Fabrication and Characterization of Thymol-Loaded Chitosan Nanogels: Improved Antibacterial and Anti-Biofilm Activities with Negligible Cytotoxicity.

Thymol is a monoterpene phenolic derivative extracted from the Thymus vulgaris which has antimicrobial effects. In the present study, thymol-loaded chitosan nanogels were prepared and their physicochemical properties were characterized. The encapsulation efficiency of thymol into chitosan and its stability were determined. The in vitro antimicrobial and anti-biofilm activities of thymol-loaded chitosan nanogel (Ty-CsNG), free thymol (Ty), and free chitosan nanogel (CsNG) were evaluated against both Gram-negative and Gram-positive multidrug-resistant (MDR) bacteria including Staphylococcus aureus, Acinetobacter baumanii, and Pseudomonas aeruginosa strains using the broth microdilution and crystal violet assay, respectively. After treatment of MDR strains with sub-minimum inhibitory concentration (Sub-MIC) of Ty-CsNG, free Ty and CsNG, biofilm gene expression analysis was studied. Moreover, cytotoxicity of Ty-CsNG, free Ty, and CsNG against HEK-293 normal cell line was determined using MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) method. The average size of Ty-CsNG was 82.71±9.6 nm, encapsulation efficiency was 76.54±0.62 % with stability up to 60 days at 4 °C. Antibacterial activity test revealed that Ty-CsNG reduced the MIC by 4-6 times in comparison to free thymol. In addition, the expression of biofilm-related genes including ompA, and pgaB were significantly down-regulated after treatment of strains with Ty-CsNG (P<0.05). In addition, free CsNG displayed negligible cytotoxicity against HEK-293 normal cell lines and presented a biocompatible nanoscale delivery system. Based on the results, it can be concluded that Ty-CsNG can be considered a promising candidate for enhancing antimicrobial and anti-biofilm activities.

A study on the antioxidant and antimicrobial activities in the chloroformic and methanolic extracts of 6 important medicinal plants collected from North of Iran.

BACKGROUND: As possible sources of natural bioactive molecules, the plant essential oils and extracts have been used globally in new antimicrobial compounds, food preservatives, and alternatives to treat infectious disease. METHODS: In this research, the antimicrobial activities of chloroformic and methanolic extracts of Sophora flavescens, Rhaponticum repens, Alhagi maurorum, Melia azedarach, Peganum harmala, and Juncus conglomeratus were evaluated against 8 bacteria (S. aureus, B. subtilis, R. toxicus, P. aeruginosa, E. coli, P. syringae, X. campestris, P. viridiflava) and 3 fungi (Pyricularia oryzae, Fusarium oxysporum and Botrytis cinerea), through disc diffusion method. Furthermore, the essential oils of plants with the highest antibacterial activity were analyzed utilizing GC/MS. Moreover, the tested plants were exposed to screening for possible antioxidant effect utilizing DPPH test, guaiacol peroxidas, and catalase enzymes. Besides, the amount of total phenol and flavonoid of these plants was measured. RESULTS: Among the tested plants, methanolic and chloroformic extracts of P. harmala fruits showed the highest antibacterial activity against the tested bacteria. Besides, the investigation of free radical scavenging effects of the tested plants indicated the highest DPPH, protein, guaiacol peroxidase, and catalase in P. harmala, M. azedarach, J. conglomeratus fruits, and J. conglomeratus fruits, respectively. In addition, the phytochemical analysis demonstrated the greatest amounts of total phenolic and flavonoid compositions in J. conglomeratus and P. harmala, respectively. CONCLUSION: The results indicated that these plants could act as a promising antimicrobial agent, due to their short killing time.

Magnetic nano fluids for isolation of genomic DNA and total RNA from various prokaryote and eukaryote cells.

The correct isolation of nucleic acid from various cells is an important preliminary step before many biochemical and diagnostic processes such as cloning, sequencing, replication, hybridization, and complementary DNA (cDNA) synthesis. In this study, the coated magnetic nanoparticles (MNFs) with Tween 20 and oleic acid because of paramagnetic and bio-compatibility properties used in the extractions of genomic DNA (gDNA) and total RNA from prokaryote and eukaryote cells. The amount and accuracy of gDNA and total RNA extracted were proved via agarose gel electrophoresis, digestion and polymerase chain reaction (PCR) techniques. According to UV-Vis spectrophotometry data and gDNA and ribosomal RNA (rRNA) bands observed on the agarose gel, the results showed that extraction of this nano-kit can be comparable with the existing methods used to purifying nucleic acids such as purification based on the use of Cetyltrimethylammonium bromide (CTAB) and phenol-chloroform methods. Characterization of the particles defines them to be ~34.85 nm in diameter and exhibiting high saturation magnetization (28 emu/g). Elimination of hazardous reagents such as phenol and chloroform from extraction solutions, the replacement for inorganic coating such as silica with organic oil, and reduction of reaction time are some advantages of this method. Therefore, according to the challenges in the nucleic acid purification pathway, the use of these kits can be remarkable.

Chemical Composition, Antioxidant and Biological Activities of the Essential Oil and Extract of the Seeds of Glycine max (Soybean) from North Iran.

Glycine max (L.) Merrill (soybean) is a major leguminous crop, cultivated globally as well as in Iran. This study examines the chemical composition of soybean essential oil, and evaluates the antioxidant and antimicrobial activities of seeds on various plant pathogens that commonly cause irreparable damages to agricultural crops. The essential oil of soybean seeds was analyzed by gas chromatography coupled to mass spectrometry. Antimicrobial activity was tested against 14 microorganisms, including three gram-positive, five gram-negative bacteria, and six fungi, using disk diffusion method and the Minimum Inhibitory Concentration technique. The soybean seeds were also subjected to screening for possible antioxidant activity by using catalase, peroxidase, superoxide dismutase, and 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay. Forty components were identified, representing 96.68% of the total oil. The major constituents of the oil were carvacrol (13.44%), (E,E)-2,4-decadienal (9.15%), p-allylanisole (5.65%), p-cymene (4.87%), and limonene (4.75%). The oil showed significant activity against Pseudomonas syringae subsp. syringae, Rathayibacter toxicus with MIC = 25 µg/mL, and Pyricularia oryzae with MIC = 12.5 µg/mL. In addition, the free radical scavenging capacity of the essential oil was determined with an IC50 value of 162.35 µg/mL. Our results suggest that this plant may be a potential source of biocide, for economical and environmentally friendly disease control strategies. It may also be a good candidate for further biological and pharmacological investigations.

Phytochemical screening and antimicrobial activities of the constituents isolated from Koelreuteria paniculata leaves.

Methanolic extract of Golden rain leaves was fractionated by column chromatography on silica gel and 18 fractions were obtained. Antimicrobial activities of fractions were investigated against Bacillus subtilis, Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa as quality control bacteria and fungus Pyricularia grisea which causes Blast disease in rice. Fractions showed more antibacterial activity at 0.04 g/mL concentration only on B. subtilis and S. aureus as gram positive bacteria. Also, three fractions indicated excellent antifungal effect on fungus P. grisea. Moreover, in the present study, fractions that showed very good effect on microorganisms were used for gas chromatography-mass spectrometry analysis to identify different phytochemicals.