G. Vani

Cigarette smoking induces heat shock protein 70 kDa expression and apoptosis in rat brain: Modulation by bacoside A

Cigarette smoking is associated with the development of several diseases and antioxidants play a major role in the prevention of smoking-related diseases. Apoptosis is suggested as a possible contributing factor in the pathogenesis of smoking-induced toxicity. Therefore the present study was designed to investigate the influence of chronic cigarette smoke exposure on apoptosis and the modulatory effect of bacoside A (triterpenoid saponin isolated from the plant Bacopa monniera) on smoking-induced apoptosis in rat brain. Adult male albino rats of Wistar strain were exposed to cigarette smoke and simultaneously administered with bacoside A (10 mg/kg b.w./day, orally) for a period of 12 weeks. Expression of brain hsp70 was analyzed by Western blotting. Apoptosis was identified by DNA fragmentation, terminal deoxynucleotidyl transferase-mediated deoxy uridine triphosphate nick end labeling (TUNEL) staining and transmission electron microscopy. The results showed that exposure to cigarette smoke induced hsp70 expression and apoptosis as characterized by DNA laddering, increased TUNEL-positive cells and ultrastructural apoptotic features in the brain. Administration of bacoside A prevented expression of hsp70 and neuronal apoptosis during cigarette smoking. We speculate that apoptosis may be responsible for the smoking-induced brain damage and bacoside A can protect the brain from the toxic effects of cigarette smoking.

Effect of methanolic extract of Terminalia arjuna against Helicobacter pylori 26695 lipopolysaccharide-induced gastric ulcer in rats.

Helicobacter pylori lipopolysaccharide (HP‐LPS) is a potent virulence factor in the causation of gastric ulcer and gastritis. H. pylori‐induced gastric pathology is prevalent throughout the world. Herbal medicines are attracting attention because of their traditional values, popularity and belief, as well as for their advantages such as less toxicity, affordability and medicinal value. The present study aimed to evaluate the anti‐ulcer effect of a methanolic extract of Terminalia arjuna (TA) against HP‐LPS‐induced gastric damage in rats. Ulcers were induced with HP‐LPS (50 μg per animal) administered orally daily for 3 days. The efficacy of TA on gastric secretory parameters such as volume of gastric juice, pH, free and total acidity, pepsin concentration, and the cytoprotective parameters such as protein‐bound carbohydrate complexes in gastric juice and gastric mucosa was assessed. The protective effect of TA was also confirmed by histopathological examination of gastric mucosa. HP‐LPS‐induced alterations in gastric secretory parameters were altered favourably in rats treated with TA, suggesting that TA has an anti‐secretory role. Furthermore, HP‐LPS‐induced impairments in gastric defence factors were also prevented by treatment with TA. These results suggest that the severe cellular damage and pathological changes caused by HP‐LPS are mitigated by TA; these effects are comparable with those of sucralfate. The anti‐ulcer effect of TA may reflect its ability to combat factors that damage the gastric mucosa, and to protect the mucosal defensive factors.

Regulation of Intracellular Calcium Levels and Urokinase Activity in MDA MB 231 Cells by Quercetin

Background: The common plant bioflavonoid, quercetin, is cytotoxic to various tumor cell lines, particularly breast cancer, by affecting the protein-kinase-C-dependent signal pathways and by cell cycle regulation. However, its role in breast cancer metastasis has not been studied so far. Increased uPA activity is evident in highly metastatic breast cancer, which is calcium dependent. Methods: MDA MB 231 cells were treated with various concentrations of quercetin (15–45 µg/ml). The cytotoxic effect of quercetin was assessed by MTT assay and DNA fragmentation analysis. Intracellular calcium levels were measured using Fura-2, a specific Ca2+ fluorescence indicator. Calcium uptake and release in cells treated with quercetin were measured using radioactive 45Ca2+. Urokinase enzyme activity was assayed by a casein zymogram. Results: Quercetin elicited dose- and time-dependent cytotoxicity as evidenced by the MTT assay. The maximum effect was observed at 48 h with a quercetin concentration of (45 µg/ml). DNA agarose gel electrophoresis showed dose-dependent DNA fragmentation on quercetin treatment. Quercetin caused significant depletion of cytosolic calcium levels and decreased calcium uptake from the intracellular stores. Casein zymogram showed a marked reduction of urokinase activity as evident by clear lysis bands on a dark background on treatment with quercetin. Conclusion: Quercetin was found to exhibit cytotoxicity in the highly invasive breast cancer cell line MDA MB 231 in a dose- and time-dependent manner. Quercetin inhibited calcium dependent urokinase activity and hence may prove to be an effective antimetastatic agent.

