Multi-drug resistance is a growing problem in the treatment of infectious diseases and the widespread use of broad-spectrum antibiotics has produced antibiotic resistance for many human bacterial pathogens. Advances in nanotechnology have opened new horizons in nanomedicine, allowing the synthesis of nanoparticles that can be assembled into complex architectures. Novel studies and technologies are devoted to understanding the mechanisms of disease for the design of new drugs, but unfortunately infectious diseases continue to be a major health burden worldwide. Since ancient times, silver was known for its anti-bacterial effects and for centuries it has been used for prevention and control of disparate infections. Currently nanotechnology and nanomaterials are fully integrated in common applications and objects that we use every day. In addition, the silver nanoparticles are attracting much interest because of their potent antibacterial activity. Many studies have also shown an important activity of silver nanoparticles against bacterial biofilms. This review aims to summarize the emerging efforts to address current challenges and solutions in the treatment of infectious diseases, particularly the use of nanosilver antimicrobials.

/pdf/silver-nanoparticles-as-potential-antibacterial-agents-2in1wnh11h.pdf

Silver nanoparticles as potential antibacterial agents.

Multidrug resistance of the pathogenic microorganisms to the antimicrobial drugs has become a major impediment toward successful diagnosis and management of infectious diseases. Recent advancements in nanotechnology-based medicines have opened new horizons for combating multidrug resistance in microorganisms. In particular, the use of silver nanoparticles (AgNPs) as a potent antibacterial agent has received much attention. The most critical physico-chemical parameters that affect the antimicrobial potential of AgNPs include size, shape, surface charge, concentration and colloidal state. AgNPs exhibits their antimicrobial potential through multifaceted mechanisms. AgNPs adhesion to microbial cells, penetration inside the cells, ROS and free radical generation, and modulation of microbial signal transduction pathways have been recognized as the most prominent modes of antimicrobial action. On the other side, AgNPs exposure to human cells induces cytotoxicity, genotoxicity and inflammatory response in human cells in a cell-type dependent manner. This has raised concerns regarding use of AgNPs in therapeutics and drug delivery. We have summarized the emerging endeavors that address current challenges in relation to safe use of AgNPs in therapeutics and drug delivery platforms. Based on research done so far, we believe that AgNPs can be engineered so as to increase their efficacy, stability, specificity, biosafety and biocompatibility. In this regard, three perspectives research directions have been suggested that include 1) synthesizing AgNPs with controlled physico-chemical properties, 2) examining microbial development of resistance towards AgNPs, and 3) ascertaining the susceptibility of cytoxicity, genotoxicity, and inflammatory response to human cells upon AgNPs exposure.

/pdf/mechanistic-basis-of-antimicrobial-actions-of-silver-1vmm44o6it.pdf

Mechanistic Basis of Antimicrobial Actions of Silver Nanoparticles.

Silver nanoparticles: A new view on mechanistic aspects on antimicrobial activity

Polyphenols, including flavonoids, phenolic acids, proanthocyanidins and resveratrol, are a large and heterogeneous group of phytochemicals in plant-based foods, such as tea, coffee, wine, cocoa, cereal grains, soy, fruits and berries. Growing evidence indicates that various dietary polyphenols may influence carbohydrate metabolism at many levels. In animal models and a limited number of human studies carried out so far, polyphenols and foods or beverages rich in polyphenols have attenuated postprandial glycemic responses and fasting hyperglycemia, and improved acute insulin secretion and insulin sensitivity. The possible mechanisms include inhibition of carbohydrate digestion and glucose absorption in the intestine, stimulation of insulin secretion from the pancreatic β–cells, modulation of glucose release from the liver, activation of insulin receptors and glucose uptake in the insulin-sensitive tissues, and modulation of intracellular signalling pathways and gene expression. The positive effects of polyphenols on glucose homeostasis observed in a large number of in vitro and animal models are supported by epidemiological evidence on polyphenol-rich diets. To confirm the implications of polyphenol consumption for prevention of insulin resistance, metabolic syndrome and eventually type 2 diabetes, human trials with well-defined diets, controlled study designs and clinically relevant end-points together with holistic approaches e.g., systems biology profiling technologies are needed.

/pdf/impact-of-dietary-polyphenols-on-carbohydrate-metabolism-2sp0n4vkol.pdf

Impact of dietary polyphenols on carbohydrate metabolism.

