فهرست مطالب s. m.m. hamdi

Biofilms are a community of bacteria on surfaces coated with extracellular polymeric materials, and one strategy to remove biofilms is to use nanoparticles. The aim of this study was to synthesize green zinc oxide (ZnO) nanoparticles and determine its anti-biofilm effects on biofilm gene expression in multidrug-resistant Klebsiella pneumoniae strains.

In this in vitro study, ZnO nanoparticles were synthesized by green method using zinc nitrate solution and Typha latifolia extract. Its physical and chemical properties were confirmed by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and FTIR (Fourier-transform infrared spectroscopy) methods. Its antimicrobial and anti-biofilm effects against multidrug-resistant Klebsiella pneumoniae isolates were investigated using minimum inhibitory concentration and plate microtiter methods, respectively. Finally, the effects of ZnO nanoparticles on the expression of wzm biofilm gene were investigated using Real Time PCR.

The synthesized ZnO nanoparticles had a spherical morphology and had a size of less than 100 nm. The results also showed that the synthesized ZnO nanoparticles had significant antimicrobial and anti-biofilm effects against multidrug-resistant K. pneumoniae strains and these nanoparticles significantly reduced the expression of wzm biofilm gene (p<0.05).

The findings of this study showed that the synthesized ZnO nanoparticles have significant antimicrobial and anti-biofilm effects and in the future, with further studies, these nanoparticles can be used as an anti-biofilm candidate.

Among the photosynthetic microorganisms, cyanobacteria belonging to the genus Fischerella appear particularly promising for new polysaccharides producing strains. Extracellular polysaccharides (EPS) serve as a boundary to the immediate environment and play a protective role against antimicrobial agents. That iswhy cyanobacteria are so popular in the industry today as thickeners or floating agents, heavy metal absorbers, or in the case of sulfate polysaccharides as bioactive substances. This is an advantage over other polysaccharides extracted from plants or other macroalgae. There are many factors  affecting cell growth and metabolite accumulation in cell cultures. However, there is insufficient knowledge about the factors affecting maximal EPS biosynthesis and antibacterial activity. In this regard, in this paper, the effect of some physical, environmental, and nutritional factors on the simultaneous production of exopolysaccharide by Fischerella sp. SH.A was investigated in order to select the best cultivation conditions for the industrial application of exopolysaccharides.

In this study, the cyanobacterium isolated from the fresh water of Golestan province was undertaken with the aim of investigating the key factors regulating EPS biosynthesis and antibacterial activity. After the morphological and molecular identification, the possible correlations between the type of stress and the amount of polysaccharides production were also investigated.

The obtained results indicated that EPS production and antibacterial activity were highly dependent on the culture conditions and light intensity. Furthermore, the production of exopolysaccharides in non-diastrophic conditions was highly correlated with the concentration of nitrate up to 500 mM and the illumination of 50 or 150 microeinsteins per second per square meter. 

Discussion and conclusion:

Since cyanobacterial extracellular polysaccharides are interesting from the biotechnological point of view, considering some other parameters are of crucial importance for the maximization of EPS production in this genus.

The aim of the current work was to investigate the anticancer activities of Zinc Oxide nanoparticles (ZnONPs) through modulation of Glutation peroxidase and Glutationreductase gene expression in breast cancer cells.

In this investigation, the breast cancer MCF-7 and normal HEK293 cell lines were treated with various concentrations of ZnONPs for overnight. Cell viability was measured using MTT(3-(4, 5-Dimethylthiazol-2-yl)-2,5-Diphenyltetrazolium Bromide) assay against cancer and normalcells. The quantity of Glutation peroxidase and Glutationreductase genes compared to GAPDH gene expressions were evaluated using the real time PCR method.

The MTT data showed that ZnONPs significantly decreased the viability of cancer cells compared to normal cells in dose-dependent mode. Moreover, the mRNA levels of Glutation peroxidase and Glutation reductase genes was significantly increased by 2.13±0.07 (P<0.001) and 1.22±0.05 (P<0.05) fold, respectively, following treatment withZnONPs.

According to the results of this investigation, the Glutation peroxidase and Glutation reductase gene expression was the key factors of glutathione system in elimination of increasing reactive oxygen species treated with ZnONPs.

Synthesis of silver nanoparticles (AgNPs) using plant extract is cost effective, while, one of the applications of AgNPs is its antimicrobial and anti-biofilm activities. The aim of this study was to investigate the anti-biofilm activity of synthesized AgNPs using A. dendroides against antibiotic resistant and biofilm forming clinical isolates of Klebsiella pneumoniae.

