The Influence of Sequence Alignment Length of template on the Accuracy and Quality of Homology modelling: Human Cytochrome P450 2D6 (CYP2D6) case study

Homology modelling is one of the important alternative techniques to X-ray crystallography and nuclear magnetic resonance (NMR) spectroscopy in structural determination of protein. CYP2D6 drug metabolizing enzymes have extensively studied prior to the successful determination of its 3D structure using X-ray crystallography. This study is one of the earlier works being carried out before the crystal structure was solved. The enzyme is polymorphic and more than 80 different alleles have been identified. The aim of this study is to identify possible criteria to improve the quality of 2D6 model. Four mammalian crystal structures CYP2C8, CYP2B4, CYP2C9 and CYP2C5 were selected from protein databank as template for CYP2D6 model. Multiple sequence alignment between the selected target and template was performed. Secondary structure prediction was generated using CYP2D6 sequence and the 3D models built based on each template. The quality of the models was evaluated using Ramachandran’s plot. The final models were superimposed with CYP2D6 crystal structure. The result shows that not only the sequence identity is important for the template selection but also the alignment length of sequence. The secondary structure prediction of CYP2D6 sequence was found significantly matched the secondary structure prediction of the 3D structures of CYP2D6 models. The stereochemical quality of CYP2D6 models were found adequately satisfied the Ramachandran.plot requirements and comparable to the stereochemical quality crystal structure proteins used as templates and CYP2D6 crystal structure. The criteria set shows that CYP2C8 is the better template for homology modelling of CYP2D6 since it has scored lower E-value and longer alignment length, high sequence identity provided by ClustalW . In addition the secondary structure prediction of the model better matched the consensus and satisfy the criteria of Ramachandran’s plot as well it retained lowest RMSD value from the crystal structure. The study concludes to that the length of the sequence alignment is a critical factor in template selection it is also shows the important primary and secondary structure prediction.Keywords: Homology modelling, CYP2D6, CYP2C8, CYP2C9, CYP2B4, CYP2C5

Effect of surfactant and surfactant blends on pseudoternary phase diagram behavior of newly synthesized palm kernel oil esters

Background: The purpose of this study was to select appropriate surfactants or blends of surfactants to study the ternary phase diagram behavior of newly introduced palm kernel oil esters. Methods: Nonionic surfactant blends of Tween® and Tween®/Span® series were screened based on their solubilization capacity with water for palm kernel oil esters. Tween® 80 and five blends of Tween® 80/Span® 80 and Tween® 80/Span® 85 in the hydrophilic-lipophilic balance (HLB) value range of 10.7–14.0 were selected to study the phase diagram behavior of palm kernel oil esters using the water titration method at room temperature. Results: High solubilization capacity was obtained by Tween® 80 compared with other surfactants of Tween® series. High HLB blends of Tween® 80/Span® 85 and Tween® 80/Span® 80 at HLB 13.7 and 13.9, respectively, have better solubilization capacity compared with the lower HLB values of Tween® 80/Span® 80. All the selected blends of surfactants were formed as waterin- oil microemulsions, and other dispersion systems varied in size and geometrical layout in the triangles. The high solubilization capacity and larger areas of the water-in-oil microemulsion systems were due to the structural similarity between the lipophilic tail of Tween® 80 and the oleyl group of the palm kernel oil esters. Conclusion: This study suggests that the phase diagram behavior of palm kernel oil esters, water, and nonionic surfactants is not only affected by the HLB value, but also by the structural similarity between palm kernel oil esters and the surfactant used. The information gathered in this study is useful for researchers and manufacturers interested in using palm kernel oil esters in pharmaceutical and cosmetic preparation. The use of palm kernel oil esters can improve drug delivery and reduce the cost of cosmetics

Anti-inflammatory and analgesic effects of ketoprofen in palm oil esters nanoemulsion

