In the present study, KBiO 3 is synthesized by a standard oxidation technique while LiBiO 3 is prepared by hydrothermal method. The synthesized catalysts are characterized by X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), BET surface area analysis and Diffuse Reflectance Spectroscopy (DRS). The XRD patterns suggest that KBiO 3 crystallizes in the cubic structure while LiBiO 3 crystallizes in orthorhombic structure and both of these adopt the tunnel structure. The SEM images reveal micron size polyhedral shaped KBiO 3 particles and rod-like or prismatic shape particles for LiBiO 3 . The band gap is calculated from the diffuse reflectance spectrum and is found to be 2.1 eV and 1.8 eV for KBiO 3 and LiBiO 3 , respectively. The band gap and the crystal structure data suggest that these materials can be used as photocatalysts. The photocatalytic activity of KBiO 3 and LiBiO 3 are evaluated for the degradation of anionic and cationic dyes, respectively, under UV and solar radiations.
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Background:
Curcumin (diferuloylmethane) is an active ingredient of turmeric and has been suggested to have antiproliferative, pro-oxidant and cytotoxic effects (Das R, Apoptosis 2008). Curcumin has also been shown to have antioxidant effects (Rastogi M, Free Radic Res 2008). Our aim was to assess the cytotoxic, pro-oxidant and antioxidant effects of curcumin on rat peripheral blood lymphocytes (RPL) in culture.
Methods:
Different concentrations of curcumin (0.325 μM, 0.65 μM, 1.3 μM) were analyzed for cytotoxic effects on rat peripheral lymphocytes. The cytotoxic effect of curcumin was assessed by measuring cell viability using Trypan blue exclusion assay. DNA damage by curcumin (at 0.65 μM) was confirmed by the COMET assay. The effect of curcumin (at 0.65 μM) on oxidation was assessed by measuring the activity of superoxide dismutase (SOD), catalase, glutathione peroxidase (GPx) and lipid peroxidation (LP) by spectrophotometry. RPLs were cultured for 72 hr in vitro. The pro-oxidant effect of curcumin was determined by comparing LP induction in control (PBS treated) vs curcumin treated RPLs. Parameters were measured at 0, 24 and 48 hrs of curcumin exposure. Reactive oxygen species (ROS) generated by treatment with FeCl3 (10 mM) and H2O2 (5 mM) (Fe/H) were used to demonstrate the ROS scavenging effect of curcumin. Lymphocyte cultures were treated with either Fe/H alone or in combination with Curcumin. Oxidation levels were assessed as described above at 0, 24, 48 hrs following exposure.
Results:
Cytotoxic effects were seen at different curcumin concentrations (Table 1). Viability of RPLs were 42% at 0.64 μM concentration vs 72% at 0.325 μM. 30% decrease in cell viability of RPLs were seen at 0.65 μM concentration compared to 0.325 μM. Hence, 0.65 μM concentration was used for further experiments. There was a significant increase in DNA damage in curcumin exposed lymphocytes at 48hr (table 2). There was a significant increase in LP in curcumin exposed RPLs compared to control lymphocytes. By contrast, there was no significant change in LP values in presence of Fe/H at all time points compared to control. There was a significant decrease in LP when RPL cultures were incubated with curcumin for 48 hr compared to 0 hr of incubation. There was significant increase in activities of SOD, catalase and GPx in presence of curcumin and Fe/H (table 3 and 4).
Conclusions:
Dose dependent cytotoxic and DNA damage effects of curcumin are seen in RPLs. Treatment with curcumin alone increases lipid peroxidation, However in the presence of oxidative stress, curcumin may act as an antioxidant (ROS scavenging effect) by stimulating activities of antioxidant enzyme and preventing lipid peroxidation.
Disclosures:
No relevant conflicts of interest to declare.
. -KBiO 3 is synthesized by oxidation of Bi2O3 with Br2 in 50% aq. KOH (reflux). LiBiO3 is hydrothermally prepared from aqueous solution of NaBiO3 and LiOH (autoclave, 120°C, 2 d). The samples are characterized by powder XRD, SEM, and UV/VIS diffuse reflectance spectroscopy. KBiO3 crystallizes with a cubic tunnel structure and LiBiO3 crystallizes with an orthorhombic tunnel structure. The band gaps of 2.1 and 1.8 eV for KBiO3 and LiBiO3, respectively suggest that these materials can be used as photocatalysts. The photocatalytic activities of KBiO3 and LiBiO3 are determined for the degradation of anionic and cationic dyes, respectively, under UV and solar irradiation.
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