photoinduced chemical reaction between p-benzoquinone and tryptophan in homogeneous solution.

Photoinduced electron transfer (PET) and energy transfer between amino acids and bioquinones have become research hotspots, due to the important roles they play in a physiological environment. However, as classic benzoquinones and amino acids, the reaction mechanism of p-benzoquinone (PBQ) and tryptophan (Trp) is still unclear. In this work, the photoinduced chemical reaction of PBQ and Trp was investigated in homogeneous solution using time-resolved electron paramagnetic resonance and laser flash photolysis techniques. Under photoexcitation at 355 nm, the 3PBQ* produced via intersystem crossing (ISC) in ethylene glycol aqueous (EG-H2O) solution followed by the H-atom transfer (HAT) from EG to 3PBQ* was a significant process in competition with the non-radiative transition of 3PBQ*, which was clearly observed in the transient absorption spectra and chemically induced dynamic electron polarization spectra. When Trp was added into the PBQ/EG-H2O solution, a new decay channel of 3PBQ* was produced that reacted with Trp to form a p-benzoquinone anion radical (PBQ˙-) and a tryptophan cationic radical (Trp˙+), indicating that the photoinduced chemical reaction mechanism was the electron transfer. By fitting the decay dynamic curves, the quenching rate constant of 3PBQ* to Trp in homogeneous solution was determined as 6.8 × 108 M-1 s-1, which was close to the diffusion-controlled rate.

Sanguinarine triggers intrinsic apoptosis to suppress colorectal cancer growth through disassociation between STRAP and MELK.

BACKGROUND: Previous studies showed sanguinarine induced apoptosis in CRC cells but did not define the underlying mechanisms. The purpose of this work was to determine the in vivo and in vitro effects of sanguinarine on CRC tumors and to elucidate the mechanism in regulating the intrinsic apoptosis. METHODS: Cell viability of CRC cell lines treated with sanguinarine was measured by MTT assay. Apoptotic cells stained with Annexin V and 7-AAD were detected by flow cytometry. Mitochondrial membrane potential and reactive oxygen species (ROS) were analyzed by JC-1 and DCFH-DA staining, respectively. The in vitro kinase activity of MELK was analyzed by using HTRF® KinEASE™-STK kit. The expression of proteins were determined using Western blotting and immunohistochemistry. Co-immunoprecipitation and immunofluorecence were used to study the interaction between STRAP and MELK. The anti-neoplastic effect of sanguinarine was observed in vivo in an orthotopic CRC model. RESULTS: Sanguinarine decreased the tumor size in a dose-dependent manner in orthotopical colorectal carcinomas through intrinsic apoptosis pathway in BALB/c-nu mice. It significantly increased cleavage of caspase 3 and PARP in implanted colorectal tissues. Sanguinarine increased mitochondrial ROS and triggered mitochondrial outer membrane permeabilization in multiple colorectal cancer (CRC) cell lines. NAC pretreatment lowered ROS level and downregulated apoptosis induced by sanguinarine. The intrinsic apoptosis induced by sanguinarine was Bax-dependent. The elevated expression and association between serine-threonine kinase receptor-associated protein (STRAP) and maternal embryonic leucine zipper kinase (MELK) were observed in Bax positive cells but not in Bax negative cells. Sanguinarine dephosphorylated STRAP and MELK and disrupted the association between them in HCT116 and SW480 cells. The expression and association between STRAP and MELK were also attenuated by sanguinarine in the tumor tissues. Importantly, we found that STRAP and MELK were overexpressed and highly phosphorylated in colorectal adenocarcinomas and their expression were significantly correlated with tumor stages. Furthermore, the expression of MELK, but not STRAP, was associated with lymph node metastasis. CONCLUSIONS: Sanguinarine dephosphorelates STRAP and MELK and disassociates the interaction between them to trigger intrinsic apoptosis. Overexpression of STRAP and MELK may be markers of CRC and their disassociation may be a determinant of therapeutic efficacy.

Ent-11α-hydroxy-15-oxo-kaur-16-en-19-oic-acid inhibits hepatocellular carcinoma in vitro and in vivo via stabilizing IkBα.