Ketoprofen is a potent non-steroidal anti-inflammatory drug has been used in the treatment of various kinds of pains, inflammation and arthritis. However, oral administration of ketoprofen produces serious gastrointestinal adverse effects. One of the promising methods to overcome these adverse effects is to administer the drug through the skin. The aim of the present work is to evaluate the anti-inflammatory and analgesic effects from topically applied ketoprofen entrapped palm oil esters (POEs) based nanoemulsion and to compare with market ketoprofen product, Fastum® gel. The novelty of this study is, use of POEs for the oil phase of nanoemulsion. The anti-inflammatory and analgesic studies were performed on rats by carrageenan-induced rat hind paw edema test and carrageenan-induced hyperalgesia pain threshold test to compare the ketoprofen entrapped POEs based nanoemulsion formulation and market formulation. Results indicated that there are no significant different between ketoprofen entrapped POEs nanoemulsion and market formulation in carrageenan-induced rat hind paw edema study and carrageenan-induced hyperalgesia pain threshold study. However, it shows a significant different between POEs nanoemulsion formulation and control group in these studies at p<0.05. From these results it was concluded that the developed nanoemulsion have great potential for topical application of ketoprofen

Effect of surfactant and surfactant blends on pseudoternary phase diagram behavior of newly synthesized palm kernel oil esters

Elrashid Saleh Mahdi1, Mohamed HF Sakeena1, Muthanna F Abdulkarim1, Ghassan Z Abdullah1,3, Munavvar Abdul Sattar2, Azmin Mohd Noor11Department of Pharmaceutical Technology, 2Department of Physiology, School of Pharmaceutical Sciences, Universiti Sains Malaysia, Minden, Penang, Malaysia; 3Department of Pharmaceutical Technology, International Medical University, Bukit Jalil, Kuala Lumpur, MalaysiaBackground: The purpose of this study was to select appropriate surfactants or blends of surfactants to study the ternary phase diagram behavior of newly introduced palm kernel oil esters.Methods: Nonionic surfactant blends of Tween&amp;reg; and Tween&amp;reg;/Span&amp;reg; series were screened based on their solubilization capacity with water for palm kernel oil esters. Tween&amp;reg; 80 and five blends of Tween&amp;reg; 80/Span&amp;reg; 80 and Tween&amp;reg; 80/Span&amp;reg; 85 in the hydrophilic-lipophilic balance (HLB) value range of 10.7&amp;ndash;14.0 were selected to study the phase diagram behavior of palm kernel oil esters using the water titration method at room temperature.Results: High solubilization capacity was obtained by Tween&amp;reg; 80 compared with other surfactants of Tween&amp;reg; series. High HLB blends of Tween&amp;reg; 80/Span&amp;reg; 85 and Tween&amp;reg; 80/Span&amp;reg; 80 at HLB 13.7 and 13.9, respectively, have better solubilization capacity compared with the lower HLB values of Tween&amp;reg; 80/Span&amp;reg; 80. All the selected blends of surfactants were formed as water-in-oil microemulsions, and other dispersion systems varied in size and geometrical layout in the triangles. The high solubilization capacity and larger areas of the water-in-oil microemulsion systems were due to the structural similarity between the lipophilic tail of Tween&amp;reg; 80 and the oleyl group of the palm kernel oil esters.Conclusion: This study suggests that the phase diagram behavior of palm kernel oil esters, water, and nonionic surfactants is not only affected by the HLB value, but also by the structural similarity between palm kernel oil esters and the surfactant used. The information gathered in this study is useful for researchers and manufacturers interested in using palm kernel oil esters in pharmaceutical and cosmetic preparation. The use of palm kernel oil esters can improve drug delivery and reduce the cost of cosmetics.Keywords: phase diagram, palm kernel oil esters, nonionic surfactants, microemulsion

Formulation and in vitro release evaluation of newly synthesized palm kernel oil esters-based nanoemulsion delivery system for 30% ethanolic dried extract derived from local Phyllanthus urinaria for skin antiaging

