Thiolated Polymeric Hydrogels for Biomedical Applications: A Review.

Hydrogels are a three-dimensional (3D) network of hydrophilic polymers. The physical and chemical crosslinking of polymeric chains maintains the structure of the hydrogels even when they are swollen in water. They can be modified with thiol by thiol epoxy, thiol-ene, thiol-disulfide, or thiol-one reactions. Their application as a matrix for protein and drug delivery, cellular immobilization, regenerative medicine, and scaffolds for tissue engineering was initiated in the early 21st century. This review focuses on the ingredients, classification techniques, and applications of hydrogels, types of thiolation by different thiol-reducing agents, along with their mechanisms. In this study, different applications for polymers used in thiolated hydrogels, including dextran, gelatin, polyethylene glycol (PEG), cyclodextrins, chitosan, hyaluronic acid, alginate, poloxamer, polygalacturonic acid, pectin, carrageenan gum, arabinoxylan, carboxymethyl cellulose (CMC), gellan gum, and polyvinyl alcohol (PVA) are reviewed.

Development of Statistically Optimized Chemically Cross-Linked Hydrogel for the Sustained-Release Delivery of Favipiravir.

Nowadays, the use of statistical approaches, i.e., Box-Bhenken designs, are becoming very effective for developing and optimizing pharmaceutical drug formulations. In the current work, a Box-Bhenken design was employed using Design Expert version 11 to develop, evaluate, and optimize a hydrogel-based formulation for sustained release of an antiviral drug, i.e., favipiravir. The hydrogels were prepared using the free radical polymerization technique. ß-Cyclodextrin (ß-CD), N,N'-methylenebisacrylamide (MBA), acrylic acid (AA), and potassium per sulfate (KPS) were used as oligomer, crosslinker, monomer, and initiator, respectively. Three variables, including ß-CD (X1), MBA (X2), and AA (X3) were used at various concentrations for the preparation of hydrogels, followed by evaluation of a sol-gel fraction, swelling, porosity, chemical compatibilities, in vitro drug release, and entrapment efficiency. The results of the studies revealed that the degree of swelling was pH dependent, the best swelling being at pH 7.2 (1976%). On the other hand, for the low sol fraction of 0.2%, the reasonable porosity made the hydrogel capable of loading 99% favipiravir, despite its hydrophobic nature. The maximum entrapment efficiency (99%) was observed in optimized hydrogel formulation (F15). Similarly, in vitro drug release studies showed that the prepared hydrogels exhibited a good, sustained release effect till the 24th hour. The kinetic modelling of drug release data revealed that the Korsmeyer-Peppas model was best fit model, describing a diffusion type of drug release from the prepared hydrogels. Conclusively, the outcomes predict that the hydrogel-based system could be a good choice for developing a sustained-release, once-daily dosage form of favipiravir for improved patient compliance.

Formulation optimization, in vitro and in vivo evaluation of agomelatine-loaded nanostructured lipid carriers for augmented antidepressant effects.

The present study was intended to prepare and optimize agomelatine-loaded nanostructured lipid carriers (AGM-NLCs) for augmented in vivo antidepressant potential. AGM-NLCs were optimized on several parameters including cumulative hydrophilic-lipophilic balance of surfactants, proportions of solid and liquid lipids, total amounts of drug and surfactants. AGM-NLCs were assessed for their physicochemical properties, in vitro AGM release and in vivo antidepressant effects in mice model. The optimized AGM-NLCs demonstrated spherical morphology with average particle size of 99.8 ± 2.6 nm, PDI of 0.142 ± 0.017, zeta potential of - 23.2 ± 1.2 mV and entrapment efficiency of 97.1 ± 2.1%. Thermal and crystallinity studies depict amorphous nature of AGM after its incorporation into NLCs. AGM-NLCs exhibit a sustained drug release profile after initial 2 h. Mice treated with AGM-NLCs exhibited reduced immobility time in behavioral analysis. Furthermore, cresyl violet staining demonstrated an improved neuronal morphology and survival in AGM-NLCs group. The concentrations and the expression of inflammatory markers (TNF-α and COX-2) in mice brain were significantly reduced by AGM-NLCs. Taken together, therapeutic effectiveness of AGM was markedly augmented in AGM-NLCs and thereby they could be promising nanocarriers for the effective delivery of antidepressants to brain.

