Eco-friendly microbial route to synthesize cobalt nanoparticles using Bacillus thuringiensis against malaria and dengue vectors

The developments of resistance and persistence to chemical insecticides and concerns about the non-target effects have prompted the development of eco-friendly mosquito control agents. The aim of this study was to investigate the larvicidal activities of synthesized cobalt nanoparticles (Co NPs) using bio control agent, Bacillus thuringiensis against malaria vector, Anopheles subpictus and dengue vector, Aedes aegypti (Diptera: Culicidae). The synthesized Co NPs were characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR), Field-emission scanning electron microscopy (FESEM) with energy dispersive X-ray spectroscopy, and Transmission electron microscopy (TEM). XRD analysis showed three distinct diffraction peaks at 27.03°, 31.00°, and 45.58° indexed to the planes 102, 122, and 024, respectively on the face-centered cubic cobalt acetate with an average size of 85.3 nm. FTIR spectra implicated role of the peak at 3,436 cm^?1 for O–H hydroxyl group, 2924 cm^?1 for methylene C–H stretch in the formation of Co NPs. FESEM analysis showed the topological and morphological appearance of NPs which were found to be spherical and oval in shape. TEM analysis showed polydispersed and clustered NPs with an average size of 84.81 nm. The maximum larvicidal mortality was observed in the cobalt acetate solution, B. thuringiensis formulation, and synthesized Co NPs against fourth instar larvae of A. subpictus and A. aegypti with LC₅₀ values of 29.16, 8.12, 3.59 mg/L; 34.61, 6.94, and 2.87 mg/L; r ² values of 0.986, 0.933, 0.942; 0.962, 0.957, and 0.922, respectively.     

Green synthesis of titanium dioxide nanoparticles using Psidium guajava extract and its antibacterial and antioxidant properties

Objective:To determine the efficacies of antibacterial and antioxidant activities of aqueous leaf extract of Psidium guajava mediated biosynthesis of titanium dioxide nanoparticles(TiO_2,NPs).Methods:Synthesized TiO_2 NPs were tested by disc diffusion method against against human pathogenic bacteria.The total antioxidant activity and phenolic content(Folin—Ciocalteau method) of synthesized TiO_2 NTs and aqueous plant extract were determined.The scavenging radicals were estimated hv DPPH method.The synthesized TiO_2 NPs were characterized by XRD,FTIR.FESEM and EDX,Results:FTIR spectra of synthesized TiO_2 NPs exhibited prominent peaks at 3410 cm~(-1)(alkynes),1 578 cm~(-1).1 451 cm~(-1)(alkanes),and 1 123 cm~(-1)(C-O absorption).The morphological characterization of synthesized TiO_2 NPs was analysed by FESEM which showed spherical shape and clusters with an average size of 32.58 nm.The maximum zone of inhibition was observed in the synthesized TiO_2 NPs(20 μg/mL) against Staphylococcus aureus(25 mm) and Escherichia coli(23 mm).The synthesized TiO_2 NPs showed more antibacterial activity than the standard antibiotic disk,tetracycline which drastically reduces the chances for the development of antibiotics resistance of bacterial species.The plant aqueous extract and synthesized TiO_2NPs were found to possess maximum antioxidant activity when compared with ascorbic acid.The content of phenolic compounds(mg/g) in Leaf aqueous extract and synthesized TiO_2 NPs were found to be 85.4 and 18.3 mgTA/g,respectively.Conclusions:Green synthesized TiO_2 NPs provides a promising approach can satisfy the requirement of large-scale industrial production hearing the advantage of low—cost,eco—friendly and reproducible.     

Copper nanoparticles synthesized by polyol process used to control hematophagous parasites