Elrashid Saleh Mahdi1, Azmin Mohd Noor1, Mohamed Hameem Sakeena1, Ghassan Z Abdullah1, Muthanna F Abdulkarim1, Munavvar Abdul Sattar2 1Department of Pharmaceutical Technology, 2Department of Physiology, School of Pharmaceutical Sciences, Universiti Sains Malaysia, Pulau Pinang, Malaysia Background: Recently there has been a remarkable surge of interest about natural products and their applications in the cosmetic industry. Topical delivery of antioxidants from natural sources is one of the approaches used to reverse signs of skin aging. The aim of this research was to develop a nanoemulsion cream for topical delivery of 30% ethanolic extract derived from local Phyllanthus urinaria (P. urinaria) for skin antiaging. Methods: Palm kernel oil esters (PKOEs)-based nanoemulsions were loaded with P. urinaria extract using a spontaneous method and characterized with respect to particle size, zeta potential, and rheological properties. The release profile of the extract was evaluated using in vitro Franz diffusion cells from an artificial membrane and the antioxidant activity of the extract released was evaluated using the 2, 2-diphenyl-1-picrylhydrazyl (DPPH) method. Results: Formulation F12 consisted of wt/wt, 0.05% P. urinaria extract, 1% cetyl alcohol, 0.5% glyceryl monostearate, 12% PKOEs, and 27% Tween&amp;reg; 80/Span&amp;reg; 80 (9/1) with a hydrophilic lipophilic balance of 13.9, and a 59.5% phosphate buffer system at pH 7.4. Formulation F36 was comprised of 0.05% P. urinaria extract, 1% cetyl alcohol, 1% glyceryl monostearate, 14% PKOEs, 28% Tween&amp;reg; 80/Span&amp;reg; 80 (9/1) with a hydrophilic lipophilic balance of 13.9, and 56% phosphate buffer system at pH 7.4 with shear thinning and thixotropy. The droplet size of F12 and F36 was 30.74 nm and 35.71 nm, respectively, and their nanosizes were confirmed by transmission electron microscopy images. Thereafter, 51.30% and 51.02% of the loaded extract was released from F12 and F36 through an artificial cellulose membrane, scavenging 29.89% and 30.05% of DPPH radical activity, respectively. Conclusion: The P. urinaria extract was successfully incorporated into a PKOEs-based nanoemulsion delivery system. In vitro release of the extract from the formulations showed DPPH radical scavenging activity. These formulations can neutralize reactive oxygen species and counteract oxidative injury induced by ultraviolet radiation and thereby ameliorate skin aging. Keywords: nanoemulsions, Phyllanthus urinaria, skin antiaging, palm kernel oil ester

Carbopol 934, 940 and Ultrez 10 as viscosity modifiers of palm olein esters based nano-scaled emulsion containing ibuprofen

Micro-emulsions and sometimes nano-emulsions are well known candidates to deliver drugs locally. However, the poor rheological properties are marginally affecting their acceptance pharmaceutically. This work aimed to modify the poor flow properties of a nano-scaled emulsion comprising palm olein esters as the oil phase and ibuprofen as the active ingredient for topical delivery. Three Carbopol ® resins: 934, 940 and Ultrez 10, were utilized in various concentrations to achieve these goals. Moreover, phosphate buffer and triethanolamine solutions pH 7.4 were used as neutralizing agents to assess their effects on the gel-forming and swelling properties of Carbopol ® 940. The addition of these polymers caused the produced nano-scaled emulsion to show a dramatic droplets enlargement of the dispersed globules, increased intrinsic viscosity, consistent zeta potential and transparent-to-opaque change in appearance. These changes were relatively influenced by the type and the concentration of the resin used. Carbopol ® 940 and triethanolamine appeared to be superior in achieving the proposed tasks compared to other materials. The higher the pH of triethanolamine solution, the stronger the flow-modifying properties of Carbopol ® 940. Transmission electron microscopy confirmed the formation of a well-arranged gel network of Carbopol ® 940, which was the major cause for all realized changes. Later in vitro permeation studies showed a significant decrease in the drug penetration, thus further modification using 10% w/w menthol or limonene as permeation promoters was performed. This resulted in in vitro and in vivo pharmacodynamics properties that are comparably higher than the reference chosen for this study

Formulation and characterization of palm oil esters based nano-cream for topical delivery of piroxicam

Palm oil esters are high molecular weight esters oil that has been newly synthesized by University Putra Malaysia researchers. It has received a lot of attention for its pharmaceutical and chemical application. Piroxicam is a nonsteroidal anti-inflammatory drug with analgesic and antipyretic activity. It has low solubility in water as well as in oil with Log P value of 1.8. Generally, drugs with Log P value of more than 0.5 are needed to be formulated into a modified dosage form. One of these formulations is nano sized cream. Hence, the ability of formulating of these tricky drugs into dispersed system is questionable. The aim of this study is to investigate the ability of palm oil esters to be the oil phase for formulation of piroxicam into O/W nano-cream. Three points were selected from prepared pseudoternary diagram of palm oil esters and different Tween and Span mixtures. Piroxicam solubility and partition coefficient in oil and external phase was detected. Rheological properties, droplet size, structural properties and zeta potential of the dispersion system containing piroxicam were measured. O/W cream was formed with droplet size measurement by TEM of less than 100 nm. It could be concluded that palm oil esters is suitable oil for the formulation of suitable nano-cream containing piroxicam.Keywords: Palm oil esters; Piroxicam Solubility; partition coefficient; Rheology; Surface activity

