Molecular Insights on the Therapeutic Effect of Selected Flavonoids on Diabetic Neuropathy.

One of the common clinical complications of diabetes is diabetic neuropathy affecting the nervous system. Painful diabetic neuropathy is widespread and highly prevalent. At least 50% of diabetes patients eventually develop diabetic neuropathy. The four main types of diabetic neuropathy are peripheral neuropathy, autonomic neuropathy, proximal neuropathy (diabetic polyradiculopathy), and mononeuropathy (Focal neuropathy). Glucose control remains the common therapy for diabetic neuropathy due to limited knowledge on early biomarkers that are expressed during nerve damage, thereby limiting the cure through pharmacotherapy. Glucose control dramatically reduces the onset of neuropathy in type 1 diabetes but proves to be less effective in type 2 diabetes. Therefore, the focus is on various herbal remedies for prevention and treatment. There is numerous research on the use of anticonvulsants and antidepressants for the management of pain in diabetic neuropathy. Extensive research is being conducted on natural products, including the isolation of pure compounds like flavonoids from plants and their effect on diabetic neuropathy. This review focuses on the use of important flavonoids such as flavanols (e.g., quercetin, rutin, kaempferol, and isorhamnetin), flavanones (e.g., hesperidin, naringenin and class eriodictyol), and flavones (e.g., apigenin, luteolin, tangeretin, chrysin, and diosmin) for the prevention and treatment of diabetic neuropathy. The mechanisms of action of flavonoids against diabetic neuropathy by their antioxidant, anti-inflammation, anti-glycation properties, etc., are also covered in this review article.

Role of GLP-1 Analogs in the Management of Diabetes and its Secondary Complication.

The cardiovascular complications of Type 2 Diabetes Mellitus (T2DM) including myocardial infarction, heart failure, peripheral vascular disease and, stroke and retinopathy, nephropathy and neuropathy are microvascular complications. While the newer therapies like glitazones or even Dipeptidyl- peptidase-IV (DPP-IV) inhibitors increase the risk of therapy, the Glucagon Like Peptide-1 Receptor Agonists (GLP-1RAs), were reported as suitable alternates. The GLP-1RAs reduce Major Adverse Cardiovascular Events (MACE), have anti-atherogenic potential, and possess pleiotropic activity. The GLP-1RAs were found to improve neuroprotection, enhance neuronal growth, reduce the incidence of stroke, and improve central insulin resistance. The GLP-1RAs are beneficial in improving the glycemic profile, preventing macroalbuminuria and reducing the decline in eGFR and enhancing renal protection. The renal benefits of add-on therapy of GLP-1RAs with SGLT-2 inhibitors have composite renal outcomes such as suppression of inflammatory pathways, improvement in natriuresis, diuresis, found to be nephroprotective. Improvement in glycemic control with a reduction in body weight and intraglomerular pressure and prevention of tubular injury makes the GLP-1RAs as suitable add-on therapies in improving cardiorenal outcomes. Obesity, an important contributor to insulin resistance and a reduction in weight, is an essential therapeutic option in addressing diabetic-obesity. It also reduces the damage to blood-retinal-barrier, thus beneficial in halting the development of diabetic retinopathy. In diabetic complications, glycemic control, addressing insulin resistance through weight loss, controlling atherosclerosis through anti-inflammatory effects and cardio-renal-neuro protection, makes GLP-1RAs a suitable therapeutic strategy on long-term treatment of T2DM. This review discusses the role of GLP-1RAs in diabetes, the dosage, mono or combination therapy with other antidiabetics in long-term treatment and its effect in uncontrolled diabetes.

Current Trends in the Therapeutic Strategies for Diabetes Management.

