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Articles by Z.A. Zakaria
Total Records ( 16 ) for Z.A. Zakaria
  Z.A. Zakaria , B.C. Chen , M.O. Hassan and J.X. Yuan
  This study addresses the transient studies of electrical networks with embedded, distribution static compensator (DSTATCOM) as example of Custom Power (CP) controllers. The transient analysis and modeling is performed with the state-of-the-art digital Simulator PSCAD/EMTDC.4.2. Simulations were carried out for both cases where, DSTATCOM was connected into the system and not, with simulation interval 0.8-1 sec. The aim of the DSTATCOM here to provide voltage regulation at the load point and mitigate the voltage sag generated when the load is increased.
  M.O. Hassan , S.J. Cheng and Z.A. Zakaria
  In this study, steady-state modeling of Static Synchronous Compensator (STATCOM) and Thyristor Controlled Series Compensator (TCSC) for power flow studies has been represented. STATCOM is modeled as a controllable voltage source in series with impedance and firing angle model for TCSC is used to control active power flow of the line to which TCSC is installed. Proposed model for TCSC takes firing angle as state variable in power flow formulation. To validate the effectiveness of the proposed models Newton-Raphson method algorithm was implemented to solve power flow equations in presence of STATCOM and TCSC. Case studies are carried out on 9-bus system to demonstrate the performance of the proposed models. Simulation results show the effectiveness and robustness of the proposed models; moreover the power solution using the Newton-Raphson algorithm developed incorporating firing angle model possesses excellent convergence characteristics.
  Z.A. Zakaria , M.N. Somchit , H. Zaiton , A.M. Mat Jais , M.R. Sulaiman , W.O. Farah , R. Nazaratulmawarina and C.A. Fatimah
  The presence study was carried out to investigate on the possible antibacterial activity of methanol (MECO) and chloroform (CECO) extracts of Corchorus olitorius (Senaung betina) using the in vitro disc diffusion methods. The sterilized blank discs (6 mm diameter) was impregnated with 20 μL of the respective extract (in the concentration of 10,000; 20,000; 40,000 and 50,000 ppm) and tested against Corneybacterium diphtheria, Staphylococcus aureus (ATCC 25923), Bacillus cereus, Proteus vulgaris, Staphylococcus epidermidis, Kosuria rhizophila, Shigella flexneri, Escherichia coli (O 157), Aeromonas hydrophila and Listeria monocytogenes. The MECO and CECO, at all concentrations, were effective against C. diptheria and K. rhozophila with the latter also effective against S. aureus and B. cereus. At the concentration of 40,000 ppm and above, the MECO was effective only against S. aureus, B. cereus and S. epidermidis while the CECO was effective against S. epidermidis, S. flexneri and A. hydrophila. Based on this study, it was concluded that C. olitorius possesses antibacterial activity that is comparable to some of the standard antibiotics.
  Z.A. Zakaria , A.M. Mat Jais , M. Mastura , S.H. Mat Jusoh , A.M. Mohamed , N.S. Mohd. Jamil , M.S. Rofiee and M.R. Sulaiman
  The present study was carried out to evaluate the antibacterial activity of the aqueous, methanol and chloroform extracts of several plants available in Malaysia, namely Muntingia calabura (L.), Melastoma malabathricum (L.), Bauhinia purpurea (L.), Corchorus capsularis (L.) and Dicranopteris linearis (L.) using the single screening in vitro microtiter plate dilution methods. The extracts, at the dose of 5 μg μL-1, were screened against various strains of Staphylococcus aureus, namely S. aureus 29213α, S. aureus 33591, S. aureus 700699, vancomycin-intermediate S. aureus (VISA) and vancomycin-resistant S. aureus (VRSA). Results: Interestingly, only the methanol extracts of D. linearis exhibited an antibacterial activity against all strains of S. aureus whereas all extracts of M. calabura were effective only against the S. aureus 29213α, S. aureus 33591 and S. aureus 700699. The Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) for D. linearis range between 0.625-1.250 and 1.250-2.500 μg μL-1, respectively whereas for the M. calabura extracts the MIC and MBC range between 1.250-5.000 and 2.500-5.000 μg μL-1, respectively. Although the other plants gave negative results in this study, their potential antibacterial properties should not be disregarded as the present study was carried out using only one low concentration (5 μg μL-1) and that the activity was determined using crude, but not pure, extracts. The present study demonstrated the potential of chloroform extract of D. linearis, which indicate the present of non-polar bioactive compounds, as VRSA antibacterial agents and all extracts of M. calabura as a potential source of antibacterial agents for the treatment of normal S. aureus infection.
