Salehhuddin Hamdan

Antioxidant, total phenolic content and cytotoxicity evaluation of selected Malaysian plants

Aqueous and ethanol extracts of different traditional Malaysian plants (Polygonum minus, Andrographis paniculata, Curcuma xanthorrhiza, Momordica charantia and Strobilanthes crispus) were evaluated for their antioxidant properties, total phenolic content and cytotoxic activity. Antioxidant activity was evaluated by using 1,1-diphenyl-1-picrylhydrazyl (DPPH) and ferric reducing antioxidant power (FRAP) assays. The results showed that ethanol extracts contain high antioxidant activities compared to aqueous extracts. The findings exhibited a strong correlation between antioxidant activity and the total phenol contents. In addition, all the plant extracts showed non-toxic effects against a normal human lung fibroblast cell line (Hs888Lu). Although traditionally aqueous extracts are used, we determined that ethanol extracts usually achieved better activity in the assays.

Bioactivity assessment of poly( ε -caprolactone)/hydroxyapatite electrospun fibers for bone tissue engineering application

Electrospinning is useful for fabricating nanofibrous structure with different composition and morphologies. It offers great advantages through its geometrical structure and biomimetic property, which can provide a suitable environmental site for cell growth. The fiber diameter is entangled by the concentration of PCL with some adjustment of parameters during electrospinning process. PCL with lower concentration had bead structure while higher concentration had smooth fiber. The incorporation of nanoparticle hydroxyapatite (nHA) into poly(e-caprolactone) fiber was studied. The fiber diameter of PCL was increased with the addition of nHA. Composition of fiber at lower concentrations of PCL and nHA into the polymer produced fiber with a homogenous distribution of nHA in PCL fiber with less agglomeration. The immersion of PCL/nHA fiber in simulated body fluid (SBF) had bonelike apatite layer on its surface while PCL showed no results. PCL/nHA showed high water uptake and had improved wettability compared to PCL alone, suggesting that PCL/nHA fibers were more hydrophilic than PCL fiber.

A mutant l-asparaginase II signal peptide improves the secretion of recombinant cyclodextrin glucanotransferase and the viability of Escherichia coli

Abstractl-Asparaginase II signal peptide was used for the secretion of recombinant cyclodextrin glucanotransferase (CGTase) into the periplasmic space of E. coli. Despite its predominant localisation in the periplasm, CGTase activity was also detected in the extracellular medium, followed by cell lysis. Five mutant signal peptides were constructed to improve the periplasmic levels of CGTase. N1R3 is a mutated signal peptide with the number of positively charged amino acid residues in the n-region increased to a net charge of +5. This mutant peptide produced a 1.7-fold enhancement of CGTase activity in the periplasm and significantly decreased cell lysis to 7.8% of the wild-type level. The formation of intracellular inclusion bodies was also reduced when this mutated signal peptide was used as judged by SDS–PAGE. Therefore, these results provide evidence of a cost-effective means of expression of recombinant proteins in E. coli.

Modeling and Docking Studies on Novel Mutants (K71L and T204V) of the ATPase Domain of Human Heat Shock 70 kDa Protein 1

The purpose of exploring protein interactions between human adenovirus and heat shock protein 70 is to exploit a potentially synergistic interaction to enhance anti-tumoral efficacy and decrease toxicity in cancer treatment. However, the protein interaction of Hsp70 with E1A32 kDa of human adenovirus serotype 5 remains to be elucidated. In this study, two residues of ATPase domain of human heat shock 70 kDa protein 1 (PDB: 1 HJO) were mutated. 3D mutant models (K71L and T204V) using PyMol software were then constructed. The structures were evaluated by PROCHECK, ProQ, ERRAT, Verify 3D and ProSA modules. All evidence suggests that all protein models are acceptable and of good quality. The E1A32 kDa motif was retrieved from UniProt (P03255), as well as subjected to docking interaction with NBD, K71L and T204V, using the Autodock 4.2 program. The best lowest binding energy value of −9.09 kcal/mol was selected for novel T204V. Moreover, the protein-ligand complex structures were validated by RMSD, RMSF, hydrogen bonds and salt bridge analysis. This revealed that the T204V-E1A32 kDa motif complex was the most stable among all three complex structures. This study provides information about the interaction between Hsp70 and the E1A32 kDa motif, which emphasizes future perspectives to design rational drugs and vaccines in cancer therapy.

