Effect of pluronic acid F-127 on the toxicity towards eukaryotic cells of CSA-13, a cationic steroid analogue of antimicrobial peptides

Aims: CSA‐13 is an antimicrobial cationic steroid with some toxicity against eukaryotic cells. The purpose of this work was to test whether pluronic acid F‐127 could interfere with the toxicity of CSA‐13 on human umbilical vein endothelial (HUVEC) without modifying its bactericidal activity against Pseudomonas aeruginosa. Methods and Results: The addition of pluronic acid F‐127 slightly decreased the number of dead cells after exposure to CSA‐13. Pluronic acid F‐127 blocked the permeabilizing effect of CSA‐13 on the plasma membrane of HUVEC (uptake of ethidium bromide, release of lactate dehydrogenase) without modifying its toxic effect on their mitochondrial function (MTT test, uptake of tetramethyl rhodamine ethyl ester). Conclusion: Pluronic acid F‐127 decreased the toxicity of CSA‐13 against eukaryotic cells without completely protecting them from mitochondrial damage at high concentrations of the drug. Significance and Impact of the Study: This work establishes that studies on the toxic effects of synthetic antimicrobials on eukaryotic cells should not only focus on the permeability of the plasma membrane but also on the integrity of the mitochondria.     

弯蕊开口箭中的多羟基甾体皂甙元

从弯蕊开口箭(Tupistra wattii Hook. f.)的新鲜根茎中分离出2个新的多羟基甾体皂甙元,分别命名为弯蕊皂甙元B (wattigenin B) (1) 和弯蕊皂甙元C (wattigenin C) (2), 同时分离到2个已知的甾体皂甙元--凯替皂甙元kitigenin (3)和铃兰皂甙元B (convallagenin B) (4).通过波谱解析鉴定了这4个皂甙元的结构,并测定了它们在体外对肿瘤细胞K562和A2780a的细胞毒活性.化合物1～4为首次从该种植物中分离得到.     

4-Deoxyraputindole C induces cell death and cell cycle arrest in tumor cell lines

Several molecules extracted from natural products exhibit different biological activities, such as ion channel modulation, activation of signaling pathways, and anti-inflammatory or antitumor activity. In this study, we tested the antitumor ability of natural compounds extracted from the Raputia praetermissa plant. Among the compounds tested, an alkaloid, here called compound S4 (4-Deoxyraputindole C), showed antitumor effects against human tumor lineages. Compound S4 was the most active against Raji, a lymphoma lineage, promoting cell death with characteristics that including membrane permeabilization, dissipation of the mitochondrial potential, increased superoxide production, and lysosomal membrane permeabilization. The use of cell death inhibitors such as Z-VAD-FMK (caspase inhibitor), necrostatin-1 (receptor-interacting serine/threonine-protein kinase 1 inhibitor), E-64 (cysteine peptidases inhibitor), and N-acetyl- L -cysteine (antioxidant) did not decrease compound S4-dependent cell death. Additionally, we tested the effect of cellular activity on adherent human tumor cells. The highest reduction of cellular activity was observed in A549 cells, a lung carcinoma lineage. In this lineage, the effect on the reduction of the cellular activity was due to cell cycle arrest, without plasma membrane permeabilization, loss of the mitochondrial potential or lysosomal membrane permeabilization. Compound S4 was able to inhibit cathepsin B and L by a nonlinear competitive (negative co-operativity) and simple-linear competitive inhibitions, respectively. The potency of inhibition was higher against cathepsin L. Compound S4 promoted cell cycle arrest at G ₀ and G ₂ phase, and increase the expression of p16 and p21 proteins. In conclusion, compound S4 is an interesting molecule against cancer, promoting cell death in the human lymphoma lineage Raji and cell cycle arrest in the human lung carcinoma lineage A549.     

