Study on synthesis, characterization and biological activity of some new nitrogen heterocycle porphyrins.

Abstract:

:Seven new nitrogen heterocycle porphyrins, 5,10,15,20-tetra[4-(N-pyrrolidinyl)phenyl]porphine (TBPPH(2)), 5,10,15,20-tetra[4-(4'-ethylpiperazinyl)phenyl]porphine (TEPPH(2)), 5,10,15,20-tetra [4-(4'-butylpiperazinyl)phenyl]porphine (TUPPH(2)), 5,10,15,20-tetra[4-(4'-heptylpiperazinyl) phenyl]porphine (THPPH(2)), 5-[4-(4'-ethylpiperazinyl)phenyl]-10,15,20-triphenylporphine (MEPPH(2)), 5-[4-(4'-buthylpiperazinyl)phenyl]-10,15,20-triphenylporphine (MUPPH(2)) and piperazine bridge porphine dimer N,N'-di(5,10,15,20-tetraphenylporphinato)piperazine (DiPPH(2)) have been synthesized by the direct condensation of nitrogen heterocycle substituted benzaldehydes with pyrrole. Each porphine bears one or four substituted pyrrolidine or piperazine moieties that have been used as drugs. Their structures were characterized by elementary analysis, MS, 1H NMR, IR and UV-vis. These nitrogen heterocycle porphyrins aggregates in water and THF solution were studied by the spectrophotofluorimetry. The anticancer activity of these porphines for the liver cancer cells, the stomach tumor cells and the nasopharyngeal carcinoma cancer cells were tested by the MTT assay. Compared with cis-platinum (cis-Pt) and 5-Fluorouracil (5-Fu), the nitrogen heterocycle porphyrins have the better biological activity and might have potential application in medicine.

journal_name

Bioorg Med Chem

authors

Guo CC,Li HP,Zhang XB

doi

10.1016/s0968-0896(03)00027-0

subject

Has Abstract

pub_date

2003-04-17 00:00:00

pages

1745-51

issue

8

eissn

0968-0896

issn

1464-3391

pii

S0968089603000270

journal_volume

11

pub_type

杂志文章
  • Substituted thiophene-anthranilamides as potent inhibitors of human factor Xa.

    abstract::A series of thiophene-containing non-amidine factor Xa inhibitors is described. Simple methyl-substituted thiophene analogs were relatively weak inhibitors. However, introduction of hydrophilic substituents at C-4 or C-5 of the thiophene afforded inhibitors with low nanomolar potency. Optimization of the thiophene sub...

    journal_title:Bioorganic & medicinal chemistry

    pub_type: 杂志文章

    doi:10.1016/j.bmc.2006.12.019

    authors: Kochanny MJ,Adler M,Ewing J,Griedel BD,Ho E,Karanjawala R,Lee W,Lentz D,Liang AM,Morrissey MM,Phillips GB,Post J,Sacchi KL,Sakata ST,Subramanyam B,Vergona R,Walters J,White KA,Whitlow M,Ye B,Zhao Z,Shaw KJ

    更新日期:2007-03-01 00:00:00

  • Synthesis and anti-HIV activity of trivalent CD4-mimetic miniproteins.

    abstract::A series of trivalent CD4-mimetic miniproteins was synthesized, in which three CD4M9 miniprotein moieties were tethered on a threefold-symmetric scaffold. The trivalent miniproteins were designed to target the CD4-binding sites displayed in the trimeric gp120 complex of HIV-1. The synthesis takes advantage of the high...

    journal_title:Bioorganic & medicinal chemistry

    pub_type: 杂志文章

    doi:10.1016/j.bmc.2007.03.064

    authors: Li H,Guan Y,Szczepanska A,Moreno-Vargas AJ,Carmona AT,Robina I,Lewis GK,Wang LX

    更新日期:2007-06-15 00:00:00

  • Furocoumarins from grapefruit juice and their effect on human CYP 3A4 and CYP 1B1 isoenzymes.

    abstract::Bioactive compounds present in grapefruit juice are known to increase the bioavailability of certain medications by acting as potent CYP 3A4 inhibitors. An efficient technique has been developed for isolation and purification of three furocoumarins. The isolated compounds have been tested for the inhibition of human C...

