Fabrication of chitosan/silica hybrid coating on AZ31 Mg alloy for orthopaedic applications

Biocompatible conversion of chitosan and chitosan/silica hybrid coating were prepared to enhance the biocompatibility and corrosion resistance of biodegradable AZ31 Mg alloy. The coatings were optimized and analysed with potentiodynamic polarization, SEM, ATR-IR and XPS studies. Potentiodynamic polarization studies, revealed that the coatings exhibited high corrosion resistance. The surface morphology of the Ch-3/Si coating showed small globular rough structure. The presence of functional groups was confirmed by ATR-IR. For a better understanding of chitosan/silica hybrid coating, the chemical states were examined by XPS studies. The in-vitro bioactivity of the coated samples was evaluated in Earle’s solution, which formed a dense layer of coral-like structure and calcium-deficient apatite with less stoichiometric ratio than the hydroxyapatite. In-vitro cell culture studies exhibited a good cell proliferation rate and the fabricated Ch-3/Si coating was found to be non-hemolytic. The bacterial studies proved that Ch-3/Si coating possessed inherent antibacterial activity.

Antibacterial efficacy of five medicinal plants against multidrug-resistant enteropathogenic bacteria infecting under-5 hospitalized children

OBJECTIVE： To evaluate in vitro antibacterial effectiveness of five medicinal plants used by an Indian aborigine, against 8 multidrug-resistant （MDR） enteropathogenic bacteria isolated from clinical samples of under-5 hospitalized children. METHODS： Antibiotic sensitivity patterns of eight clinically isolated strains of enteropathogenic bacteria, Enterobacter aerogenes, Escherichia coli, Klebsiella pneumoniae, Salmonella paratyphi, S. typhi, Shigella dysenteriae, S. sonnei and Vibrio cholerae were assessed by disc-diffusion method. Antibacterial activities of 8 solvent-extracts of leaves and bark of five medicinal plants were monitored by the agar-well diffusion method. The microbroth dilution method was used to assess minimum inhibitory concentration （MIC） and minimum bactericidal concentration （MBC）. Qualitative phytochemical analyses of active plant extracts were carried out. RESULTS： Ethanol, ethyl acetate and methanol extracts of Holarrhena antidysenterica leaf tissue were most effective against 8 MDR pathogens in vitro. Similarly, acetone, ethanol and methanol extracts of Terminalia alata leaf tissue; chloroform, ethyl acetate and methanol extracts of Terminalia aquna leaf tissue and ethyl acetate, ethanol and methanol extracts of Paederia foetida leaf tissue were most effective in inhibiting in vitro growth of the 8 MDR enteropathogens. Ethyl acetate and methanol extracts of H. antidysenterica bark tissue; acetone, ethanol and methanol extracts of T. alata bark tissue and acetone, ethanol and methanol extracts of T. arjuna bark tissue were most effective in controlling enteropathogen growth. The minimum inhibitory concentration and minimum bactericidal concentration values of the 3 most antimicrobial leaf and bark extracts from the five plants were in the range of 1.56 to 50 mg/mL. CONCLUSION： These 5 plants exhibited in vitro control over a cohort of 8 enteropathogenic bacteria strains isolated from clinical samples.

The anti-angiogenic and antibacterial effect of Tinomiscium philippinense Miers.(Menispermaceae)leaf extract

Objective:To determine the toxicity profile,anti-angiogenic and antibacterial activity of the crude and semi-crude leaf extracts of Tinomiscium philippinense(T.philippinense).Methods:The leaves of T.philippinense were extracted with methanol and partitioned with solvents of different polarities,namely,hexane,dichloromethane and butanol.The extracts were subjected to duck chorioallantoic membrane assay to establish its anti-angiogenic property.Microwell assay was utilized to determine the minimum inhibitory concentration and minimum bactericidal concentration of the different extracts of the plant.Results:The dichloromethane leaf extract of T.philippinense at 1000μg/disc showed the highest anti-angiogenic activity with 37.46%inhibition.All the fractions exhibited a bacteriostatic and bactericidal effect on the three bacterial strains with Pseudomonas aeruginosa,a Gram negative lactose fermenter exhibiting a higher sensitivity to dichloromethane semi-crude extract among the treatment groups.For the toxicity test,no mortality and no change in behavior were observed in the Sprague-Dawley rats 14 days after the oral administration of the plant extracts.The methanolic leaf extract of T.philippinense is non-toxic at a maximum dose of 5000 mg/kg.Conclusions:The dichloromethane leaf extract of T.philippinense is a potential antiangiogenic endemic plant species.This plant extract is also a potential antibacterial candidate as determined by microwell assay.The anti-angiogenic and antibacterial activity of the plant may be attributed to the essential oil,steroid,flavonoid,sterol and triterpene content of the plant.