ABSTRACT
Nano-sized rare earth europium [Eu(III)]-benzoic acid [HL] luminescent complex powders have been synthesized in polyvinylpyrrolidone matrix by precipitation method. The chemical constitution of the complex has been demonstrated as PVP/EuL3 by a combination of elemental analysis, inductively coupled plasma-atomic emission spectroscopy (ICP-AES) and fourier-transform infrared spectroscopy (FT-IR). X-ray diffraction analysis (XRD) and scanning electron microscopy (SEM) have shown that the complex is a new nanocrystal whose structure is totally different from the ligand. Thermogravimetric/Differential thermal analysis (TG/DTA) have indicated that the luminescent complex is thermally stable below 500 degrees C. Photoluminescence spectra (PL) have shown that the nanocomplex can emit Eu3+ characteristic red fluorescence under ultraviolet excitation.
ABSTRACT
The purpose of this study was to explore the anti-leukemia effect of quercetin and kaempferol and its mechanism. The HL-60 cells were used as the leukemia models. The inhibitory effects of quercetin and kaempferol on growth of HL-60 cells was assessed by MTT assay. The effect of quercetin and kaempferol on cell cycle in HL-60 cells was detected by flow cytometry. The cytotoxic effect of these 2 drugs was analysed by single cell electrophoresis assay. Western blot analysis was used to study the apoptotic mechanism of HL-60 cells. The results showed that the quercetin and kaempferol had a significant anti-leukemia effect in vitro. The proliferation of HL-60 cells was significantly inhibited in dose-and time-dependent manners after treating with quercetin (r = 0.77) and kaempferol (r = 0.76) respectively, and the cytotoxicity of quercetin was superior to that of kaempferol. The quercetin and kaempferol induced G(2)/M arrest and apoptosis of HL-60 cells. The quercetin and kaempferol could down-regulate the survivin expression. It is concluded that the quercetin and kaempferol have significant anti-leukemia effect in vitro. Furthermore the apoptosis-inducing effect of quercetin is stronger than that of kaempferol, both of which induce apoptosis of HL-60 cells through depressing cell growth, arresting cell cycle and inhibiting expression of survivin.
Subject(s)
Apoptosis/drug effects , Kaempferols/pharmacology , Quercetin/pharmacology , Cell Cycle/drug effects , Cell Proliferation/drug effects , Gene Expression Regulation, Leukemic , HL-60 Cells , Humans , Inhibitor of Apoptosis Proteins/metabolism , SurvivinABSTRACT
Ricin A-chain can inactivate eukaryotic ribosomes, but exhibits no N-glycosidase activity on intact E. coli ribosomes. In the present research, in order to avoid using radiolabeled oligoribonucleotides, two kinds of synthetic 5'-FAM fluorescence-labeled oligoribonucleotide substrates were used to mimic the sarcin/ricin domains of rat 28S rRNA and E. coli 23S rRNA (32mer and 25mer, named as Rat FAM-SRD and E. coli FAM-SRD, respectively). Ricin A-chain was able to specifically release adenine from the first adenosine of the GAGA tetraloop and exhibited specific N-glycosidase activity under neutral and weak acidic conditions with both substrates. However, under more acidic conditions, ricin A-chain was able to release purines from other sites on eukaryotic substrates, but it retained specific depurination activity on prokaryotic substrates. At pH 5.0, the Michaelis constant (K(m)) for the reaction with Rat FAM-SRD (4.57+/-0.28microM) corresponded to that with E. coli FAM-SRD (4.64+/-0.26microM). However, the maximum velocity (V(max)) for ricin A-chain with Rat FAM-SRD was 0.5+/-0.024microM/min, which is higher than that with E. coli FAM-SRD (0.32+/-0.011microM/min).
