Antioxidant activity and mineral composition of three Mediterranean common seaweeds from Abu-Qir Bay,Egypt

Antioxidant activity and mineral composition were evaluated seasonally from spring to autumn 2010 in the three common seaweeds Ulva lactuca Linnaeus (Chlorophyta), Jania rubens (Linnaeus) J.V. Lamouroux and Pterocladia capillacea (S.G. Gmelin) Bornet (Rhodophyta). The antioxidant activity was measured with β-carotene, total phenol content and DPPH (2,2-diphenyl-1-picrylhydrazyl). Seaweeds were collected from the rocky site near Boughaz El-Maadya Abu-Qir Bay of Alexandria, Egypt. The results showed maximum increase of β-carotene in P. capillacea during summer. A significant increase in total phenolic content at P ⩽ 0.05 was found in the red alga (J. rubens) during summer. Also, U. lactuca showed the maximum antioxidant scavenging activity especially during summer. Minerals in all investigated samples were higher than those in conventional edible vegetables. Na/K ratio ranged between 0.78 and 2.4 mg/100 g, which is a favorable value. All trace metals exceeded the recommended doses by Reference Nutrient Intake (RNI). During summer season, it was found that Cu = 2.02 ± 0.13 and Cr = 0.46 ± 0.14 mg/100 g in U. lactuca and Fe had a suitable concentration (18.37 ± 0.5 mg/100 g) in P. capillacea. The studied species were rich in carotenoids, phenolic compounds, DPPH free radicals and minerals, therefore, they can be used as potential source of health food in human diets and may be of use to food industry.     

Co-expression of d-glucose isomerase and d-psicose 3-epimerase: Development of an efficient one-step production of d-psicose

d-Psicose has been attracting attention in recent years because of its alimentary activities and is used as an ingredient in a range of foods and dietary supplements. To develop a one-step enzymatic process of d-psicose production, thermoactive d-glucose isomerase and the d-psicose 3-epimerase obtained from Bacillus sp. and Ruminococcus sp., respectively, were successfully co-expressed in Escherichia coli BL21 strain. The substrate of one-step enzymatic process was d-glucose. The co-expression system exhibited maximum activity at 65 °C and pH 7.0. Mg²⁺ could enhance the output of d-psicose by 2.32 fold to 1.6 g/L from 10 g/L of d-glucose. When using high-fructose corn syrup (HFCS) as substrate, 135 g/L d-psicose was produced under optimum conditions. The mass ratio of d-glucose, d-fructose, and d-psicose was almost 3.0:2.7:1.0, when the reaction reached equilibrium after an 8 h incubation time. This co-expression system approaching to produce d-psicose has potential application in food and beverage products, especially softdrinks.     

Green biosynthesis of silver nanoparticles from Annona squamosa leaf extract and its in vitro cytotoxic effect on MCF-7 cells

The biological method for the synthesis of silver nanoparticles (AgNPs) using Annona squamosa leaf extract and its cytotoxicity against MCF-7 cells are reported. The synthesized AgNPs using A. squamosa leaf extract was determined by UV–visible spectroscopy and it was further characterized by FT-IR, X-ray diffraction (XRD), Transmission electron microscopy (TEM), Zeta potential and energy dispersive spectrometric (EDS) analysis. The UV–visible spectrum showed an absorption peak at 444 nm which reflects surface plasmon resonance (SPR) of AgNPs. TEM photography showed biosynthesized AgNPs were predominantly spherical in shape with an average size ranging from 20 to 100 nm. The Zeta potential value of ?37 mV revealed the stability of biosynthesized AgNPs. Furthermore, the green synthesized AgNPs exhibited a dose-dependent cytotoxicity against human breast cancer cell (MCF-7) and normal breast epithelial cells (HBL-100) and the inhibitory concentration (IC₅₀) were found to be 50 μg/mL, 30 μg/mL, and 80 μg/mL, 60 μg/ml for AgNPs against MCF-7 and normal HBL-100 cells at 24 h and 48 h incubation respectively. An induction of apoptosis was evidenced by (AO/EtBr) and DAPI staining. Application of such eco-friendly nanoparticles makes this method potentially exciting for the large scale synthesis of nanoparticles.     