  Z.A. Zakaria , H.M. Khairi , M.N. Somchit , M.R. Sulaiman , A.M. Mat Jais , I. Reezal , N.N. Mat Zaid , S.N.Z. Abdul Wahab , N.S. Fadzil , M. Abdullah and C.A. Fatimah
  To determine on the antibacterial activity of the leaves and acute toxicity level of the leaves, tender leaves and rhizomes of Manihot esculenta var. Sri Pontian extracts. The chloroform (CME1) and ethanol (EME1) leaves extracts of M. esculenta (25, 50 and 100% concentrations) were tested against a selected groups of Gram positive and Gram negative bacteria using the disc diffusion method. On the other hand, the chloroform and ethanol leaves (CME2 and EME2), as well as the tender young leaves (CME3 and EME3) and rhizomes (CME4 and EME4), extracts of M. esculenta, (concentration ranging from 200 to 2600 ppm) were tested for their chronic toxicity level using the brine shrimp bioassay. CME1 was found to give positive antibacterial activity against L. monocytogenes, Vibrio cholerae, Shigella flexneri and Salmonella typhi while EME1 was effective against P. aeroginosa, C. diphtheria and V. cholerae. The results also showed that among the chloroform extracts, CME4 (LC50) = 413.9±51.6) possessed significantly (p<0.05) high toxicity followed by CME3 (LC50 = 496.2±33.1) and CME2 (LC50 = 532.9±22.9) while among the ethanol extracts, EME3 (LC50 = 344.7±33.9) was significantly (p<0.05) more toxic followed by EME2 (LC50 = 534.3±81.5) and EME4 (LC50 = 609.6±74.8). Overall, EME3 and CME4 were highly toxic than their counterpart (CME3 and EME4), respectively, while CME2 and EME2 did no show any discrepancy in their LD50 value. M. esculenta possess an antibacterial property and low toxicity level.
  Z.A. Zakaria , N.I. Abdul Rahman , Y.W. Loo , A.H. Abdul Ayub , M.R. Sulaiman , A.M. Mat Jais , H.K. Gopalan and C.A. Fatimah
  Bauhinia purpurea L. (Leguminosae), has been used traditionally to treat ailments like sores, wounds and diarrhea. The present study was carried out to establish the antinociceptive and anti-inflammatory activities of chloroform extract of B. purpurea leaves using animal models. The air-dried, powdered leaves (≈ 20 g) were soaked in chloroform (1:20; w v-1) for 72 h and the supernatant obtained was then evaporated to dryness. The crude dried extract (≈ 1.323 g), dissolved in dimethyl sulfoxide, was prepared in the doses of 20, 100 and 200 mg kg-1 and then subjected to the respective antinociceptive (abdominal constriction, hot plate and formalin tests) and anti-inflammatory (carrageenan-induced paw edema test) assays. The results obtained indicate that the extract possess significant (p<0.05), but concentration-independent, antinociceptive activity when assessed using the abdominal constriction-and hot plate-test. This activity was also, significantly (p<0.05) observed in the early and late phases of the formalin test. The extract also exhibited significant (p<0.05) anti-inflammatory activity in a non-concentration-dependent manner. Unexpectedly, the 100 mg kg-1 extract showed a less remarkable anti-inflammatory activity compared to the other doses tested. The chloroform extract of B. purpurea contain bioactive compounds with potential peripheral and central antinociceptive and anti-inflammatory activities that requires further investigation.
