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  1. Optimization of a greener method for removal phenol species by cloud point extraction and spectrophotometry
    Zain NN, Abu Bakar NK, Mohamad S, Saleh NM
    Spectrochim Acta A Mol Biomol Spectrosc, 2014 Jan 24;118:1121-8.
    PMID: 24161875 DOI: 10.1016/j.saa.2013.09.129
    A greener method based on cloud point extraction was developed for removing phenol species including 2,4-dichlorophenol (2,4-DCP), 2,4,6-trichlorophenol (2,4,6-TCP) and 4-nitrophenol (4-NP) in water samples by using the UV-Vis spectrophotometric method. The non-ionic surfactant DC193C was chosen as an extraction solvent due to its low water content in a surfactant rich phase and it is well-known as an environmentally-friendly solvent. The parameters affecting the extraction efficiency such as pH, temperature and incubation time, concentration of surfactant and salt, amount of surfactant and water content were evaluated and optimized. The proposed method was successfully applied for removing phenol species in real water samples.
  2. Molecular docking of compounds from Clinacanthus nutans extract detected by GC-MS analysis with the SARS-CoV-2 main protease and ACE2 protein
    Ismail NZ, Adebayo IA, Mohamad Zain NN, Arsad H
    Nat Prod Res, 2021 May 05.
    PMID: 33949277 DOI: 10.1080/14786419.2021.1919104
    Clinacanthus nutans has been reported to have many medicinal properties and it is traditionally used in treating viral lesions. This study aims to determine the molecular docking of C. nutans compounds detected by Gas Chromatography-Mass Spectrometry (GC-MS) with the novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2 main protease) protein and its host receptor angiotensin-converting enzyme 2 (ACE2) protein using the AutoDock 4.2 tool. The drug-likeness and molecular docking analyses showed that fourteen compounds of C. nutans satisfied the Lipinski's rule of five and they exhibited good inhibitory effects against the SARS-Cov-2 main protease and ACE2 proteins. In addition, the glyceryl 2-linolenate compound was found to have the most potent binding affinities with both proteins. The results provide useful insights into the molecular inhibitory interactions of C. nutans compounds detected by GC-MS analysis with the targeted SARS-CoV-2 main protease and ACE2 protein.
  3. Poly-(MMA-IL) filter paper: A new class of paper-based analytical device for thin-film microextraction of multi-class antibiotics in environmental water samples using LC-MS/MS analysis
    Shahriman MS, Mohamad S, Mohamad Zain NN, Raoov M
    Talanta, 2023 Mar 01;254:124188.
    PMID: 36521327 DOI: 10.1016/j.talanta.2022.124188
    A paper-based polymeric ionic liquid (p-Poly-(MMA-IL)) was successfully developed by grafting the polymeric ionic liquid on the surface of commercial filter paper (FP) by using the dipping method, presenting a new cost-effective film. The newly developed p-Poly-(MMA-IL) FP was then applied as a paper-based thin-film microextraction (p-TFME) analytical device to extract 14 compounds as representative of five groups of antibiotic drugs, which were sulfonamides, tetracyclines, fluoroquinolones, penicillin and macrolides in environmental water samples. Besides, p-Poly-(MMA-IL) FP, p-Poly-(MMA) FP, and unmodified filter paper were successfully characterised by FTIR, NMR, FESEM, TGA, and XRD techniques. They underwent significant parameters optimisation, which affected the extraction efficiency. Under optimal conditions, the proposed (p-Poly-(MMA-IL) FP-TFME) device method was evaluated and applied to analyse multi-class antibiotic drugs in environmental water samples by using a liquid chromatography-mass spectrometry (LC-MS). The validation method showed that a good linearity (0.1 μg L-1 - 500 μg L-1) was noted (R2 > 0.993, n = 3). Detection and quantification limits were within 0.05 μg L-1 - 4.52 μg L-1 and 0.15 μg L-1 - 13.6 μg L-1, respectively. The relative standard deviation (RSD) values ranged at 1.4%-12.2% (intra-day, n = 15) and 4.4%-11.0% (inter-day, n = 10). The extraction recoveries of environmental water samples ranged from 79.1% to 126.8%, with an RSD of less than 15.4% (n = 3). The newly developed paper-based polymeric ionic liquid (p-Poly-(MMA-IL) FP) for analysis of multi-class antibiotic drugs under the p-TFME analytical device procedure was successfully achieved with limited sample volume and organic solvent, fast extraction, and feasible in daily analysis. The detection concentration and relative RSD of multi-class antibiotics determined in various environmental water samples by the proposed method (n = 5) were within 0.44 μg L-1 - 54.41 μg L-1 and 0.69%-15.56%, respectively. These results signified the potential of the p-Poly-(MMA-IL) FP-TFME device as an efficient, sensitive and environmentally friendly approach for analysing antibiotics.