Formulation and evaluation of sustained release ocular inserts of betaxolol hydrochloride using arabinoxylan from Plantago ovata.

The purpose of the current studies was to develop ocular insert of betaxolol hydrochloride (BXH), using arabinoxylan (AX) as a film former. The inserts were prepared by sandwiching I mg of BXH between two films of AX. Six different formulations of ocular inserts were prepared in such a way that first three formulations contained varying concentrations of AX along with glycerol as plasticizer, whereas, rest of the formulations were added with 0.5mg of sodium alginate, sandwiched between two films of AX along with 1mg of BXH. Chemical compatibilities of the ingredients were assessed by using FTIR. Prepared ocular inserts were subjected to various physicochemical characterizations. The dissolution studies showed that ocular inserts containing sodium alginate with the AX showed sustained release effect better than the formulations with AX alone. Addition of sodium alginate resulted in inhibition of sudden release in initial phase and further sustained the release of drug from ocular inserts. Ocular inserts were pH compatible to the eyes as well as there was no interaction among the drug and excipients, suggesting that the selected excipients were suitable for the development of sustained release ocular inserts of BXH.

Formulation development and in-vitro evaluation of gastroretentive drug delivery system of loxoprofen sodium: A natural excipients based approach.

The limitations of conventional type delivery systems to retain drug (s) in the stomach has resulted in the development of novel gastroretentive drug delivery system. We developed single-layer effervescent floating tablets of loxoprofen sodium for prolong delivery in the stomach using natural polymers xanthan gum, guar gum and semisynthetic polymer HPMCK4M. All the formulations (F1-F9) were developed by varying concentrations of xanthan gum and HPMCK4M while guar gum concentration was kept constant. Two gas generating agent (s) incorporated were sodium bicarbonate and citric acid. All compendial pre and post-compression tests results were in the acceptable limits. FTIR analysis confirmed drug-polymer compatibility. The in-vitro drug release in simulated conditions i.e., 0.1 N HCl for 12 h revealed orderly increase in total floating time, i.e., less than 6 h for F1 over 12 h for F9. Formulations F1 to F4 were not capable to retard drug release up to 12 h, whereas F5-F7 for 12 h, while F8 and F9 for more than 12 h. Data fitting in various kinetic models showed that drug release best fit in first order kinetic model and F9 in zero order. Based on results data, F7 was the best among all.

Antidepressant-like effect of ethanol in mice forced swimming test is mediated via inhibition of NMDA/nitric oxide/cGMP signaling pathway.

There is evidence for a dramatic relationship between depression and alcohol consumption. Depressed patients may abuse ethanol because this agent reduces the symptoms of depression. In the current study, we aimed to investigate the NMDA/nitric oxide/cGMP pathway in the antidepressant-like effect of ethanol in an animal model of behavioral despair. Animals were subjected to locomotor activity in an open-field test separately, followed by a forced swimming test. During the forced swimming test (FST), ethanol (2 and 2.5 g/kg) significantly decreased the immobility time without altering the locomotor activity of animals. The antidepressant-like effect of ethanol (2.5 g/kg) was reversed by co-administration of N-methyl-D-aspartate (NMDA, 75 mg/kg), L-arginine (750 mg/kg), or sildenafil (5 mg/kg). In contrast, co-administration of MK-801 (0.05 mg/kg), ketamine (1 mg/kg), and ifenprodil (0.5 mg/kg) as antagonists of NMDAR, and NG-nitro-L-arginine methyl ester (L-NAME, 10 mg/kg), 7-nitroindazole (7-NI, 30 mg/kg), and methylene blue (10 mg/kg) as inhibitors of nitric oxide synthase (NOS), or 1H-[1,2,4]oxadiazole[4,3-a]quinoxalin-1-one (ODQ) (20 mg/kg), a nitric oxide/cyclic-guanosine monophosphate (NO-cGMP) inhibitor, with a subeffective dose of ethanol (1.5 g/kg), significantly decreased the immobility time in the FST. Furthermore, injection of ethanol 2.5 g/kg alone or 1.5 g/kg with a 7-NI subeffective dose, significantly decreased the nitrite levels in the hippocampus and prefrontal cortex. Hence, it is concluded that blockade of NMDA receptors and the nitric oxide/cyclic-guanosine monophosphate (NO-cGMP) pathway might be involved in the antidepressant-like effect of ethanol in mice.

