Monday, November 11, 2019

Propolis an Eco-Friendly Antibacterial Coating for Wound Sutures

Characterization of silk sutures coated with propolis and biogenic silver nanoparticles (AgNPs); an eco-friendly solution with wound healing potential against surgical site infections (SSIs)

Turk J Med Sci. 2019 Oct 27


Bacterial adherence to a suture material is one of the main reasons that cause surgical site infections. An antibacterial suture material with enhanced wound healing function may prevent the surgical site from infections. Thus, the present study was aimed to investigate the synergistic effect of propolis and biogenic metallic nanoparticles when combined with silk sutures for biomedical use.


Silver nanoparticle (AgNP) synthesis was carried out via a microbial-mediated biological route and impregnated on propolis-loaded silk sutures using an in situ process. silk sutures fabricated with propolis and biosynthesized AgNPs (bioAgNP-propolis coated sutures) were intensively characterized using Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Spectroscopy (EDS), Thermogravimetric Analysis (TGA) and Differential Scanning Calorimetry (DSC). Antibacterial characteristics of the bioAgNP-propolis coated sutures was evaluated using agar plate method. Biocompatibility of the bioAgNP-propolis coated sutures was evaluated using 3T3 fibroblast cells and their wound healing potential was also investigated.

BioAgNP-propolis coated sutures displayed potent antibacterial activity against pathogenic Gram negative and Gram positive bacteria; Escherichia coli and Staphylococcus aureus, respectively. BioAgNP-propolis coated silk sutures were found to be biocompatible with 3T3 fibroblast cell culture. In vitro wound healing scratch assay was also demonstrated that the extract of bioAgNP-propolis coated sutures stimulated the 3T3 fibroblasts? cell proliferation.


Coating the silk sutures with propolis and biogenic AgNPs gained an effective antibacterial capacity to surgical sutures besides providing biocompatibility and wound healing activity.

Friday, November 08, 2019

Honey and Its Combination with Metformin Prevents Hyperglycemia, Stimulates Insulin Secretion, Reduces Liver Fat Accumulation, Attenuates Liver Injury and Kidney Damage

Combination of honey with metformin enhances glucose metabolism and ameliorates hepatic and nephritic dysfunction in STZ-induced diabetic mice

Food Funct. 2019 Nov 5

Honey is a natural sweetener that contains a large amount of monosaccharides such as glucose and fructose, as well as small amounts of disaccharides and trisaccharides such as sucrose and pine trisaccharides. In addition to carbohydrates, honey also contains vitamins, minerals, enzymes, amino acids, and polyphenols including phenolic acids and flavonoids.

The polyphenols in honey have been proved to have great antioxidant activity, besides inhibiting α-glycosidase activity and improving blood-lipid metabolism. However, whether it is safe for diabetic patients to consume honey remains controversial.

This study investigated the effects of honey, metformin and their combination on the characteristic pathological changes and glucose metabolism in STZ-induced diabetic mice over five weeks.

Our results showed that honey and its combination with metformin could prevent hyperglycemia, stimulate insulin secretion, reduce liver fat accumulation, attenuate liver injury and kidney damage in STZ-induced diabetic mice.

Moreover, treatment with honey or combination of honey and metformin significantly enhanced glucokinase (GK) activity (p < 0.05), and meanwhile suppressed the activities of glucose-6-phosphatase (G6Pase), phosphoenolpyruvate carboxykinase (PEPCK), pyruvate carboxylase (PC) and pyruvate dehydrogenase kinases (PDK) (p < 0.05) in diabetic mice.

Thursday, November 07, 2019

Bee Venom Has Anticoagulant Properties

The anticoagulant effect of Apis mellifera phospholipase A2 is inhibited by CORM-2 via a carbon monoxide-independent mechanism

J Thromb Thrombolysis. 2019 Nov 2

Bee venom phospholipase A2 (PLA2) has potential for significant morbidity. Ruthenium (Ru)-based carbon monoxide releasing molecules (CORM) inhibit snake venoms that are anticoagulant and contain PLA2. In addition to modulating heme-bearing proteins with carbon monoxide, these CORM generate reactive Ru species that form adducts with histamine residues resulting in changes in protein function.

This study sought to identify anticoagulant properties of bee venom PLA2 via catalysis of plasma phospholipids required for thrombin generation. Another goal was to determine if Ru-based CORM inhibit bee venom PLA2 via carbon monoxide release or via potential binding of reactive Ru species to a key histidine residue in the catalytic site of the enzyme. Anticoagulant activity of bee venom PLA2 was assessed via thrombelastography with normal plasma.

Bee venom PLA2 was then exposed to different CORM and a metheme forming agent and anticoagulant activity was reassessed. Using Ru, boron and manganese-based CORM and a metheme forming agent, it was demonstrated that it was unlikely that carbon monoxide interaction with a heme group attached to PLA2 was responsible for inhibition of anticoagulant activity by Ru-based CORM. Exposure of PLA2 to a Ru-based CORM in the presence of histidine-rich human albumin resulted in loss of inhibition of PLA2.

Ru-based CORM likely inhibit bee venom PLA2 anticoagulant activity via formation of reactive Ru species that bind to histidine residues of the enzyme.

Tuesday, November 05, 2019

UMF Value a Not Reliable Indicator of Manuka Honey Antibacterial Activity

Antibacterial activity of varying UMF-graded Manuka honeys

PLoS One. 2019 Oct 25;14(10):e0224495

Honey has been used as a traditional remedy for skin and soft tissue infections due to its ability to promote wound healing. Manuka honey is recognized for its unusually abundant content of the antibacterial compound, methylglyoxal (MGO).

The Unique Manuka Factor (UMF) grading system reflects the MGO concentration in Manuka honey sold commercially. Our objective was to observe if UMF values correlated with the antibacterial activity of Manuka honey against a variety of pathogens purchased over the counter.

The antibacterial effect of Manuka honey with UMF values of 5+, 10+, and 15+ from the same manufacturer was assessed by the broth microdilution method. Minimum inhibitory concentration (MIC) values were determined against 128 isolates from wound cultures representing gram-positive, gram-negative, drug-susceptible, and multi-drug resistant (MDR) organisms.

Lower MICs were observed with UMF 5+ honey for staphylococci (n = 73, including 25 methicillin-resistant S. aureus) and Pseudomonas aeruginosa (n = 22, including 10 MDR) compared to UMF 10+ honey (p < 0.05) and with UMF 10+ compared to UMF 15+ (p = 0.01). For Enterobacteriaceae (n = 33, including 14 MDR), MIC values were significantly lower for UMF 5+ or UMF 10+ compared to UMF 15+ honey (p < 0.01). MIC50 for UMF 5+, UMF 10+, and UMF 15+ honey against staphylococci was 6%, 7%, and 15%, and for Enterobacteriaceae was 21%, 21%, and 27%, respectively.

For Pseudomonas aeruginosa MIC50 was 21% and MIC90 was 21-27% for all UMFs. Manuka honey exhibited antimicrobial activity against a spectrum of organisms including those with multi-drug resistance, with more potent activity overall against gram-positive than gram-negative bacteria.

Manuka honey with lower UMF values, in our limited sampling, paradoxically demonstrated increased antimicrobial activity among the limited samples tested, presumably due to changes in MGO content of honey over time. The UMF value by itself may not be a reliable indicator of antibacterial effect.