Mazatulikhma Mat Zain

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.

Evaluation of the bioactivity of novel spiroisoxazoline typecompounds against normal and cancer cell lines.

The aim of this study was to investigate the in vitro cellular activity of novel spiroisoxazoline type compounds against normal and cancer cell lines from lung tissue (Hs888Lu), neuron-phenotypic cells (SH-SY5Y), neuroblastoma (SH-SY5Y), human histiocytic lymphoma (U937), lung cancer (A549), and leukaemia (HL-60). Our bioassay program revealed that the spiroisoxazoline type compounds show cytotoxicity only in lymphoma cell lines, which is in contrast with the pyrrolidine precursor of these spiroisoxazoline compounds, where significant cytotoxicity is seen in all normal and cancer cell lines. These data suggest a tumour-specific mechanism of action. In addition these data also show that spiroisoxazoline compounds are non-toxic in the human neuron-phenotypic neuroblastoma SH-SY5Y cell line, and furthermore that they might protect cells from neurodegenerative disease.

Effects of the absorption behaviour of ZnO nanoparticles on cytotoxicity measurements

ZnO absorbs certain wavelengths of light and this behavior is more pronounced for nanoparticles of ZnO. As many toxicity measurements rely on measuring light transmission in cell lines, it is essential to determine how far this light absorption influences experimental toxicity measurements. The main objective was to study the ZnO absorption and how this influenced the cytotoxicity measurements. The cytotoxicity of differently sized ZnO nanoparticles in normal and cancer cell lines derived from lung tissue (Hs888Lu), neuron-phenotypic cells (SH-SY5Y), neuroblastoma (SH-SY5Y), human histiocytic lymphoma (U937), and lung cancer (A549) was investigated. Our results demonstrate that the presence of ZnO affected the cytotoxicity measurements due to the absorption characteristic of ZnO nanoparticles. The data revealed that the ZnO nanoparticles with an average particle size of around 85.7nm and 190nm showed cytotoxicity towards U937, SH-SY5Y, differentiated SH-SY5Y, and Hs888Lu cell lines. No effect on the A549 cells was observed. It was also found that the cytotoxicity of ZnO was particle size, concentration, and time dependent. These studies are the first to quantify the influence of ZnO nanoparticles on cytotoxicity assays. Corrections for absorption effects were carried out which gave an accurate estimation of the concentrations that produce the cytotoxic effects.

Radical scavenging and neurotoxicity of four varieties of Ficus deltoidea

Ficus deltoidea or locally known as ‘Mas Cotek’ is a very common herb found throughout the tropics is available in many varieties. In Malaysia, traditional practitioners use this plant in herbal remedies to treat several illnesses like headache, hypertension, and hyperglycemia which may be related to antioxidant properties of the plant. The first objective of the study was to evaluate antioxidant properties of aqueous extracts of four varieties of Ficus deltoidea namely var angustifolia, deltoidea, intermedia, and kunstleri in order to identify which variety possess the highest antioxidant potential. In this study, the antioxidant of aqueous extract of the leaves and fruits of the four varieties of Ficus deltoidea were evaluated by their DPPH (1,1-diphenyl-2-picrylhydrazyl) radical scavenging activity. In addition, total phenolic content (TPC) of the aqueous extracts were also determined by the Folin-Ciocalteu method. The TPC value of var intermedia was very good both for the leaves and fruits (86.52 and 96.58 mg GAE/100 g extract respectively) compared to other varieties. In the DPPH assay, var deltoidea showed the highest radical scavenging activity both for the leaves and fruits (82.04% and 71.43% respectively) compared to other varieties. The second objective was to study the neurotoxicity. In this study, neuroblastoma cell line, SH-SY5Y was used to determine the neurotoxicity of aqueous extracts of four varieties of Ficus deltoidea. Cell viability was assessed using MTS assay. Results showed that the aqueous extracts of four varieties of Ficus deltoidea were not toxic within the tested concentration range from 1 ng/ml to 1 mg/ml. The study also showed that the aqueous extracts could protect neuron cells and suggested that the varieties possess potential neuroprotective effects.

Synthesis, characterization and neurotoxicity of schiff bases derived from 1,8-diaminonaphthalene

Six Schiff bases L1–L6 are successfully synthesized by reacting 1,8-diaminonaphthalene with aldehyde and ketone derivatives in the ratio of 1∶2 (amine: aldehyde / ketone). The Schiff bases are characterized using various physical and spectral techniques namely elemental analysis, IR spectroscopy, 1H NMR spectroscopy and melting point determination. The neurotoxicity of the compounds is evaluated using neuroblastoma SH-SY5Y cell lines at which they are indicated to be non-toxic.