    journal_title:Bioorganic & medicinal chemistry

    pub_type: 杂志文章

    doi:10.1016/j.bmc.2005.11.039

    authors: Girennavar B,Poulose SM,Jayaprakasha GK,Bhat NG,Patil BS

    更新日期:2006-04-15 00:00:00

  • Bis-pyrene-labeled molecular beacon: a monomer-excimer switching probe for the detection of DNA base alteration.

    abstract::A new bis-pyrene-labeled oligonucleotide probe (BP-probe) has been designed for the detection of a single base mismatch in single strand (ss) DNA as a target. The sequence of BP-probe was chosen to form stem-loop structure similar to a molecular beacon (MB-probe), yielding bis-pyrene-labeled molecular beacon (BP-MB-pr...

    journal_title:Bioorganic & medicinal chemistry

    pub_type: 杂志文章

    doi:10.1016/j.bmc.2007.04.053

    authors: Yamana K,Ohshita Y,Fukunaga Y,Nakamura M,Maruyama A

    更新日期:2008-01-01 00:00:00

  • Design, synthesis and evaluation of novel quinazoline-2,4-dione derivatives as chitin synthase inhibitors and antifungal agents.

    abstract::A series of novel 1-methyl-3-substituted quinazoline-2,4-dione derivatives were designed, synthesized, and characterized by (1)H NMR, (13)C NMR and MS spectral data. Their inhibition against chitin synthase (CHS) and antifungal activities were evaluated in vitro. Results showed compounds 5b, 5c, 5e, 5f, 5j, 5k, 5l, an...

    journal_title:Bioorganic & medicinal chemistry

    pub_type: 杂志文章

    doi:10.1016/j.bmc.2014.04.042

    authors: Ji Q,Yang D,Wang X,Chen C,Deng Q,Ge Z,Yuan L,Yang X,Liao F

    更新日期:2014-07-01 00:00:00

  • Photo-control of nitric oxide synthase activity using a caged isoform specific inhibitor.

    abstract::Nitric oxide (NO) plays a critical role in a number of physiological processes and is produced in mammalian cells by nitric oxide synthase (NOS) isozymes. Because of the diverse functions of NO, pharmaceutical interventions which seek to abrogate adverse effects of excess NOS activity must not interfere with the norma...

    journal_title:Bioorganic & medicinal chemistry

    pub_type: 杂志文章

    doi:10.1016/s0968-0896(02)00050-0

    authors: Montgomery HJ,Perdicakis B,Fishlock D,Lajoie GA,Jervis E,Guy Guillemette J

    更新日期:2002-06-01 00:00:00

  • The synthesis and anti-proliferative effects of beta-elemene derivatives with mTOR inhibition activity.

    abstract::Fourteen beta-elemene derivatives containing a piperazine, a morpholine, a tetrahydropyrrole, a thiophenylethylamine, or a cyclohexamine group were synthesized. The structures of these beta-elemene derivatives were characterized with IR, 1H NMR, MS, and elemental analyses. All these derivatives had an increased anti-p...

    journal_title:Bioorganic & medicinal chemistry

    pub_type: 杂志文章

    doi:10.1016/j.bmc.2006.03.041

    authors: Xu L,Tao S,Wang X,Yu Z,Wang M,Chen D,Jing Y,Dong J

    更新日期:2006-08-01 00:00:00

  • Studies on 6-chloro-5-(1-naphthyloxy)-2-(trifluoromethyl)-1H-benzimidazole/2-hydroxypropyl-β-cyclodextrin association: Characterization, molecular modeling studies, and in vivo anthelminthic activity.

    abstract::The purpose of this work is to study the molecular association that occurs between 2-hydroxypropyl-β-cyclodextrin (HPβCD) and 6-chloro-5-(1-naphthyloxy)-2-(trifluoromethyl)-1H-benzimidazole (RCB20), an antiparasitic compound recently found by our research group, with poor aqueous solubility. The complex stability cons...

    journal_title:Bioorganic & medicinal chemistry

    pub_type: 杂志文章

    doi:10.1016/j.bmc.2010.12.015

    authors: Rojas-Aguirre Y,Yépez-Mulia L,Castillo I,López-Vallejo F,Soria-Arteche O,Hernández-Campos A,Castillo R,Hernández-Luis F

    更新日期:2011-01-15 00:00:00

  • Design, synthesis and bioactivities of Celecoxib analogues or derivatives.

