Ligand Based Drug Discovery Of Novel Dengue-2 NS2B-NS3 Protease Inhibitors

Kes demam denggi dilaporkan meningkat setiap tahun, namun sehingga kini belum ada ubat anti-denggi boleh didapati di pasaran. Oleh itu, pencarian ejen anti-denggi adalah kritikal. Pemotongan poliprotein pelopor oleh enzim protease NS2B-NS3 merupakan proses yang sangat penting untuk replikasi flavivirus. Oleh itu enzim protease NS2B-NS3 sesuai dijadikan sasaran untuk membangunkan ubat anti-denggi. Di Malaysia, Denggi-2 adalah jenis sera yang paling lazim. Dalam kajian ini, pendekatan berasaskan ligan telah dilaksanakan dalam mencari perencat enzim protease NS2B-NS3 Denggi-2 baharu yang berpotensi. Model farmakofor telah dihasilkan daripada pelbagai struktur perencat enzim protease NS2B-NS3 Denggi-2 yang pernah dilaporkan, yang terdiri daripada molekul peptida dan bukan peptida. Model farmakofor terpilih telah digunakan untuk menyaring senarai sebatian dalam pengkalan data National Cancer Institute, AS (NCI) untuk mencari perencat protease NS2B-NS3 Denggi-2 yang baharu secara maya. The reported dengue cases are increasing yearly, yet no anti-dengue agent is available in the market. Therefore, the search for anti-dengue is critical. In Malaysia, Dengue-2 (DEN-2) is the most prevalent serotype. NS2B-NS3 protease is the enzyme for the cleavage of polyprotein precursor, which is crucial for the flavivirus replications. This makes it a potential target for the development of therapeutics against the dengue virus. In this study, ligand-based approach was implemented in searching for the new potential DEN-2 NS2B-NS3 protease inhibitors. Pharmacophore models were developed from diverse reported structures of DEN-2 NS2B-NS3 protease inhibitors, comprising peptide and non-peptide molecules. The selected pharmacophore models were employed to screen the US National Cancer Institute (NCI) list of compounds to search for new DEN-2 NS2B-NS3 protease inhibitors

Morphological, teratogenic and behavioral evaluations of Gelidium spinosum methanol extract on zebrafish embryos

Gelidium spinosum is an edible red seaweed from the family Gelidiaceae with possibility to be developed. The potential medical benefits of G. spinosum have been established, yet adequate empirical research on its toxicity is still lacking. Hence, the present work was aimed to examine the toxicity of G. spinosum methanol extract (GsME) on zebrafish (Danio rerio) embryos and to identify the phytoconstituents using gas chromatography-mass spectrometry (GC-MS) analysis. Results of this study showed that GsME induced morphological defects in zebrafish embryos, including reduction in eye size and body length. Moreover, yolk sac size and mortality were increased in zebrafish embryos exposed to GsME in a dose-dependent manner. GsME at high concentrations triggered teratogenic effects in zebrafish embryos such as decrease in heartbeat/minute, lack of pigmentation, lack of somite, structural deformity, pericardial oedema, and yolk oedema. The LC50 and EC50 of GsME were 1, indicating its teratogenic attribute. Additionally, GsME exerted behavioral effects i.e. significantly lower total distance of movement and slower swimming speed of zebrafish embryos. GC-MS analysis of GsME was confirmed the presence of amino acid, phenolics, carboxylic acids, reducing sugars, saturated fatty acids and brominated saturated fatty acid in the extract. It suggesting that compounds of 13-bromotetradecanoic acid, palmitic acid, and stearic acid containing in GsME were contributed to the toxic effects

Preliminary study on the formulation of syariah compliant generic sustained release gliclazide tablet using xanthan gum

Gliclazide (1-(3,3a,4,5,6,6a-hexahydro-1H-cyclopenta[c]pyrrol-2-yl)-3-(4-methylphenyl)sulfonylurea) is a second-generation sulfonylurea which is orally administered in the treatment of non-insulin-dependent diabetes mellitus in adults. Sustain release drugs help to improve drugs bioavailability by controlling the time of drug release or prolonging it. We are reporting the preliminary formulation of sustain release gliclazide tablets with careful choice of all the ingredients and processes related to syariah compliance manufacturing of pharmaceutical products. In this work, xanthan gum, a natural gum was used to achieve the sustain release criteria. The tablets were produced by wet granulation and semi-automatic tableting process. Tablet characterisation was done following the British Pharmacopoeia (BP) criteria. We expect that the outcome of our study will result in a suitable formulation that could be useful for the formulation of such product that will be helpful for the Muslim patient especially during the fasting month