Formulation of instant disintegrating buccal films without using disintegrant: An in-vitro study.

The current study was conducted to fabricate Metoclopramide HCL (MCH) and Sumatriptan succinate (SS) instant release buccal films (IRBF) without using any super disintegrant. The solvent casting method was used for the preparation of IRBFs and prepared IRBFs were physicochemically evaluated. Spectrophotometric analysis was done to determine the lambda max followed by the linearity determination of both drugs. Different concentrations such as 100, 125, and 150mg of hydrophilic polymer (HPMC E5) were employed but the concentration of glycerol was variable. Comparatively better results were observed for the formulation with 150mg of HPMC E5 and 30% glycerol. Formulated IRBFs showed good tensile strength with a mean disintegration time of 12.4-28.4 seconds and rapid dissolution with more than 50% drug release within 2 minutes. It was concluded that the chosen combination of polymers was appropriate for the fabrication of MCH and SS buccal strips.

Licofelone, a dual cyclooxygenase/5-lipoxygenase inhibitor, reverses endotoxin-induced impaired atrial chronotropic responsiveness to cholinergic stimulation in rats.

Evidence show that endotoxemia is linked with tachycardia. The exact mechanism of tachycardia is not well-understood, but it seems that impaired cardiac chronotropic responsiveness to cholinergic stimulation plays a role in this phenomenon. The aim of this experiment was to study the effect of licofelone as a dual cyclooxygenase (COX)/5-lipoxygenase (5-LOX) inhibitor in modulation of atrial chronotropic hyporesponsiveness to cholinergic stimulation in endotoxemic rats, compared with hydrocortisone and indomethacin in in vitro and in vivo studies. Rats were injected by either of lipopolysaccharide (LPS) or saline. The isolated atria were incubated with licofelone, hydrocortisone, or indomethacin in an organ bath set up. In a separate experiment, rats were injected with licofelone, hydrocortisone, or indomethacin prior to isolation of the atria. Then, in both experiments, chronotropic responsiveness to cumulative concentrations of carbacholine in organ bath was recorded. LPS injection decreased the chronotropic responsiveness to cholinergic stimulation in both in vitro and in vivo experiments, significantly (P < 0.0001), while either incubation of isolated atria with licofelone (a dual COX/5-LOX inhibitor) or injection of licofelone to animals could reverse it, completely (P < 0.01). Hydrocortisone (phospholipase A2 and COX-2 inhibitor) in vitro and in vivo (P < 0.001, P < 0.05, respectively) as well as indomethacin (COX inhibitor) in vitro and in vivo (P < 0.05, P < 0.01, respectively) exerted some lesser effects. Our data revealed that in endotoxemic rats, chronotropic hyporesponsiveness to cholinergic stimulation was modulated by the dual COX/5-LOX inhibitor licofelone, and this effect is comparable with hydrocortisone and indomethacin.

Nanostructured lipid carriers-mediated brain delivery of carbamazepine for improved in vivo anticonvulsant and anxiolytic activity.