Evaluation of insecticidal activity of the essential oil of Allium chinense G. Don and its major constituents against Liposcelis bostrychophila Badonnel

Water-distilled essential oil from the dried bulbs of Allium chinense (Liliaceae) was analyzed by gas chromatography–mass spectrometry (GC–MS). Eighteen compounds, accounting for 98.4% of the total oil, were identified and the main components of the essential oil of A. chinense were methyl allyl trisulfide (30.7%), dimethyl trisulfide (24.1%), methyl propyl disulfide (12.8%) and dimethyl disulfide (9.6%) followed by methyl allyl disulfide (3.4%) and methyl propyl trisulfide (3.6%). The essential oil exhibited contact toxicity against the booklice (Liposcelis bostrychophila) with an LC₅₀ value of 441.8 μg/cm² while the two major constituents, dimethyl trisulfide and methyl propyl disulfide had LC₅₀ values of 153.0 μg/cm² and 738.0 μg/cm² against the booklice, respectively. The essential oil of A. chinense possessed strong fumigant toxicity against the booklice with an LC₅₀ value of 186.5 μg/l while methyl allyl trisulfide (LC₅₀ = 90.4 μg/l) and dimethyl trisulfide (LC₅₀ = 114.2 μg/l) exhibited stronger fumigant toxicity than methyl propyl disulfide (LC₅₀ = 243.4 μg/l) and dimethyl disulfide (LC₅₀ = 340.8 μg/l) against the booklice. The results indicated that the essential oil and its major constituents have potential for development into natural insecticides or fumigants for control of insects in stored grains.     

Bromeliothrix metopoides,a boom and bust ciliate (Ciliophora,Colpodea) from tank bromeliads

We investigated the recently described colpodid ciliate Bromeliothrix metopoides in a series of laboratory experiments to reveal the environmental factors that constrain this species to its peculiar habitat, i.e. the tanks of bromeliads. Our results demonstrated that the various life stages of this ciliate (bacterivorous theronts and microstome trophonts, flagellate-feeding macrostomes) have specific demands in terms of food quality and quantity. Bromeliothrix required a high food threshold (>1.4 mg C L^?1) in order to thrive. Food quality also affected resting cyst formation of B. metopoides when the experimental containers dried out. Its maximum growth rates (μ_max = 4.71 d^?1, i.e. 6.8 doublings d^?1) belong to the highest ones recorded thus far for free-living ciliates. The pH niche of B. metopoides was relatively wide (pH ～4 to >9) under optimal food conditions. However, its high sensitivity to unfavourable environmental conditions let the population collapse within several hours. We conclude that B. metopoides is a boom and bust ciliate that is specifically adapted to its peculiar habitat but virtually unviable in other environments.     

Facile fabrication of eco-friendly nano-mosquitocides: Biophysical characterization and effectiveness on neglected tropical mosquito vectors

Mosquito (Diptera: Culicidae) vectors are solely responsible for transmitting important diseases such as malaria, dengue, chikungunya, Japanese encephalitis, lymphatic filariasis and Zika virus. Eco-friendly control tools of Culicidae vectors are a priority. In this study, we proposed a facile fabrication process of poly-disperse and stable silver nanoparticles (Ag NPs) using a cheap leaf extract of Ichnocarpus frutescens (Apocyanaceae). Bio-reduced Ag NPs were characterized by UV–vis spectrophotometry, Fourier transform infrared spectroscopy (FTIR), X-ray diffraction analysis (XRD), atomic force microscopy (AFM), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The acute toxicity of I. frutescens leaf extract and green-synthesized Ag NPs was evaluated against larvae of the malaria vector Anopheles subpictus, the dengue vector Aedes albopictus and the Japanese encephalitis vector Culex tritaeniorhynchus. Compared to the leaf aqueous extract, Ag NPs showed higher toxicity against A. subpictus, A. albopictus, and C. tritaeniorhynchus with LC₅₀ values of 14.22, 15.84 and 17.26 μg/mL, respectively. Ag NPs were found safer to non-target mosquito predators Anisops bouvieri, Diplonychus indicus and Gambusia affinis, with LC₅₀ values ranging from 636.61 to 2098.61 μg/mL. Overall, this research firstly shed light on the mosquitocidal potential of I. frutescens, a potential bio-resource for rapid, cheap and effective synthesis of poly-disperse and highly stable silver nanocrystals.     