Ent-11-hydroxy-15-oxo-kaur-16-en-19-oic-acid (5F) isolated from Pteris Semipinnata L is known to inhibit certain tumor cells in vitro. The information on the in vivo effect of 5F is limited and its effect on hepatocellular carcinoma (HCC) is unknown. In this study, the anti-tumor effect of 5F was investigated in a diethylnitrosamine (DEN)-induced mouse HCC model. In addition to therapeutic effect, the potential side effect was monitored. A panel of cultured HCC cells was used to confirm the in vivo data and explore the responsible molecular pathway. The result showed that 5F significantly inhibited the DEN-induced HCC tumors by reducing the number of tumor foci and the volume of tumors. Furthermore, 5F induced the death of cultured HCC cells in dose- and time-dependent manners. The cell death was confirmed to be apoptotic by in vivo and in vitro TUNEL assays. 5F inhibited NF-kB by stabilizing its inhibitor IkBα, reducing the nuclear p65 and inhibiting NF-kB activity. Subsequently it affected the NF-kB downstream molecules with a decrease in anti-apoptotic Bcl-2 and increase in pro-apoptotic Bax and Bak. During the whole period of the experiment, mice receiving 5F appeared to be healthy, though they suffered from a mild degree of hair loss. 5F did not damage liver and renal functions. In conclusion, 5F is effective against HCC with minimal side effects. It induces apoptosis in HCC cells via inhibiting NF-kB, leading to the decrease of Bcl-2 but the increase of Bax and Bak.

Ent-11α-Hydroxy-15-oxo-kaur-16-en-19-oic-acid Inhibits Growth of Human Lung Cancer A549 Cells by Arresting Cell Cycle and Triggering Apoptosis.

OBJECTIVE: To examine the apoptotic effect of ent-11α-hydroxy-15-oxo-kaur-16-en-19-oic-acid (5F), a compound isolated from Pteris semipinnata L (PsL), in human lung cancer A549 cells. METHODS: A549 cells were treated with 5F (0-80 µg/ml) for different time periods. Cytotoxicity was examined using a MTT method. Cell cycle was examined using propidium iodide staining. Apoptosis was examined using Hoechst 33258 staining, enzyme-linked immunosorbent assay (ELISA) and caspase-3 activity analysis. Expression of representative apoptosis-related proteins was evaluated by Western blot analysis. Reactive oxygen species (ROS) level was measured using standard protocols. Potential interaction of 5F with cisplatin was also examined. RESULTS: 5F inhibited the proliferation of A549 cells in a concentration- and time-dependent manner. 5F increased the accumulation of cells in sub-G1 phase and arrested the cells in the G2 phase. Exposure to 5F induced morphological changes and DNA fragmentation that are characteristic of apoptosis. The expression of p21 was increased. 5F exposure also increased Bax expression, release of cytochrome c and apoptosis inducing factor (AIF), and activation of caspase-3. 5F significantly sensitized the cells to cisplatin toxicity. Interestingly, treatment with 5F did not increase ROS, but reduced ROS production induced by cisplatin. CONCLUSION: 5F could inhibit the proliferation of A549 cells by arresting the cells in G2 phase and by inducing mitochondrial-mediated apoptosis.

[ROS is not involved in induction of cell death by Ent-11 alpha-hydroxy-15-oxo-kaur-16-en-19-oic-acid in HepG2 cells].

OBJECTIVE: To identify the role of reactive oxygen species (ROS) formation on cell death induced by Ent-11alpha-hydroxy-15-oxo-kaur-16-en-19-oic-acid (5F) in HepG2 cells. METHOD: MTT assay was used to determine the effect of 5F on proliferation of HepG2 cells, and apoptotic morphological changes were assessed using Hoechst/PI assay. To evaluate intracellular ROS levels, a GENMED kit was used. HepG2 cells were treated with 5F for 24 h or with 1 mmol x L(-1) GSH for 1 h prior to treatment with 5F for 24 h, then cytoplasmic mono- and oligonucleosomes were assessed with Cell Death Detection ELISA kit. RESULT: The cytotoxicity of 5F on HepG2 cells was elevated with increasing 5F concentrations, as evidenced by the cell viability assay, and the apoptotic changes such as chromatin condensation were confirmed by Hoechst/PI staining. The decrease in ROS generation was observed in HepG2 cells following treatment with 5F. Cytoplasmic mono- and oligonucleosomes induced by 5F were not changed by decreasing basal level of ROS-mediated signaling with GSH. Further more, induction of ROS production by cisplatinum (CDDP) was canceled by treatment with 5F and 5F revealed a additive effect to cell killing by CDDP. CONCLUSION: 5F can not only induce apoptosis through non-ROS-depandent pathway, and can abate oxidant stress.

