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Monte Carlo simulation of mixed nonionic Brij surfactants in water

Yahya R, Karjiban RA, Basri M, Rahman MB, Girardi M

J Mol Model, 2014 Nov;20(11):2512.
PMID: 25381172 DOI: 10.1007/s00894-014-2512-1

Nonionic surfactants such as the Brij® series are important in the preparation of transdermal drug nanodelivery products using nanoemulsions because of their low toxicity and low irritancy. Here, Monte Carlo (MC) simulation was used to examine the physical behavior of the model deterministic system by using sampling procedures. Metropolis MC simulations were run on three mixtures of two different nonionic surfactants, Brij92 and Brij96, with different compositions in aqueous solution. The system was simulated in the canonical ensemble with constant temperature, volume and number of molecules. Hence, the acceptance ratio for single atom moves of the mixed surfactants increased as the concentration of surfactants increased from 0.494 to 0.591. The lowest total energy for the mixed surfactant systems was -99,039 kcal mol(-1) due to the interaction between all molecules in the system simulated. The physicochemical properties of models such as the radius of gyration and radial distribution function, were also determined. These observations indicate that the behavior and physicochemical of mixed surfactant and PKOEs nanoemulsion systems were described adequately during the simulation.
Fulltext Binding mode analysis of zerumbone to key signal proteins in the tumor necrosis factor pathway

Fatima A, Abdul AB, Abdullah R, Karjiban RA, Lee VS

Int J Mol Sci, 2015 Jan 26;16(2):2747-66.
PMID: 25629232 DOI: 10.3390/ijms16022747

Breast cancer is the second most common cancer among women worldwide. Several signaling pathways have been implicated as causative and progression agents. The tumor necrosis factor (TNF) α protein plays a dual role in promoting and inhibiting cancer depending largely on the pathway initiated by the binding of the protein to its receptor. Zerumbone, an active constituent of Zingiber zerumbet, Smith, is known to act on the tumor necrosis factor pathway upregulating tumour necrosis factor related apoptosis inducing ligand (TRAIL) death receptors and inducing apoptosis in cancer cells. Zerumbone is a sesquiterpene that is able to penetrate into the hydrophobic pockets of proteins to exert its inhibiting activity with several proteins. We found a good binding with the tumor necrosis factor, kinase κB (IKKβ) and the Nuclear factor κB (NF-κB) component proteins along the TNF pathway. Our results suggest that zerumbone can exert its apoptotic activities by inhibiting the cytoplasmic proteins. It inhibits the IKKβ kinase that activates the NF-κB and also binds to the NF-κB complex in the TNF pathway. Blocking both proteins can lead to inhibition of cell proliferating proteins to be downregulated and possibly ultimate induction of apoptosis.
Fulltext Comparison of process parameter optimization using different designs in nanoemulsion-based formulation for transdermal delivery of fullerene

Ngan CL, Basri M, Lye FF, Fard Masoumi HR, Tripathy M, Karjiban RA, et al.

Int J Nanomedicine, 2014;9:4375-86.
PMID: 25258528 DOI: 10.2147/IJN.S65689

This research aims to formulate and to optimize a nanoemulsion-based formulation containing fullerene, an antioxidant, stabilized by a low amount of mixed surfactants using high shear and the ultrasonic emulsification method for transdermal delivery. Process parameters optimization of fullerene nanoemulsions was done by employing response surface methodology, which involved statistical multivariate analysis. Optimization of independent variables was investigated using experimental design based on Box-Behnken design and central composite rotatable design. An investigation on the effect of the homogenization rate (4,000-5,000 rpm), sonication amplitude (20%-60%), and sonication time (30-150 seconds) on the particle size, ζ-potential, and viscosity of the colloidal systems was conducted. Under the optimum conditions, the central composite rotatable design model suggested the response variables for particle size, ζ-potential, and viscosity of the fullerene nanoemulsion were 152.5 nm, -52.6 mV, and 44.6 pascal seconds, respectively. In contrast, the Box-Behnken design model proposed that preparation under the optimum condition would produce nanoemulsion with particle size, ζ-potential, and viscosity of 148.5 nm, -55.2 mV, and 39.9 pascal seconds, respectively. The suggested process parameters to obtain optimum formulation by both models yielded actual response values similar to the predicted values with residual standard error of <2%. The optimum formulation showed more elastic and solid-like characteristics due to the existence of a large linear viscoelastic region.
Fulltext Formulation development and optimization of palm kernel oil esters-based nanoemulsions containing sodium diclofenac