The present study was based on assessments of the anti-parasitic activities of the hematophagous (blood feeding) larvae of malaria vector, Anopheles subpictus Grassi, filariasis vector, Culex quinquefasciatus, Say (Diptera: Culicidae), and the larvae of cattle tick Rhipicephalus (Boophilus) microplus, Canestrini (Acari: Ixodidae). The metallic copper nanoparticles (Cu NPs) synthesized by polyol process from copper acetate as precursor and Tween 80 were used as both the medium and the stabilizing reagent. The efficacy of synthesized Cu NPs was tested against the larvae of blood-sucking parasites. UV-vis spectra characterization was performed, and peak was observed at 575 nm, which is the characteristic to the surface plasmon bond of Cu NPs. The strong surface plasmon absorption band observed at 575 nm may be due to the formation of non-oxidized Cu NPs. X-ray diffraction (XRD) spectral data showed concentric rings corresponding to the 26.79 (111), 34.52 (200), and 70.40 (220) reflections. XRD spectrum of the copper nanoparticles exhibited 2θ values corresponding to the copper nanocrystal. No peaks of impurities are observed in XRD data. The scanning electron micrograph (SEM) showed structures of irregular polygonal, cylindrical shape, and the size range was found to be 35–80 nm. The size of the Cu NPs was measured by atomic force microscope (AFM) in non-contact mode. For imaging by AFM, the sample was suspended in acetone and spins coated on a silicon wafer. The line profile image was drawn by the XEI software and the horizontal line at 6 μm on a 2D AFM image. Research has demonstrated that metallic nanoparticles produce toxicity in aquatic organisms that is due largely to effects of particulates as opposed to release of dissolved ions. Copper acetate solution tested against the parasite larvae exposed to varying concentrations and the larval mortality was observed for 24 h. The larval percent mortality observed in synthesized Cu NPs were 36, 49, 75, 93,100; 32, 53, 63, 73, and 100 and 36, 47, 69, 88, 100 at 0.5, 1.0, 2.0, 4.0, and 8.0 mg/L against A. subpictus, C. quinquefasciatus and R. microplus, respectively. The larval percent mortality shown in copper acetate solution were 16, 45, 57, 66 and 100, 37, 58, 83, 87, and 100 and 41, 59, 79, 100, and 100 at 10, 20, 30, 40, and 50 mg/L against A. subpictus, C. quinquefasciatus, and R. microplus, respectively. The maximum efficacy was observed in Cu NPs and copper acetate solution against the larvae of A. subpictus, C. quinquefasciatus, and R. microplus with LC₅₀ and r ² values of 0.95 and 23.47, 1.01 and 15.24, and 1.06 and 14.14 mg/L with r ² = 0.766; 0.957 and 0.908; 0.946; and 0.816 and 0.945, respectively. The control (distilled water) showed nil mortality in the concurrent assay. The chi-square value was significant at p ≤ 0.05 level. This is the first report on anti-parasitic activity of the synthesized Cu NPs and copper acetate solution.     

Pinocembrin triggers Bax-dependent mitochondrial apoptosis in colon cancer cells

Bioflavanoids are the major pigments in plants with multitude of biological activities including inhibition of proliferation or induction of apoptosis in tumor cells. Even though the safety records of most flavanoids are exceptional, its therapeutic use is still in its infancy. We have isolated pinocembrin (5,7-dihydroxyflavanone) from Alpinia galanga that showed cytotoxicity against a variety of cancer cells including normal lung fibroblasts with relative nontoxicity to human umbilical cord endothelial cells. The compound induced loss of mitochondrial membrane potential with subsequent release of cytochrome c and processing of caspase-9 and -3 in colon cancer cell line HCT 116. Processing of caspase-8 was minimal. The initial trigger for mitochondrial apoptosis appears to be by the translocation of cytosolic Bax protein to mitochondria. Overexpression of proapoptotic Bax protein sensitized the colon cancer cells to pinocembrin-induced apoptosis and Bax knockout cells were resistant to pinocembrin-induced apoptosis. Antiapoptotic protein Bcl-X(L) only partially prevented apoptosis induced by this compound. The Bax-dependent cell death involving classical cytochrome c release and processing of caspase-9 and -3 suggests that pinocembrin is a classical mitochondrial apoptosis inducer. But the failure of Bcl-X(L) overexpression to completely prevent apoptosis induced by this compound suggests that pinocembrin is capable of triggering mitochondrial-independent cell death that needs to be clarified. The existence of cell death upon Bcl-X(L) overexpression is a promising feature of this compound that can be exploited against drug resistant forms of cancer cells either alone or in combination with other drugs.     