The limited brain delivery of carbamezapine (CBZ) presents a major hurdle in the successful epilepsy treatment. The potential of carbamezapine-loaded nanostructured lipid carriers (CBZ-NLCs) for improved brain delivery is investigated in the current study. CBZ-NLCs were prepared by using binary mixture of trilaurin and oleic acid as a lipid core stabilized with Poloxamer 188, Tween 80 and Span 80. CBZ-NLCs were evaluated for physicochemical properties, in vitro release, in vivo brain kinetics, anticonvulsant and anxiolytic activities. The optimized CBZ-NLCs demonstrated nanometric particle size (97.7 nm), surface charge of -22 mV and high drug incorporation (85%). CBZ-NLCs displayed biphasic release pattern with initial fast followed by sustained drug release. CBZ-NLCs significantly enhanced the AUC of CBZ (520.4 µg·h/mL) in brain compared with CBZ dispersion (244.9 µg·h/mL). In vivo anticonvulsant activity of CBZ-NLCs in PTZ-induced seizure model showed a significant increase in the onset time (143.0 sec) and reduction in duration (17.2 sec) of tonic-clonic seizures compared with CBZ dispersion (75.4 and 37.2 sec). The anxiolytic activity in light-dark box and elevated-plus maze models also demonstrated superiority of CBZ-NLCs to CBZ dispersion. From the results, CBZ-NLCs presents a promising strategy to improve brain delivery and therapeutic outcomes of CBZ in epilepsy.

In Silico, Cytotoxic and Antioxidant Potential of Novel Ester, 3-hydroxyoctyl -5- trans-docosenoate Isolated from Anchusa arvensis (L.) M.Bieb. Against HepG-2 Cancer Cells.

BACKGROUND: Cancer is one of the chronic health conditions worldwide. Various therapeutically active compounds from medicinal plants were the current focus of this research in order to uncover a treatment regimen for cancer. Anchusa arvensis (A. anchusa) (L.) M.Bieb. contains many biologically active compounds. METHODS: In the current study, new ester 3-hydroxyoctyl -5- trans-docosenoate (compound-1) was isolated from the chloroform soluble fraction of A. anchusa using column chromatography. Using MTT assay, the anticancer effect of the compound was determined in human hepatocellular carcinoma cells (HepG-2) compared with normal epithelial cell line (Vero). DPPH and ABTS radical scavenging assays were performed to assess the antioxidant potential. The Molecular Operating Environment (MOE-2016) tool was used against tyrosine kinase. RESULTS: The structure of the compound was elucidated based on IR, EI, and NMR spectroscopy technique. It exhibited a considerable cytotoxic effect against HepG-2 cell lines with IC50 value of 6.50 ± 0.70 µg/mL in comparison to positive control (doxorubicin) which showed IC50 value of 1.3±0.21 µg/mL. The compound did not show a cytotoxic effect against normal epithelial cell line (Vero). The compound also exhibited significant DPHH scavenging ability with IC50 value of 12 ± 0.80 µg/mL, whereas ascorbic acid, used as positive control, demonstrated activity with IC50 = 05 ± 0.15 µg/mL. Similarly, it showed ABTS radical scavenging ability (IC50 = 130 ± 0.20 µg/mL) compared with the value obtained for ascorbic acid (06 ± 0.85 µg/mL). In docking studies using MOE-2016 tool, it was observed that compound-1 was highly bound to tyrosine kinase by having two hydrogen bonds at the hinge region. This good bonding network by the compound might be one of the reasons for showing significant activity against this enzyme. CONCLUSION: Our findings led to the isolation of a new compound from A. anchusa which has significant cytotoxic activity against HepG-2 cell lines with marked antioxidant potential.

Computer-aided design and synthesis of 3-carbonyl-5-phenyl-1H-pyrazole as highly selective and potent BRAFV600E and CRAF inhibitor.