Rezaee M, Basri M, Rahman RN, Salleh AB, Chaibakhsh N, Karjiban RA

Int J Nanomedicine, 2014;9:539-48.
PMID: 24531324 DOI: 10.2147/IJN.S49616

Response surface methodology was employed to study the effect of formulation composition variables, water content (60%-80%, w/w) and oil and surfactant (O/S) ratio (0.17-1.33), as well as high-shear emulsification conditions, mixing rate (300-3,000 rpm) and mixing time (5-30 minutes) on the properties of sodium diclofenac-loaded palm kernel oil esters-nanoemulsions. The two response variables were droplet size and viscosity. Optimization of the conditions according to the four variables was performed for preparation of the nanoemulsions with the minimum values of particle size and viscosity. The results showed that the experimental data could be sufficiently fitted into a third-order polynomial model with multiple regression coefficients (R(2) ) of 0.938 and 0.994 for the particle size and viscosity, respectively. Water content, O/S ratio and mixing time, quadrics of all independent variables, interaction between O/S ratio and mixing rate and between mixing time and rate, as well as cubic term of water content had a significant effect (P<0.05) on the particle size of nanoemulsions. The linear effect of all independent variables, quadrics of water content and O/S ratio, interaction of water content and O/S ratio, as well as cubic term of water content and O/S ratio had significant effects (P<0.05) on the viscosity of all nanoemulsions. The optimum conditions for preparation of sodium diclofenac nanoemulsions were predicted to be: 71.36% water content; 0.69 O/S ratio; 950 rpm mixing rate, and 5 minute mixing time. The optimized formulation showed good storage stability in different temperatures.
Formulation optimization of palm kernel oil esters nanoemulsion-loaded with chloramphenicol suitable for meningitis treatment

Musa SH, Basri M, Masoumi HR, Karjiban RA, Malek EA, Basri H, et al.

Colloids Surf B Biointerfaces, 2013 Dec 1;112:113-9.
PMID: 23974000 DOI: 10.1016/j.colsurfb.2013.07.043

Palm kernel oil esters nanoemulsion-loaded with chloramphenicol was optimized using response surface methodology (RSM), a multivariate statistical technique. Effect of independent variables (oil amount, lecithin amount and glycerol amount) toward response variables (particle size, polydispersity index, zeta potential and osmolality) were studied using central composite design (CCD). RSM analysis showed that the experimental data could be fitted into a second-order polynomial model. Chloramphenicol-loaded nanoemulsion was formulated by using high pressure homogenizer. The optimized chloramphenicol-loaded nanoemulsion response values for particle size, PDI, zeta potential and osmolality were 95.33nm, 0.238, -36.91mV, and 200mOsm/kg, respectively. The actual values of the formulated nanoemulsion were in good agreement with the predicted values obtained from RSM. The results showed that the optimized compositions have the potential to be used as a parenteral emulsion to cross blood-brain barrier (BBB) for meningitis treatment.
Fulltext Formulation optimization of a palm-based nanoemulsion system containing levodopa

Zainol S, Basri M, Basri HB, Shamsuddin AF, Abdul-Gani SS, Karjiban RA, et al.

Int J Mol Sci, 2012;13(10):13049-64.
PMID: 23202937 DOI: 10.3390/ijms131013049

Response surface methodology (RSM) was utilized to investigate the influence of the main emulsion composition; mixture of palm and medium-chain triglyceride (MCT) oil (6%-12% w/w), lecithin (1%-3% w/w), and Cremophor EL (0.5%-1.5% w/w) as well as the preparation method; addition rate (2-20 mL/min), on the physicochemical properties of palm-based nanoemulsions. The response variables were the three main emulsion properties; particle size, zeta potential and polydispersity index. Optimization of the four independent variables was carried out to obtain an optimum level palm-based nanoemulsion with desirable characteristics. The response surface analysis showed that the variation in the three responses could be depicted as a quadratic function of the main composition of the emulsion and the preparation method. The experimental data could be fitted sufficiently well into a second-order polynomial model. The optimized formulation was stable for six months at 4 °C.
Ultrasonic emulsification of parenteral valproic acid-loaded nanoemulsion with response surface methodology and evaluation of its stability

Tan SF, Masoumi HR, Karjiban RA, Stanslas J, Kirby BP, Basri M, et al.