    abstract::A series of Celecoxib analogues or derivatives were designed and synthesized, and their biological activities were studied. The results of inhibitory activity in vitro proved that compounds 1a, 1h, 1i, 1l and 1p had better inhibitory effect on COX-2, and the selectivity was higher. Among them, the inhibitory activity ...

    journal_title:Bioorganic & medicinal chemistry

    pub_type: 杂志文章

    doi:10.1016/j.bmc.2017.07.038

    authors: Zhou S,Yang S,Huang G

    更新日期:2017-09-01 00:00:00

  • The novel GABA adamantane derivative (AdGABA): design, synthesis, and activity relationship with gabapentin.

    abstract::A facile preparation of 2-aminomethyl-2-tricyclo[3.3.1.1(1,7)]decaneacetic acid hydrochloride 5 (AdGABA) is described. The synthesis of AdGABA involves the hydrogenation of 2-cyano-2-tricyclo[3.3.1.1(1,7)]decaneacetic acid 11, which was synthesized by two different synthetic routes. AdGABA was found to antagonize the ...

    journal_title:Bioorganic & medicinal chemistry

    pub_type: 杂志文章

    doi:10.1016/j.bmc.2005.02.030

    authors: Zoidis G,Papanastasiou I,Dotsikas I,Sandoval A,Dos Santos RG,Papadopoulou-Daifoti Z,Vamvakides A,Kolocouris N,Felix R

    更新日期:2005-04-15 00:00:00

  • Optimization of thiazole analogues of resveratrol for induction of NAD(P)H:quinone reductase 1 (QR1).

    abstract::NAD(P)H:quinone reductase 1 (QR1) belongs to a class of enzymes called cytoprotective enzymes. It exhibits its cancer protective activity mainly by inhibiting the formation of intracellular semiquinone radicals, and by generating α-tocopherolhydroquinone, which acts as a free radical scavenger. It is therefore believe...

    journal_title:Bioorganic & medicinal chemistry

    pub_type: 杂志文章

    doi:10.1016/j.bmc.2012.10.006

    authors: Mayhoub AS,Marler L,Kondratyuk TP,Park EJ,Pezzuto JM,Cushman M

    更新日期:2012-12-15 00:00:00

  • Cytotoxicity of new polyfluorinated 1,4-naphtoquinones with diverse substituents in the quinone moiety.

    abstract::Fluorinated derivatives of 1,4-naphthoquinones are highly potent inhibitors of Cdc25A and Cdc25B phosphatases and growth of tumor cells. Eight new derivatives of polyfluoro-1,4-naphthoquinone were synthesized and their cytotoxicity in human myeloma, human mammary adenocarcinoma, mouse fibroblasts and primary mouse fib...

    journal_title:Bioorganic & medicinal chemistry

    pub_type: 杂志文章

    doi:10.1016/j.bmc.2010.11.027

    authors: Zakharova OD,Ovchinnikova LP,Goryunov LI,Troshkova NM,Shteingarts VD,Nevinsky GA

    更新日期:2011-01-01 00:00:00

  • Preclinical evaluation of a CXCR4-specific (68)Ga-labelled TN14003 derivative for cancer PET imaging.

    abstract::Molecular imaging is an ideal platform for non-invasive detection and assessment of cancer. In recent years, the targeted imaging of CXCR4, a chemokine receptor that has been associated with tumour metastasis, has become an area of intensive research. In our pursuit of a CXCR4-specific radiotracer, we designed and syn...

    journal_title:Bioorganic & medicinal chemistry

    pub_type: 杂志文章

    doi:10.1016/j.bmc.2013.12.012

    authors: George GP,Stevens E,Åberg O,Nguyen QD,Pisaneschi F,Spivey AC,Aboagye EO

    更新日期:2014-01-15 00:00:00

  • Peroxisome proliferator-activated receptor agonists with phenethylphenylphthalimide skeleton derived from thalidomide-related liver X receptor antagonists: relationship between absolute configuration and subtype selectivity.

    abstract::Introduction of an alkylcarboxylic acid unit, which is a partial structure of endogenous peroxisome proliferator-activated receptor (PPAR) ligands, into a phenethylphenylphthalimide skeleton, which possesses liver X receptor (LXR) antagonistic activity, afforded novel PPAR ligands. The results of structure-activity re...