Pharmacological Mechanisms Underlying Gastroprotective Activities of the Fractions Obtained from Polygonum minus in Sprague Dawley Rats

The leaves of Polygonum minus were fractionated using an eluting solvent to evaluate the pharmacological mechanisms underlying the anti-ulcerogenic activity of P. minus. Different P. minus fractions were obtained and evaluated for their ulcer preventing capabilities using the ethanol induction method. In this study, Sprague Dawley rats weighing 150–200 g were used. Different parameters were estimated to identify the active fraction underlying the mechanism of the gastroprotective action of P. minus: the gastric mucus barrier, as well as superoxide dismutase, total hexosamine, and prostaglandin synthesis. Amongst the five fractions from the ethanolic extract of P. minus, the ethyl acetate:methanol 1:1 v/v fraction (F2) significantly (p < 0.005) exhibited better inhibition of ulcer lesions in a dose-dependent manner. In addition, rats pre-treated with F2 showed a significant elevation in superoxide dismutase (SOD), hexosamine and PGE2 levels in the stomach wall mucosa in a dose-dependent matter. Based on these results, the ethyl acetate:methanol 1:1 v/v fraction was considered to be the best fraction for mucous protection in the ethanol induction model. The mechanisms underlying this protection were attributed to the synthesis of antioxidants and PGE2.

Porous PCL/Chitosan and nHA/PCL/Chitosan scaffolds for tissue engineering applications: fabrication and evaluation

Two semicrystalline polymers were blended to fabricate porous scaffolds for tissue engineering applications. Scaffolds containing polycaprolactone (PCL)/chitosan and nanohydroxyapatite (nHA) incorporated nHA/PCL/chitosan were produced using the freeze-drying technique. A model drug, tetracycline hydrochloride (tetracycline HCL), was incorporated into the scaffolds. The scaffolds were characterized using a scanning electron microscope (SEM), EDX, and water contact angle. The antibacterial properties of the nHA/PCL/chitosan/tetracycline HCL scaffold were tested and the scaffolds showed positive results on gram-positive and gram-negative bacteria. The cell biocompatibility using human skin fibroblast cells (HSF 1184) was examined. The scaffold materials were found to be nontoxic to human skin fibroblast cells (HSF 1184) and showed positive proliferation activities. The nHA/PCL/chitosan/tetracycline HCL scaffold has potential for controlling implant-associated bacterial infections during operative procedures and can potentially be used as a scaffold for tissue engineering applications.

Elucidation of acid strength effect on ibuprofen adsorption and release by aluminated mesoporous silica nanoparticles

Mesoporous silica nanoparticles (MSN) with 1–10 wt% loading of aluminum (Al) were prepared and characterized by XRD, N2 physisorption, 29Si and 27Al NMR, FT-IR and FT-IR preadsorbed pyridine. All samples were evaluated for ibuprofen adsorption and release. The results showed that MSN gave almost complete ibuprofen adsorption while the addition of 1, 5, and 10 wt% Al onto MSN (1Al-MSN, 5Al-MSN and 10Al-MSN) resulted in 35%, 58%, and 79% of adsorption, respectively. The characterization results elucidated that the highest adsorptivity of MSN was due to its highest surface silanol groups, while the increase in Bronsted acidity upon loading of Al provided more adsorption sites for the higher activity. Regardless of its highest adsorption capacity, MSN demonstrated the highest and fastest release (∼100%) in 10 h, followed by 1Al-MSN, 5Al-MSN and 10Al-MSN. The increase in Al loading increased the acid sites that hold the ibuprofen molecules, which raised the retention in ibuprofen release. The pKa of Si–OH–Al that is lower than Si–OH sites also attracted the ibuprofen more strongly, which resulted in the slower release of Al-MSN as compared to MSN. The cytotoxicity study exhibited that ibuprofen loaded Al-MSN was able to reduce the toxicity in the WRL-68 cells, verifying its ability to hold and slow the release of ibuprofen as well as minimize the risk of drug overdose.