  4. Magnetic poly(β-cyclodextrin-ionic liquid) nanocomposites for micro-solid phase extraction of selected polycyclic aromatic hydrocarbons in rice samples prior to GC-FID analysis
    Boon YH, Mohamad Zain NN, Mohamad S, Osman H, Raoov M
    Food Chem, 2019 Apr 25;278:322-332.
    PMID: 30583379 DOI: 10.1016/j.foodchem.2018.10.145
    Poly(β-cyclodextrin functionalized ionic liquid) immobilized magnetic nanoparticles (Fe3O4@βCD-Vinyl-TDI) as sorbent in magnetic µ-SPE was developed for the determination of selected polycyclic aromatic hydrocarbons (PAHs) in rice samples coupled with gas chromatographic-flame ionization detector (GC-FID). The nanocomposite was characterized by various tools and significant parameters that affected the extraction efficiency of PAHs were investigated. The calibration curves were linear for the concentration ranging between 0.1 and 500 μg kg-1 with correlation determinations (R2) from 0.9970 to 0.9982 for all analytes. Detection limits ranged at 0.01-0.18 μg kg-1 in real matrix. The RSD values ranged at 2.95%-5.34% (intra-day) and 4.37%-7.05% (inter-day) precision for six varied days. The sorbents showed satisfactory reproducibility in 2.9% to 9.9% range and acceptable recovery values at 80.4%-112.4% were obtained for the real sample analysis. The optimized method was successfully applied to access content safety of selected PAHs for 24 kinds of commercial rice available in Malaysia.
  5. Poly(cyclodextrin-ionic liquid) based ferrofluid: A new class of magnetic colloid for dispersive liquid phase microextraction of polycyclic aromatic hydrocarbons from food samples prior to GC-FID analysis
    Yih Hui B, Mohamad Zain NN, Mohamad S, Varanusupakul P, Osman H, Raoov M
    Food Chem, 2020 Jun 01;314:126214.
    PMID: 31972404 DOI: 10.1016/j.foodchem.2020.126214
    Poly(β-cyclodextrin-ionic liquid) grafted magnetic nanoparticles combined with 1-octanol as supramolecular solvents (SUPRASs) presenting new ferrofluid was developed and successfully applied in the dispersive liquid-phase microextraction of seven representative polycyclic aromatic hydrocarbons. One variable at-a-time (OVAT) analysis and response surface methodology (RSM) were used for efficient optimization of the main variables. The calibration curves were found to be linear in the range of 0.1-150 ng mL-1 with correlation of determinations (R2) ranging from 0.9944 to 0.9986. Detection limits ranged at 0.02-0.07 ng mL-1 for all studied PAHs. The intra and inter-day precision values (RSD %) were in the range of 1.80%-7.56% and 2.97%-8.23%, respectively. The ferrofluid showed a satisfactory reproducibility between 1.72% and 5.90%, and acceptable recovery values at 84%-110% were obtained for the real samples analysis. The optimized method was successfully applied to access the content safety of the PAHs studied in a variety of commercial food and beverages available in Malaysia.
  6. Fulltext Antioxidant Effects, Antiproliferative Effects, and Molecular Docking of Clinacanthus nutans Leaf Extracts
    Ismail NZ, Md Toha Z, Muhamad M, Nik Mohamed Kamal NNS, Mohamad Zain NN, Arsad H
    Molecules, 2020 Apr 29;25(9).