Modulation of acute steroidogenesis,peroxisome proliferator-activated receptors and CYP3A/PXR in salmon interrenal tissues by tributyltin and the second messenger activator,forskolin

There are uncertainties regarding the role of sex steroids in sexual development and reproduction of gastropods, leading to the recent doubts as to whether organotin compounds do inhibit steroidogenic enzymes in these species. These doubts have led us to suspect that organotin compounds may affect other target molecules, particularly signal transduction molecules or secondary mediators of steroid hormone and lipid synthesis/metabolism. Therefore, we have studied the effects of TBT exposure through food on acute steroidogenesis, PPARs and CYP3A responses in the presence and absence of a cyclic AMP (cAMP) activator, forskolin. Two experiments were performed. Firstly, juvenile salmon were force-fed once with diet containing TBT doses (0.1, 1 and 10 mg/kg fish) dissolved in ethanol and sampled after 72 h. Secondly, fish exposed to solvent control and 10 mg/kg TBT for 72 h were transferred to new tanks and exposed to waterborne forskolin (200 μg/L) for 2 and 4 h. Our data show that juvenile salmon force-fed TBT showed modulations of multiple biological responses in interrenal tissues that include, steroidogenesis (cAMP/PKA activities; StAR and P450scc mRNA, and plasma cortisol), and mRNA for peroxisome proliferator-activated receptor (PPAR) isoforms (α, β, γ), acyl-CoA oxidase-1 (ACOX1) and CYP3A/PXR (pregnan X receptor). In addition, forskolin produced differential effects on these responses both singly and also in combination with TBT. Overall, combined forskolin and TBT exposure produced higher effects compared with TBT exposure alone, for most of the responses (cortisol, PPARβ, ACOX1 and CYP3A). Interestingly, forskolin produced PPAR isoform-specific effects when given singly or in combination with TBT. Several TBT mediated toxicity in fish that includes thymus reduction, decrease in numbers of lymphocytes, inhibition of gonad development and masculinization, including the imposex phenomenon have been reported. When these effects are considered with the present findings, it suggests that studies on mechanisms of action or field studies may reveal endocrine, reproductive or other effects of TBT at lower concentrations than those reported to date from subchronic tests of fishes. Since the metabolic fate of organotin compounds may contribute to the toxicity of these chemicals, the present findings may represent some new aspects of TBT toxicity not previously reported.     

Phenolic profile,biological activities and fraction analysis of the medicinal halophyte Retama raetam

Retama raetam is a medicinal and aromatic plant present in the humid to the arid bioclimatic regions of Tunisia. In this work, we investigated R. raetam shoots antioxidant and antimicrobial activities and its natural antioxidant contents obtained from four fractions (petroleum ether, acetone 60%, ethyl acetate and water). Results showed that the ethyl acetate fraction exhibits the highest antioxidant activity as compared to the other ones. In fact, IC₅₀ values of ethyl acetate extract were equal to 33.5, 500 and 1380 μg/ml (DPPH and ABTS radicals scavenging activity and reducing power, respectively). Accordingly, this fraction presented the highest total polyphenol and flavonoid contents (401 mg GAE/g DR and 33.21 mg CE/g DR, respectively). Moreover, RP-HPLC analysis showed that syringic acid and coumarin were the major phenolic compounds. Furthermore, this moderately polar fraction showed considerable antibacterial properties against human pathogen strains especially against Escherichia coli and Bacillus cereus. Finally, fractionation allows the identification of R. raetam most active molecules and therefore the optimization of their utilization. Our findings pointed out the appropriate solvent for extracting R. raetam potent phenolics which might provide a rich and novel source of natural antioxidants as food additives replacing synthetic ones in food industry.     