BRAF belongs to the upstream portion of the MAPK pathway, which is involved in cell proliferation and survival. When mutations occur in BRAF, downstream MEK and ERK are phosphorylated irrespective of RAS, resulting in melanoma-like cancer. Over the years, small molecules targeting BRAFV600E have been discovered to be very effective melanoma drugs, but they are known to cause the BRAF paradox. Recently, it was shown that this paradox is caused by the heterodimer phenomenon of BRAF/CRAF. Here, we suggest one method by which paradoxical activation can be avoided by selectively inhibiting BRAFV600E and CRAF but not wild-type BRAF. From previous report of N-(3-(3-alkyl-1H-pyrazol-5-yl) phenyl) aryl amide as a selective inhibitor of BRAFV600E and CRAF, we present compounds that offer enhanced selectivity and efficacy with the aid of molecular modelling.

Discovery of novel 4-aryl-thieno[1,4]diazepin-2-one derivatives targeting multiple protein kinases as anticancer agents.

A series of 4-aryl-thieno[1,4]diazepin-2-one were synthesized and evaluated for their antiproliferative activities against the A375P melanoma and U937 hematopoietic cell lines. Several compounds showed very potent antiproliferative activities toward both cell lines and the activities were better than that of sorafenib, the reference standard. Derivatives were made as amide (8a-8i, 9a-9m) and urea (10a-10d, 11a-11d) with diverse hydrophobic moieties. One of the most potent inhibitor 10d, 1-(4-((4-ethylpiperazin-1-yl)methyl)-3-(trifluoromethyl)phenyl)-3-(4-(2-oxo-2,3-dihydro-1H-thieno [3,4-b][1,4]diazepin-4-yl)phenyl)urea was found to be very potent inhibitor of multi-protein kinases including FMS kinase (IC50 = 3.73 nM) and is a promising candidate for further development in therapeutics for cancer.

Physicochemical Modifications and Nano Particulate Strategies for Improved Bioavailability of Poorly Water Soluble Drugs.

BACKGROUND: Bioavailability is the segment of dose that is bioavailable for its therapeutic effect on the systemic circulation without any change in its characteristics, after administration by either route. It is one of the fundamental pharmacokinetic properties of drugs. It is important because, it defines the amount of drug to be administered for its intended therapeutic effect. If drug is more bioavailable, less amount of it is required to obtain therapeutic effect. However, it is also worth mentioning that most of the newly discovered therapeutic agents have poor solubility and thus low bioavailability. OBJECTIVES: In this article, various methods including conventional and advanced, have been reviewed that could be potentially used for the enhancement of bioavailability. Moreover, the benefits and drawbacks of all the strategies are deliberated to comprehend the probable use of each method supported by latest references. METHODS: Various strategies have been developed to enhance the solubility and thus bioavailability of numerous drugs, some of which are discussed here. All these strategies involve different approaches to improve the bioavailability including physical adaptation, chemical modification and controlling particle size of the engineered particle. RESULTS: These strategies, particularly the nano-particulate systems, not only improve the bioavailability of drugs but at the same time diminish the possible toxicities of the incorporated drugs. CONCLUSION: It can be concluded that this would be a new source of information for the readers.

Effective use of nanocarriers as drug delivery systems for the treatment of selected tumors.

Nanotechnology has recently gained increased attention for its capability to effectively diagnose and treat various tumors. Nanocarriers have been used to circumvent the problems associated with conventional antitumor drug delivery systems, including their nonspecificity, severe side effects, burst release and damaging the normal cells. Nanocarriers improve the bioavailability and therapeutic efficiency of antitumor drugs, while providing preferential accumulation at the target site. A number of nanocarriers have been developed; however, only a few of them are clinically approved for the delivery of antitumor drugs for their intended actions at the targeted sites. The present review is divided into three main parts: first part presents introduction of various nanocarriers and their relevance in the delivery of anticancer drugs, second part encompasses targeting mechanisms and surface functionalization on nanocarriers and third part covers the description of selected tumors, including breast, lungs, colorectal and pancreatic tumors, and applications of relative nanocarriers in these tumors. This review increases the understanding of tumor treatment with the promising use of nanotechnology.

Novel scaffold evolution through combinatorial 3D-QSAR model studies of two types of JNK3 inhibitors.