Diabetes mellitus is one of the fastest-growing non-communicable diseases. Diabetes mellitus is caused due by the destruction of pancreatic ß-cell or due to insulin resistance and characterized by hyperglycemia. Diabetes imposes a very serious economic crisis as the diabetic drug market is growing very rapidly. Even after very path-breaking scientific discoveries, the availability of better healthcare infrastructure, and a rise in literacy rates, the diabetes burden is continuously spreading in various sections all over the world but more especially in low- and middle-income countries. The recent developments in scientific discoveries have given several new generations of antidiabetic medicines such as sulphonylurea, biguanides, thiazolidinedione, α-glucosidase inhibitors. All these drugs have proved a significant reduction in blood glucose level. There are some new classes of hypoglycaemic drugs that have also been developed and reported, such as GLP-1 analogous, DPP-IV inhibitors, amylin inhibitors, and peroxisome proliferator- activated receptors. There are some active molecules and bioactive substances that have been purified from herbs and plants, which add value to the war against diabetes. These phytoconstituents have overturned drug development and lead identification for drugs against diabetes. The review also focuses on some critical areas of diabetes with more focus on statin-based diabetes management approach and stem cell therapy based next generation antidiabetic therapy.

Design of antimicrobial polycaprolactam nanocomposite by immobilizing subtilisin conjugated Au/Ag core-shell nanoparticles for biomedical applications.

Preparation of the gold core and silver shell NP (AuAgNP) is challenging because of the facile oxidation of silver. Here such a NP is carefully synthesized and conjugated with subtilisin to arrive at a stable spherical material of 120-130 nm in diameter (AuAgSNP). A biomaterial prepared by immobilizing AuAgSNP on polycaprolactam (PCL) exhibits antibiofilm properties against S. aureus and E. coli, but with lesser potency than the one prepared with bare AuAgNP. Subtilisin degrades the adhesive surface proteins of the bacteria thereby preventing the biofilm formation. Subtilisin conjugated AuAgSNP is not cytotoxic to 3T3 cells at its MIC, in contrast to AuAgNP. The presence of subtilisin promotes the fibroblast proliferation. This study indicates that AuAgSNP has antibacterial/antibiofilm activities as well as biocompatibility unlike NPs which are very cytotoxic to cells. Hence AuAgSNP can be used in medical implants and devices.

Design of a papain immobilized antimicrobial food package with curcumin as a crosslinker.

Contamination of food products by spoilage and pathogenic microorganisms during post process handling is one of the major causes for food spoilage and food borne illnesses. The present green sustainable approach describes the covalent immobilization of papain to LDPE (low density polyethylene), HDPE (high density polyethylene), LLDPE (linear low density polyethylene) and PCL (polycaprolactam) with curcumin as the photocrosslinker. About 50% of curcumin and 82-92% of papain were successfully immobilized on these polymers. After 30 days, the free enzyme retained 87% of its original activity, while the immobilized enzyme retained more than 90% of its activity on these polymers. Papain crosslinked to LLDPE exhibited the best antibiofilm properties against Acinetobacter sp. KC119137.1 and Staphylococcus aureus NCIM 5021 when compared to the other three polymers, because of the highest amount of enzyme immobilized on this surface. Papain acts by damaging the cell membrane. The enzyme is able to reduce the amount of carbohydrate and protein contents in the biofilms formed by these organisms. Meat wrapped with the modified LDPE and stored at 4°C showed 9 log reduction of these organisms at the end of the seventh day when compared to samples wrapped with the bare polymer. This method of crosslinking can be used on polymers with or without functional groups and can be adopted to bind any type of antimicrobial agent.

Functionalized polycaprolactam as an active food package for antibiofilm activity and extended shelf life.

Papain is covalently crosslinked on polycaprolactam and tested as a wrapper for packaging cottage cheese, against E. coli biofilm. The bacterial count on neat polycaprolactam (NP) was 50×10(6)/ml on the 5th day which dramatically increased to 300×10(6) colony forming units (CFU)/ml by the end of 30th day. The corresponding CFU/ml on papain functionalized polycaprolactam (FP) was 10×10(2) on 5th day and 20×10(2) by the end of 30th day. Fourier transform infrared spectroscopic (FTIR) analysis of biofilm on NP showed the presence of polysaccharide, protein, lipid and metabolites which was three times reduced on FP. FT Raman spectroscopy showed the effect of papain on functional groups such as hydroxyl, amino, carbonyl, phosphoryl and aliphatic, leading to the inhibition of the biofilm. Motility, hydrophobicity and zeta potential of E. coli on NP and FP were 10.67 and 5.65 µm/s/V/cm; 88 and 20%; 8.93±2.09 and 2.65±0.52 mV respectively, thereby decreasing the biofilm forming ability of E. coli.

