Tehran University Medical Journal

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Background: Biosynthesis of nanoparticles has attracted the attention of the scientific community in nanotechnology and biotechnology due to their extensive application in the area of material sciences and medicine. Nowadays, despite a various application of nanomaterial’s, there is a little information about their impact on human health. In this study, we investigated the comparative study on cytotoxicity effect of biological and commercial synthesized nanosilver on human gastric carcinoma (AGS) and normal lung fibroblast (MRC-5) cell lines. Methods: The current experimental study was carried out in Islamic Azad University, East Tehran Branch, from April to November 2014. The biological synthesis of nanosilver was obtained from Eucalyptus plant extract as a reducing agent. Further to more analysis, morphological study on size and shape of developed biological nanosilver was characterized by performing scanning electron microscopy and dynamic light scattering. AGS and MCR-5 cell lines were treated with various concentration of nanosilver for 24, 48 and 72 hours. Finally, the cell viability was evaluated by using MTT assay. Results: The results show that the nanosilver exerts a dose-dependent inhibitory effect on viability of cells. At 100µg/mL of commercial and biological synthesized nanosilver, the viability of AGS was reduced to 7.47±0.002% (P=0.002) and 3.65±0.01% (P=0.003) after 72 hours, respectively. In addition, the viability of MRC-5 at the same condition was reduced to 10.27±0.19% (P=0.001) and 9.16±1.53% (P=0.002), respectively. Conclusion: Based on a thorough literature surveys, the present study is the first research about biosynthesis of nanosilver using Eucalyptus plant extract. This eco-friendly and cost effective method can be used for large scale production of silver nanoparticle. In addition, based on the current obtained data, commercial and biological synthesized nanosilver can more inhibitory effect on cancer cells compared to the normal cells. Hence, silver nanoparticles might be used as a new strategy for treating many human cancers. However, further studies are necessary to ascertain their potential as anticancer agents.

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Background: Aloysia citrodora belongs to the Verbenaceae family of plants, a well-known herbal medicine in Iran. The aim of the present study was to investigate the chemical composition, antioxidant, antibacterial, cytotoxic and apoptotic effect of A. citrodora extract against human colon cancer (HT29) cells by using real-time polymerase chain reaction and flow-cytometry methods.

Methods: This experimental study was carried out in Islamic Azad University, East Tehran Branch, from March to September of 2014. At first, the A. citrodora chemical constituents were analyzed by gas chromatography-mass spectrometry (GC-MS) technique. In addition, antioxidant assay, antibacterial and anti-cancer effect was performed using 1,1-diphenyl-2-picrylhydrazyl (DPPH), disk diffusion and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) methods, respectively. The half maximal inhibitory concentration (IC50) value was calculated. We extracted total RNA molecules by using RNX solution, after which cDNA was synthesized. Finally, the pro-apoptotic (Bax) and anti-apoptotic (Bcl2) gene expression was performed by real-time polymerase chain reaction and apoptotic effects were analyzed using Flow-cytometry method.

Results: GC-MS analysis of Aloysia citrodora extract was shown 37 major components and the most frequent component was belonged to Spathulenol (17.57%) and Caryophyllene oxide (15.15%) The antioxidant activity of the extract was IC50= 0.6±0.03 mg/ml. The maximum and minimum antibacterial effects of extract were belonged to gram-negative and gram-positive bacteria, respectively. Cytotoxic results revealed that the A.citrodora extract have IC50= 20.1±0.78 mg/ml against colon cancer (HT29) cell line and real-time polymerase chain reaction results showed the expression level of Bax and Bcl2 was increased and decreased respectively in colon cancer cell line (3.470±0.72 (P< 0.05), 0.43±0.35 (P< 0.05)). In addition, the flow-cytometry results indicated the 38.66% apoptosis in colon cancer cell line.

Conclusion: According to the results, it seems that A. citrodora extract has potential antioxidant, antibacterial and anticancer effects and it suggested that further studies were performed for A. citrodora pharmaceutical importance.