Cytotoxicity in vitro, cellular uptake, localization and apoptotic mechanism studies induced by ruthenium(II) complex.

Ruthenium-based complexes have been regarded as one of the most potential metal-based candidates for anticancer therapy. Herein, two ruthenium (II) methylimidazole complexes [Ru(MeIm)4(4npip)]2+ (complex 1) and [Ru(MeIm)4(4mopip)]2+ (complex 2) were synthesized and evaluated for their in vitro anticancer activities. The results showed that these ruthenium (II) methylimidazole complexes exhibited moderate antitumor activity comparable with cisplatin against A549, NCI-H460, MCF-7 and HepG2 human cancer cells, but with less toxicity to a human normal cell line HBE. Intracellular distribution studies suggested that complex 2 selectively localized in the mitochondria. Mechanism studies indicated that complex 2 caused cell cycle arrest at G0/G1 phase by regulating cell cycle relative proteins and induced apoptosis through intrinsic pathway, which involved mitochondrial dysfunction, reactive oxygen species (ROS) accumulation and ROS-mediated DNA damage. Further, studies by western blotting suggested that MAPK and AKT signaling pathways were involved in complex 2-induced apoptosis, and they were regulated by the level of ROS. Overall, these findings suggested that complex 2 could be a candidate for further evaluation as a chemotherapeutic agent in the treatment of cancers.

Ruthenium(II) salicylate complexes inducing ROS-mediated apoptosis by targeting thioredoxin reductase.

Thioredoxin reductase (TrxR), a major component of the thioredoxin system, makes a critical role in regulating cellular redox signaling and is found to be overexpressed in many human cancer cells. TrxR has become an attractive target for anticancer agents. In this work, three Ru(II) complexes with salicylate as ligand, [Ru(phen)2(SA)] (phen = 1,10-phenanthroline, SA = salicylate, 1), [Ru(dmb)2(SA)] (dmb = 4,4'-dimethyl-2,2'-bipyridine, 2) and [Ru(bpy)2(SA)] (bpy = 2,2'-bipyridine, 3), were synthesized and characterized. The anticancer effect exerted by them was evaluated. Complex 1 was found to exhibit obvious anticancer activity, in comparison with cisplatin, against cancer cell lines, while displaying low toxicity to the normal cell line BEAS-2B. The mechanism of complex 1 cancer cell growth suppress was investigated in A549 cells. Complex 1 exerted its anticancer through inducing apoptosis and triggering cell cycle arrest at the G0/G1 phase. Complex 1 can selectively inhibit TrxR activity and thus promote the generation and accumulation of reactive oxygen species (ROS), which subsequently trigger mitochondrial dysfunction and DNA damage, activate oxidative stress-sensitive mitogen activated protein kinase (MAPK), and suppress the protein kinase B (PKB or AKT) signal pathway, resulting in apoptosis in A549 cells.

[Extraction and analysis of gracilaria gigas Harvey polysaccharides].

Gracilaria Gigas Harvey Polysaccharides (GHPS) were extracted with hot water and sedimentated with ethanol. The amount of polysaccharides was determined by phenol-H2SO4 method. The mineral elements and molecular configuration were analysed by inductively coupled plasma (ICP) and infrared absorption spectrum (IR). The rate of distillation was 14.98%, the amount of polysaccharides was 78.2%, and GHPS contained manifold mineral elements (Ca, Fe, Mg and S). The IR spectra manifested that the extraction was a compound of polysaccharides, i.e. acidic polysaccharides.

The induction of autophagy against mitochondria-mediated apoptosis in lung cancer cells by a ruthenium (II) imidazole complex.

In the present study, it was found that the ruthenium (II) imidazole complex [Ru(Im)4(dppz)]2+ (Ru1) could induce significant growth inhibition and apoptosis in A549 and NCI-H460 cells. Apart from the induction of apoptosis, it was reported for the first time that Ru1 induced an autophagic response in A549 and NCI-H460 cells as evidenced by the formation of autophagosomes, acidic vesicular organelles (AVOs), and the up-regulation of LC3-II. Furthermore, scavenging of reactive oxygen species (ROS) by antioxidant NAC or Tiron inhibited the release of cytochrome c, caspase-3 activity, and eventually rescued cancer cells from Ru1-mediated apoptosis, suggesting that Ru1 inducing apoptosis was partially caspase 3-dependent by triggering ROS-mediated mitochondrial dysfunction in A549 and NCI-H460 cells. Further study indicated that the extracellular signal-regulated kinase (ERK) signaling pathway was involved in Ru1-induced autophagy in A549 and NCI-H460 cells. Moreover, blocking autophagy using pharmacological inhibitors 3-methyladenine (3-MA) and chloroquine (CQ) enhanced Ru1-induced apoptosis, indicating the cytoprotective role of autophagy in Ru1-treated A549 and NCI-H460 cells. Finally, the in vivo mice bearing A549 xenografts, Ru1 dosed at 10 or 20 mg/kg significantly inhibited tumor growth.

[Extraction and analysis of sargassum hemiphyllum polysaccharides].

Sargassum hemiphyllum polysaccharides (SHP) was extracted by thermal water method and the physical and chemical characters, the extraction rate, contents, compositions of SHP was studied. The result showed that SHP was ashen powder, water-soluble, insoluble in organic solvents. The reaction of iodide-potassium iodide was negative to evaluate that SHP was nonstarch polysaccharides. Extraction rate was 7.04% and the content of polysaccharides was 82.9%. Ultraviolet spectrum showed that there were little DNA and protein. Infrared spectroscopy showed that SHP was main pyrano polysaccharides and had beta-linked glycopolysaccharides in molecule structure of SHP. Thin layer chromatography traced that SHP could be xylan. The results indicated that the extract was not only polysaccharides but also higher purity and the method was high efficiency.