Induction of intrinsic apoptotic signaling pathway in A549 lung cancer cells using silver nanoparticles from Gossypium hirsutum and evaluation of in vivo toxicity.

In the past decade, the research communities raised wide concerns on using medicinal plants for synthesis of nanomaterials due to its effective biological activity, lower side effects and also eco-friendly manner. Our previous report concentrated on the biomedical efficacy of fine characterized silver nanoparticles (AgNPs) from Gossypium hirsutum (cotton) leaf extract. Further, the current examination is planned to reveal the molecular mechanisms involving for activation of mitochondria-mediated signaling pathway by AgNPs in human lung cancer cells (A549) using various biological endpoints such as apoptotic induction by HOECHST 33342, AO/EtBr and Rhodamine 123 staining, cell cycle analysis using flow cytometry, gene and protein expressions by RT-PCR and immunoblotting respectively. This study was further extended to identify the toxicity of AgNPs using an animal model. Interestingly, we observed that A549 cells treated with AgNPs resulted in G2/M arrest and ultimately leads to induction of apoptosis cell death. Moreover, gene analysis demonstrated that diminished expression of anti-apoptotic (Bcl-2) and enhanced expression of pro-apoptotic (Bax) mitochondrial genes. The alterations in the gene pattern may interrupt of mitochondrial membrane potential which facilitates the releasing of cytochrome c (cyt c) into cytosol. The cyt c act as a key molecule for activation of caspases (9 and 3) to initiate intrinsic apoptotic signaling cell death process. The histological analysis proven the application of AgNPs in nanomedicine is quietly harmless and would not cause any discernible stress like swelling and inflammation to the organs of mice. Taken together, this investigation may provide solid evidence for cotton crop mediated AgNPs induced apoptosis cell death pathway and offer a novel approach for cancer therapy.

Activation of intrinsic apoptotic signaling pathway in cancer cells by Cymbopogon citratus polysaccharide fractions.

Essential oils of Cymbopogon citratus were already reported to have wide ranging medical and industrial applications. However, information on polysaccharides from the plant and their anticancer activities are limited. In the present study, polysaccharides from C. citratus were extracted and fractionated by anion exchange and gel filtration chromatography. Two different polysaccharide fractions such as F1 and F2 were obtained, and these fractions were found to have distinct acidic polysaccharides as characterized by their molecular weight and sugar content. NMR spectral analysis revealed the presence of (1→4) linked b-d-Xylofuranose moiety in these polysaccharides. Using these polysaccharide fractions F1 and F2, anti-inflammatory and anticancer activities were evaluated against cancer cells in vitro and the mechanism of action of the polysaccharides in inducing apoptosis in cancer cells via intrinsic pathway was also proposed. Two different reproductive cancer cells such as Siha and LNCap were employed for in vitro studies on cytotoxicity, induction of apoptosis and apoptotic DNA fragmentation, changes in mitochondrial membrane potential, and profiles of gene and protein expression in response to treatment of cells by the polysaccharide fractions. These polysaccharide fractions exhibited potential cytotoxic and apoptotic effects on carcinoma cells, and they induced apoptosis in these cells through the events of up-regulation of caspase 3, down-regulation of bcl-2 family genes followed by cytochrome c release.