Green synthesized doxorubicin loaded zinc oxide nanoparticles regulates the Bax and Bcl-2 expression in breast and colon carcinoma

The green synthesis of zinc oxide nanoparticles (ZnONPs) using Borassus flabellifer fruit extract was characterized by UV–visible spectroscopy, FT-IR, XRD, TEM, Zeta potential and EDS analysis. The UV–visible spectrum showed an absorption peak at 368 nm that reflects surface Plasmon resonance (SPR) ZnONPs. TEM photograph showed that the green synthesized ZnONPs were porous in nature and rod like structure with an average size of 55 nm. The Zeta potential value of −21.5 mV revealed the surface charge of green synthesized ZnONPs. In this study, we examined the synthesized DOX-ZnONPs exhibited a dose-dependent cytotoxicity against MCF-7 and HT-29. The inhibitory concentration (IC₅₀) was found to be 0.125 μg mL⁻¹ for MCF-7 and HT-29 cells. An induction of apoptosis was evidenced by nuclear stain Hoechst 33258. In vivo toxicity assessment showed that DOX-ZnONPs have low systemic toxicity in murine model system. The results prove that the DOX-ZnONPs has low toxicity and high therapy efficacy, which provides convincing evidence for the green biosynthesized ZnO as a promising candidate for a drug delivery system.     

Acute toxicity of Orthosiphon stamineus Benth standardized extract in Sprague Dawley rats

The acute toxicity of standardized extract of Orthosiphon stamineus was studied in Sprague Dawley rats. The rats were administered a single dose of 5000 mg/kg body weight (BW) orally on Day 0 and observed for 14 days. There were no deaths recorded and the animals did not show signs of toxicity during the experimental period. The effect of the extract on general behavior, BW, food and water intake, relative organ weight per 100 g BW, hematology and clinical biochemistry were measured. All the parameters measured were unaffected as compared to the control. The acute toxicity LD₅₀ was estimated to be >5000 mg/kg BW.     

Co-fermentation of lignocellulose-based glucose and inhibitory compounds for lipid synthesis by Rhodococcus jostii RHA1

The recalcitrant nature of lignocellulosic biomass entails pretreatment during which multiple byproducts (e.g., weak acids, furan derivatives, lignin-derived compounds) are generated. Such byproducts are generally inhibitory to fuel-producing microorganisms. In this study, lignin-derived monomers and acetate were co-fermented with glucose by Rhodococcus jostii RHA1 for lipid synthesis. The ability of R. jostii RHA1 to utilize acetate and representative lignin-derived monomers, namely p-coumaric acid, ferulic acid, 4-hydroxylic acid, and vanillic acid, were tested. The experimental results showed that R. jostii RHA1 utilized individual lignin monomers in varying degrees. The mixtures of inhibitory compounds at different levels showed higher toxicity than individual compounds, indicating synergistic effects of these monomers. When the mixture contained lower levels of glucose (5 g/L or below), adaptive-evolved (AE) R. jostii RHA1 utilized such inhibitory mixtures better for lipid synthesis. When the glucose levels were increased to 20 g/L or above, adaption evolution appeared to shorten the lag phase of co-fermentation but not necessarily enhance lipid production. This study demonstrated that R. jostii RHA1 was capable of utilizing commonly unfavorable carbon sources for lipid synthesis, which would also serve as a means to in situ detoxify inhibitory compounds.     

Evaluation of single cell oil from Aureobasidium pullulans var. melanogenum P10 isolated from mangrove ecosystems for biodiesel production

In this study, the yeast strain P10 which was identified to be a member of Aureobasidium pullulans var. melanogenum isolated from the mangrove ecosystems was found to be able to accumulate high content of oil in its cells. After optimization of the medium for lipid production and cell growth by the yeast strain P10, it was found that 8.0 g of glucose per 100 ml, 0.02 g of yeast extract per 100 ml, 0.02 g of ammonium sulfate per 100 ml, pH 6.0 in the medium were the most suitable for lipid production. During 10-l fermentation, a titer was 66.3 g oil per 100 g of cell dry weight, cell mass was 1.3 g per 100 ml, a yield was 0.11 g of oil per g of consumed sugar and a productivity was 0.0009 g of oil per g of consumed sugar per h within 120 h. At the same time, only 0.07 g of reducing sugar per 100 ml was left in the fermented medium. The compositions of the fatty acids produced were C_16:0 (26.7%), C_16:1(1.7%), C_18:0 (6.1%), C_18:1 (44.5%), and C_18:2 (21.0%). The biodiesel produced from the extracted lipid could be burnt well.     

