Comparable susceptibilities of human 293 cells and insect Tn-5B1-4 cells to photoactivated alpha-terthienyl

Exposure to emamectin benzoate confers cytotoxic effects on human molt-4 T-cells and possible ameliorative role of vitamin E and dithiothreitol

Emamectin benzoate (EMB) is an avermectin insecticide that is extensively used for pest control, but there are few reports concerning its cytotoxic effects on human lymphocytes. In the current study, the hematotoxicity of EMB was evaluated in Molt-4 T-cells, a human T-lymphoblastic cell line with high motility, and the role of vitamin E (VitE) and dithiothreitol (DTT) in attenuating EMB cytotoxicity was characterized. Exposure of Molt-4 cells to EMB decreased cell viability and proliferation, induced a loss of cell clusters, and significantly increased membrane collapse and chromatin condensation. Moreover, EMB significantly increased cell death and suppressed transglutaminase activity. EMB treatment modulated the NF-κB signaling pathway, decreased the expression of p105, p50, and p65/RelA in cytosolic and nuclear fractions, and increased nuclear IκBα expression. EMB increased oxidative stress, as demonstrated by a significant increase in the levels of reactive oxygen species (ROS). Treatment with non-cytotoxic concentrations of VitE or DTT ameliorated the hematotoxicity induced by pretreatment with EMB, increased Molt-4 cell viability, raised the IC₅₀ values of EMB, limited intracellular ROS generation, and mitigated EMB-mediated effects on NF-κB signaling. The results indicate the potential cytotoxicity of EMB on human lymphocytes, and demonstrate that VitE and DTT treatment can reduce the cytotoxic effects of EMB.

Alpha-terthienyl increases filamentous actin of Entamoeba histolytica

This study aimed to know if alpha terthienyl (α-T) affects E. histolytica viability and to analyze its effect on the actin cytoskeleton. Trophozoites of E. histolytica HM1-IMSS were treated with α-T, then, cell viability and morphology were evaluated using tetrazolium salts and scanning electron microscopy, respectively; while actin filaments (F-actin) were stained with rhodamine-phalloidin, observed by confocal microscopy and quantified by fluorometry. Data showed that α-T inhibited cell viability of trophozoites (IC₅₀, 19.43 µg / mL), affected the cell morphology, and increased the F-actin in a dose-dependent manner. Production of reactive oxygen species and RhoA-GTP levels remained normal in α-T-treated amebas. Two inhibitors that affect the organization of the trophozoites cytoskeleton, one that interacts directly with actin, Cytochalasin D (CD), and one that affects the Rho signaling pathway by inhibiting the downstream effector Rock, Y27632, were tested. Y27632 did not affect the increase of polymerized actin observed with α-T, this compound partially ameliorates the potent disrupting effects of CD on actin filaments. Docking results suggest that α-T could be an antagonist of CD for the same interaction zone in actin, however, more studies are needed to define the action mechanism of this compound.

Thiophene-Based Trimers and Their Bioapplications: An Overview

Certainly, the success of polythiophenes is due in the first place to their outstanding electronic properties and superior processability. Nevertheless, there are additional reasons that contribute to arouse the scientific interest around these materials. Among these, the large variety of chemical modifications that is possible to perform on the thiophene ring is a precious aspect. In particular, a turning point was marked by the diffusion of synthetic strategies for the preparation of terthiophenes: the vast richness of approaches today available for the easy customization of these structures allows the finetuning of their chemical, physical, and optical properties. Therefore, terthiophene derivatives have become an extremely versatile class of compounds both for direct application or for the preparation of electronic functional polymers. Moreover, their biocompatibility and ease of functionalization make them appealing for biology and medical research, as it testifies to the blossoming of studies in these fields in which they are involved. It is thus with the willingness to guide the reader through all the possibilities offered by these structures that this review elucidates the synthetic methods and describes the full chemical variety of terthiophenes and their derivatives. In the final part, an in-depth presentation of their numerous bioapplications intends to provide a complete picture of the state of the art.

Recognition of antioxidants and photosensitizers in Dyssodia pinnata by EPR spectroscopy

INTRODUCTION

Previous studies report the isolation mainly of terthiophene derivatives and flavonoids from Dyssodia species. Terthiophenes are known as photosensitizers by their capacity to generate singlet oxygen (¹ O₂ ), and flavonoid antioxidant activity is recognized. These opposite properties could represent interesting options in photodynamic therapy.

OBJECTIVE

To determine the antioxidant and photosensitizer activities of extracts and isolates of Dyssodia pinnata by electron paramagnetic resonance (EPR).

METHODOLOGY

Extracts and isolates were evaluated as antioxidants by the interactions with copper ion (Cu²⁺ ) observed in EPR, and by the 2,2-diphenyl-1-picrylhydrazyl radical (DPPH) and the thiobarbituric reactive substances (TBARS) methods. Their abilities as ¹ O₂ producers were also estimated by EPR.