[Effect of 5F from Pteris semipinnata on expression of Nr1d1 in HO-8910PM cell line].

OBJECTIVE: To investigate the effects of PsL5F (ent-11alpha-hydroxy-15-oxo-kaur-16-en-19-oic-acid, an extract from Pteris semipinnata L) on the expression of nuclear receptor subfamily 1, group D, member 1 (Nr1d1) in highly metastatic ovarian carcinoma HO-8910PM cells, and its mechanisms. METHOD: Microarray Chip was used to examine the level of Nr1d1 mRNA expression on HO-8910PM cells treated with PsL5F. Fluorescent quantitative real-time PCR assay and Western blot were performed to verify the effects of PsL5F on Nr1d1 mRNA and protein expression. RESULT: After 24 h treatment of 100 micromol x L(-1) PsL5F, the mRNA and protein levels of Nr1d1 in HO-8910PM cells were 35.34 +/- 1.07 and 7.71 +/- 0.43 times compared to those of control group (P < 0.01, P < 0.01), respectively. CONCLUSION: PsL5F can up-regulate significantly the expression of Nr1d1 in HO-8910PM cells. Antitumor effects and its mechanisms of PsL5F in HO-8910PM cells may be involved in the up-regulation of Nr1d1 expression.

Multifunctional nanoplatform based on star-shaped copolymer for liver cancer targeting therapy.

With high morbidity and death rates, liver cancer has become one of the most common cancers in the world. But, most chemotherapeutic anticancer drugs have high toxicity as well as low specificity. To improve the treatment modalities and enhance the therapeutic effect of liver cancer, a brand new liver-targeting nanoparticle (NP), Ent-11α-hydroxy-15-oxo-kaur-16-en-19-oic acid (5 F)-loaded cholic acid (CA)-functionalized star-shaped poly (lactic-co-glycolic acid) (PLGA)-polyethylene glycol (PEG)-lactobionic acid (LA) (5 F-loaded CA-PLGA-PEG-LA), was developed. The particle size, zeta potential, size distribution, surface morphology, drug loading content, drug encapsulation efficiency and drug release of 5 F-loaded NPs were characterized. Confocal microscopy and flow cytometry showed that the prepared NPs could be internalized by HepG2 cells. Furthermore, the cellular uptake efficiency of coumarin 6-loaded CA-PLGA-PEG-LA NPs was much better in compare with that of CA-PLGA-PEG and CA-PLGA NPs. Moreover, LA-conjugated NPs (CA-PLGA-PEG-LA NPs) enhanced fluorescence of HepG2 cells via ligand-mediated endocytosis. The antitumor effects of 5 F-loaded NPs were evaluated by the MTT assay in vitro and by a xenograft tumor model in vivo, demonstrating that targeted 5 F-loaded CA-PLGA-PEG-LA NPs were significantly superior to free 5 F and 5 F-loaded CA-PLGA-PEG NPs. All the results indicated the 5 F-loaded CA-PLGA-PEG-LA NPs can be employed as a novel potentially targeting drug delivery system for liver cancer therapy.

[Studies on quality standard of PsL 5F injections].

OBJECTIVE: To establish the quality standard of PsL injections containing mainly 5F (ent-11alpha-hydroxy-15-oxo-kaur-16-en-19-oic-acid). METHOD: The identification of PsL was performed by thin-layer chromatography, and the content was determined by HPLC. The column was Hypersil C18 (4.6 mm x 250 mm, 5 microm), the mobile phase was the mixture of methane-water-acitic acid (55:45: 0.045) with a flow rate of 1.0 mL x min(-1), the detective wavelength was 254 nm, and the column temperature was maintained at 35 degrees C. The pH value and K+ content of the three batchs injection were determined with pH meter and flame photometric meter, and the contents of tannin, protein, oxalic acid salt and heavy metals were detected by deferent methods. RESULT: The TLC method was suitable for the identification of PsL5F. The linearity for 5F was obtained over the range of 30-240 microg x mL(-1) (r = 0.999 8), the average recovery of 5F was 99.8%. The injections were of pH value range from 7.80 to 8.20, K+ contents less than 10 mmol x L(-1), and the contents of tannin, protein, oxalic acid salt and heavy metals were qualified with the Chinese pharmacopoeia, respectively. CONCLUSION: It's sensitive and reliable that can be used as quality control methods of PsL5F injections.