Chemical composition,angiotensin I-converting enzyme (ACE) inhibitory,antioxidant and antimicrobial activities of the essential oil from south Tunisian Ajuga pseudoiva Rob. Lamiaceae

The essential oil of Ajuga pseudoiva, collected from Tunisia, was analyzed using gas chromatography–mass spectroscopy. Thirty-two compounds accounting for 95.76% of the total oil were identified. Sesquiterpenes were found to be the most abundant components of A. pseudoiva oil. And they were mainly represented by viridiflorol (30.17%), germacrene B (9.26%) (α, β and γ)-eudesmol (8.11%) and aromadendrene (7.45%). The essential oil of A. pseudoiva showed radical scavengers activity (IC₅₀ = 0.72 mg/mL) and displayed lipid peroxidation inhibitory activity (IC₅₀ = 0.6 mg/mL). A. pseudoiva essential oil was also found to exhibit a dose-dependent ACE inhibitory activity with an IC₅₀ value of 65.5 μg/mL. Moreover, the antimicrobial activity of the essential oil was tested against 17 species of microorganisms, and the results obtained showed significant antibacterial activity against the Gram-positive and Gram-negative bacteria, with inhibition zones and minimal inhibitory concentration values of 14–32 mm and 84–137 μg/mL and 6–21 mm and 105–336 μg/mL, respectively. Higher activity was also found against several fungal strains.     

Extraction,purification and characterization of galactomannans from non-traditional sources

This work presents a methodology for the extraction of galactomannans from seeds of four different species of Leguminosae (Adenanthera pavonina, Caesalpinia pulcherrima, Gleditsia triacanthos and Sophora japonica) to be used e.g. in the food and biomedical industries. The galactomannans were obtained by aqueous extraction followed by a precipitation with ethanol. This methodology is simpler and easier to perform than other existing extraction and purification methodologies, and because it avoids the use of organic solvents (other than ethanol), it is able to generate food grade substances and is environmentally friendlier. The yield of extraction in different stages of the process, monosaccharide composition, as well as physical and chemical parameters of the isolated galactomannans were determined and compared with previously published results. The mannose/galactose ratio of the extracted galactomannans ranged from 1.35 (A. pavonina) to 5.75 (S. japonica). The intrinsic viscosity ranged from 11.34 dL/g (C. pulcherrima) to 8.74 dL/g (S. japonica), while the viscosity average molecular mass ranged between 1.81 × 10⁶ Da and 1.17 × 10⁶ Da (A. pavonina > C. pulcherrima > G. triacanthos > S. japonica). The results confirm the suitability of the extraction and purification procedure to obtain galactomannans from non-traditional sources.     

Earthworm-mediated synthesis of silver nanoparticles: A potent tool against hepatocellular carcinoma,Plasmodium falciparum parasites and malaria mosquitoes