Effect of Solanum trilobatum on hepatic drug metabolising enzymes during diethylnitrosamine-induced hepatocarcinogenesis promoted by Phenobarbital in rat.

The present study was aimed to investigate the chemopreventive effects of Solanum trilobatum (ST) extract against diethylnitrosamine (DEN)‐induced hepatocarcinogenesis promoted by Phenobarbital (PB) in Wistar rats. Hepatocarcinogenesis was initiated by a single intraperitoneal injection of DEN (200 mg/kg b.w.) and promoted with PB (0.05%) in basal diet. The experimental study extended for periods of 13 and 26 weeks. Alcoholic extract of ST was orally administered for the entire experimental period after initiation along with commencement of promotion. The chemopreventive effect of ST was assessed from the incidence of nodules, drug metabolizing phase I components such as contents of cytochrome P450, cytochrome b5, activities of NADPH cytochrome c reductase, NADH – cytochrome b5 reductase and phase II components such as levels of glutathione, activities of UDP‐glucuronyl transferase, glutathione S‐transferase and γ‐glutamyl transpeptidase in the liver. Lipid peroxidation at basal and prooxidants‐induced (NADPH + ADP + Fe and Ascorbate + Fe) states was assessed in the microsomes. Animals administered with ST extract evidenced significant inhibition of tumor nodular incidence in DEN + PB + ST animals compared to DEN + PB animals, with favorable alterations in the hepatic drug‐metabolizing phase I and phase II components. Administration of ST inhibited basal and pro‐oxidant‐induced lipid peroxidation. The present result suggests the probable mediation of chemoprevention by ST against DEN‐induced carcinogenesis by the modulation of drug metabolizing components in the liver of treated animals.

Histone H1 Modulates the Antioxidant Status in 9,10-Dimethylbenz[a]anthracene-Induced Experimental Breast Cancer

Aim: Oxidative stress is implicated in the pathogenicity of cancer cells and contributes towards the response to antineoplastic agents. This study was aimed at assessing the antioxidant status in 9,10-dimethylbenz[a]anthracene-induced experimental animals treated with histone H1. Methods: Histone H1 was injected and the antioxidant status was assessed in erythrocytes and tumour tissue of experimental animals. The antioxidant status was monitored from the levels of lipid peroxides as thiobarbituric acid reactants and conjugated dienes in the haemolysate, serum, glutathione, and plasma vitamins A, E, C and ceruloplasmin. In the haemolysate, activities of antioxidant enzymes, including superoxide dismutase, catalase, glutathione reductase, γ-glutamyl transpeptidase, glutathione S-transferase, glutathione peroxidase and glucose-6-phosphate dehydrogenase, were assayed and erythrocyte fatty acid composition was analyzed by gas chromatography-mass spectrometry. All of the above parameters except fatty acid composition were assessed within the tumour tissue to assess the antioxidant status. Results: Treatment with histone H1 enhanced the antioxidant in erythrocyte at the end of the 2nd and 4th week by significantly decreasing thiobarbituric acid-reactive substances and conjugated dienes, by increasing glutathione levels, activities of antioxidant enzymes and favourably altering the erythrocyte fatty acid composition. Within the tumour tissue, a significant atrophy with significant alteration in antioxidant and antioxidant enzyme status was evident in treatment. Conclusion: These results validate the role of histone H1 as an antitumour agent in breast cancer.

Effect of histone H1 on estrogen receptor status of human breast cancer MCF 7 cells.

The effects of exogenous histone H1 on estrogen receptor status of human breast cancer MCF 7 cells were investigated in presence and absence of estrogen. Exogenous histone H1 was significantly cytotoxic in a dose- and time-dependent manner. Cell cycle analysis revealed a significant increase in the percentage of cell accumulation in G0/G1 phase. In histone H1-treated cells, a significant decrease in the estrogen receptor content and an increase in the dissociation constant (KD) of ER was observed compared to control.