Ultrason Sonochem, 2016 Mar;29:299-308.
PMID: 26585010 DOI: 10.1016/j.ultsonch.2015.09.015

Response surface methodology (RSM) was used to optimize the formulation of a nanoemulsion for central delivery following parenteral administration. A mixture of medium-chain triglyceride (MCT) and safflower seed oil (SSO) was determined as a sole phase from the emulsification properties. Similarly, a natural surfactant (lecithin) and non-ionic surfactant (Tween 80) (ratio 1:2) were used in the formulation. A central composite design (CCD) with three-factor at five-levels was used to optimize the processing method of high energy ultrasonicator. Effects of pre-sonication ultrasonic intensity (A), sonication time (B), and temperature (C) were studied on the preparation of nanoemulsion loaded with valproic acid. Influence of the aforementioned specifically the effects of the ultrasonic processing parameters on droplet size and polydispersity index were investigated. From the analysis, it was found that the interaction between ultrasonic intensity and sonication time was the most influential factor on the droplet size of nanoemulsion formulated. Ultrasonic intensity (A) significantly affects the polydispersity index value. With this optimization method, a favorable droplet size of a nanoemulsion with reasonable polydispersity index was able to be formulated within a short sonication time. A valproic acid loaded nanoemulsion can be obtained with 60% power intensity for 15 min at 60 °C. Droplet size of 43.21±0.11 nm with polydispersity index of 0.211 were produced. The drug content was then increased to 1.5%. Stability study of nanoemulsion containing 1.5% of valproic acid had a good stability as there are no significant changes in physicochemical aspects such as droplet size and polydispersity index. With the characteristisation study of pH, viscosity, transmission electron microscope (TEM) and stability assessment study the formulated nanoemulsion has the potential to penetrate blood-brain barrier in the treatment of epilepsy.
Nanoemulsion-based Parenteral Drug Delivery System of Carbamazepine: Preparation, Characterization, Stability Evaluation and Blood-Brain Pharmacokinetics

Tan SL, Stanslas J, Basri M, Abedi Karjiban RA, Kirby BP, Sani D, et al.

Curr Drug Deliv, 2015;12(6):795-804.
PMID: 26324229

Carbamzepine (CBZ) was encapsulated in a parenteral oil-in-water nanoemulsion, in an attempt to improve its bioavailability. The particle size, polydispersity index and zeta potential were measured using dynamic light scattering. Other parameters such as pH, osmolality, viscosity, drug loading efficiency and entrapment efficiency were also recorded. Transmission electron microscopy revealed that emulsion droplets were almost spherical in shape and in the nano-range. The in vitro release profile was best characterized by Higuchi's equation. The parenteral nanoemulsion of CBZ showed significantly higher AUC0→5, AUC0→∞, AUMC0→5, AUMC0→∞, Cmax and lower clearance than that of CBZ solution in plasma. Additionally, parenteral nanoemulsion of CBZ showed significantly higher AUC0→∞, AUMC0→∞ and Cmaxthan that of CBZ solution in brain. The parenteral nanoemulsion of CBZ could therefore use as a carrier, worth exploring further for brain targeting.
Fulltext The use of innovative and efficient nanocomposite (magnetic graphene oxide) for the reduction on of Fusarium mycotoxins in palm kernel cake

Pirouz AA, Selamat J, Iqbal SZ, Mirhosseini H, Karjiban RA, Bakar FA

Sci Rep, 2017 Sep 29;7(1):12453.
PMID: 28963539 DOI: 10.1038/s41598-017-12341-3

Adsorption plays an important role in the removal of mycotoxins from feedstuffs. The main objective of this study was to investigate the efficacy of using magnetic graphene oxide nanocomposites (MGO) as an adsorbent for the reduction of Fusarium mycotoxins in naturally contaminated palm kernel cake (PKC). Liquid chromatography-tandem mass spectrometry (LC-MS/MS) was used to assess the mycotoxins in animal feed. Target mycotoxins included the zearalenone (ZEA), the fumonisins (FB1 and FB2) and trichothecenes (deoxynivalenol (DON), HT-2 and T-2 toxin). Response surface methodology (RSM) was applied to investigate the effects of time (3-7 h), temperature (30-50 °C) and pH (3-7) on the reduction. The response surface models with (R2 = 0.94-0.99) were significantly fitted to predict mycotoxins in contaminated PKC. Furthermore, the method ensured a satisfactory adjustment of the polynomial regression models with the experimental data except for fumonisin B1 and B2, which decrease the adsorption of magnetic graphene oxide (MGO). The optimum reduction was performed at pH 6.2 for 5.2 h at of 40.6 °C. Under these optimum conditions, reduced levels of 69.57, 67.28, 57.40 and 37.17%, were achieved for DON, ZEA, HT-2, and T-2, respectively.
Deciphering the flexibility and dynamics of Geobacillus zalihae strain T1 lipase at high temperatures by molecular dynamics simulation

Abdul Rahman MB, Karjiban RA, Salleh AB, Jacobs D, Basri M, Thean Chor AL, et al.

