Phytochemical Characterization, Antioxidant Activity, and Cytotoxicity of Methanolic Leaf Extract of Chlorophytum Comosum (Green Type) (Thunb.) Jacq.

Chlorophytum genus has been extensively studied due to its diverse biological activities. We evaluated the methanolic extract of leaves of Chlorophytum comosum (Green type) (Thunb.) Jacques, the species that is less studied compared to C. borivilianum. The aim was to identify phytoconstituents of the methanolic extract of leaves of C. comosum and biological properties of its different fractions. Water fraction was analyzed with matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry. Nineteen compounds belonging to different chemical classes were identified in the methanolic extract of leaves of C. comosum (Green type) (Thunb.) Jacques. In addition to several fatty acids, isoprenoid and steroid compounds were found among the most abundant constituents. One of the identified compounds, 4'-methylphenyl-1C-sulfonyl-ß-d-galactoside, was not detected earlier in Chlorophytum extracts. The water fraction was toxic to HeLa cells but not to Vero cells. Our data demonstrate that methanolic extract of leaves of C. comosum can be a valuable source of bioactive constituents. The water fraction of the extract exhibited promising antitumor potential based on a high ratio of HeLa vs. Vero cytotoxicity.

Novel Type of Tetranitrosyl Iron Salt: Synthesis, Structure and Antibacterial Activity of Complex [FeL'2(NO)2][FeL'L"(NO)2] with L'-thiobenzamide and L"-thiosulfate.

In this work a new donor of nitric oxide (NO) with antibacterial properties, namely nitrosyl iron complex of [Fe(C6H5C-SNH2)2(NO)2][Fe(C6H5C-SNH2)(S2O3)(NO)2] composition (complex I), has been synthesized and studied. Complex I was produced by the reduction of the aqueous solution of [Fe2(S2O3)2(NO)2]2- dianion by the thiosulfate, with the further treatment of the mixture by the acidified alcohol solution of thiobenzamide. Based on the structural study of I (X-ray analysis, quantum chemical calculations by NBO and QTAIM methods in the frame of DFT), the data were obtained on the presence of the NO…NO interactions, which stabilize the DNIC dimer in the solid phase. The conformation properties, electronic structure and free energies of complex I hydration were studied using B3LYP functional and the set of 6-31 + G(d,p) basis functions. The effect of an aquatic surrounding was taken into account in the frame of a polarized continuous model (PCM). The NO-donating activity of complex I was studied by the amperometry method using an "amiNO-700" sensor electrode of the "inNO Nitric Oxide Measuring System". The antibacterial activity of I was studied on gram-negative (Escherichia coli) and gram-positive (Micrococcus luteus) bacteria. Cytotoxicity was studied using Vero cells. Complex I was found to exhibit antibacterial activity comparable to that of antibiotics, and moderate toxicity to Vero cells.

A Novel Approach to the Synthesis of 1,3,4-Thiadiazole-2-amine Derivatives.

The main purpose of the study was the development of a new method for synthesis of 1,3,4-thiadiazol-2-amine derivatives in a one-pot manner using the reaction between a thiosemicarbazide and carboxylic acid without toxic additives such as POCl3 or SOCl2. The reaction was investigated in the presence of polyphosphate ester (PPE). It was found that, in the presence of PPE, the reaction between the thiosemicarbazide and carboxylic acid proceeds in one-pot through three steps with the formation of corresponding 2-amino-1,3,4-thiadiazole. Using the developed approach five, 2-amino-1,3,4-thiadiazoles were synthesized. The structures of all compounds were proven by mass spectrometry, IR, and NMR spectroscopies.

Nuclear factor YY1 inhibits transforming growth factor beta- and bone morphogenetic protein-induced cell differentiation.

Smad proteins transduce transforming growth factor beta (TGF-beta) and bone morphogenetic protein (BMP) signals that regulate cell growth and differentiation. We have identified YY1, a transcription factor that positively or negatively regulates transcription of many genes, as a novel Smad-interacting protein. YY1 represses the induction of immediate-early genes to TGF-beta and BMP, such as the plasminogen activator inhibitor 1 gene (PAI-1) and the inhibitor of differentiation/inhibitor of DNA binding 1 gene (Id-1). YY1 inhibits binding of Smads to their cognate DNA elements in vitro and blocks Smad recruitment to the Smad-binding element-rich region of the PAI-1 promoter in vivo. YY1 interacts with the conserved N-terminal Mad homology 1 domain of Smad4 and to a lesser extent with Smad1, Smad2, and Smad3. The YY1 zinc finger domain mediates the association with Smads and is necessary for the repressive effect of YY1 on Smad transcriptional activity. Moreover, downregulation of endogenous YY1 by antisense and small interfering RNA strategies results in enhanced transcriptional responses to TGF-beta or BMP. Ectopic expression of YY1 inhibits, while knockdown of endogenous YY1 enhances, TGF-beta- and BMP-induced cell differentiation. In contrast, overexpression or knockdown of YY1 does not affect growth inhibition induced by TGF-beta or BMP. Accordingly, YY1 does not interfere with the regulation of immediate-early genes involved in the TGF-beta growth-inhibitory response, the cell cycle inhibitors p15 and p21, and the proto-oncogene c-myc. In conclusion, YY1 represses Smad transcriptional activities in a gene-specific manner and thus regulates cell differentiation induced by TGF-beta superfamily pathways.

Two forms of the nuclear matrix-bound p53 protein in HEK293 cells.

Like many other transcription factors, the tumor suppressor protein p53 is bound to the nuclear matrix (NM). To study the interaction of p53 with the NM in more detail, we used alkaline and acidic extractions of NM proteins. It was found that there are two forms of p53, alkali- and acid-soluble, in NM of HEK293 cells and only one alkali-soluble form in NM of actinomycin D-treated MCF-7 cells. We suggest that distinct forms of p53 differ either in interactions with NM proteins or in their charges.

YY1 inhibits the activation of the p53 tumor suppressor in response to genotoxic stress.

The tumor suppressor p53 regulates cell-cycle progression and apoptosis in response to genotoxic stress, and inactivation of p53 is a common feature of cancer cells. The levels and activity of p53 are tightly regulated by posttranslational modifications, including phosphorylation, ubiquitination, and acetylation. Here, we demonstrate that the transcription factor Yin Yang 1 (YY1) interacts with p53 and inhibits its transcriptional activity. We show that YY1 disrupts the interaction between p53 and the coactivator p300 and that expression of YY1 blocks p300-dependent acetylation and stabilization of p53. Furthermore, expression of YY1 inhibits the accumulation of p53 and the induction of p53 target genes in response to genotoxic stress. YY1 also interacts with Mdm2 and the expression of YY1 promotes the assembly of the p53-Mdm2 complex. Consequently, YY1 enhances Mdm2-mediated ubiquitination of p53. Inactivation of endogenous YY1 enhances the accumulation of p53 as well as the expression of p53 target genes in response to DNA damage, and it sensitizes cells to DNA damage-induced apoptosis. Hence, our results demonstrate that YY1 regulates the transcriptional activity, acetylation, ubiquitination, and stability of p53 by inhibiting its interaction with the coactivator p300 and by enhancing its interaction with the negative regulator Mdm2. YY1 may, therefore, be an important negative regulator of the p53 tumor suppressor in response to genotoxic stress.