Autophagic flux is essential for the downregulation of D-dopachrome tautomerase by atractylenolide I to ameliorate intestinal adenoma formation.

Colorectal cancer is generally believed to progress through an adenoma - carcinoma sequence. Adenomatous polyposis coli (APC) mutations serve as the initiating event in adenoma formation. The ApcMin/+ mouse harbors a mutation in the APC gene, which is similar or identical to the mutation found in individuals with familial adenomatous polyposis and 70% of all sporadic CRC cases. Autophagy is a constitutive process required for proper cellular homeostasis. However, its role in intestinal adenoma formation is still controversial. Atractylenolide I (AT1) is a sesquiterpenoid that possesses various clinically relevant properties such as anti-tumor and anti-inflammatory activities. The role of AT1 on adenoma formation was tested in ApcMin/+ mice and its underlying mechanism in regulating autophagy was documented. D-dopachrome tautomerase (D-DT) was identified as a potential target of AT1 by an proteomics-based approach. The effects of p53 modification on autophgic flux was monitored in p53-/- and p53+/+ HCT116 cells. Small interfering RNA was used to investigate the function of Atg7 and D-DT on autophagy programme induce by AT1. AT1 effectively reduced the formation of adenoma and downregulated the tumorigenic proteins in ApcMin/+ mice. Importantly, AT1 stimulated autophagic flux through downregulating acetylation of p53. Activation of Sirt1 by AT1 was essential for the deacetylation of p53 and downregulation of D-DT. The lowered expression of COX-2 and ß-catenin by AT1 were partly recovered by Atg7 knockdown. AT1 activates autophagy machinery to downregulate D-DT and reduce intestinal adenoma formation. This discovery provides evidence in vivo and in vitro that inducing autophagy by natural products maybe a potential therapy to ameliorate colorectal adenoma formation.

Tubeimoside 1 Acts as a Chemotherapeutic Synergist via Stimulating Macropinocytosis.

Macropinocytosis is a highly conserved endocytic process which characterizes the engulfment of extracellular fluid and its contents into cells via large, heterogeneous vacuoles known as macropinosomes. Tubeimoside-1 (TBM1) is a low toxic triterpenoid saponin extracted from a traditional Chinese herb Bolbostemma paniculatum (Maxim.). TBM1 stimulates a quick accumulation of numerous phase-lucent cytoplasmic vacuoles in multiple colorectal cancer (CRC) cell lines. These vacuoles can be termed as macropinosomes that efficiently engulf lucifer yellow. These vesicles are not overlaps with endocytic organelle tracers, such as ERTracker, LysoTracker and mitoTracker. These vacuoles induced by TBM1 partially incorporate into lysosomes. Transmission electron microscope indicates membrane ruffling to form lamellipodia. Protrusions collapse onto and then fuse back with the plasma membrane to generate these large endocytic vacuoles. Notably, TBM1 efficiently trafficks dextrans into heterotopic xenografts in vivo, thus provide consolidated evidence that the vacuolization can be mainly defined as macropinocytosis. TBM1 downregulates cell viability and increases PI-positive, but not highlighted Hoechst 33342-positive cells. TBM1 induced cell death can be ascribed as methuosis by hyperstimulation of macropinocytosis which can be compromised by amiloride derivative 5-(Nethyl-N-isopropyl). Light chain 3 II is recruited to these vesicles to stimulate macropinocytosis. The cell death and vacuoles can be significantly neutralized by chloroquine, but can not be the inhibited by 3-methyladenine. TBM1 can coordinate with 5-FU to exert toxicity reducing and efficacy enhancing effects in vivo by increasing the uptake of the latter without hepatic injury. In conclusion, TBM1 effectively induces in vitro and in vivo macropinocytosis which can traffick small molecules into CRC cells. It is an attractive drug transporter and can be harnessed as a chemotherapeutic synergist with translational potential.