Protein Pept Lett, 2009;16(11):1360-70.
PMID: 20001926

The stability of biocatalysts is an important criterion for a sustainable industrial operation economically. T1 lipase is a thermoalkalophilic enzyme derived from Geobacillus zalihae strain T1 (T1 lipase) that was isolated from palm oil mill effluent (POME) in Malaysia. We report here the results of high temperatures molecular dynamics (MD) simulations of T1 lipase in explicit solvent. We found that the N-terminal moiety of this enzyme was accompanied by a large flexibility and dynamics during temperature-induced unfolding simulations which preceded and followed by clear structural changes in two specific regions; the small domain (consisting of helices alpha3 and alpha5, strands beta1 and beta2, and connecting loops) and the main catalytic domain or core domain (consisting of helices alpha6- alpha9 and connecting loops which located above the active site) of the enzyme. The results suggest that the small domain of model enzyme is a critical region to the thermostability of this organism.
On the importance of the small domain in the thermostability of thermoalkalophilic lipases from l1 and t1: insights from molecular dynamics simulation

Karjiban RA, Basyaruddin M, Rahman A, Salleh AB, Basri M, Zaliha RN, et al.

Protein Pept Lett, 2010 Jun;17(6):699-707.
PMID: 19958281

An all-atom level MD simulation in explicit solvent at high temperature is a powerful technique to increase our knowledge about the structurally important regions modulating thermal stability in thermenzymes. In this respect, two large-sized thermoalkalophilic enzymes from Bacillus stearothermophilus L1 (L1 lipase) and Geobacillus zalihae strain T1 (T1 lipase) are well-established representatives. In this paper, comparative results from temperature-induced MD simulations of both model systems at 300 K, 400 K and 500 K are presented and discussed with respect to identification of highly flexible regions critical to thermostability. From our MD simulation results, specific regions along the L1 lipase and T1 lipase polypeptide chain including the small domain and the main catalytic domain or core domain of both enzymes show a marked increase in fluctuations and dynamics followed by clear structural changes. Overall, the N-terminal moiety of both enzymes and their small domains exhibit hyper-sensitivity to thermal stress. The results appear to propose that these regions are critical in determining of the overall thermal stability of both organisms.
Fulltext A Sco protein among the hypothetical proteins of Bacillus lehensis G1: Its 3D macromolecular structure and association with Cytochrome C Oxidase

Tan SH, Normi YM, Leow AT, Salleh AB, Karjiban RA, Murad AM, et al.

BMC Struct Biol, 2014 Mar 19;14:11.
PMID: 24641837 DOI: 10.1186/1472-6807-14-11

BACKGROUND: At least a quarter of any complete genome encodes for hypothetical proteins (HPs) which are largely non-similar to other known, well-characterized proteins. Predicting and solving their structures and functions is imperative to aid understanding of any given organism as a complete biological system. The present study highlights the primary effort to classify and cluster 1202 HPs of Bacillus lehensis G1 alkaliphile to serve as a platform to mine and select specific HP(s) to be studied further in greater detail.
RESULTS: All HPs of B. lehensis G1 were grouped according to their predicted functions based on the presence of functional domains in their sequences. From the metal-binding group of HPs of the cluster, an HP termed Bleg1_2507 was discovered to contain a thioredoxin (Trx) domain and highly-conserved metal-binding ligands represented by Cys69, Cys73 and His159, similar to all prokaryotic and eukaryotic Sco proteins. The built 3D structure of Bleg1_2507 showed that it shared the βαβαββ core structure of Trx-like proteins as well as three flanking β-sheets, a 310 -helix at the N-terminus and a hairpin structure unique to Sco proteins. Docking simulations provided an interesting view of Bleg1_2507 in association with its putative cytochrome c oxidase subunit II (COXII) redox partner, Bleg1_2337, where the latter can be seen to hold its partner in an embrace, facilitated by hydrophobic and ionic interactions between the proteins. Although Bleg1_2507 shares relatively low sequence identity (47%) to BsSco, interestingly, the predicted metal-binding residues of Bleg1_2507 i.e. Cys-69, Cys-73 and His-159 were located at flexible active loops similar to other Sco proteins across biological taxa. This highlights structural conservation of Sco despite their various functions in prokaryotes and eukaryotes.
CONCLUSIONS: We propose that HP Bleg1_2507 is a Sco protein which is able to interact with COXII, its redox partner and therefore, may possess metallochaperone and redox functions similar to other documented bacterial Sco proteins. It is hoped that this scientific effort will help to spur the search for other physiologically relevant proteins among the so-called "orphan" proteins of any given organism.

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