Silver, known in metallic form since antiquity, has very early been recognized by mankind for its antimicrobial properties, a phenomenon observed, for example, in the context of drinking water (a silver coin in a well), food (silver cutlery, water storage recipients), and medicine (silver skull plates, teeth). Silver compounds were also shown to be useful. For example, dilute solutions of silver nitrate served long, and still do in some countries, as antimicrobial ointment to be instilled into Published in \" \" which should be cited to refer to this work.

/pdf/nanobio-silver-its-interactions-with-peptides-and-bacteria-64opkdlezj.pdf

Nanobio Silver: Its Interactions with Peptides and Bacteria, and Its Uses in Medicine

Antibacterial effect of silver nanoparticles on Staphylococcus aureus.

Hypoglycaemic effect of Teucrium polium: studies with rat pancreatic islets.

Antioxidant, free radical scavenging activities of Salvia brachyantha and its protective effect against oxidative cardiac cell injury.

In the present study various extracts of ten medicinal plants, collected in Iran, were examined for α-glucosidase and α-amylase inhibition using an in vitro model. Also total phenol content and antioxidant activity of the extracts were investigated. Various extracts of the plants (Cinnamomum zeylanicum, Crataegus oxyacantha, Hibiscus sabdariffa, Morus alba, Portulaca oleracea, Rubus fruticosus, Syzygium aromaticum, Teucrium polium,Trigonella foenum-graecum, and Vaccinium arctostaphylos) were prepared using n-hexane, dichloromethane, chloroform, ethyl acetate and methanol. Methanol, dichloromethane and n-hexane extracts of S. aromaticum exerted high in vitro inhibitory potential against α-glucosidase and α-amylase with IC50 ranging from 0.3 to 1.1 and 36.2 to 41.9 µg/ml, respectively. The mentioned extracts possessed the highest total phenolic contents (139.8, 119.6 and 136.1 mg GAE/g of extract). The antioxidant activities of the extracts, measured in terms of IC50 values were 2.2, 3.9 and 0.7 µg/ml, respectively. C. zeylanicum was another traditionally used medicinal plant, which its extracts exhibited high hypoglycaemic effect by inhibition of α-glucosidase and α-amylase (IC50 ranged from 0.5 to 8.7 and 37.1 to 52.5 µg/ml, respectively). The obtained results support the traditionally use of a number of the analyzed species.

	 

	Key words: α-Glucosidase, α-amylase, enzyme inhibition, diabetes, antioxidant activity.

-Glucosidase and -amylase inhibitory effect and antioxidant activity of ten plant extracts traditionally used in Iran for diabetes

Summary
The possible protective effects of naringenin, a naturally occurring citrus flavonone, on carbon tetrachloride (CCl4)-induced liver injury in rats and the mechanism underlying its effects were investigated. Forty rats were divided into five groups. Rats in Groups I and II served as the normal and injured liver groups, respectively; Group III rats were treated with the standard drug silymarin as a positive control; and rats in Groups IV and V (naringenin-treated groups) were administrated 50 mg/kg, p.o., naringenin for 7 days. Liver samples were collected to evaluate mRNA and protein expression, histological changes and oxidative stress. Naringenin inhibited lipid peroxidation and reduced serum levels of hepatic enzymes induced by CCl4. In addition, naringenin increased the liver content of reduced glutathione and the activity of anti-oxidant enzymes in rats treated with CCl4. Naringenin attenuated liver inflammation by downregulating CCl4-induced activation of tumour necrosis factor (TNF)-α, inducible nitric oxide synthase (iNOS) and cyclo-oxygenase (COX-2) at both the protein and mRNA levels. Naringenin treatment significantly increased NF-E2-related factor 2 (Nrf2) and heme oxygenase (HO-1) expression in injured livers. In rats treated with CCl4 alone, decreases were seen in nuclear Nrf2 expression and in the mRNA levels of its target genes (e.g. HO-1, NQO1 and glutathione S-transferase alpha 3 (GST-a3)). Together, the results suggest that naringenin can protect the liver against oxidative stress, presumably by activating the nuclear translocation of Nrf2 as well as attenuating the TNF-α pathway to elicit an anti-inflammatory response in liver tissue.

Mohammad Ali Esmaeili

Papers

Antibacterial effect of silver nanoparticles on Staphylococcus aureus.

Hypoglycaemic effect of Teucrium polium: studies with rat pancreatic islets.

Antioxidant, free radical scavenging activities of Salvia brachyantha and its protective effect against oxidative cardiac cell injury.

-Glucosidase and -amylase inhibitory effect and antioxidant activity of ten plant extracts traditionally used in Iran for diabetes

Naringenin attenuates CCl4‐induced hepatic inflammation by the activation of an Nrf2‐mediated pathway in rats