JNK3 is an emerging target for neurodegenerative diseases including AD and PD, with histological selectivity. Specifically, in AD, JNK3 is the main protein kinase for APP phosphorylation, which is an important mechanism for Aß processing, and a biomarker of Alzheimer's disease. Therefore, targeting JNK3 is a reasonable strategy for drug discovery in neurodegenerative diseases. In order to find a novel scaffold for JNK3 inhibitors, we performed 3D-QSAR modeling studies with two different JNK3 inhibitor series. The CoMFA model was obtained with a q2 value of 0.806 and an r2 value of 0.850. Based on CoMFA and CoMSIA models, rational design was conducted and led to a novel scaffold, N-(thiophen-2-yl)-8H-pyrazolo[1,5-a]pyrido[1,2-c]pyrimidine-10-carboxamide.

Discovery of highly selective CRAF inhibitors, 3-carboxamido-2H-indazole-6-arylamide: In silico FBLD design, synthesis and evaluation.

The recent success of vemurafenib shows the importance of selective BRAF V600E inhibition in melanoma. However, paradoxical activation by structurally diverse ATP-competitive RAF kinase inhibitors strongly suggests that selective CRAF inhibitors, not BRAF inhibitors, would be ideal for some Ras mutation cancer treatment. In this respect, we approached designing selective CRAF inhibitors starting from in silico fragment screening and synthesized a 3-carboxamido-2H-indazole-6-arylamide scaffold. Most of the compounds showed potent antiproliferative activity against the WM3629 melanoma cell line and the most promising compound, compound 10d, was found to be a potent and selective CRAF inhibitor with an IC50 value of 38.6 nM, which shows greater than 270-fold selectivity over BRAF kinase (9.45 µM).

Discovery of 4-arylamido 3-methyl isoxazole derivatives as novel FMS kinase inhibitors.

A series of 4-arylamido 3-methyl isoxazoles were synthesized and evaluated for their antiproliferative activities against the A375P melanoma and U937 hematopoietic cell lines. Most compounds showed selective antiproliferative activity toward the U937 cell line and the activities were better than that of sorafenib, the reference standard. Derivatives were made as amide 5a-b, 6a-o and urea 7a-n, 8a-g with hydrophobic moieties, and one of the most potent inhibitor 6a, 5-methyl-N-(2-methyl-5-(3-(4-methylpiperazin-1-yl)-5-(trifluoromethyl)benzamido)phenyl)isoxazole-4-carboxamide was found to be very potent inhibitor of FMS kinase (GI50 = 0.016 µM, IC50 = 9.95 nM) with excellent selectivity profiles and is a promising candidate for further development in therapeutics for cancer.

Click approach to the discovery of 1,2,3-triazolylsalicylamides as potent Aurora kinase inhibitors.

A series of 1,2,3-triazolylsalicylamide derivatives has been developed from the antiproliferative agent 7 and was evaluated for their Aurora kinase inhibitory activity. The novel 1,2,3-triazolylsalicylamide scaffold could be readily assembled by Cu(I)-catalyzed azide-alkyne 1,3-dipolar cycloaddition, allowing rapid access to the structurally diverse analogues. The synthesized 1,2,3-triazolylsalicylamide derivatives revealed a significant Aurora kinase inhibitory activity. In particular, 8g inhibited Aurora A with IC50 values of 0.37µM. The critical role of phenolic -OH in the binding was confirmed by a molecular modeling study.

Design, synthesis and biological evaluation of benzyl 2-(1H-imidazole-1-yl) pyrimidine analogues as selective and potent Raf inhibitors.

The synthesis of a novel series of (4-aminobenzyl/benzoyl)-1H-imidazol-1-yl pyrimidin-2-yl derivatives 9, 10, 18, 19 and their in vitro antiproliferative activities against the A375P human melanoma cell line and the U937 human leukemic monocyte lymphoma cell line are described. Potent antiproliferative effects were found from 9l, 9s and 10c; 10c was found to be a highly potent and selective BRAF V600E and CRAF inhibitor (IC50=38.3 nM and 8.79 nM).