A study on the long term effect of biofilm produced by biosurfactant producing microbe on medical implant.

Low density polyethylene (LDPE) is used as a long term medical implant. Biofilm forming ability of two pathogenic microorganisms, namely, Bacillus subtilis (B. subtilis) and Pseudomonas aeruginosa (P. aeruginosa) on this polymer and the differences in the properties of these matrices are studied for a year. There are very few long term studies on biofilms formed on medical implants. After three months, colonies of B. subtilis were two times higher when compared to those of P. aeruginosa. And at the end of one year, they were two orders of magnitude higher than the later. The exopolysaccharide (EPS) and biosurfactant recovered from the polymer surface after three months were 21 and 10.4 µg/cm(2) for B. subtilis and 13 and 8.6 µg/cm(2) for P. aeruginosa. After one year, these were higher in B. subtilis (50 and 37.1 µg/cm(2), respectively) than in P. aeruginosa (34.1 and 31.8 µg/cm(2), respectively). B. subtilis consisted of protein controlling the community and sporulation development, while P. aeruginosa had either housekeeping or metabolic proteins. The EPS in the respective biofilm consisted of biosurfactants produced by B. subtilis (surfactins, m/z=1029 to 1134) and P. aeruginosa (rhamnolipids, m/z=568 to 705). Thermogravimetric analysis indicated that LDPE incubated with these organisms underwent a weight loss of 4 and 3% after three months and 11.1 and 9.2% after one year, respectively at 435 °C. Laccase and manganese peroxidase were detected in the biofilm which could be involved in the degradation. The biosurfactant of these microorganisms altered the hydrophobicity of the surface, favoring their attachment and proliferation.

Antibiofilm properties of interfacially active lipase immobilized porous polycaprolactam prepared by LB technique.

Porous biomaterial is the preferred implant due to the interconnectivity of the pores. Chances of infection due to biofilm are also high in these biomaterials because of the presence of pores. Although biofilm in implants contributes to 80% of human infections, there are no commercially available natural therapeutics against it. In the current study, glutaraldehyde cross linked lipase was transferred onto a activated porous polycaprolactam surface using Langmuir-Blodgett deposition technique, and its thermostability, slimicidal, antibacterial, biocompatibility and surface properties were studied. There was a 20% increase in the activity of the covalently crosslinked lipase when compared to its free form. This immobilized surface was thermostable and retained activity and stability until 100°C. There was a 2 and 7 times reduction in carbohydrate and 9 and 5 times reduction in biofilm protein of Staphylococcus aureus and Escherichia coli respectively on lipase immobilized polycaprolactam (LIP) when compared to uncoated polycaprolactam (UP). The number of live bacterial colonies on LIP was four times less than on UP. Lipase acted on the cell wall of the bacteria leading to its death, which was confirmed from AFM, fluorescence microscopic images and amount of lactate dehydrogenase released. LIP allowed proliferation of more than 90% of 3T3 cells indicating that it was biocompatible. The fact that LIP exhibits antimicrobial property at the air-water interface to hydrophobic as well as hydrophilic bacteria along with lack of cytotoxicity makes it an ideal biomaterial for biofilm prevention in implants.

Chalcone coating on cotton cloth - an approach to reduce attachment of live microbes.

Drug resistant bacteria are a major threat to humans, especially those which mediate nosocomial infections. In this paper, three different 4-sulfonylmethyl chalcones are coated onto cotton cloths with acacia as the binder using a padding mangle to make them antibacterial. A 99% reduction in the adhesion of three slime producing organisms, namely Staphylococcus aureus NCIM5021, Escherichia coli NCIM2931 and Pseudomonas aeruginosa NCIM2901, on these surfaces was observed. The coated surfaces are more hydrophobic than the original one. The attachment of the bacteria (CFU ml-1) to the cloth is directly proportional (correlation coefficient, R = 0.58) to the hydrophobicity of the surface of the microorganism. The extent of bacterial attachment on the cloths (CFU ml-1) is not correlated with the minimum inhibitory concentration (MIC) of the chalcones (R = -0.1), but on the other hand it is negatively correlated with the hydrophilicity of the coated cloth (R = -0.52). This indicates that hydrophilic surfaces prevent bacterial attachment and hydrophobic organisms have a greater propensity to attach to hydrophobic surfaces than hydrophilic ones. A simple multi-linear regression model with the surface hydrophobicity of the organism and the hydrophilicity of the cloth is able to predict the extent of bacterial attachment. This study suggests that the coated cloths could find applications in hospital environments.