    journal_title:Bioorganic & medicinal chemistry

    pub_type: 杂志文章

    doi:10.1016/j.bmc.2011.03.065

    authors: Motoshima K,Ishikawa M,Hashimoto Y,Sugita K

    更新日期:2011-05-15 00:00:00

  • 11H-Isoquino[4,3-c]cinnolin-12-ones; novel anticancer agents with potent topoisomerase I-targeting activity and cytotoxicity.

    abstract::Recent studies have identified 2,3-dimethoxy-8,9-methylenedioxy-11-[(2-dimethylamino)ethyl]-11H-isoquino[4,3-c]cinnolin-12-one (1a) as a novel topoisomerase I-targeting agent with potent cytotoxic activity. The effect of varied substituents at the 11-position of 2,3-dimethoxy-8,9-methylenedioxy-11H-isoquino[4,3-c]cinn...

    journal_title:Bioorganic & medicinal chemistry

    pub_type: 杂志文章

    doi:10.1016/j.bmc.2003.10.061

    authors: Ruchelman AL,Singh SK,Ray A,Wu X,Yang JM,Zhou N,Liu A,Liu LF,LaVoie EJ

    更新日期:2004-02-15 00:00:00

  • Synthesis, induced-fit docking investigations, and in vitro aldose reductase inhibitory activity of non-carboxylic acid containing 2,4-thiazolidinedione derivatives.

    abstract::In continuation of our studies, we here report a series of non-carboxylic acid containing 2,4-thiazolidinedione derivatives, analogues of previously synthesized carboxylic acids which we had found to be very active in vitro aldose reductase (ALR2) inhibitors. Although the replacement of the carboxylic group with the c...

    journal_title:Bioorganic & medicinal chemistry

    pub_type: 杂志文章

    doi:10.1016/j.bmc.2008.04.072

    authors: Maccari R,Ottanà R,Ciurleo R,Rakowitz D,Matuszczak B,Laggner C,Langer T

    更新日期:2008-06-01 00:00:00

  • The design of a novel near-infrared fluorescent HDAC inhibitor and image of tumor cells.

    abstract::Histone deacetylases (HDACs) have been found to be biomarkers of cancers and the corresponding inhibitors have attracted much attention these years. Herein we reported a near-infrared fluorescent HDAC inhibitor based on vorinostat (SAHA) and a NIR fluorophore. This newly designed inhibitor showed similar inhibitory ac...

    journal_title:Bioorganic & medicinal chemistry

    pub_type: 杂志文章

    doi:10.1016/j.bmc.2020.115639

    authors: Huang Y,Ru HB,Bao B,Yu JH,Li J,Zang Y,Lu W

    更新日期:2020-09-01 00:00:00

  • The role of molecular modeling in the design of analogues of the fungicidal natural products crocacins A and D.

    abstract::Extensive molecular modeling based on crystallographic data was used to aid the design of synthetic analogues of the fungicidal naturally occurring respiration inhibitors crocacins A and D, and an inhibitor binding model to the mammalian cytochrome bc(1) complex was constructed. Simplified analogues were made which sh...

    journal_title:Bioorganic & medicinal chemistry

    pub_type: 杂志文章

    doi:10.1016/j.bmc.2008.10.030

    authors: Crowley PJ,Berry EA,Cromartie T,Daldal F,Godfrey CR,Lee DW,Phillips JE,Taylor A,Viner R

    更新日期:2008-12-15 00:00:00

  • Synthesis and evaluation of novel modified γ-lactam prostanoids as EP4 subtype-selective agonists.

    abstract::To identify chemically and metabolically stable subtype-selective EP4 agonists, design and synthesis of a series of modified γ-lactam prostanoids has been continued. Prostanoids bearing 2-oxo-1,3-oxazolidine, 2-oxo-1,3-thiazolidine and 5-thioxopyrrolidine as a surrogate for the γ-hydroxycyclopentanone without a troubl...

    journal_title:Bioorganic & medicinal chemistry

    pub_type: 杂志文章

    doi:10.1016/j.bmc.2011.12.009

    authors: Kambe T,Maruyama T,Nagase T,Ogawa S,Minamoto C,Sakata K,Maruyama T,Nakai H,Toda M