Virulizin, a novel immunotherapy agent, activates NK cells through induction of IL-12 expression in macrophages

Virulizin, a novel biological response modifier, has demonstrated significant antitumor efficacy in a variety of human tumor xenograft models including melanoma, pancreatic cancer, breast cancer, ovarian cancer and prostate cancer. The significant role of macrophages and NK (Natural killer) cells was implicated in the antitumor mechanism of Virulizin where expansion as well as increased activity of macrophages and NK cells were observed in mice treated with Virulizin. Depletion of macrophages compromised Virulizin-induced NK1.1⁺ cell infiltration into xenografted tumors and was accompanied by reduced antitumor efficacy. In the present study, involvement of macrophages in NK cell activation was investigated further. We found that depletion of NK cells in CD-1 nude mice by anti-ASGM1 antibody significantly compromised the antitumor activity of Virulizin. Cytotoxicity of NK cells isolated from Virulizin-treated mice was enhanced against NK-sensitive YAC-1 cells and C8161 human melanoma cells, but not against NK-insensitive P815 cells. An increased level of IL-12 was observed in the serum of mice treated with Virulizin. IL-12 mRNA and protein levels were also increased in peritoneal macrophages isolated from Virulizin-treated mice. Moreover, Virulizin-induced cytotoxic activity of NK cells isolated from the spleen was abolished when an IL-12 neutralizing antibody was co-administered. In addition, depletion of macrophages in mice significantly impaired Virulizin-induced NK cell cytotoxicty. Taken together, the results suggest that Virulizin induces macrophage IL-12 production, which in turn stimulates NK cell-mediated antitumor activity.     

Design,Synthesis, and Cytotoxic Activities of Indole and Indazole-Based Stilbenes

To develop new highly effective anticancer agents derived from naturally occurring stilbene scaffold, in total of 24 indole and indazole-based stilbenes including 17 new compounds were designed according to molecular hybridization strategy and synthesized via Witting reaction. The cytotoxic screening results against human tumor cell lines (K562 cells and MDA-MB-231 cells) showed that indole and indazole-based stilbenes are of great interest for developing anticancer agents as eight derivatives possessed strong antiproliferative activities with IC₅₀ values less than 10 μM, and those synthetic derivatives displayed more higher cytotoxicities against K562 cells than MDA-MB-231 cells. In particular, indole-based stilbene bearing piperidine exhibited the most potent cytotoxicities against both K562 and MDA-MB-231 cells with IC₅₀ values 2.4 μM and 2.18 μM, respectively, along with a remarkable selectivity towards human normal L-02 cells. Together, the results suggested that indole and indazole-based stilbenes are promising anticancer scaffolds worthy of further investigation.     

Nanoparticulate drug delivery systems for cancer chemotherapy

Abstract

Nanoparticles (NPs) are, in general, colloidal particles, less than 1000 nm, that can be used for better drug delivery and prepared either by encapsulating the drug within a vesicle and or by dispersing the drug molecules within a matrix. Nanoparticulate drug delivery systems have been extensively studied in recent years for spatial and temporal delivery, especially in tumour and brain targeting. NPs have great promise for better drug delivery as found in both pharmaceutical and clinical research. As a drug carrier, NPs have significant advantages like better bioavailability, systemic stability, high drug loading, long blood circulation time and selective distribution in the organs/tissues with longer half life. The selective targeting of NPs can be achieved by the enhanced permeability and retention effect (EPR-effect), attaching specific ligands, or by making selective distribution due to change of the physiological conditions of specific systems like nature, pH, temperature, etc. It has been observed that drug-loaded NPs can have selective distribution to organs/tissues using different types of and proportions of polymers. The current aim of researchers is to prepare NPs that are long-lived with and that demonstrate the appropriate selective distribution for better therapy and thus improved clinical outcomes. Nanoparticulate drug delivery systems have the potential to deliver a drug to the target site with specificity and to maintain the desired concentration at the site for the intended time without untoward effects. In this review article, the methods for the preparation of NPs, their characterization, biodistribution, and pharmacokinetic characteristics are discussed.     