In this laboratory study, the AgNPs were first synthesized using Asphodelus dendroides extract and their size and structural characteristics were determined using various physico-chemical methods. Subsequently, the antimicrobial and anti-biofilm activities of synthesized AgNPs on antibiotic resistant and biofilm forming clinical isolates of K. pneumoniae were investigated via minimum inhibitory concentration (MIC) and Real Time PCR, respectively.

The results of the UV-vis test showed that the synthesized AgNPs had a maximum absorbance at 420 nm. The SEM (scanning electron microscope), TEM (transmission electron microscopy) and XRD (X-ray powder diffraction) results showed that the synthesized AgNPs had a spherical structure with a mean size of 30.41±22 nm. Also, AgNPs had significant antimicrobial and anti-biofilm activities against K. pneumoniae strains, so that the AgNPs down-regulated the expression of biofilm coding gene (mrkA) in K. pneumonia strains (p<0.001).

The results of this study showed the antimicrobial and anti-biofilm activities of AgNPs against K. pneumoniae strains. According to the results, with further studies, the synthesized AgNPs may be used as biofilm inhibitors in future. 

Due to the increasing incidence of cancer-related deaths and the deficiencies of chemotherapy and radiotherapy in advanced forms of cancer, new approaches are needed to control cancer, and one of these techniques is the use of nanoparticles, especially silver nanoparticles. Nowadays, the use of plants for the synthesis of silver nanoparticles has attracted the attention of researchers due to their low cost. Therefore, the aim of this study was to investigate the green synthesis of silver nanoparticles using the extract of lonicera nummulariifolia and to study its antioxidant, antimicrobial and anticancer effects against lung cancer cell line A549. 

In this experimental study, silver nanoparticles were synthesized using the extract of lonicera nummulariifolia as a regenerative agent. The antioxidant effects of synthesized silver nanoparticles were evaluated by DPPH assay and finally its antimicrobial and anticancer activity were respectively evaluated by Broth Microdilution and MTT assays at concentrations of 3.125, 6.25, 12.5, 25, 50, 100 μg/ml on lung cancer cell line within 24 h. 

The results of DPPH assay showed that the synthesized silver nanoparticles at 100 µg/ml had an antioxidant effect of 33.77±0.83. Antimicrobial test results showed that the antimicrobial effects of silver nanoparticles were greater on gram negative bacteria. MTT results also showed that cell viability was 70.33±0.21 (p>0.05), 51.66±0.24 (p<0.05) 35.75±0.35 (p<0.01), 20.66±0.28 (p<0.001), 13.5±0.31 (p<0.001), and 7.6±0.37 (p<0.001), respectively. Results of DPPH assay showed that silver nanoparticles has significant antioxidant effects (p<0.05).

Considering the antimicrobial and anticancer effects of synthesized silver nanoparticles, it can be used as a drug candidate.

Asparagus touranensis is described as a new species from Iran. This taxon has been collected from Semnan, Khorasan, Khuzestan and Hormozgan provinces of Iran. It is related to Asparagus capitatus subsp. gracilis (Royle) Browicz in cladode shape, habit and spiny leaf on the base of stem, but differs from it in having longer pedicel, longer cladode, having articulation above the middle of pedicel and rate of pedicel to perianth. Asparagus touranensis is distributed to NW, C. and South of Iran. Characteristics, exact localities, habitat, geographical distribution and the last state of nomenclature are explained

Ornithogalum khuzestanicum (Hyacinthaceae) is described and illustrated as a new species from the subalpine areas in Khuzestan province, Iran. The new species is similar to O. brachystachys C. Koch and O. arcuatum Stev. in leaf shape, bulb shape and inflorescence shape, but differs by its stem length, margin of leaf, inflorescence length, bracts length, pedicels and ornamentation form on testa cell of seed and also pollen characters are different. The new species is currently known only from eastern Khuzestan, near the border of western Charmahale-Bakhtiari and Kohgiluye va -Boierahmad.

In Flora Iranica Chenopodium album L. includes two subspecies as Ch. album subsp. album and Ch.. album subsp. iranicum. In Flora of Iran Chenopodium album includes three subspecies as Ch. album subsp. album, Ch. album subsp. iranicum and Ch. album subsp. striatum. In this research Chenopodium album subsp. iranicum is transferred to a higher level as Chenopodium iranicum. This combination is made on the base of results of morphological studies, and SEM studies of the seed coat surface, ornamentation of pollen grain, leaf and stem anatomy.

Linaria boushehrensis (Scrophulariaceae) is described as a new species from Boushehr and Khuzestan provinces. This species belongs to the section Difusae. The new species is compared with its closest relative Linaria albifrons. Linaria boushehrensis differs from L. albifrons in having longer bracts, corolla and spur and also smaller capsules and different microsculpturing pattern of the seed and capsule surfaces.