The development of parasites and pathogens resistant to synthetic drugs highlighted the needing of novel, eco-friendly and effective control approaches. Recently, metal nanoparticles have been proposed as highly effective tools towards cancer cells and Plasmodium parasites. In this study, we synthesized silver nanoparticles (EW–AgNP) using Eudrilus eugeniae earthworms as reducing and stabilizing agents. EW–AgNP showed plasmon resonance reduction in UV–vis spectrophotometry, the functional groups involved in the reduction were studied by FTIR spectroscopy, while particle size and shape was analyzed by FESEM. The effect of EW–AgNP on in vitro HepG2 cell proliferation was measured using MTT assays. Apoptosis assessed by flow cytometry showed diminished endurance of HepG2 cells and cytotoxicity in a dose-dependent manner. EW–AgNP were toxic to Anopheles stephensi larvae and pupae, LC₅₀ were 4.8 ppm (I), 5.8 ppm (II), 6.9 ppm (III), 8.5 ppm (IV), and 15.5 ppm (pupae). The antiplasmodial activity of EW–AgNP was evaluated against CQ-resistant (CQ-r) and CQ-sensitive (CQ-s) strains of Plasmodium falciparum. EW–AgNP IC₅₀ were 49.3 μg/ml (CQ-s) and 55.5 μg/ml (CQ-r), while chloroquine IC₅₀ were 81.5 μg/ml (CQ-s) and 86.5 μg/ml (CQ-r). EW–AgNP showed a valuable antibiotic potential against important pathogenic bacteria and fungi. Concerning non-target effects of EW–AgNP against mosquito natural enemies, the predation efficiency of the mosquitofish Gambusia affinis towards the II and II instar larvae of A. stephensi was 68.50% (II) and 47.00% (III), respectively. In EW–AgNP-contaminated environments, predation was boosted to 89.25% (II) and 70.75% (III), respectively. Overall, this research highlighted the EW–AgNP potential against hepatocellular carcinoma, Plasmodium parasites and mosquito vectors, with little detrimental effects on mosquito natural enemies.     

Modeling the physicochemical properties of orange beverage emulsion as function of main emulsion components using response surface methodology

The effect of main beverage emulsion components namely Arabic gum (7–13% w/w), xanthan gum (0.1–0.3% w/w) and orange oil (6–10% w/w) on physicochemical properties of orange beverage emulsion was determined by using a three-factor central composite design (CCD). The reduced models with high R² (?0.80) values and non significant (p > .05) lack of fit were significantly (p < .05) fitted to the experimental data, thus ensuring a satisfactory fitness of the regression models relating the response to independent variables. The quadratic effect of xanthan gum had a significant (p < .05) term in all reduced models. The independent variables had the most significant (p < .05) effect on turbidity loss rate and viscosity ratio. The overall optimum region resulted in the desirable orange beverage emulsion was predicted at a combined level of 13% (w/w) Arabic gum, 0.3% (w/w) xanthan gum and 10% (w/w) orange oil.     

Rapid bactericidal action of alpha-mangostin against MRSA as an outcome of membrane targeting

The emergence of methicillin-resistant Staphylococcus aureus (MRSA) has created the need for better therapeutic options. In this study, five natural xanthones were extracted and purified from the fruit hull of Garcinia mangostana and their antimicrobial properties were investigated. α-Mangostin was identified as the most potent among them against Gram-positive pathogens (MIC = 0.78–1.56 μg/mL) which included two MRSA isolates. α‐Mangostin also exhibited rapid in vitro bactericidal activity (3-log reduction within 5 min). In a multistep (20 passage) resistance selection study using a MRSA isolated from the eye, no resistance against α-mangostin in the strains tested was observed. Biophysical studies using fluorescence probes for membrane potential and permeability, calcein encapsulated large unilamellar vesicles and scanning electron microscopy showed that α‐mangostin rapidly disrupted the integrity of the cytoplasmic membrane leading to loss of intracellular components in a concentration-dependent manner. Molecular dynamic simulations revealed that isoprenyl groups were important to reduce the free energy for the burial of the hydrophobic phenyl ring of α-mangostin into the lipid bilayer of the membrane resulting in membrane breakdown and increased permeability. Thus, we suggest that direct interactions of α-mangostin with the bacterial membrane are responsible for the rapid concentration-dependent membrane disruption and bactericidal action.     