Larvicidal activity of green synthesized silver nanoparticles using bark aqueous extract of Ficus racemosa against Culex quinquefasciatus and Culex gelidus

ObjectiveTo investigate the larvicidal activity of synthesized silver nanoparticles (Ag NPs) utilizing aqueous bark extract of Ficus racemosa (F. racemosa) was tested against fourth instar larvae of filariasis vector, Culex quinquefasciatus (Cx. quinquefasciatus) and japanese encephalitis vectors, Culex gelidus (Cx. gelidus).MethodsThe synthesized Ag NPs was characterized by UV-vis spectrum, X-ray diffraction (XRD), Scanning electron microscopy (SEM) and Fourier transform infrared (FTIR). The larvicidal activities were assessed for 24 h against the larvae of Cx. quinquefasciatus and Cx. gelidus with varying concentrations of aqueous bark extract of F. racemosa and synthesized Ag NPs. LC₅₀ and r² values were calculated.ResultsThe maximum efficacy was observed in crude aqueous extract of F. racemosa against the larvae of Cx. quinquefasciatus and Cx. gelidus (LC₅₀=67.72 and 63.70 mg/L; r²=0.995 and 0.985) and the synthesized Ag NPs (LC₅₀=12.00 and 11.21 mg/L; r²=0.997 and 0.990), respectively. Synthesized Ag NPs showed the XRD peaks at 2 θ values of 27.61, 29.60, 35.48, 43.48 and 79.68 were identified as (210), (121), (220), (200) and (311) reflections, respectively. The FTIR spectra of Ag NPs exhibited prominent peaks at 3 425, 2 878, 1 627 and 1 382 in the region 500-3 000 cm^?1. The peaks correspond to the presence of a stretching vibration of (NH) C=O group. SEM analysis showed shape in cylindrical, uniform and rod with the average size of 250.60 nm.ConclusionsThe biosynthesis of silver nanoparticles using bark aqueous extract of F. racemosa and its larvicidal activity against the larvae of disease spreading vectors. The maximum larvicidal efficacy was observed in the synthesized Ag NPs.     

4-Amino-5-benzoyl-2-(4-methoxyphenylamino)thiazole (DAT1): a cytotoxic agent towards cancer cells and a probe for tubulin-microtubule system

Microtubule binding drugs are of special interest as they have important roles in the modulation of cellular functions and many of them act as anticancer agents. 4-Amino-5-benzoyl-2-(4-methoxyphenylamino)thiazole (DAT1) was identified as one of the active compounds from a series of diaminoketothiazoles in a cell-based screening assay to discover cytotoxic compounds. DAT1 shows cytotoxicity with GI(50) values ranging from 0.05 to 1 microM in different malignant cell lines with an average value of 0.35 microM. It blocks mitosis in the prometaphase and metaphase stages. In HeLa cells, DAT1 blocks the spindle function by disturbing spindle microtubule and chromosome organization. The drug also inhibits assembly of brain microtubules and binds tubulin specifically at a single site with induction of fluorescence. The dissociation constant of DAT1 binding to tubulin was determined as 2.9+/-1 microM at 24 degrees C. The binding site of DAT1 on tubulin overlaps with that of the conventional colchicine-binding site. DAT1 can thus be considered as a lead compound of a new class of small molecules and this study can be used as a step to develop potent antimitotic agents for the control of cytoskeletal functions and cell proliferation. It would also be an interesting probe for the structure-function studies of tubulin-microtubule system.     

Tricin 4′-O-(erythro-β-guaiacylglyceryl) ether and tricin 4′-O-(threo-β-guaiacylglyceryl) ether isolated from Njavara (Oryza sativa L. var. Njavara), induce apoptosis in multiple tumor cells by mitochondrial pathway

Njavara is an important medicinal rice variety of Kerala, India widely used in Ayurveda for the treatment of rheumatoid arthritis, paralysis, neurodegenerative diseases and in rejuvenation therapy. The study evaluated, for the first time, antitumor effects of the two rare flavonolignans, tricin 4′-O-(erythro-β-guaiacylglyceryl) ether (compound 1) and tricin 4′-O-(threo-β-guaiacylglyceryl) ether (compound 2), isolated from ‘Njavara’ black. Both the compounds induced apoptosis in three cancer cell lines colon adenocarcinoma cell line HCT 116, ovarian cancer cell line SKOV3 and breast cancer cell line MCF-7. Chromatin condensation in the three cancer cell lines by Hoechst staining showed >50 % of apoptosis by compounds 1 and 2 at concentration 40 and 30 μg/ml, respectively after 48 h. Further studies substantiated that both the compounds targeted cancer cells through mitochondrial membrane potential loss and subsequent chromatin condensation. Both compounds significantly increased the Annexin V binding thus confirming compounds 1 and 2 to be potential apoptotic agents.     