    更新日期:2012-01-15 00:00:00

  • Trypanocidal activity of new 1,6-diphenyl-1H-pyrazolo[3,4-b]pyridine derivatives: Synthesis, in vitro and in vivo studies.

    abstract::Despite the serious public health problems caused by Chagas disease in several countries, the available therapy remains with only two drugs that are poorly active during the chronic phase of the disease in addition to having severe side effects. In search of new trypanocidal agents, herein we describe the synthesis an...

    journal_title:Bioorganic & medicinal chemistry

    pub_type: 杂志文章

    doi:10.1016/j.bmc.2020.115855

    authors: Ribeiro JLS,Soares JCAV,Portapilla GB,Providello MV,Lima CHS,Muri EMF,de Albuquerque S,Dias LRS

    更新日期:2021-01-01 00:00:00

  • Flavonoids as noncompetitive inhibitors of Dengue virus NS2B-NS3 protease: inhibition kinetics and docking studies.

    abstract::NS2B-NS3 is a serine protease of the Dengue virus considered a key target in the search for new antiviral drugs. In this study flavonoids were found to be inhibitors of NS2B-NS3 proteases of the Dengue virus serotypes 2 and 3 with IC50 values ranging from 15 to 44 μM. Agathisflavone (1) and myricetin (4) turned out to...

    journal_title:Bioorganic & medicinal chemistry

    pub_type: 杂志文章

    doi:10.1016/j.bmc.2014.12.015

    authors: de Sousa LR,Wu H,Nebo L,Fernandes JB,da Silva MF,Kiefer W,Kanitz M,Bodem J,Diederich WE,Schirmeister T,Vieira PC

    更新日期:2015-02-01 00:00:00

  • Synergistic reduction of HIV-1 infectivity by 5-azacytidine and inhibitors of ribonucleotide reductase.

    abstract::Although many compounds have been approved for the treatment of human immunodeficiency type-1 (HIV-1) infection, additional anti-HIV-1 drugs (particularly those belonging to new drug classes) are still needed due to issues such as long-term drug-associated toxicities, transmission of drug-resistant variants, and devel...

    journal_title:Bioorganic & medicinal chemistry

    pub_type: 杂志文章

    doi:10.1016/j.bmc.2016.03.052

    authors: Rawson JM,Roth ME,Xie J,Daly MB,Clouser CL,Landman SR,Reilly CS,Bonnac L,Kim B,Patterson SE,Mansky LM

    更新日期:2016-06-01 00:00:00

  • Studies on phenothiazines: New microtubule-interacting compounds with phenothiazine A-ring as potent antineoplastic agents.

    abstract::New phenothiazine derivatives 6-20 have been designed, synthesized and evaluated in vitro for their ability to inhibit tubulin polymerization and antiproliferative activity against 60 cancer cell lines, including several multi-drug resistant (MDR) tumor cell lines. The phenothiazine unit may successfully replace the c...

    journal_title:Bioorganic & medicinal chemistry

    pub_type: 杂志文章

    doi:10.1016/j.bmc.2016.04.001

    authors: Ghinet A,Moise IM,Rigo B,Homerin G,Farce A,Dubois J,Bîcu E

    更新日期:2016-05-15 00:00:00

  • Cyclic MOG35-55 ameliorates clinical and neuropathological features of experimental autoimmune encephalomyelitis.

    abstract::EAE is induced to susceptible mice using linear peptides of myelin proteins of the central nervous system. Specific peptide motifs within the peptide-binding groove of the MHC peptide-complex determines the affinity of the peptide in each animal and the consequent T-cell receptor recognition and activation of the cell...

    journal_title:Bioorganic & medicinal chemistry

    pub_type: 杂志文章

    doi:10.1016/j.bmc.2017.06.005

    authors: Lourbopoulos A,Deraos G,Matsoukas MT,Touloumi O,Giannakopoulou A,Kalbacher H,Grigoriadis N,Apostolopoulos V,Matsoukas J

    更新日期:2017-08-01 00:00:00

  • Studies on 3'-quaternary ammonium cephalosporins--IV. Synthesis and antibacterial activity of 3'-(2-alkyl-3-aminopyrazolium) cephalosporins related to FK037.