  M.A. Yassir , A.K. Arifah , H. Yaakub , A. Zuraini and Z.A. Zakaria
  Special attention has been given to the milk Fatty Acids (FA) that have a beneficial effect for human health such as mono and poly unsaturated fatty acids in particularly the Conjugated Linoleic Acids (CLA). This study was undertaken to investigate the milk fat contents of CLA variables (CLA and CLA-desaturase index) and other FA composition of Mafriwal and Jersey cows under same feeding system. In addition, the relationship between these two CLA variables with milk production and milk fat percent was determined. All the cows were grazed on pasture and given 5.5 kg of concentrate per head daily. Milk FA composition was determined using gas chromatography after extraction of milk fat using modified Folch’s method. The results showed a significant variation (p<0.05) in the FA contents of the two breeds. The cis-9, trans-11 CLA and CLA-desaturase index in milk fat of Mafriwal were significantly higher (p<0.05) than that of Jersey cows. Mafriwal cows produced significantly (p<0.05) higher concentrations of C18:0, C18:1 cis-9, C18:3 and C20:1 than that of Jersey, while Jersey cows produced significantly (p<0.05) higher concentrations of C12:0 and C14:0 than Mafriwal cows. Additionally, significant positive correlations were observed between CLA variables and milk production. This study indicates that the breed of cows has an effect on CLA and other FA composition of milk fat and Mafriwal cows produced significantly higher percentages of CLA than Jersey cows which would provide better benefits for human health. Furthermore, the milk fat content of CLA and CLA-desaturase index were positively related to the milk production.
  M.B. Achenef , A.K. Arifah , Y.M. Goh , A.Q. Sazili , O. Fauziah , Z.A. Zakaria , A. Zuraini and M.N. Somchit
  Conjugated Linoleic Acids (CLAs) are group of positional and geometric isomers of octadecadienoic acid with conjugated double bonds and believed to have many health promoting effects. The present study focused on the quantitative analysis of CLAs in liver, Superficial Pectoral (SP), Longissimus Dorsi (LD) and Semimembranosus (SM) muscles of local Malaysian Kedah-Kelantan (KK) cattle slaughtered for human consumption. Fatty acids were extracted using Folch method and determined by gas chromatography. The average content of CLAs in the liver, SP, LD and SM muscles were 38.71, 18.24, 11.03 and 13.04 mg/100 g of sample, respectively. The quantity of CLAs in the liver was significantly (p<0.05) higher than other samples. The percentages of cis-9, trans-11 CLA isomer were 63.39, 76.04, 90.66 and 82.82% of total CLAs in the liver, SP, LD and SM muscles, respectively. Positive correlations between CLAs and trans-11-octadecenoic acid concentration were observed in all samples. This study confirmed that meat from KK cattle could be the potential source of CLA but still its content has to be improved to make their meat more beneficial for consumers.
  Z.A. Zakaria , A.M. Mat Jais , E.F.P. Henie , H. Zaiton , M.N. Somchit , M.R. Sulaiman and F.O. Faizal
  The present study was carried out to evaluate the potential of aqueous (AETT), ethanol (EETT) and chloroform (CETT) extracts of Tinosprora crispa as antibacterial agent against selected Gram positive (Bacillus cereus, Staphylococcus aureus, Listeria monocytogenes, Stretococcus pneumoniae and Clostridium diphtheriae) and Gram negative (Shigella flexneri, Salmonella typhi, Klebsiella pneumoniae, Proteus vulgaris and Escherichia coli) bacteria using the in vitro disc diffusion methods. Twenty microliter of the extracts, prepared in the concentrations of 25, 50, 74 and 100% (stock solution) by diluting the stock solution in distilled water (DH2O) or dimethyl sulfoxide (DMSO), were impregnated on sterilized blank discs (6 mm diameter) and tested against the respective bacteria. The AETT, at all concentrations, was effective only against S. pneumoniae and C. diphtheriae but show an activity against E. coli at the concentrations of 50% and above. At all concentrations used, the EETT was effective against S. aureus, S. pneumoniae, C. diphtheriae and S. flexneri while the CETT was effective against S. pneumoniae, C. diphtheriae and S. flexneri. Furthermore, the CETT, at the concentrations of 50% and above, was effective against E. coli. As a conclusion, T. crispa possesses potential antibacterial properties and further studies are being carried out to isolate and identify the responsible compound.