    PMID: 32365508 DOI: 10.3390/molecules25092067
    Clinacanthus nutans is a well-known herb that has been used as an alternative and therapeutic medicine, however more selective C. nutans extracts are needed. In this study, leaves were extracted with 80% methanol and further fractionated with n-hexane, dichloromethane, chloroform, n-butanol, and aqueous residue. Subsequently, the total phenolic content (TPC), total flavonoid content (TFC), antioxidant scavenging activity, and antiproliferative effects on breast cancer (Michigan Cancer Foundation-7 [MCF7]) and normal breast (Michigan Cancer Foundation-10A [MCF 10A]) cells of the extracts were measured. Additionally, molecular docking simulation of the major compounds from C. nutans extracts was conducted. The aqueous residue had the highest TPC and TFC, whereas the crude extract had the highest scavenging activity. Among the extracts, dichloromethane extract (CN-Dcm) was selected as it had the highest selectivity index (SI) (1.48). Then, the chosen extract (CN-Dcm) was proceed for further analysis. The compounds from CN-Dcm were identified using gas chromatography-mass spectrometry (GC-MS). The major compounds from CN-Dcm were further investigated through molecular docking studies. Palmitic acid and linolenyl alcohol were the compounds found in the CN-Dcm extract that exhibited the highest binding affinities with p53-binding protein Mdm-2. These results highlight the potential of C. nutans as a source of anticancer activities.
  7. Christia vespertilionis extract induced antiproliferation and apoptosis in breast cancer (MCF7) cells
    Ismail NZ, Adebayo IA, Mohamed WAS, Mohamad Zain NN, Arsad H
    Mol Biol Rep, 2021 Nov;48(11):7361-7370.
    PMID: 34665399 DOI: 10.1007/s11033-021-06743-w
    BACKGROUND: C. vespertiliomis extracts were evaluated for antiproliferative and apoptosis effect on breast cancer (MCF7) cells.

    METHODS AND RESULTS: The leaves extracts were analysed for its antiproliferative effect on breast cancer (MCF7) cells and normal epithelial breast (MCF 10A) cells using Sulforhodamine B (SRB) assay. The selective extract was evaluated for its ability to induce apoptosis using Annexin V-FITC apoptosis staining and the expression of molecular genes using qualitative reverse transcription-polymerase chain reaction (RT-PCR) against MCF7 cells. Gas chromatography-mass spectrometry (GC-MS) was used to identify the compounds from the selective extract. The findings showed that dichloromethane fraction (CV-Dcm) extract had high antiproliferative effect against MCF7 cells (IC50 = 24 µg/mL, selective index (SI) = 8.17). The percentages of apoptosis cells in CV-Dcm-treated MCF7 cells was 58.8%. The CV-Dcm extract induced downregulation of PCNA level. The apoptotic genes were also triggered in both extrinsic and intrinsic signaling pathways, affecting a 1.5-fold increase in BAX, 1.4-fold increase in cytochrome c, 1.3-fold increase in caspase-8, 1.7-fold increase in caspase-3 and 0.5-fold-decrease in BCL-2. Treated MCF7 cells also activated P53-dependent apoptotic death pathway.

    CONCLUSIONS: The present work strongly suggests that high efficacy of CV-Dcm extract was attributed to its antiproliferative and apoptosis-inducing activation in MCF7 cells, most likely due to its favourable compounds.

  8. The antiproliferative and apoptotic potential of Clinacanthus nutans against human breast cancer cells through targeted apoptosis pathway
    Ismail NZ, Md Saad S, Adebayo IA, Md Toha Z, Abas R, Mohamad Zain NN, et al.
    Environ Sci Pollut Res Int, 2022 Nov;29(54):81685-81702.
    PMID: 35737268 DOI: 10.1007/s11356-022-20858-y
    Clinacanthus nutans dichloromethane fraction (CN-Dcm) extract has previously been proven to suppress breast cancer (MCF7) cell proliferation. Despite this, the extrinsic and intrinsic apoptosis mechanisms involved in C. nutans extract-treated MCF7 cells are still unknown. This study was intended to subfractionate CN-Dcm extract using column chromatography and analyse the treated MCF7 cells using the CellTiter 96® AQueous One Solution Cell Proliferation (MTS) assay, Annexin V/propidium iodide (PI) assay, western blot, and reverse transcription-qualitative polymerase chain reaction (RT-qPCR). Out of nine subfraction extracts (SF1 to SF9), SF2 extract strongly inhibited MCF7 cells with the lowest IC50 value (23.51 ± 1.00 µg/mL) and substantially induced apoptosis in the MCF7 cells. In treated MCF7 cells, SF2 extract significantly upregulated the expression of P53, BAX, BID, caspase-8, caspase-9, and caspase-3, while downregulating the expression of BCL2. The presence of potential bioactive chemical compounds in the SF2 extract was identified using liquid chromatography coupled to quadrupole time-of-flight mass spectrometry (LC-QTOF-MS). Thus, the SF2 extract has the potential to induce apoptosis in MCF7 cells through intrinsic and extrinsic pathways.
