Search results for "C50"
showing 10 items of 182 documents
Acute, chronic and sublethal effects of the herbicide propanil on Daphnia magna.
2003
Acute and chronic toxicity tests with propanil were conducted on Daphnia magna. The 24 and 48 h LC50 were 43.74 and 5.01 mg/l respectively. Chronic toxicity tests were carried out using sublethal propanil concentrations (0.07, 0.10, 0.21 and 0.55 mg/l) during 21 days. The effect of propanil on survival, reproduction and growth of D. magna organisms was monitored. The parameters used to evaluate herbicide effect on reproduction were: mean total young ones per female, mean brood size, time to first reproduction, mean number broods per female and intrinsic rate of natural increase (r). Survival and growth (body length) were also determined after 21 days of exposure to the herbicide. Reproducti…
Disturbances in energy metabolism of Daphnia magna after exposure to tebuconazole.
2008
Abstract This study was conducted to investigate the change of some biochemical parameters in the aquatic invertebrate Daphnia magna following exposure to the fungicide tebuconazole and to determine the most sensitive biomarker among the ones tested in this species. Four biochemical biomarkers (protein, glycogen, lipids and caloric content) were correlated with feeding behaviour studies of D. magna after fungicide exposure. Juveniles of D. magna were exposed to four sublethal concentrations of tebuconazole (0.41, 0.52, 0.71 and 1.14 mg L−1) for 5 d. Daphnid samples were taken from each test and control group at 24, 48, 72, 96 and 120 h after the start of the experiment. Tebuconazole EC50 va…
Effect of the insecticide methylparathion on filtration and ingestion rates of Brachionus calyciflorus and Daphnia magna
1993
The freshwater rotifer Brachionus calyciflorus and the cladocera Daphnia magna were exposed to sublethal levels of methylparathion to determine the effect on filtration and ingestion rates. The experiments were performed using the unicellular algae, Nannochloris oculata in a density of 5 × 105 cell/ml. Prior to feeding experiments, preliminary acute toxicity tests were carried out to determine 24-h LC50 values for both species, these values indicated that Daphnia magna was more sensitive to methylparathion acute exposure than Brachionus calyciflorus was. Rates of filtration and ingestion declined with increasing methylparathion concentrations after an exposure of 5 h to this toxicant. The e…
Caffeate and piperidine-3-ol derivatives from the stem bark of Cassia sieberiana
2019
A new caffeate derivative from the ethanol extract of the stem bark of Cassia sieberiana DC. is described herein along with the known secondary metabolites spectaline (2), iso-6-cassine (3), 3-O-methyl-chiro-inositol (4), monobehenin (5), octyl nonadecyloate (6), β-sitosterol (7), stigmasterol (8) and sitosterol 3-O-β-D-glucopyranoside (9). The chemical structures were elucidated by means of various spectroscopic and spectrometric techniques. Extract and isolated compounds were devoid of inhibitory action against the herein selected bacterial strains (MICs > 256 μg/mL) but showed capacities to reduce 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical (EC50 < 3 μg/mL) considerably better than the …
Implementation of Technology Acceptance Model (TAM) and Importance Performance Analysis (IPA) in Testing the Ease and Usability of E-wallet Applicati…
2021
Digital payment innovation is currently increasingly needed by the community, especially in making non-cash payment transactions. The purpose of this research is to know and measure the ease and usefulness of e-wallet digital wallet services, especially in the GoPay application. The population in this study are users of the Go-Pay service on the GO-JEK platform. The sample of this study consisted of 124 respondents from distributing questionnaires in Depok, West Java using a modified Technology Acceptance Model (TAM) based on existing references. The data processing in this research uses Importance Performance Analysis (IPA) analysis. The results show that based on the gap analysis, it is f…
An approach to electromagnetism from the general relativity
2010
Classical gravitation is so similar to the electrostatic that the possible unification has been investigated for many years. Although electromagnetism is formulated successfully by quantum field theory, this paper proposes a simple approach to describe the electromagnetism from the macroscopic perspective of general relativity. The hypothesis is based on two charged particles that cause disturbance energy sufficient to disrupt the space-time and explain approximately Maxwell's equations. Therefore, with such this simple idea, we suggest the possibility that the geometric relationship between electromagnetism and gravitation is not yet fully exhausted.
Isolation and purification of enniatins A, A1, B, B1, produced by Fusarium tricinctum in solid culture, and cytotoxicity effects on Caco-2 cells
2010
Enniatins (ENs) are antibiotic compounds of hexadepsipeptidic structure produced by several strains of Fusarium spp. The ENs A, A(1), B, B-1 were purified from extracts of Fusarium tricinctum grown on a solid medium of corn, by a low pressure liquid chromatography (LPLC) on reverse phase of Amberlite XAD-7 followed by semipreparative LC. The purity and the structure of the isolated compounds were confirmed by LC-MS/MS. The technique of the purification of the fungal extract enabled complete separation of the ENs A, A(1), B, B-1 with a mean purity of 97% for all the compounds. The cytoxicity of the ENs was tested in the cell lines of human origin (epithelial colorectal adenocarcinoma cells, …
Isolactarane and Sterpurane Sesquiterpenoids from the Basidiomycete Phlebia uda
2012
Three new sesquiterpenoids, named udasterpurenol A, udalactarane A, and udalactarane B, as well as the known compounds hyphodontal and sterpuric acid have been isolated from the basidiomycete Phlebia uda. These compounds represent the first natural products described from this species. The structures were elucidated by NMR spectroscopy and mass spectrometry. Udalactaranes A and B were isolated as mixtures with their respective epimeric acetals. These mixtures inhibited the spore germination of the plant pathogenic fungus Fusarium graminearum at 10 and 5 μg/mL, respectively, and were active against Jurkat cells with IC(50) values of 101 and 42 μM, respectively.
Highly potent artemisinin-derived dimers and trimers: Synthesis and evaluation of their antimalarial, antileukemia and antiviral activities
2015
New pharmaceutically active compounds can be obtained by modification of existing drugs to access more effective agents in the wake of drug resistance amongst others. To achieve this goal the concept of hybridization was established during the last decade. We employed this concept by coupling two artemisinin-derived precursors to obtain dimers or trimers with increased in vitro activity against Plasmodiumfalciparum 3D7 strain, leukemia cells (CCRF-CEM and multidrug-resistant subline CEM/ADR5000) and human cytomegalovirus (HCMV). Dimer 4 (IC50 of 2.6 nM) possess superior antimalarial activity compared with its parent compound artesunic acid(3) (IC50 of 9.0 nM). Dimer5 and trimers6 and 7 disp…
Demographic parameters of Brachionus calyciflorus Pallas (Rotifers) exposed to sublethal endosulfan concentrations
1991
The effects of sublethal levels of endosulfan (0, 1, 1.5, 2.5 and 3.3 mg 1−1) on the demography of the rotifer Brachionus calyciorus were studied. Life expectancy at birth (e o), net reproductive rate (Ro), generation time (T) and intrinsic rate of natural increase (r) were significant differentes between blank controls and controls with acetone. The effective endosulfan concentration at which a given parameter value was reduced to 50% of the controls (EC50) was calculated for life expectancy.