  M.B. Achenef , A.K. Arifah , Y.M. Goh , A.Q. Sazili , O. Fauziah , A. Zuraini , M.N. Somchit and Z.A. Zakaria
  This study was focused on the quantitative analysis of Conjugated Linoleic Acids (CLAs) in rumen liquor and assessment of the relationship between CLAs and other carbon 18 fatty acids and rumen pH of cattle slaughtered for meat consumption. The fatty acids were extracted using modified Folch method and determined by gas chromatography. The mean (n = 22) level of CLAs in the rumen liquor was 14.97 ±7.46 mg/100 mL. Cis-9, trans-11(c9, t11) was the dominant isomer of CLA followed by trans-10,cis-12 (t10, c12). The level of CLAs was positively correlated with the concentration of octadecatrienoic (18:3), cis-9, cis-12 octadecadienoic (18:2), trans-11octadecenoic (18:1) and octadecenoic (18:0) acids. Ruminal pH was positively correlated with the amount of c9, t11 and total CLA and negatively correlated with t10, c12 CLA isomer. All these correlations and relationships indicated that CLAs production in the rumen is dependent on availability of carbon 18 fatty acids and pH of the rumen liquor.
  Z.A. Zakaria , H. Zaiton , E.F.P. Henie , A.M. Mat Jais , D. Kasthuri , M. Thenamutha , F.W. Othman , R. Nazaratulmawarina and C.A. Fatimah
  The present study was carried out to evaluate the possible antibacterial activity of aqueous (AEMC), methanol (MEMC) and chloroform (CEMC) extracts of Muntingia calabura as well as methanol (MECO) and chloroform (CECO) extracts of Corchorus olitorius using the in vitro disc diffusion methods. The sterilized blank discs (6 mm diameter) was impregnated with 20 μL of the respective extract (the concentrations were 10,000, 20,000, 40,000 and 50,000 ppm for C. olitorius and 10,000, 40,000, 70,000 and 100,000 ppm for M. calabura) and tested against Salmonella enteriditis, Citrobacter fruendii, Enterobacter aerogenes, Klebsiella pneumoniae, Vibrio cholerae, Vibrio parahemolyticus, Pseudomonas aeruginosa and Salmonella typhi. The AEMC was effective in inhibiting the growth of all bacteria at the concentration of 70,000 ppm; the MEMC was effective in inhibiting the growth of C. fruendii, K. pneumoniae, V. cholerae, V. parahemolyticus and S. typhi; and the CEMC was ineffective at all concentrations tested. However, the MECO and CECO were ineffective against all bacteria tested. Except for P. aeruginosa, the standard antibiotic chloramphenicol (30 μg μL-1) was found to give inhibition zone of more than 20 mm against all bacteria tested. Based on this study, we concluded that M. calabura, but not C. olitorius, possesses a potential antibacterial activity against the selected microorganisms and this may provide a basis for the isolation of compounds of biological interest from M. calabura.
  Z.A. Zakaria , M.R. Sulaiman , A.K. Arifah , A.M. Mat Jais , M.N. Somchit , K. Kirisnaveni , D. Punnitharrani , M. Safarul , C.A. Fatimah and R. Johari
  The objective of this study was to elucidate the effects of C. olitorius as agent for relieving inflammation and fever. The aqueous extract of C. olitorius, in the concentration of 10, 50 and 100%, was used throughout the studies. The carrageenan-induced paw edema and brewer`s yeast-induced pyrexia assays were used as the anti-inflammatory and anti-pyretic assays, respectively. The extract, in the concentrations ranging from 50 to 100% and 10 to 100%, also exhibited significant (p<0.05) anti-inflammatory and anti-pyretic activities that lasted until the end of the experiments, respectively. In conclusion, the present studies provide scientific proof for the folklore medicinal used of C. olitorius as agent in the treatment of inflammation and fever.
  Z.A. Zakaria , A.M. Mat Jais , M.R. Sulaiman , S.S.P. Mohamed Isa and S. Riffin
  The present study was carried out to evaluate the possible antibacterial activity of methanol and ethanol extracts of Mangifera indica leaves and Carica papaya flowers using the in vitro disc diffusion methods. The sterilized blank discs (6 mm diameter) was impregnated with 20 μL of the respective extract in the concentrations of 12.5, 25, 50 and 100% and tested against Corneybacterium diptheriae, Staphylococcus aureus, Streptococcus pneumoniae, Salmonella typhi, Pseudomonas aeruginosa, Escherichia coli, Klebsiella pneumoniae and Proteus vulgaris. The methanol and ethanol extracts of M. indica were effective against C. diptheriae, S. aureus, S. typhi and P. aeruginosa, with the latter producing slightly bigger inhibitory zone against some of the bacteria when compared to the former. The methanol and ethanol extracts of C. papaya were effective only against S. aureus and S. pneumoniae, with the latter also effective against C. diptheriae. As a conclusion, the present study demonstrated the potential of M. indica leaves and C. papaya flowers as antibacterial agents against some of the bacteria tested and thus may provide the basis for the isolation of bioactive compounds with antibacterial activity from the respective plant leaves or flowers.
