Antimicrobial activity of zinc oxide (ZnO) nanoparticle against Klebsiella pneumoniae.

CONTEXT: Zinc oxide nanoparticles (ZnO Nps) have potential application in piezoelectric nanogenerator and in biotechnology. OBJECTIVE: The antibacterial activity of ZnO Nps on Klebsiella pneumoniae (ATCC 70068) and mode of action of ZnO Nps was investigated. METHODS: ZnO Nps was synthesized by a precipitation method and characterized using scanning electron microscopy (SEM) and X-ray diffraction (XRD) methods. In vitro susceptibility of K. pnumoniae of the ZnO Nps was detected using the disk diffusion method, and the minimum inhibitory concentration (MIC) value was determined using the serial dilution method. The chemical and physical interaction between the cell envelope of K. pneumonia and ZnO Nps was investigated. The effect of ZnO Nps on the cytotoxic activities of K. pneumonia was investigated using a HEp-2 cell line. RESULTS: The MIC of ZnO Nps was found in 40 µg/ml. The standard growth curve showed that ZnO Nps of 0.75 mM inhibited K. pneumoniae after 4 h. The interaction with outer membrane protein (OMP) and lipoploysacharride (LPS) residues showed modulation in ∼66 kDa and ∼29 kDa proteins with the use of increasing concentrations of ZnO Nps. The amount of nucleic acid and protein released from the cells increased with the ZnO Nps concentration used. Importantly, the OD of the ZnO Nps-treated cells decreased within 30 min of incubation in the presence of SDS. ZnO Nps-treated K. pneumoniae were five-fold less infectious in the HEp-2 cell line at doses between 0.50 and 0.75 mM. DISCUSSION: These results suggest the potential antibacterial use of ZnO Nps against K. pneumoniae infections.

Ameliorative effect of methanol extract of Rubia cordifolia in N-nitrosodiethylamine-induced hepatocellular carcinoma.

CONTEXT: Rubia cordifolia Linn. (Rubiaceae) is a medicinal plant used in the ayurvedic system of medicine. It is also known as Indian Madder or Manjistha and is traditionally used as an antiinflammatory, antiseptic, and galactopurifier, but its anticancer propertis are yet not known. OBJECTIVE: The ameliorative effect of the Rubia cordifolia methanol extract on N-nitrosodiethylamine-induced experimental hepatocellular carcinogenesis in rats. MATERIALS AND METHODS: Changes in liver weight, serum markers of liver damage, hydroxyl radicals, lipid peroxidation, levels of enzymic and nonenzymic antioxidants; mitochondrial and respiratory chain enzymes were also investigated using various biochemical parameters and histopathological studies. Male albino rats of Wistar strain were divided into four groups for a study period of 3 months. Animals of group I and group IV served as control and drug control, respectively. Hepatocellular carcinoma was induced in animals of groups II and III with 0.02% N-nitrosodiethylamine. RESULTS: Upon Rubia cordifolia methanol extract co-treatment (250, 500, and 750 mg/kg bodyweight) in group III alone levels of serum marker enzymes and antioxidants increased significantly in a dose-dependent manner. The levels of hydroxyl radicals and lipid peroxidation decreased. Mitochondrial enzymes and respiratory chain enzymes, which were decreased in N-nitrosodiethylamine-induced rats, increased significantly in RC treated rats. Further histological analysis of liver confirmed the prevention of pathological changes caused by N-nitrosodiethylamine on Rubia cordifolia supplementation. DISCUSSION AND CONCLUSION: These findings demonstrate that Rubia cordifolia can be a source of potent antioxidants for treatment of diseases such as cancer.

Antibacterial and antidiarrhoeal effects of alkaloids of Holarrhena antidysenterica WALL.

The alkaloids from the ethanolic extract of H. antidysenterica seeds were evaluated for their antibacterial activity against clinical isolates of enteropathogenic Escherichia coli (EPEC) in vitro, and their antidiarrhoeal activity on castor oil-induced diarrhoea in rats, in vivo. The plasmid DNA, whole cell lysate and outer membrane protein profile of a clinical isolate of EPEC was determined in presence of alkaloids of H. antidysenterica. The disc diffusion and agar well diffusion methods were used to evaluate the antibacterial efficacy. The alkaloids showed strong antibacterial activity against EPEC strains. In castor oil-induced diarrhoea, alkaloids reduced the diarrhoea with decrease in the number of wet faeces in pretreated rats at a dose of 200-800 mg/kg. The loss of plasmid DNA and suppression of high molecular weight proteins were observed on alkaloids treatment. Taking into account the multiple antibiotic resistance of EPEC, the results suggest usefulness of alkaloids of H. antidysenterica seeds as antibacterial and antidiarrhoeal agents.

Induction of apoptosis by methanolic extract of Rubia cordifolia Linn in HEp-2 cell line is mediated by reactive oxygen species.

Rubia cordifolia Linn, which belongs to the Rubiaceae family, is a well-known herb used in Ayurvedic medicine. In the present study, we investigated the influence of a methanolic extract (RC) on the induction of apoptosis in HEp-2 (human laryngeal carcinoma) cell line, as evidenced by cytotoxicity, morphological changes and modification in the levels of pro-oxidants. Inhibition of cell proliferation and lactate dehydrogenase (LDH) release increased in a time and dose-dependent manner. Further, reduced glutathione (GSH), glutathione transferase (GST) and protein levels decreased and lipid peroxidation increased significantly on RC treatment in a dose dependent manner when compared to controls. Based on the results we determined the optimal dose as 30 mg/ ml and the apoptotic effect of RC extract (30 mg/ml) on HEp-2 cells was confirmed by fluorescent microscopy and transmission electron microscopy (TEM) based on morphological and ultrastructural changes. RC extract suppressed the proliferation of HEp-2 oral cancer cells inducing apoptotic cell death in vitro. These results point to potential of RC extract as an agent for the treatment of laryngeal squamous cell carcinoma.

Human amniotic membrane as a chondrocyte carrier vehicle/substrate: in vitro study.

Human amniotic membrane (HAM) is an established biomaterial used in many clinical applications. However, its use for tissue engineering purposes has not been fully realized. A study was therefore conducted to evaluate the feasibility of using HAM as a chondrocyte substrate/carrier. HAMs were obtained from fresh human placenta and were process to produced air dried HAM (AdHAM) and freeze dried HAM (FdHAM). Rabbit chondrocytes were isolated and expanded in vitro and seeded onto these preparations. Cell proliferation, GAG expression and GAG/cell expression were measured at days 3, 6, 9, 12, 15, 21, and 28. These were compared to chondrocytes seeded onto plastic surfaces. Histological analysis and scanning electron microscopy was performed to observe cell attachment. There was significantly higher cell proliferation rates observed between AdHAM (13-51%, P=0.001) or FdHAM (18-48%, p = 0.001) to chondrocytes in monolayer. Similarly, GAG and GAG/cell expressed in AdHAM (33-82%, p = 0.001; 22-60%, p = 0.001) or FdHAM (41-81%, p = 0.001: 28-60%, p = 0.001) were significantly higher than monolayer cultures. However, no significant differences were observed in the proliferation rates (p = 0.576), GAG expression (p = 0.476) and GAG/cell expression (p = 0.135) between AdHAM and FdHAM. The histology and scanning electron microscopy assessments demonstrates good chondrocyte attachments on both HAMs. In conclusion, both AdHAM and FdHAM provide superior chondrocyte proliferation, GAG expression, and attachment than monolayer cultures making it a potential substrate/carrier for cell based cartilage therapy and transplantation.