A Novel Protein Interaction between Nucleotide Binding Domain of Hsp70 and p53 Motif

Currently, protein interaction of Homo sapiens nucleotide binding domain (NBD) of heat shock 70 kDa protein (PDB: 1HJO) with p53 motif remains to be elucidated. The NBD-p53 motif complex enhances the p53 stabilization, thereby increasing the tumor suppression activity in cancer treatment. Therefore, we identified the interaction between NBD and p53 using STRING version 9.1 program. Then, we modeled the three-dimensional structure of p53 motif through homology modeling and determined the binding affinity and stability of NBD-p53 motif complex structure via molecular docking and dynamics (MD) simulation. Human DNA binding domain of p53 motif (SCMGGMNR) retrieved from UniProt (UniProtKB: P04637) was docked with the NBD protein, using the Autodock version 4.2 program. The binding energy and intermolecular energy for the NBD-p53 motif complex were −0.44 Kcal/mol and −9.90 Kcal/mol, respectively. Moreover, RMSD, RMSF, hydrogen bonds, salt bridge, and secondary structure analyses revealed that the NBD protein had a strong bond with p53 motif and the protein-ligand complex was stable. Thus, the current data would be highly encouraging for designing Hsp70 structure based drug in cancer therapy.

Cytostatic Activity of Clinoptilolite against Human Cervical Cancer Cell Lines Using Three Different Media-Sterilization Techniques

Clinoptilolite has been proven useful in cancer therapy in the last decade. The use of natural zeolite such as clinoptilolite requires some purification of the raw material before it can be applied in biomedical applications, yet microorganism contamination is still viewed as a possible issue for most researchers. Therefore, the clinoptilolite-treated media must undergo filter sterilization process prior to its use in any in vitro research of human cell studies. The aim of this study was to determine whether clinoptilolite cytostatic effect on cervical cancer (HeLa) cells will differ when a different media-sterilization technique is used on the clinoptilolite-treated medium. Comparison of the effect of clinoptilolite-treated medium on cell cytostatic activity was made between three sterilization methods; heat sterilization using an autoclave, UV radiation and filter sterilization. Results showed that there were inhibition of HeLa cell growth after clinoptilolite treatment in all three media-sterilization techniques. Significant differences were shown in all except between sterilizing using UV radiation and filter sterilization. This proved that in vitro cytostatic activity of clinoptilolite on human cervical cancer cells may be affected if different sterilization methods are used to sterilize the pre-treated media. Nonetheless, filter sterilization is still the preferred choice for sterilizing treated-media in cell culture. Keywords: Zeolite, clinoptilolite, cytotoxicity, cancer cell lines, sterilization.

Computational Approach Towards Exploring Interaction of Target Protein-Phytocompounds in Drug Development for Breast Cancer

Breast cancer is one of the leading cause of cancer related deaths in women, worldwide. In Malaysia, it is the most common cancer, where 1 in 19 Malaysian women are diagnosed with breast cancer. The incidence rate is increasing because of the lack of specific symptoms in the early stage of disease leading to delay in diagnosis. Unfortunately, recently used treatments such as chemotherapeutic, surgery and radiation therapies have not been fully effective against breast cancer. Therefore, there is a need of developing new approaches for the treatment of breast cancer. In this regards, plant derived compounds have been identified as a class of promising anticancer agents in the quest for novel pharmaceutical compounds to built the new target protein, their simulation and interaction with phytocompounds. The molecular docking method has been explored for its binding affinity towards the site of interactions. The best binding affinity is chosen based on the lowest binding energy, total intermolecular energy and highest number of hydrogen bonds to target the phytocompounds. Thus, the aim of this chapter is to focus on the potentiality of the phytocompound based drug discovery for the treatment of breast cancer.