RESULTS

Terthiophenes were obtained from hexane (DPH) and acetone (DPA) extracts, and flavonoids from DPA and methanol (DPM) extracts. The interaction with Cu²⁺ of extracts and isolated compounds of Dyssodia pinnata showed two effects in EPR: reduction and chelation; flavonoids exhibited both effects, while terthiophenes showed only reduction. DPA, DPM, and flavonoids were active in DPPH and TBARS assays. Quercetagetin-7-O-β-glucoside showed the highest antioxidant and chelating activities, 3-glycosidated flavonoids were less active. Upon irradiation extracts and terthiophenes induced ¹ O₂ formation.

CONCLUSION

Flavonoid reducing activity on Cu²⁺ and free radical scavenging capacity were related to the number of hydroxy groups and to the conjugation between the B and C rings. All tested flavonols showed a major complex with Cu²⁺ , with the most probable site of chelation between the 5-hydroxy and 4-oxo groups. Extracts and terthiophene derivatives showed photosensitizer activity. Thus, EPR is useful to evaluate free radical scavenging and pro-oxidant properties.

Cell death induced by α-terthienyl via reactive oxygen species-mediated mitochondrial dysfunction and oxidative stress in the midgut of Aedes aegypti larvae

α-Terthienyl (α-T) is a photosensitizer that produces many reactive oxygen species (ROS) under ultraviolet light. Here, we aimed to evaluate the oxidation mechanism of the 25%, 50%, and 75% lethal concentrations in Aedes aegypti larvae; the lethal concentration of α-T was used as the test value. The effects on mitochondria, oxidative stress, and cell death patterns caused by ROS were evaluated. The results showed that α-T mainly produced large amounts of ROS in the midgut of larvae. Moreover, mitochondrial ROS were increased in midgut cells, and the production of ROS sites, such as complex enzymes, was inhibited, resulting in enhanced production of ROS. Ultrastructural analysis of mitochondria revealed significant vacuolation, decreased activity of tricarboxylic acid cycle enzymes, and reduced ATP content and mitochondrial membrane potential in the high concentration group compared with those in the control group. Additionally, mitochondrial biosynthesis was blocked in the high concentration group. Thus, exposure to α-T disrupted mitochondrial function, although the mitochondrial DNA content may have increased because of mitochondrial self-protection mechanisms against oxidative stress. Furthermore, high concentrations of α-T aggravated oxidative stress and increased the number of intracellular oxidative damage products. Reverse transcription polymerase chain reaction and fluorescence staining showed that ROS induced by low α-T concentrations upregulated apoptotic genes, including Dronc (P < 0.05), thereby promoting apoptosis. Moderate concentrations of α-T promoted autophagy through induction of ROS, inhibited apoptosis, and induced necrosis. In contrast, high α-T concentrations induced high levels of ROS, which caused mitochondrial dysfunction and increased cytoplasmic Ca²⁺ concentration, directly inducing cell necrosis. We also found that α-T may disrupt the permeability of the peritrophic membrane, leading to intestinal barrier dysfunction. These results provided insights into the mode of action of α-T in Aedes aegypti.

Transketolase Is Identified as a Target of Herbicidal Substance α-Terthienyl by Proteomics

α-terthienyl is a natural phytotoxin isolated originally from Flaveria bidentis (L.) Kuntze. The bioassay presented here shows the strong herbicidal activity of α-terthienyl on Digitaria sanguinalis, Arabidopsis thaliana and Chlamydomonas reinhardtii. The α-terthienyl-induced response of A. thaliana at the protein level was analyzed at different times. Changes in the protein expression profiles were analyzed by two-dimensional gel electrophoresis and liquid chromatography tandem mass spectrometry (LC-MS/MS) mass spectrometry. Sixteen protein spots were identified that showed reproducible changes in the expression of at least 2-fold when compared to the control. Among these 16 spots, three were up-regulated and 13 were down-regulated. The decreased expression of several proteins associated with energy production and carbon metabolism suggested that these processes were affected by α-terthienyl. To search for the candidate proteins in this screen, A. thaliana T-DNA mutants of the candidate proteins were used to test their susceptibility to α-terthienyl. Amongst the others, attkl1, a mutant of transketolase, exhibited a significantly lower sensitivity to α-terthienyl when hit compared with Col-0. Based on the identification of the proteins associated with the response to α-terthienyl by proteomics, a candidate target protein transketolase was identified.

Phytochemical Composition and Biological Activities of Dyssodia tagetiflora Lag

While plants of the genus Dyssodia are used by man to a certain extent, few phytochemical and pharmacological studies have been performed with species of this genus. D. tagetiflora is an endemic plant of Mexico and has been used as fodder. The aim of this research was to isolate and identify the main bioactive components and evaluate the insecticidal, antioxidant, genotoxic and cytoprotective activities of D. tagetiflora. The isolated substances included an essential oil composed of six monoterpenes, and extracts containing two flavonols, three flavonol-glycosides and four thiophenes. The compounds were characterized using spectroscopic and spectrometric methods, including GC/MS, MS and NMR. The essential oil showed insecticidal activity against Drosophila melanogaster larvae. The methanolic extract of D. tagetiflora (DTME) had strong antioxidant activity against DPPH and ABTS radicals; DTME showed no evidence of genotoxic or cytotoxic effects. In contrast, DTME showed a cytoprotective effect attenuating the formation of H₂ O₂ -induced micronuclei in Vicia faba roots. This report is the first to describe the phytochemical and biological activity of D. tagetiflora.

