Phytochemical profile, antioxidant, antimicrobial and antipancreatic lipase activities of fermented Camellia japonica L leaf extracts

Purpose: To investigate the probable antioxidant, antimicrobial and  antipancreatic lipase effects of fermented Camellia japonica leaf extracts.Methods: Camellia japonica leaves fermented with Nuruk were extracted using methanol and ethanol. Total phenolic, flavonoid, carotenoid and L-ascorbic acid contents were determined by UV-visible spectrophotometry. The antioxidant activities of these extracts were determined by free radical scavenging, ferrous ion chelating and reducing power assays. Their  antimicrobial properties against Gram-positive Staphylococcus epidermidis and Bacillus subtilis, and Gram-negative Klebsiella pneumonia and Escherichia coli bacteria were evaluated by disc diffusion method. Inhibition of pancreatic lipase was measured based on the hydrolytic reaction of p-nitrophenyl butyrate with pancreatic lipase.Results: The ethanol extracts of fermented Camellia japonica leaves exhibited higher phenolic (32274mg GAE/100 g) and flavonoid (20519 mg RE/100 g) contents with higher superoxide (IC50 = 0.23  mg/mL), hydrogen peroxide (IC50 = 0.28 mg/mL) radical scavenging and ferrous ion chelating (IC50 = 0.21 mg/mL) activities than those of methanol. These ethanol extracts also showed higher antimicrobial activities against all bacterial strains tested with higher inhibitory effects on pancreatic lipase than methanol extracts.Conclusion: The results highlight the possible use of fermented Camellia japonica leaf extracts as a source of antioxidant, antibacterial and antiobesity agents. Ethanol is recommended as solvent for extracting antioxidants, antibacterial and antiobesity agents from this plant.Keywords: Antioxidant activity, Antimicrobial activity, Fermented Camellia japonica extracts, Pancreatic lipase inhibitio

GENOTOXICITY OF N-HYDROXY AND AMINOPHENOL METABOLITES OF 2,6- AND 3,5-DIMETHYLANILINE AT THE HYPOXANTHINEGUANINE PHOSPHORIBOSYLTRANSFERASE LOCUS IN TK6 CELLS

Objective: The objective of this study as to characterize the genotoxicity of reactive metabolites of 2,6-dimethylaniline (2,6-DMA) and 3,5-DMA in the hypoxanthineguanine phosphoribosyltransferase (HPRT) gene of human lymphoblastoid TK6 cells.Methods: Cultures were exposed to N-hydroxylamine and aminophenol metabolites of 2,6- and 3,5-DMA for 1 h in serum-free medium. Cell survival 24 h after exposure was determined by trypan blue exclusion. Cells were then subcultured for 7–10 days to allow to phenotypic expression of HPRT mutants. After the expression period, cells were plated in the presence of 2 μg/ml 6-thioguanine for the selection of HPRT mutants. Plating efficiency was determined and mutant fraction calculated. Electron paramagnetic resonance (EPR) was also used to determine whether 3,5- dimethylaminophenol (DMAP) produced reactive oxygen species (ROS).Results: All of the metabolites tested were cytotoxic to these cells but exhibited a considerable variation in potency. The aminophenol metabolites of 2,6- and 3,5-DMA were considerably more toxic than the corresponding N-hydroxylamines. Furthermore, each metabolite of 3,5-DMA was more toxic than its 2,6-DMA counterpart; N-OH-3,5-DMA and 3,5-DMAP were clearly mutagenic at a level of 50 μM. EPR studies showed intracellular oxidative stress induced under 3,5-DMAP treatment.Conclusions: Our findings suggest that genotoxic responses of 2,6- and 3,5-DMA are mediated through the generation of ROS by hydroxylamine and/ or aminophenol metabolites.Â

METABOLIC ACTIVATION OF 2,6-DIMETHYLANILINE: MUTATIONAL SPECIFICITY IN THE GPT GENE OF AS52 CELLS

Objective: The purpose of the current work was to characterize the mechanisms of cytotoxicity and mutagenesis of a potential human bladder carcinogen 2,6-dimethylaniline (2,6-DMA).Methods: Chinese hamster ovary (CHO) AS52 cells were exposed to either human S9 activated 2,6-DMA for 6 h or its N-hydroxylamine and aminophenol metabolites for 1 h in serum-free medium. Cell survival was determined by trypan blue exclusion 24 h after treatment, and 6-thioguanine-resistant mutants at the xanthine-guanine phosphoribosyl transferase (gpt) gene locus were assessed with doses, of which relative survival is 30% or more. Nested polymerase chain reaction-based deletion analysis was also performed.Results: AS52 cells exhibited a dose-dependent increase in cytotoxicity and mutant fraction on treatment of 2,6-DMA and its metabolites but show a considerable variation in potency with aminophenol metabolites having the highest potency and parent compound at least; at the highest 2,6-dimethylaminophenol dose (10 μM), the mutant fraction in AS52 cells was 8-fold (13.2×10−5) greater than the spontaneous fraction of 1.62×10−5. Total deletion of the gpt gene sequences was found in 1 (4%) spontaneous and 2 (6%) the 6-thioguanine mutants generated by N-hydroxy-2,6-DMA.Conclusions: These findings indicate the mutagenicity of 2,6-DMA at the gpt gene, which is mediated through hydroxylamine and aminophenol metabolites, and contribute to the elucidation of mechanisms through which 2,6-DMA may exert its effects in vivo