Thioguanine-based DENV-2 NS2B/NS3 protease inhibitors: Virtual screening, synthesis, biological evaluation and molecular modelling

Dengue virus Type 2 (DENV-2) is predominant serotype causing major dengue epidemics. There are a number of studies carried out to find its effective antiviral, however to date, there is still no molecule either from peptide or small molecules released as a drug. The present study aims to identify small molecules inhibitor from National Cancer Institute database through virtual screening. One of the hits, D0713 (IC50 = 62 μM) bearing thioguanine scaffold was derivatised into 21 compounds and evaluated for DENV-2 NS2B/NS3 protease inhibitory activity. Compounds 18 and 21 demonstrated the most potent activity with IC50 of 0.38 μM and 16 μM, respectively. Molecular dynamics and MM/PBSA free energy of binding calculation were conducted to study the interaction mechanism of these compounds with the protease. The free energy of binding of 18 calculated by MM/PBSA is -16.10 kcal/mol compared to the known inhibitor, panduratin A (-11.27 kcal/mol), which corroborates well with the experimental observation. Results from molecular dynamics simulations also showed that both 18 and 21 bind in the active site and stabilised by the formation of hydrogen bonds with Asn174

Medicinal potential of isoflavonoids: Polyphenols that may cure diabetes

In recent years, there is emerging evidence that isoflavonoids, either dietary or obtained from traditional medicinal plants, could play an important role as a supplementary drug in the management of type 2 diabetes mellitus (T2DM) due to their reported pronounced biological effects in relation to multiple metabolic factors associated with diabetes. Hence, in this regard, we have comprehensively reviewed the potential biological effects of isoflavonoids, particularly biochanin A, genistein, daidzein, glycitein, and formononetin on metabolic disorders and long-term complications induced by T2DM in order to understand whether they can be future candidates as a safe antidiabetic agent. Based on in-depth in vitro and in vivo studies evaluations, isoflavonoids have been found to activate gene expression through the stimulation of peroxisome proliferator-activated receptors (PPARs) (α, γ), modulate carbohydrate metabolism, regulate hyperglycemia, induce dyslipidemia, lessen insulin resistance, and modify adipocyte differentiation and tissue metabolism. Moreover, these natural compounds have also been found to attenuate oxidative stress through the oxidative signaling process and inflammatory mechanism. Hence, isoflavonoids have been envisioned to be able to prevent and slow down the progression of long-term diabetes complications including cardiovascular disease, nephropathy, neuropathy, and retinopathy. Further thoroughgoing investigations in human clinical studies are strongly recommended to obtain the optimum and specific dose and regimen required for supplementation with isoflavonoids and derivatives in diabetic patients

Palm olein emulsions potential vehicles for drug delivery

Palm olein emulsions were produced using the combinations of Span® and Tween® surfactants by mechanical homogenisation. Effects of the types of surfactants, concentrations, effective HLB and the types of viscosity modifiers and concentrations on the characteristics of the emulsions were investigated. With palm olein content of 20% (w/w), stable oil droplets were produced at HLB values ranging from 8.5 to 11.0. Optimal concentrations of surfactants ranged from 25 to 30% (w/w to oil) depending on the types of the Span®/Tween® mixtures. Among the viscosity modifiers used, Carbopol®940 was the most effective. Suitable concentrations of Carbopol®940 for the emulsions prepared with Span®20/Tween®20 ranged from 0.1 to 0.3% (w/w). Beyond this concentration, destabilisation of emulsion due to at least depletion of water molecules could have occurred as a result of competitive hydration between Carbopol®940 and the surfactants. The emulsions produced exhibited viscoelastic and pseudoplastic behaviour, with yield value ranging from 0.1 to 35.2 Pa. Depending on the concentration of Carbopol®940 and within the linear viscoelastic region, the emulsions were elastic in nature as shown by domination of storage modulus (G’) over the loss modulus (G”) and with tan δ < 1 in the frequency range of 0.01 to 10 Hz. These favourable rheological properties were induced by the formation of three-dimensional network of Carbopol®940 molecules in the continuous aqueous phase, which also entrapped the oil droplets and thus increased the stability of the emulsio