Characteristics of Dammar Based Paint System with the Addition of Silver Nanoclay

Five different paint systems are formulated using mixture of dammar, silver and nanoclay in various compositions. The paint mixture is spin coated onto Aluminium Q-panel (substrate) and then is left to dry at room temperature. This paper describes the characteristics of the dammar based paint system. Adhesion property is evaluated by using the crosshatch method based on ASTM D3359 standards. The wettability property of coating is characterized by using contact angle measurement. The resistances of paint systems are also described against microbial activity by using disc diffusion and agar well diffusion. The result of crosshatch test shows that the coating system containing 50 wt. % of dammar (PD) exhibits an excellent adhesion property. The addition of dammar to polyol helps to increase the contact angle measurement up to 45.8 degree. The largest inhibition diameter zone against E. coli and S. aureus is obtained for the silver nanoclay polyol dammar, PDS3 paints system.

Antimicrobial activity of marine bacteria from Malaysian coastal area

The marine environment is an abundant resource for the isolation of less exploited microorganisms. The unexploited habitats in the sea exist with unique characteristics. Additionally, the potential contribution of marine sources to the discovery of new bioactive molecules was recently recognized. In order to explore marine microorganisms with medical potential, marine bacteria were isolated from sea water collected from different areas of Pulau Kapas Beach and Pantai Batu Burok, Terengganu. The growth curve and the antimicrobial activities of these bacteria were investigated. Organic extracts (hexane, ethyl acetate, and butanol) of marine bacterial fermentation were screened for antimicrobial activities using disk diffusion method. The results revealed that the marine bacteria D7 entered the stationary phase at 24 hr of growth. The ethyl acetate extracts displayed antibacterial activity against Staphylococcus aureus, Bacillus subtilis, Pseudomonas aeruginosa, and Klebsiella pneumoniae, but possessed no effect on bacterium Escherichia coli, and yeasts Candida albicans. These marine bacteria are expected to be potential resources of natural antibiotic products.

Quantitative structure-activity relationship (QSAR) modelling of N-aryl derivatives as cholinesterase inhibitors

A QSAR study on a series of N-aryl derivatives was performed to explore the important molecular descriptor which is responsible for their inhibitory activity towards choli nest erase enzyme, the common target for the treatment of Alzheimers disease. Molecular descriptors were calculated using DRAGON version 5.2 software Two methods of descriptor selection, stepwise regression and forward selection procedure, were performed and compared. Multiple Linear Regression (MLR) analysis was carried out to derive QSAR models, which were further evaluated for statistical significance and predictive power by leave-one-out (LOO) cross validation test. The best QSAR models against acetylcholinesterase and butylcholinesterase inhibitory activity were selected, having squared correlation coefficient R2=945% and 98.4%, and cross-validated squared correlation coefficient R2cv = 91.9% and 97.2%, respectively. The statistical outcomes derived from the present study demonstrate good predictability and may be useful in the design of more potent substituted N-aryl derivatives as cholinesterase inhibitor.

Synthesis, characterization and neurotoxicity of multidentate azomethine series and their Cu(II) and Ni(II) Complexes

Two novel azomethine ligands L1 and L2 are synthesized from guanidine where L1 is (1E,3E)-1,3-bis(2,4-dihydroxybenzylidene)guanidine and L2 is (1E,3E)-1,3-bis(1-(2,4-dihydroxyphenyl)ethylidene)guanidine. The ligands are reacted with Cu(II) and Ni(II) to produce complexes CuL1, CuL2, NiL1 and NiL2. All the compounds are characterized by Fourier Transform Infrared (FTIR) spectroscopy, CHN elemental analysis, Proton Nuclear Magnetic Resonance spectroscopy and magnetic susceptibility measurements. The shift of ν(C=N) peaks upon complexation indicates that the azomethine nitrogens are involved in the chelation to the metal centres. The magnetic susceptibility measurements show that copper(II) complexes are paramagnetic with 1 unpaired electron while nickel(II) complexes are diamagnetic. An investigation for neurotoxicity against treated neuroblastoma SH-SY5Y cell lines showed non-toxic effect for the range of concentrations investigated.

Toxicity study of Schiff bases derived from 2,6-diaminopyridine and their novel metal complexes

Two Schiff bases (L1∶C<inf>19</inf>H<inf>15</inf>N<inf>3</inf>O<inf>2</inf> and L3∶C<inf>21</inf>H<inf>19</inf>N<inf>3</inf>O<inf>6</inf>) derived from 2,6-diaminopyridine with salicylaldehyde and o-vanillin, respectively, were successfully synthesized and characterized. Four novel metal complexes of these ligands with Zn(II) and Cd(II) namely ZnL1, ZnL3, CdL1 and CdL3 were obtained and the chemical structures were investigated by means of elemental analysis, FTIR, conductivity and magnetic susceptibility measurements. All the complexes were diamagnetic, displayed ν(C=N) bands in the range 1599–1615 cm⁻¹ and non-electrolytic in solution. The toxicity of the Schiff base ligands and their novel metal complexes was studied from the viability of treated human neuroblastoma SH-SY5Y cell lines.