Modulation of A375 human melanoma cell proliferation and apoptosis by nitric oxide

The present study aimed to assess the effect of NO• on melanoma A375 cell growth and apoptotic cell death. Trypan blue exclusion assay was employed to detect the cytotoxicity induced by controlled steady-state concentrations (given in µM • min) of NO•. The characteristics of the cellular cell cycle and apoptosis in NO•-treated A375 cells were also analyzed by Annexin V/PI and DNA fragmentation assays. Western blotting was applied to detect the expression of apoptosis-related proteins (p53, Bax, Fas, DR5, caspase-3 and -9, and PARP). When exposed to preformed 100% NO• for 8 h reactor system, a cumulative dose of 3360 μM • min reduced the viability by 22% 24 h after treatment and promoted apoptosis, 2.9- and 12.2-folds 24 and 48 h after treatment higher than the argon control, respectively. Cell cycle analysis 48 h after treatment revealed S-phase arrest in cells treated with 3360 μM • min NO•. It was also observed that the expression of p53, DR5, caspase 9 and PARP increased significantly upon NO• treatment. In addition, the present study assessed the inhibitory effects of endogenous NO• on the proliferation of human melanoma cells by employing specific (AMG, 1400W and/or SMTC) and nonspecific (NMA) NO• synthase (NOS) inhibitors resulting in melanoma cell growth inhibition; the highest cytotoxic effect was seen when inducible NOS inhibition by 1 mM 1400W treatment. Collectively, the present data suggest that NO• is involved in a key mechanism limiting melanoma proliferation and apoptosis, which may play in improving the efficacy of melanoma treatment

Angle Dependence of Landau Level Spectrum in Twisted Bilayer Graphene

In the context of the low energy effective theory, the exact Landau level spectrum of quasiparticles in twisted bilayer graphene with small twist angle is analytically obtained by spheroidal eigenvalues. We analyze the dependence of the Landau levels on the twist angle to find the points, where the two-fold degeneracy for twist angles is lifted in the nonzero modes and below/above which massive/massless fermion pictures become valid. In the perpendicular magnetic field of 10\,T, the degeneracy is removed at $\theta_{{\rm deg}}\sim 3^\circ$ %angles around 3 degrees for a few low levels, specifically, $\theta_{\rm deg}\simeq 2.56^\circ$ for the first pair of nonzero levels and $\theta_{\rm deg}\simeq 3.50^\circ$ for the next pair. Massive quasiparticle appears at $\theta<\theta_{{\rm c}}\simeq 1.17^\circ$ in 10\,T, %angles less than 1.17 degrees. which match perfectly with the recent experimental results. Since our analysis is applicable to the cases of arbitrary constant magnetic fields, we make predictions for the same experiment performed in arbitrary constant magnetic fields, e.g., for B=40\,T we get $\theta_{\rm c}\simeq 2.34^\circ$ and the sequence of angles $\theta_{\rm deg} = 5.11, 7.01, 8.42,...$ for the pairs of nonzero energy levels. The symmetry restoration mechanism behind the massive/massless transition is conjectured to be a tunneling (instanton) in momentum space.Comment: 8 pages, 7 figures, version to appear in PR

The avian-specific small heat shock protein HSP25 is a constitutive protector against environmental stresses during blastoderm dormancy

ArticleScientific Reports. 6: 36704 (2016).journal articl

Online home appliance control using EEG-Based brain-computer interfaces

Brain???computer interfaces (BCIs) allow patients with paralysis to control external devices by mental commands. Recent advances in home automation and the Internet of things may extend the horizon of BCI applications into daily living environments at home. In this study, we developed an online BCI based on scalp electroencephalography (EEG) to control home appliances. The BCI users controlled TV channels, a digital door-lock system, and an electric light system in an unshielded environment. The BCI was designed to harness P300 andN200 components of event-related potentials (ERPs). On average, the BCI users could control TV channels with an accuracy of 83.0% ?? 17.9%, the digital door-lock with 78.7% ?? 16.2% accuracy, and the light with 80.0% ?? 15.6% accuracy, respectively. Our study demonstrates a feasibility to control multiple home appliances using EEG-based BCIs