Antibiofilm properties of silver and gold incorporated PU, PCLm, PC and PMMA nanocomposites under two shear conditions.

Silver and gold nanoparticles (of average size ∼20-27 nm) were incorporated in PU (Polyurethane), PCLm (Polycaprolactam), PC (polycarbonate) and PMMA (Polymethylmethaacrylate) by swelling and casting methods under ambient conditions. In the latter method the nanoparticle would be present not only on the surface, but also inside the polymer. These nanoparticles were prepared initially by using a cosolvent, THF. PU and PCLm were dissolved and swollen with THF. PC and PMMA were dissolved in CHCl3 and here the cosolvent, THF, acted as an intermediate between water and CHCl3. FTIR indicated that the interaction between the polymer and the nanoparticle was through the functional group in the polymer. The formation of E.coli biofilm on these nanocomposites under low (in a Drip flow biofilm reactor) and high shear (in a Shaker) conditions indicated that the biofilm growth was higher (twice) in the former than in the latter (ratio of shear force = 15). A positive correlation between the contact angle (of the virgin surface) and the number of colonies, carbohydrate and protein attached on it were observed. Ag nanocomposites exhibited better antibiofilm properties than Au. Bacterial attachment was highest on PC and least on PU nanocomposite. Casting method appeared to be better than swelling method in reducing the attachment (by a factor of 2). Composites reduced growth of organisms by six orders of magnitude, and protein and carbohydrate by 2-5 times. This study indicates that these nanocomposites may be suitable for implant applications.

Computational approaches to improve aggrecanase-1 inhibitory activity of (4-keto) phenoxy) methyl biphenyl-4-sulfonamide: group based QSAR and docking studies.

Group based Quantitative Structure Activity Relationship (GQSAR) was developed for thirty (4-keto-phenoxy) methyl biphenyl-4-sulfonamides which exhibit aggrecanase-1 enzyme inhibitory activity. This enzyme is involved in osteoarthritis. The data is divided into training and test sets, where the latter is used for validating the model. Substitution in the R(1) position plays a major role when compared to substitution in R(2) position. The former position is influenced by two descriptors, namely electrotopological and connectivity indices. R(2) position is influenced by radius of gyration. The statistical parameters for the training set (r(2) = 0.80, r(2)adj = 0.77, q(2) = 0.69, F-ratio = 26.80 and standard error = 0.24) and the predicted r(2) (r(2)(test) =0.95) are satisfactory. Docking of the compounds with aggrecanase-1 enzyme showed that there is a strong negative correlation between the binding energy and aggrecanase-1 inhibitory activity. Compounds with the carbonyl substitution interact with the S'1 pocket which is needed for enhanced activity. The two methodologies described here can help in lead optimization.

Chalcone embedded polyurethanes as a biomaterial: Synthesis, characterization and antibacterial adhesion.

An antibacterial dimethylamino-chalcone embedded multiblock copolymer (PCL-PEG) was synthesized and characterized using FT-IR, 1H NMR, SEM and SEC and the compound was characterized using FT-IR, 1H NMR, and 13C NMR. A 10% copolymer composite was prepared and casted as film to be used as a biomaterial and the copolymer films without the compound acted as control. TGA, DSC, AFM, SEM and EDAX analysis were performed for the above samples. Surface roughness (Ra) of the copolymer composite film was less when compared to the copolymer film which indicated the proper distribution of chalcone in the composite film. copolymer composite film was hydrophilic compared to copolymer film. Antibacterial adhesion studies were performed for copolymer composite polymer film and evaluated using CFU measurement and SEM analysis. Copolymer composite film shows promising antibacterial adhesion compared to the copolymer film. Hence the copolymer composite film can be used as a new biomaterial endowed with antibacterial properties.