Apoptosis of leukemia K562 and Molt-4 cells induced by emamectin benzoate involving mitochondrial membrane potential loss and intracellular Ca2+ modulation

Leukemia threatens millions of people's health and lives, and the pesticide-induced leukemia has been increasingly concerned because of the etiologic exposure. In this paper, cytotoxic effect of emamectin benzoate (EMB), an excellent natural-product insecticide, was evaluated through monitoring cell viability, cell apoptosis, mitochondrial membrane potential and intracellular Ca²⁺ concentration ([Ca²⁺]_i) in leukemia K562 and Molt-4 cells. Following the exposure to EMB, cell viability was decreased and positive apoptosis of K562 and Molt-4 cells was increased in a concentration- and time- dependent fashion. In the treatment of 10μM EMB, apoptotic cells accounted for 93.0% to K562 cells and 98.9% to Molt-4 cells based on the control, meanwhile, 63.47% of K562 cells and 81.15% of Molt-4 cells exhibited late apoptotic and necrotic features with damaged cytoplasmic membrane. 48h exposure to 10μM EMB increased significantly the great number of cells with mitochondrial membrane potential (MMP) loss, and the elevation of [Ca²⁺]_i level was peaked and persisted within 70s in K562 cells whilst 50s in Molt-4 cells. Moreover, a stronger cytotoxicity of EMB was further observed than that of imatinib. The results authenticate the efficacious effect of EMB as a potential anti-leukemia agent and an inconsistency with regard to insecticide-induced leukemia.

Antioxidative cellular response of lepidopteran ovarian cells to photoactivated alpha-terthienyl

Photodynamic sensitizers as useful alternative agents have been used for population control against insect pests, and the response of insect ovarian cells towards the photosensitizers is gaining attention because of the next reproduction. In this paper, antioxidative responses of lepidopteran ovarian Tn5B1-4 and Sf-21 cells to photoactivated alpha-terthienyl (PAT) are investigated. PAT shows positive inhibitory cytotoxicity on the two ovarian cells, and its inhibition on cell viability is enhanced as the concentrations are increased and the irradiation time is extended. Median inhibitory concentrations (IC₅₀) are 3.36μg/ml to Tn5B1-4 cells, and 3.15μg/ml to Sf-21 cells at 15min-UV-A irradiation 2h-dark incubation. Under 10.0μg/ml PAT exposure, 15min-UV-A irradiation excites higher ROS production than 5min-UV-A irradiation does in the ovarian cells, the maximum ROS content is about 7.1 times in Tn5B1-4 cells and 4.3 times in Sf-21 cells, and the maximum malondialdehyde levels in Tn5B1-4 and Sf-21 cells are about 1.47- and 1.36-fold higher than the control groups, respectively. Oxidative stress generated by PAT strongly decreases the activities of POD, SOD and CAT, and induces an accumulation of Tn5B1-4 cells in S phase and Sf-21 cells in G2/M phase in a concentration-dependent fashion. Apoptosis accumulation of Tn5B1-4 cells and the persistent post-irradiation cytotoxicity are further observed, indicating different antioxidative tolerance and arrest pattern of the two ovarian cells towards the cytotoxicity of PAT.

Antiamoebic Activity of Adenophyllum aurantium (L.) Strother and Its Effect on the Actin Cytoskeleton of Entamoeba histolytica

In Mexico, the Adenophyllum aurantium (L.) Strother plant is consumed as an infusion to treat intestinal diseases such as amoebiasis, which is an endemic health problem in Mexico and other countries. However, the effect of A. aurantium on Entamoeba histolytica, the causative agent of amoebiasis, is unknown. An aerial part methanolic extract (AaMeA), a root methanolic extract (AaMeR) and a root ethyl acetate extract (AaEaR) were tested on E. histolytica trophozoites. AaMeA and AaMeR did not show antiproliferative activity; however, AaEaR exhibited an in vitro GI50 of 230 μg/ml, and it was able to inhibit the differentiation of Entamoeba invadens trophozoites into cysts. The intraperitoneal administration of AaEaR (2.5 or 5 mg) to hamsters that were infected with E. histolytica inhibited the development of amoebic liver abscesses in 48.5 or 89.0% of the animals, respectively. Adhesion to fibronectin and erythrophagocytosis were 28.7 and 37.5% inhibited by AaEaR, respectively. An ultrastructure analysis of AaEaR-treated trophozoites shows a decrease in the number of vacuoles but no apparent cell damage. Moreover, this extract affected the actin cytoskeleton structuration, and it prevented the formation of contractile rings by mechanism(s) that were independent of reactive oxygen species and RhoA activation pathways. (13)C NMR data showed that the major compounds in the AaEaR extract are thiophenes. Our results suggest that AaEaR may be effective in treatments against amoebiasis, nevertheless, detailed toxicity studies on thiophenes, contained in AaEaR, are required to avoid misuse of this vegetal species.