Caesalpanins A–C,Three Dimeric Cassane Diterpenoids from the Seeds of Caesalpinia sappan L.

Three dimeric cassane diterpenoids, caesalpanins A–C, were isolated from the seeds of Caesalpinia sappan L., as well as three known compounds. Their structures were determined via analysis of 1D‐, 2D‐NMR, and HR‐ESI‐MS data. Caesalpanins A and B were the second and third compounds that presented a nitrogen‐containing cassane diterpenoid dimer linked through one ether bond between C‐19 and C‐20′. Caesalpanin B exhibited moderate cytotoxic activity against MCF‐7 cell lines with IC₅₀ value of 29.98 μm . Caesalpanins A and B had weak inhibitory effects against LPS‐induced nitric oxide (NO) production in RAW 264.7 macrophages at 50 μm with inhibitory rate of 36.01 % and 32.93 %, respectively.     

Chondrocyte-specific phenotype confers susceptibility of rat chondrocytes to lysis by NK cells

Normal chondrocytes are targets for natural killer (NK) cells. Since the mechanism of this phenomenon remains unknown, the present study was aimed at testing whether it is associated with chondrocyte-specific phenotype defined as ability of cartilage cells to produce sulfated glycosaminoglycans (GAG) and express collagen II and aggrecan mRNA. Lysis of rat epiphyseal chondrocytes by syngeneic spleen mononuclear cells (SMCs) was evaluated by ⁵¹Cr-release assay. Loss of chondrocyte phenotype following long-term culture resulted in their decreased susceptibility to lysis. Similar effect was also observed after suppression of chondrocyte phenotype by TNF. On the other hand, stimulation of cartilage-specific matrix component synthesis by IGF-1 resulted in increased chondrocyte killing and exogenous chondroitin sulfate A stimulated NK cell-mediated cytotoxicity against chondrocytes and human K562 cells. This suggests that chondrocyte susceptibility to lysis by NK cells depends on chondrocyte-specific phenotype, especially sulfated GAG production.     

The regulation of ionic nickel uptake and cytotoxicity by specific amino acids and serum components

The effects of serum components and amino acids on the uptake and cytotoxicity of NiCl₂ were examined in cultured Chinese hamster ovary (CHO) cells. CHO cells maintained in a minimal salts/glucose medium accumulated 10-fold more⁶³Ni than did cells maintained in complete medium supplemented with 10% fetal bovine serum. Cell-surface binding of⁶³Ni appeared to account for the majority of this increased accumulation of cell-associated nickel observed in the simple maintenance medium since such increases were reduced 70% by trypsin treatment. The addition of the Ni²⁺-binding amino acids cysteine or histidine to the salts/glucose medium markedly decreased⁶³Ni accumulations, an effect not observed following addition of any of several amino acids that do not bind Ni²⁺. Supplementation of the salts/glucose medium with fetal bovine serum decreased in a concentration dependent fashion both the⁶³Ni²⁺ uptake and cell detachment caused by Ni²⁺, while dialyzed (amino acid-free) serum was 3–5-fold less effective than undialyzed serum at reducing⁶³Ni²⁺ uptake and similarly exhibited only a slight protective effect against nickel-induced cytotoxicity. Supplementation of dialyzed serum with cysteine at levels approximating those in whole serum partially restored its inhibitory activity toward nickel uptake by cells and restored completely its inhibition of nickel's cytotoxicity, indicating the predominant role of specific amino acids over serum proteins in regulating the uptake and subsequent cytotoxicity of Ni²⁺. Addition of cysteine to the salts/glucose medium during a 2 h exposure of cells to either 100 μM HgCl₂ or 1 mM NiCl₂ masked the cytotoxic effects of these metal ions. These results demonstrate the importance of extracellular small molecular weight metal ion chelators in altering the biological effects of metal ions at the level of metal uptake.