Effects of nitrogen concentration and media replacement on cell growth and lipid production of oleaginous marine microalga Nannochloropsis oceanica DUT01

Cell growth and lipid production of a marine microalga Nannochloropsis oceanica DUT01 were investigated, and fresh medium replacement with different ratios to promote long term cell growth and lipid accumulation was also tested. The highest lipid content reached 64% in nitrogen deplete f/2 medium containing 37.5 mg/L NaNO₃ combined with 1/5 fresh medium replacement, however, the highest lipid titer (0.6 g/L) and lipid productivity (31 mg/L/d) were achieved using BG11 medium containing 1.5 g/L NaNO₃, taking advantage of 1/5 fresh medium replacement as well, which corresponded to the maximum biomass production of 1.4 g/L, highlighting the importance of high biomass accumulation for efficient lipid production. When biomass compositions were monitored throughout the culture, decreased protein content was found to be coupled with increased lipid production, whereas relatively stable carbohydrate content was observed. The fatty acids in the lipid of N. oceanica DUT01 comprise over 65% saturated fatty acids and monounsaturated acids (i.e. palmitic acid (C16:0) and oleic acid (C18:1)), suggesting that N. oceanica DUT01 is a promising candidate for biodiesel production. Interestingly, very high content of hexadecadienoic acid (C16:2, about 26–33%) was produced by DUT01, which distinguished this microalga with other microalgae strains reported so far.     

The human antimicrobial peptide LL-37 and its fragments possess both antimicrobial and antibiofilm activities against multidrug-resistant Acinetobacter baumannii

Acinetobacter baumannii infections are difficult to treat due to multidrug resistance. Biofilm formation by A. baumannii is an additional factor in its ability to resist antimicrobial therapy. The antibacterial and antibiofilm activities of the human antimicrobial peptide LL-37 and its fragments KS-30, KR-20 and KR-12 against clinical isolates of multidrug-resistant (MDR) A. baumannii were evaluated. The minimal inhibitory concentration (MIC) of LL-37 against MDR A. baumannii isolates ranged from 16 to 32 μg/mL. The MIC of KS-30 fragment varied from 8.0 to16 μg/mL and the KR-20 fragment MIC ranged from 16 to 64 μg/mL. LL-37 and KS-30 fragment exhibited 100% bactericidal activity against five A. baumannii strains, including four MDR clinical isolates, within 30 min at concentrations of 0.25–1 μg/mL. By 0.5 h, the fragments KR-20 and KR-12 eliminated all tested strains at 8 and 64 μg/mL respectively. LL-37 and its fragments displayed anti-adherence activities between 32-128 μg/mL. A minimum biofilm eradication concentration (MBEC) biofilm assay demonstrated that LL-37 inhibited and dispersed A. baumannii biofilms at 32 μg/mL respectively. Truncated fragments of LL-37 inhibited biofilms at concentrations of 64–128 μg/mL. KS-30, the truncated variant of LL-37, effectively dispersed biofilms at 64 μg/mL. At 24 h, no detectable toxicity was observed at the efficacious doses when cytotoxicity assays were performed. Thus, LL-37, KS-30 and KR-20 exhibit significant antimicrobial activity against MDR A. baumannii. The prevention of biofilm formation in vitro by LL-37, KS-30 and KR-20 adds significance to their efficacy. These peptides can be potential therapeutics against MDR A. baumannii infections.     

Immunomodulatory effects of polysaccharides isolated from Hericium erinaceus on dendritic cells

Hericium erinaceus (H. erinaceus; HE) polysaccharides (HE-PS) have been shown to have immunomodulatory activity. We found that the bioactive components of β-glucan derivatives consisted of 20% in HE-PS. We used an analytic platform for investigating the effects of HE-PS on the maturation of rat dendritic cells (DCs), which are derived from rat bone marrow hematopoietic cells (BMHCs). The results showed that treatment with 50 μg/mL HE-PS changed the morphology of the DCs to an active form in parallel with a significant two fold increase in MHC class II and CD80/86 surface antigens compared to the control. Furthermore, endocytosis by the DCs was significantly reduced at the same dosage. IL-12, IFN-γ and IL-10 cytokine secretion was significantly increased by 2.7, 1.5 and 1.6-fold, respectively, compared to the control after treatment with 50 μg/mL of HE-PS. This study used a powered analysis platform to show that HE-PS induces DCs activation and modulates the T_H1 immune response. Thus, HE-PS has potential as an immunopotentiating agent that could be further developed in the health food industry.