Cellular and Nuclear Toxicity of HgCl2 to In Vitro Grown Lymphocytes from Human Umbilical Cord Blood

Monitoring of antibacterial capabilities of biosynthesized gold nanoparticles facilitated cyanobacterium, Spirulina subsalsa, against MDR pathogenic bacteria

Gold nanoparticles (AuNPs) were biosynthesized with the non-nitrogen fixing cyanobacterium Spirulina subsalsa (Ss-AuNPs), and their antibacterial properties were monitored. Several analytical techniques, i.e., UV-visible spectroscopy, dynamic light scattering, zeta potential, Fourier transform infrared spectroscopy, and field emission scanning electron microscopy, were employed for characterization. Thereafter, antibacterial efficacies of the biosynthesized AuNPs against multidrug-resistant bacterial strains, Escherichia coli, Acinetobacter baumannii, Staphylococcus aureus, and Streptococcus pyogenes were assessed. During synthesis of nanoparticles, a color change signified a change in the oxidation state of gold, whereby electrons in nanoparticles respond to light, which creates the color change called "plasmon resonance." Bioactive substances such as proteins and polysaccharides, and pigments like phycocyanin are crucial in converting Au (III) ions to Au (0). Here, S. subsalsa underplays to reduce AuNPs. A color shifts from pale green to pink-purple by UV-visible spectra with a strong absorption peak at 531 nm. The zeta potential of - 50 mV could increase the capacity of the compounds to interact with bacterial membranes, therefore enhancing their antibacterial effect. The FTIR spectral examination yielded a range of absorbance bands at 3321, 1633, and 513 cm-1, which were bound to the surface of AuNPs for agglomeration prevention to provide colloidal stability that acts as a stabilizing agent. It could be taken as a novelty that Ss-AuNPs had potent antibacterial activities against four MDR pathogenic bacteria with cited zone of inhibition, E. coli (25 ± 0.5), A. baumannii (22 ± 0.5), S. aureus (25 ± 0.5), and S. pyogenes (27 ± 0.5) mm.

Comparative study on toxicity of methylmercury chloride and methylmercury hydroxide to the human neuroblastoma cell line SH-SY5Y

Toxicities of methylmercury chloride (CH₃HgCl) and methylmercury hydroxide (CH₃HgOH) to cultured neuroblastoma cell line SH-SY5Y in vitro are evaluated. This is the comparative study between two methylmercury compounds to find out the extent of toxicity of these compounds are toxic to SH-SY5Y cell line. Both cytotoxicity and genotoxicity experiments were carried out to find out the more toxic compound. For cytotoxicity study, four staining assay methods independently with trypan blue (TB), acridine orange/ethidium bromide (AO/EB), 3-(4,5-dimethylthiazol-2-yl) 2,5-diphenyl tetrazolium bromide (MTT), and neutral red (NR) were used and the comet assay method was done for genotoxicity study. The obtained toxicity data were used for probit analysis. In cytotoxicity, CH₃HgCl had minimum inhibitory concentration (MIC) value in each assay method as 3 mg/L invariably; LC₂₅ values were in the range 7.41 to 10.23 mg/L, and LC₅₀ values were 14.79 to 15.48 mg/L; while LC₇₅ values were 20.89 to 26.91 mg/L. Moreover, LC₁₀₀ value was 30 mg/L, known from comet assay experiments for CH₃HgCl. Similarly for CH₃HgOH, the MIC value in each assay method was invariably 3 mg/L, the LC₂₅ values were in the range 12.58 to 16.59 mg/L, and LC₅₀ values were 19.49 to 23.44 mg/L; LC₇₅ values were 27.54 to 30.90 mg/L and LC₁₀₀ value was 42 mg/L in each assay done for cytotoxicity and genotoxicity studies. Computed DNA fragmentation indices in comet assays were 98.6 ± 0.57 30 mg/L with CH₃HgCl and 76 ± 5.29 30 mg/L with CH₃HgOH. This study clearly indicated that methylmercury chloride is more toxic than methylmercury hydroxide to SH-SY5Y cell line. Toxicity of Hg had been quantified with in vitro cultured human neuroblastoma cell line; since it has neurotoxic effects, its neural evaluation has implications in environmental health issues.

Human Umbilical Cord Blood-Derived Neural Stem Cell Line as a Screening Model for Toxicity

The aim was to investigate whether a human neural stem cell (NSC) line derived from human umbilical cord blood (hUCB) can be used for toxicity study. Toxicity of both neurotoxic environmental xenobiotics, methyl mercury chloride (CH₃HgCl), lead acetate (CH₃COOPb), and chlorpyrifos (CP), and non-neurotoxic insecticide, dichlorvos, as well as non-neurotoxic drugs, theophylline and acetaminophen were assessed. Additionally, differentiation of neuronal and glial cell lines derived from hUCB was elucidated. It was observed that CH₃HgCl was more toxic to human NSCs in comparison to CH₃COOPb and CP. The minimum inhibitory concentration (MIC) value against NSCs was 3, 10, and 300 mg/L, in each staining process, acridine orange/ethidium bromide (AO/EB) staining, 3-(4,5-dimethylthiazol-2-yl)2,5-diphenyl tetrazolium bromide (MTT) assay, and Hoechst staining, for CH₃HgCl, CP, and CH₃COOPb, respectively. CH₃HgCl had the LC₂₅ value as 10.0, 14.4, and 12.7 mg/L, by staining method mentioned in succession. CP had the LC₂₅ value as 21.9, 23.7, and 18.4 mg/L; similarly, CH₃COOPb had LC₂₅ values, successively as 616.9, 719.2, and 890.3 mg/L. LC₅₀ values ranged from 18.2 to 21.7 mg/L for CH₃HgCl, 56.4 to 60.2 mg/L for CP, and 1000 to 1460.1 for CH₃COOPb. Theophylline, acetaminophen, and dichlorvos had no impact on the viability of NSCs. This work justified that hUCB-NSC model can be used for toxicity study.

Evaluation of geno-toxicity of methyl parathion and chlorpyrifos to human liver carcinoma cell line (HepG2)

Insecticides and their residues are known to cause several types of ailments in human body. An attempt had been made to assess digitally the geno-toxicity of methyl parathion (MP) and chlorpyrifos (CP) to in vitro-grown HepG2 cell line, with Hoechst 33342 staining, comet, and micronucleus assays. Additionally, "acridine orange/ethidium bromide" (AO/EB) staining was done for the determination of insecticide-induced cytotoxicity, in corollary. Hoechst 33342 staining of cells revealed a decrease in live cell counts at 8-40 mg/L MP and 15-70 mg/L CP. Moreover, nuclear fragmentations in ranges 8 to 40 mg/L MP and 15 to 70 mg/L CP were recorded dependant on individual doses, increasingly with concomitant increases in comet tail length values. DNA fragmentation index measured in comet assays was 94.3 ± 0.57 at 40 mg/L MP and 93.3 ± 2.08 at 70 mg/L CP. Average micronuclei number was 59.0 ± 2.00 at 40 mg/L MP and 62.6 ± 1.52 at 70 mg/L CP, per 1000 cell nuclei, in micronucleus assay. Minimum inhibitory concentration (MIC) values with AO/EB staining for monitoring cytotoxicity were 4 and 10 mg/L for MP and CP, respectively. Lethal concentration50 (LC50) values were 20.89 mg/L MP and 79.43 mg/L CP in AO/EB staining, for cytotoxicity with probit analyses. It was concluded that MP was comparatively more geno-toxic than CP to HepG2 cell. It was discernible that at lower levels of each insecticide, geno-toxicity was recorded in comparison to cytotoxicity.