  Z.A. Zakaria , R.N.S. Raden Mohd Nor , M.R. Sulaiman , Z.D.F. Abdul Ghani , G. Hanan Kumar and C.A. Fatimah
  The present study was carried out to establish the antinociceptive, anti-inflammatory and antipyretic properties of Melastoma malabathricum leaves chloroform extract in experimental animals. The antinociceptive activity was measured using the abdominal constriction, hot plate and formalin tests, while the anti-inflammatory was measured using the carrageenan-induced paw edema. The extract, obtained after 72 h soaking of the air-dried leaves in chloroform followed by evaporation under vacuo (40°C) to dryness (4.38 g), was dissolved in dimethyl sulfoxide to the doses of 20, 100 and 200% and administered subcutaneously 30 min prior to subjection to the above mentioned assays. The extract, at all concentration used, was found to exhibit significant (p<0.05) antinociceptive and anti-inflammatory activities. Only the effect observed with the formalin test occurred in a concentration-dependent manner. It is concluded that the lipid-soluble compounds within the chloroform extract of M. malabathricum leaves possess potential antinociceptive and anti-inflammatory agents that require further attention.
  Z.A. Zakaria , I. Reezal , A.M. Mat Jais , M.N. Somchit , M.R. Sulaiman , A.H.I. Marmin , H. Sidek , S.H. Husin , M.H.A. Rahim and L. Abdul Rahman
  The present study was carried out to evaluate the potential of C. nucifera as antipyretic, anti-inflammatory and wound healing agents. The fresh juice of C. nucifera (FJCN) was directly used while its aqueous kernel extract (AKCN) was obtained after 72 h soaking of 1:2 (w/v) fresh kernel in 2:1 (v/v) chloroform:methanol. The extracts, in the concentrations/strengths of 10, 50 and 100%, were used in the anti-pyretic and anti-inflammatory studies while those in the concentration of 100% were used only in the wound healing study. The fresh juice and aqueous kernel extract of C. nucifera exhibited significant (p<0.05) anti-inflammatory and antipyretic activities and promote wound healing with the latter producing a more effective effects in all assays used. This finding has scientifically supported the folkloric used of C. nucifera in the treatment of inflammation, pyrexia and wound.
  Z.A. Zakaria , M.R. Sulaiman , A.M. Mat Jais and M.N. Somchit
  This study was attempted to preliminarily establish the basic chemical properties of the bioactive compound responsible for Channa striatus (Haruan) mucus extract antinociceptive activity using the acetic acid-induced abdominal constriction test in mice. Pre-treatment of extract with enzymes were carried out at the temperature of 40°C for 60 min. The extract, pre-treated with distilled water (DH2O), was found to show a significant and concentration-dependent antinociceptive activity with the 25 and 50% concentration extracts showing insignificant activity when compared together. The extracts, at the concentrations of 50 and 100%, were pre-treated with 10% concentration α-amylase and lipase and 0.1% concentration protease, respectively. The extracts, pre-treated with α-amylase or protease, were found to produce a concentration-dependent activity, which are, however, not significant when compared to the extracts pre-treated with DH2O (positive control). Interestingly, pre-treatment of the extracts with lipase enhanced the activity significantly (p<0.001). However, this activity did not follow the concentration-dependent pattern. The failure of -amylase and protease to influence the extracts antinociception seems to suggest that the bioactive compound is neither a simple carbohydrate nor protein. Meanwhile, the ability of lipase to enhance the extracts activity, especially of the 50% concentration extract, lead to suggestions that the lipid may act as a carrier of the bioactive compound or the bioactive compound itself is a lipid-based compound. Finally, the bioactive compound is suggested to be a short chain macromolecule, which is resistant to the effect of the three respective enzymes. However, further studies need to be carried out to clarify this finding before the real chemical properties of the bioactive compound can be ruled out.
 
 
 
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