Stability studies of nano-cream containing piroxicam

The aim of this study is to study the stability of the nano-cream formula containing the newly synthesized palm oil esters when stored for reasonable storage duration. The prepared 0.5% piroxicam nano-cream formula contained phosphate buffer as external phase, palm oil esters as the oil phase and a combination of (80:20) of Tween 80 and Span 20 as emulsifier at a ratio of 37:25:38, respectively. Piroxicam is a hydro-lipophobic drug. Stability on storage is an important aspect which ensures the dosage form can exert the effects it is supposed to exert for the duration of storage. Droplets size, electrical conductivity, drug content, pH and rheological parameters are the parameters that have been assessed under different temperature to evaluate the stability of nano-cream preparation. Thus, experiments which measure the above parameters were conducted at storage temperatures of 4, 25 and 40οC.The data obtained from the stability study conducted on nano-cream formula showed that this formulation was stable for the whole 3 months period of the study when stored at tested several temperatures.Keywords: Palm oil esters; Nonionic surfactant; Piroxicam; Nano-crea

Stability studies of nano-cream containing piroxicam

The aim of this study is to study the stability of the nano-cream formula containing the newly synthesized palm oil esters when stored for reasonable storage duration. The prepared 0.5% piroxicam nano-cream formula contained phosphate buffer as external phase, palm oil esters as the oil phase and a combination of (80:20) of Tween 80 and Span 20 as emulsifier at a ratio of 37:25:38, respectively. Piroxicam is a hydro-lipophobic drug. Stability on storage is an important aspect which ensures the dosage form can exert the effects it is supposed to exert for the duration of storage. Droplets size, electrical conductivity, drug content, pH and rheological parameters are the parameters that have been assessed under different temperature to evaluate the stability of nano-cream preparation. Thus, experiments which measure the above parameters were conducted at storage temperatures of 4, 25 and 40οC.The data obtained from the stability study conducted on nano-cream formula showed that this formulation was stable for the whole 3 months period of the study when stored at tested several temperatures.Keywords: Palm oil esters; Nonionic surfactant; Piroxicam; Nano-crea

The influence of sequence alignment length of template on the accuracy and quality of homology modelling: human cytochrome P450 2D6 (CYP2D6) case study

Homology modelling is one of the important alternative techniques to X-ray crystallography and nuclear magnetic resonance (NMR) spectroscopy in structural determination of protein. CYP2D6 drug metabolizing enzymes have extensively studied prior to the successful determination of its 3D structure using X-ray crystallography. This study is one of the earlier works being carried out before the crystal structure was solved. The enzyme is polymorphic and more than 80 different alleles have been identified. The aim of this study is to identify possible criteria to improve the quality of 2D6 model. Four mammalian crystal structures CYP2C8, CYP2B4, CYP2C9 and CYP2C5 were selected from protein databank as template for CYP2D6 model. Multiple sequence alignment between the selected target and template was performed. Secondary structure prediction was generated using CYP2D6 sequence and the 3D models built based on each template. The quality of the models was evaluated using Ramachandran’s plot. The final models were superimposed with CYP2D6 crystal structure. The result shows that not only the sequence identity is important for the template selection but also the alignment length of sequence. The secondary structure prediction of CYP2D6 sequence was found significantly matched the secondary structure prediction of the 3D structures of CYP2D6 models. The stereochemical quality of CYP2D6 models were found adequately satisfied the Ramachandran.plot requirements and comparable to the stereochemical quality crystal structure proteins used as templates and CYP2D6 crystal structure. The criteria set shows that CYP2C8 is the better template for homology modelling of CYP2D6 since it has scored lower E-value and longer alignment length, high sequence identity provided by ClustalW . In addition the secondary structure prediction of the model better matched the consensus and satisfy the criteria of Ramachandran’s plot as well it retained lowest RMSD value from the crystal structure. The study concludes to that the length of the sequence alignment is a critical factor in template selection it is also shows the important primary and secondary structure prediction