Diaminothiazoles inhibit angiogenesis efficiently by suppressing Akt phosphorylation

The prevention of neovessel formation or angiogenesis is a recent popular strategy for limiting and curing cancer. Diaminothiazoles are a class of compounds that have been reported to show promise in the treatment of cancer by inhibiting cancer cell proliferation and inducing apoptosis, because of their effects on microtubules and as inhibitors of cyclin-dependent kinases. Many microtubule-targeting agents are being studied for their antiangiogenic activity, and a few have shown promising activity in the treatment of cancer. Here, we report that diaminothiazoles can be highly effective as antiangiogenic agents, as observed in the chick membrane assay. The lead compound, 4-amino-5-benzoyl-2-(4-methoxyphenylamino)thiazole (DAT1), inhibits endothelial cell processes such as invasion, migration, and tubule formation, which require a functional cytoskeleton. DAT1 also decreases the expression of cell adhesion markers. The antiangiogenic activities of DAT1 occur at concentrations that are not cytotoxic to the normal endothelium. Analysis of intracellular signaling pathways shows that DAT1 inhibits Akt phosphorylation, which is actively involved in the angiogenic process. The antiangiogenic properties of diaminothiazoles, in addition to their promising antimitotic and cytotoxic properties in cancer cell lines, give them an extra advantage in the treatment of cancer.     

Evaluation of Catharanthus roseus leaf extract-mediated biosynthesis of titanium dioxide nanoparticles against Hippobosca maculata and Bovicola ovis

The purpose of the present study was based on assessments of the antiparasitic activities of synthesized titanium dioxide nanoparticles (TiO₂ NPs) utilizing leaf aqueous extract of Catharanthus roseus against the adults of hematophagous fly, Hippobosca maculata Leach (Diptera: Hippoboscidae), and sheep-biting louse, Bovicola ovis Schrank (Phthiraptera: Trichodectidae). The synthesized TiO₂ NPs were analyzed by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and atomic force microscopy (AFM). The formation of the TiO₂ NPs synthesized from the XRD spectrum compared with the standard confirmed spectrum of titanium particles formed in the present experiments were in the form of nanocrystals, as evidenced by the peaks at 2?? values of 27.43°, 36.03°, and 54.32°. The FTIR spectra of TiO₂ NPs exhibited prominent peaks at 714 (Ti?CO?CO bond), 1,076 (C?CN stretch aliphatic amines), 1,172 (C?CO stretching vibrations in alcoholic groups), 1,642 (N?CH bend bond), and 3,426 (O?CH stretching due to alcoholic group). SEM analysis of the synthesized TiO₂ NPs clearly showed the clustered and irregular shapes, mostly aggregated and having the size of 25?C110?nm. By Bragg??s law and Scherrer??s constant, it is proved that the mean size of synthesized TiO₂ NPs was 65?nm. The AFM obviously depicts the formation of the rutile and anatase forms in the TiO₂ NPs and also, the surface morphology of the particles is uneven due to the presence of some of the aggregates and individual particles. Adulticidal parasitic activity was observed in varying concentrations of aqueous leaf extract of C. roseus, TiO₂ solution, and synthesized TiO₂ NPs for 24?h. The maximum parasitic activity was observed in aqueous crude leaf extracts of C. roseus against the adults of H. maculata and B. ovis with LD₅₀ values of 36.17 and 30.35?mg/L, and r ² values of 0.948 and 0.908, respectively. The highest efficacy was reported in 5?mM TiO₂ solution against H. maculata and B. ovis (LD₅₀?=?33.40 and 34.74?mg/L; r ²?=?0.786 and 0.873), respectively, and the maximum activity was observed in the synthesized TiO₂ NPs against H. maculata and B. ovis with LD₅₀ values of LD₅₀?=?7.09 and 6.56?mg/L, and r ² values of 0.880 and 0.913, respectively. This method is considered as an innovative alternative approach to control the hematophagous fly and sheep-biting louse.