[Advances in study on chemical constituents and pharmacological activities of plants of genus Pteris].

The main chemical constituents in plants of genus pteris include diterpenoids, diterpenoid glycosides, flavonoids, flavonoid glycosides, sesquiterpenoids and volatile oils, etc. Some of extracts show the following activities, such as antitumor, antifungi and antibacteria. Some of compounds have inhibitory effect on platelet aggregation and antiinflamatory action. The latest progress on chemical constituents and pharmacological activity were reviewed in the paper. Main problems and study directions in future of pteris were indicated.

[Determination of 5F in Pteris semipinnata L. from various origins by TLC-scanning].

OBJECTIVE: To determine the content of 5F in Pteris semipinnata L. from various origins. METHODS: 5F was determined by TLC-Scanning. RESULTS: The linear relationship was in range of 0. 504 - 2. 520 microg. The mean recovery was 96. 68% and RSD = 1.24% (n = 5). CONCLUSION: The method is available with a good reproducibility, and pretreatment is simple and easy to operate.

Induction of laryngeal cancer cell death by Ent-11-hydroxy-15-oxo-kaur-16-en-19-oic acid.

BACKGROUND: Ent-11-hydroxy-15-oxo-kaur-16-en-19-oic acid (5F) is known to exhibit antitumor activity, but its mechanism is not completely understood. 5F has not been tested in laryngeal cancer. METHODS: Two laryngeal cancer cell lines were treated with 5F. Cell death was analyzed by MTT [3-(4,5-dimethylthiozol-2-yl)-2,5-diphenyltetrazolium bromide] and Annexin V assay. Nuclear factor kappa beta (NF-κB)- and apoptosis-related molecules were examined. RESULTS: 5F induced laryngeal cancer cell death in a dose-dependent manner. The Annexin V assay and the measurement of cleavage of procaspase-3 and poly(ADP-ribose) polymerase demonstrated that the 5F-induced cell death was mainly apoptotic. 5F slightly reduced the basal level of NF-κB, but significantly suppressed the inducible NF-κB by reducing its transcriptional activity, protecting its inhibitory subunit IκBα from degradation, and suppressing its level in the nucleus. 5F also inhibited pro-proliferative and anti-apoptotic molecules but promoted pro-apoptotic Bax. CONCLUSIONS: 5F induces apoptosis of laryngeal cancer cells by inhibiting NF-κB activation/induction, suppressing pro-proliferative and anti-apoptotic molecules, and promoting pro-apoptotic Bax.

Anticancer efficacy of 5F in NNK-induced lung cancer development of A/J mice and human lung cancer cells.

The mechanism responsible for the apoptotic effect induced by ent-11α-hydroxy-15-oxo-kaur-16-en-19-oic-acid (5F) is not fully understood and its in vivo effect has not been tested. In this study, the effect and mechanism of 5F was investigated in cigarette smoking carcinogen 4-methylnitrosamino-1-3-pyridyl-butanone (NNK)-induced mouse lung tumor model and in cultured lung cancer cells NCI-H23 and CRL-2066. 5F were given to mice after they were treated with NNK for 18 weeks. The effect of 5F on the lung tumor formation was examined, and its side effect was monitored. Cell proliferation and apoptosis were determined through expression of PCNA, Bcl-2, Bax, and TUNEL assay in in vivo animal model. 5F significantly inhibited the NNK-induced lung tumors by inducing apoptosis and suppressing cell proliferation in vivo with minimal side effects. Cell culture experiments showed that 5F translocated Bax into the mitochondria, downregulated Bcl-2, activated caspase-9 and caspase-3, released cytochrome c into the cytosol, and translocated AIF from the mitochondria to the nucleus, which leading to G2-M cell cycle arrest and cell apoptosis. 5F also activated ERK1/2 and the inhibition of ERK1/2 suppressed 5F-mediated changes in apoptotic molecules. In addition to ERK1/2, 5F activated Akt. The inhibition of Akt further facilitated the apoptosis induced, suggesting that Akt activation was anti-apoptotic rather than pro-apoptotic. Collectively, 5F is effective against lung cancer in vivo with minimal side effects. It induces apoptosis in lung cancer through the mitochondrial-mediated pathway, in which the activation of ERK is critical.