    abstract::The synthesis and in vitro antibacterial activity of 7 beta-[(Z)-2-(2-aminothiazol-4-yl)-2-methoxyiminoacetamido] cephalosporins bearing various 2-alkyl-3-aminopyrazolium groups at the 3-position are described. Antibacterial activity against MRSA was affected by the nature of the substituent at the 2-position on the 3...

    journal_title:Bioorganic & medicinal chemistry

    pub_type: 杂志文章

    doi:10.1016/s0968-0896(97)00092-8

    authors: Ohki H,Kawabata K,Inamoto Y,Okuda S,Kamimura T,Sakane K

    更新日期:1997-08-01 00:00:00

  • Synthesis and biological evaluation of Aspergillomarasmine A derivatives as novel NDM-1 inhibitor to overcome antibiotics resistance.

    abstract::The β-lactam antibiotic resistance of Gram-negative bacteria has shown to be a critical global health problem. One of the primary reasons for the drug resistance is the existence of β-lactamases especially metallo-β-lactamases such as New Delhi metallo-β-lactamase (NDM-1) and Verona Integron-encoded metallo-β-lactamas...

    journal_title:Bioorganic & medicinal chemistry

    pub_type: 杂志文章

    doi:10.1016/j.bmc.2017.07.025

    authors: Zhang J,Wang S,Wei Q,Guo Q,Bai Y,Yang S,Song F,Zhang L,Lei X

    更新日期:2017-10-01 00:00:00

  • Synthesis and structure–activity relationships of small molecule inhibitors of the simian virus 40 T antigen oncoprotein, an anti-polyomaviral target.

    abstract::Polyomavirus infections are common and relatively benign in the general human population but can become pathogenic in immunosuppressed patients. Because most treatments for polyomavirusassociated diseases nonspecifically target DNA replication, existing treatments for polyomavirus infection possess undesirable side ef...

    journal_title:Bioorganic & medicinal chemistry

    pub_type: 杂志文章

    doi:10.1016/j.bmc.2014.09.019

    authors: Ireland AW,Gobillot TA,Gupta T,Seguin SP,Liang M,Resnick L,Goldberg MT,Manos-Turvey A,Pipas JM,Wipf P,Brodsky JL

    更新日期:2014-11-15 00:00:00

  • Astersedifolioside A-C, three new oleane-type saponins with antiproliferative activity.

    abstract::A phytochemical analysis of Aster sedifolius has led to the isolation of three novel triterpenoid saponins, based on an oleane-type skeleton and named astersedifolioside A (1), B (2) and C (3). On the basis of chemical, and 2D NMR and mass spectrometry data, the structures of the new compounds were elucidated as 3-O-[...

    journal_title:Bioorganic & medicinal chemistry

    pub_type: 杂志文章

    doi:10.1016/j.bmc.2004.06.042

    authors: Corea G,Iorizzi M,Lanzotti V,Cammareri M,Conicella C,Laezza C,Bifulco M

    更新日期:2004-09-15 00:00:00

  • Chiral resolution of serial potent and selective σ1 ligands and biological evaluation of (-)-[18F]TZ3108 in rodent and the nonhuman primate brain.

    abstract::Twelve optically pure enantiomers were obtained using either crystallization or chiral high performance liquid chromatography (HPLC) separation methodologies to resolve six racemic sigma-1 (σ1) receptor ligands. The in vitro binding affinities of each enantiomer for σ1, σ2 receptors and vesicular acetylcholine transpo...

    journal_title:Bioorganic & medicinal chemistry

    pub_type: 杂志文章

    doi:10.1016/j.bmc.2017.01.017

    authors: Yue X,Jin H,Luo Z,Liu H,Zhang X,McSpadden ED,Tian L,Flores HP,Perlmutter JS,Parsons SM,Tu Z

    更新日期:2017-02-15 00:00:00

  • A credit-card library approach for disrupting protein-protein interactions.

    abstract::Protein-protein interfaces are prominent in many therapeutically important targets. Using small organic molecules to disrupt protein-protein interactions is a current challenge in chemical biology. An important example of protein-protein interactions is provided by the Myc protein, which is frequently deregulated in h...

    journal_title:Bioorganic & medicinal chemistry

    pub_type: 杂志文章

    doi:10.1016/j.bmc.2005.11.052

    authors: Xu Y,Shi J,Yamamoto N,Moss JA,Vogt PK,Janda KD

    更新日期:2006-04-15 00:00:00