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1.  Phase Behaviour and Formation of Fatty Acid Esters Nanoemulsions Containing Piroxicam 
AAPS PharmSciTech  2013;14(1):456-463.
Fatty acid esters are long-chain esters, produced from the reaction of fatty acids and alcohols. They possess potential applications in cosmetic and pharmaceutical formulations due to their excellent wetting behaviour at interfaces and a non-greasy feeling when applied on the skin surfaces. This preliminary work was carried out to construct pseudo-ternary phase diagrams for oleyl laurate, oleyl stearate and oleyl oleate with surfactants and piroxicam. Then, the preparation and optimization study via ‘One-At-A-Time Approach’ were carried out to determine the optimum amount of oil, surfactants and stabilizer using low-energy emulsification method. The results revealed that multi-phase region dominated the three pseudo-ternary phase diagrams. A composition was chosen from each multi-phase region for preparing the nanoemulsions systems containing piroxicam by incorporating a hydrocolloid stabilizer. The results showed that the optimum amount (w/w) of oil for oleyl laurate nanoemulsions was 30 and 20 g (w/w) for oleyl stearate nanoemulsions and oleyl oleate nanoemulsions. For each nanoemulsions system, the amount of mixed surfactants and stabilizer needed for the emulsification to take place was found to be 10 and 0.5 g (w/w), respectively. The emulsification process via high-energy emulsification method successfully produced nano-sized range particles. The nanoemulsions systems passed the centrifugation test and freeze–thaw cycle with no phase failures, and stable for 3 months at various storage temperatures (3°C, 25°C and 45°C). The results proved that the prepared nanoemulsions system cannot be formed spontaneously, and thus, energy input was required to produce nano-sized range particles.
PMCID: PMC3581649  PMID: 23386307
high-energy emulsification method; low-energy emulsification method; particle size; pseudo-ternary phase diagram; stabilizer
2.  Chemoenzymatic Epoxidation of Alkenes and Reusability Study of the Phenylacetic Acid 
The Scientific World Journal  2014;2014:756418.
Here, we focused on a simple enzymatic epoxidation of alkenes using lipase and phenylacetic acid. The immobilised Candida antarctica lipase B, Novozym 435 was used to catalyse the formation of peroxy acid instantly from hydrogen peroxide (H2O2) and phenylacetic acid. The peroxy phenylacetic acid generated was then utilised directly for in situ oxidation of alkenes. A variety of alkenes were oxidised with this system, resulting in 75–99% yield of the respective epoxides. On the other hand, the phenylacetic acid was recovered from the reaction media and reused for more epoxidation. Interestingly, the waste phenylacetic acid had the ability to be reused for epoxidation of the 1-nonene to 1-nonene oxide, giving an excellent yield of 90%.
PMCID: PMC3921943  PMID: 24587751
3.  Discovery of a new class of inhibitors for the protein arginine deiminase type 4 (PAD4) by structure-based virtual screening 
BMC Bioinformatics  2012;13(Suppl 17):S4.
Rheumatoid arthritis (RA) is an autoimmune disease with unknown etiology. Anticitrullinated protein autoantibody has been documented as a highly specific autoantibody associated with RA. Protein arginine deiminase type 4 (PAD4) is the enzyme responsible for catalyzing the conversion of peptidylarginine into peptidylcitrulline. PAD4 is a new therapeutic target for RA treatment. In order to search for inhibitors of PAD4, structure-based virtual screening was performed using LIDAEUS (Ligand discovery at Edinburgh university). Potential inhibitors were screened experimentally by inhibition assays.
Twenty two of the top-ranked water-soluble compounds were selected for inhibitory screening against PAD4. Three compounds showed significant inhibition of PAD4 and their IC50 values were investigated. The structures of the three compounds show no resemblance with previously discovered PAD4 inhibitors, nor with existing drugs for RA treatment.
Three compounds were discovered as potential inhibitors of PAD4 by virtual screening. The compounds are commercially available and can be used as scaffolds to design more potent inhibitors against PAD4.
PMCID: PMC3521205  PMID: 23282142
4.  Effect of Alcohol Structure on the Optimum Condition for Novozym 435-Catalyzed Synthesis of Adipate Esters 
Immobilized Candida antarctica lipase B, Novozym 435, was used as the biocatalyst in the esterification of adipic acid with four different isomers of butanol (n-butanol, sec-butanol, iso-butanol, and tert-butanol). Optimum conditions for the synthesis of adipate esters were obtained using response surface methodology approach with a four-factor-five-level central composite design concerning important reaction parameters which include time, temperature, substrate molar ratio, and amount of enzyme. Reactions under optimized conditions has yielded a high percentage of esterification (>96%) for n-butanol, iso-butanol, and sec-butanol, indicating that extent of esterification is independent of the alcohol structure for primary and secondary alcohols at the optimum conditions. Minimum reaction time (135 min) for achieving maximum ester yield was obtained for iso-butanol. The required time for attaining maximum yield and also the initial rates in the synthesis of di-n-butyl and di-sec-butyl adipate were nearly the same. Immobilized Candida antarctica lipase B was also capable of esterifying tert-butanol with a maximum yield of 39.1%. The enzyme is highly efficient biocatalyst for the synthesis of adipate esters by offering a simple production process and a high esterification yield.
PMCID: PMC3282151  PMID: 22389769
5.  1H,3H-Imidazolium (R,S)-camphor-10-sulfonate 
The title compound, C3H5N2 +·C10H15O4S−, comprises two crystallographically independent ion pairs (A and B) in the asymmetric unit with slightly different conformations due to the disordered methyl groups in the anion of molecule A. Two intra­molecular C—H⋯O hydrogen bonds generate S(6) ring motifs. In mol­ecule A, the methyl groups are disordered over two sets of positions with a site-ocuppancy ratio of 0.547 (9):0.453 (9). Extensive inter­molecular N—H⋯O and C—H⋯O hydrogen-bonding inter­actions occur in the crystal structure which link the mol­ecules into a two-dimensional network parallel to the (100) plane.
PMCID: PMC2968277  PMID: 21581842
6.  Tetra­ethyl­ammonium l-malate 1.36-hydrate 
The asymmetric unit of the title compound, C8H20N+·C4H5O5 −·1.36H2O, contains two independent ion pairs, with similar conformations, and three water mol­ecules of crystallization, one water mol­ecule haing a site-occupancy factor of 0.721 (5). Intra­molecular O—H⋯O hydrogen bonds, involving the hydr­oxy groups and an O atom of each carboxyl­ate anion, generate five-membered rings involving S(5) ring motifs. In the crystal structure, mol­ecules are linked together by water mol­ecules through four-membered O—H⋯O—H⋯O—H inter­actions to form one-dimensional infinite chains along the a axis. Since the mol­ecules are also linked into one-dimensional infinite chains along the b axis, mol­ecular sheets parallel to the (001) plane are created. Overall, the crystal structure is stabilized by two intra­molecular O—H⋯O hydrogen bonds, nine inter­molecular O—H⋯O and ten C—H⋯O hydrogen bonds.
PMCID: PMC2967964  PMID: 21581690

Results 1-6 (6)