The effect of carbopol 940 on physical stability of palm olein emulsions stabilised by span and tween surfactants

Viscosity inducing agents are commonly used to modify the rheological properties of emulsions. The objective of the study was to determine the effects of the concentration of Carbopo1 940 on the physical stability and rheological properties of palm olein-in-water emulsions prepared with Span 20/Tween 20 and Span 20/Tween 80. Based on the creaming behaviour and particle size analysis, 0.1 to 0.3% (w/w) of Carbopo1 940 was found to be suitable for the further stabilisation of the emulsions with Span 20/Tween 20. However, the emulsions with a combination of Carbopol 940 and Span 20/Tween 80 were not stable. Destabilisation could have resulted from the depletion of water molecules as a result of further hydration of hydrophilic Carbopol 940 and thus adversely affected the hydration of the hydrophilic moieties of the non-ionic surfactants used. This tendency is suspected to be more prominent for the Tween 80 as it is less hydrophilic than Tween 20. The stable emulsions produced exhibited viscoelastic and pseudoplastic behaviour with yield stress. Within the linear viscoelastic region, the emulsions were elastic in nature. Desired rheological properties can be obtained by changing the concentration of Carbopol 940 to make it suitable for the development of topical cream and lotion

Rheology of palm olein emulsions stabilized by non-ionic surfactants as potential carriers for drug delivery

Palm olein emulsions were prepared by homogenising the oil with varied ratios of sorbitan monolaurate (Span 20®) and polyoxyethylene 20 sorbitan monolaurate (Tween 20®). Viscosity changes of these emulsions with and without Tragacanth gum, were measured. The viscosity of emulsions increased drastically with increasing ratios of Span 20/Tween 20, and decreased with increasing shear rate, indicating shear thinning. As the ratio of Span 20/Tween 20 increased to 1: 0.4 ratio, a small amount of hysteresis was observed. Significant thixotropic behaviour was noted with the addition of 0.01% Tragacanth gum into the oil emulsion

Combination of xanthan gum and HPMC as retardants in sustained release gliclazide formulation

Gliclazide tablet is widely used for the treatment of non-insulin-dependent diabetes mellitus. However, there is still lack of study done in formulating the sustained release gliclazide tablet. Combination of xanthan gum, a natural gum and hydroxypropyl methylcellulose (HPMC) were used to act as retardants for the sustained release gliclazide tablet. In this study, sustained release 60 mg gliclazide tablets were formulated with different ratios and content of xanthan gum and HPMC. The tablets were produced by wet granulation and semi-automatic tableting process. The content variation, weight variation, hardness, and friability of the tablet met the specification by British Pharmacopoeia. In vitro dissolution profiles of the tablets were compared with the commercially available sustained release 60 mg gliclazide tablet. Keywords: Gliclazide; sustained release; xanthan gum; HPM

Addressing formulation issues of syariah compliant generic sustained release antidiabetic solid dosage form.

Gliclazide (1-(3,3a,4,5,6,6a-hexahydro-1H-cyclopenta[c]pyrrol-2-yl)-3-(4-methylphenyl)sulfonylurea) is a second-generation sulfonylurea which is orally administered in the treatment of non-insulin-dependent diabetes mellitus in adults. Sustain release drugs help to improve drugs bioavailability by controlling the time of drug release or prolonging it. We are reporting the formulations of 60 mg sustain release gliclazide tablets with careful choice of all the ingredients and processes related to syariah compliance manufacturing of pharmaceutical products. In this work, different ratios of xanthan gum, a natural gum and hydroxypropyl methylcellulose (HPMC) had been used as the release retardants to achieve the sustain release criteria. The tablets were produced by wet granulation and semi-automatic tableting process. All the formulations were evaluated for the thickness, hardness, friability, weight variation, content of active ingredient, and in vitro dissolution profile following the British Pharmacopoeia (BP) criteria. Tablet assay of active pharmaceutical ingredient (High Performance Liquid Chromatography [HPLC] method) was adopted from British Pharmacopoeia (BP) with some modification. The HPLC method validation covered the specificity, linearity, range, accuracy, precision, limit of detection (LOD), and limit of quantitation (LOQ). We expect that the outcome of our study could be useful for the formulation of such product that will be helpful for the Muslim patient especially during the fasting month