  9. Fulltext Cytotoxicity of Plant-Mediated Synthesis of Metallic Nanoparticles: A Systematic Review
    Hanan NA, Chiu HI, Ramachandran MR, Tung WH, Mohamad Zain NN, Yahaya N, et al.
    Int J Mol Sci, 2018 Jun 11;19(6).
    PMID: 29891772 DOI: 10.3390/ijms19061725
    In the field of medicine, nanomaterials, especially those derived using the green method, offer promise as anti-cancer agents and drug carriers. However, the biosafety of metallic nanoparticles used as anti-cancer agents remains a concern. The goal of this systematic review was to compare the cytotoxicity of different plant-mediated syntheses of metallic nanoparticles based on their potency, therapeutic index, and cancer cell type susceptibility in the hopes of identifying the most promising anti-cancer agents. A literature search of electronic databases including Science Direct, PubMed, Springer Link, Google Scholar, and ResearchGate, was conducted to obtain research articles. Keywords such as biosynthesis, plant synthesis, plant-mediated, metallic nanoparticle, cytotoxicity, and anticancer were used in the literature search. All types of research materials that met the inclusion criteria were included in the study regardless of whether the results were positive, negative, or null. The therapeutic index was used as a safety measure for the studied compound of interest. Data from 76 selected articles were extracted and synthesised. Seventy-two studies reported that the cytotoxicity of plant-mediated synthesis of metallic nanoparticles was time and/or dose-dependent. Biosynthesised silver nanoparticles demonstrated higher cytotoxicity potency compared to gold nanoparticles synthesised by the same plants (Plumbago zeylanica, Commelina nudiflora, and Cassia auriculata) irrespective of the cancer cell type tested. This review also identified a correlation between the nanoparticle size and morphology with the potency of cytotoxicity. Cytotoxicity was found to be inversely proportional to nanoparticle size. The plant-mediated syntheses of metallic nanoparticles were predominantly spherical or quasi-spherical, with the median lethal dose of 1⁻20 µg/mL. Nanoparticles with other shapes (triangular, hexagonal, and rods) were less potent. Metallic nanoparticles synthesised by Abutilon inducum, Butea monosperma, Gossypium hirsutum, Indoneesiella echioides, and Melia azedarach were acceptably safe as anti-cancer agents, as they had a therapeutic index of >2.0 when tested on both cancer cells and normal human cells. Most plant-mediated syntheses of metallic nanoparticles were found to be cytotoxic, although some were non-cytotoxic. The results from this study suggest a focus on a selected list of potential anti-cancer agents for further investigations of their pharmacodynamic/toxicodynamic and pharmacokinetic/toxicokinetic actions with the goal of reducing the Global Burden of Diseases and the second leading cause of mortality.
  10. Enantioseparation of ketoconazole and miconazole by capillary electrophoresis and a study on their inclusion interactions with β-cyclodextrin and derivatives
    Azhari NR, Yahaya N, Mohd Suah FBM, Prabu S, Yih Hui B, Shahriman MS, et al.
    Chirality, 2021 01;33(1):37-50.
    PMID: 33197086 DOI: 10.1002/chir.23285
    A chiral separation method coupled with capillary electrophoresis (CE) analysis for ketoconazole and miconazole enantiomers using chiral selectors such as β-cyclodextrin (β-CD) and hydroxypropyl-β-CD (HP-β-CD) was developed in this study, which included the optimisation, validation and application of the method on the antifungal cream samples. The formation of inclusion complex between the hosts (β-CD and HP-β-CD) and guests (ketoconazole and miconazole) were compared and analysed using ultraviolet-visible spectrophotometry, nuclear magnetic resonance (NMR) spectroscopy and molecular docking methods. Results from the study showed that in a concentration that ranged between 0.25 and 50 mg L-1 , the linear calibration curves of each enantiomer had a high coefficient of regression (R2 > 0.999), low limit of detection (0.075 mg L-1 ) and low limit of quantification (0.25 mg L-1 ). The relative standard deviation (RSD) of the intraday and interday analyses ranged from 0.79% to 8.01% and 3.30% to 11.43%, respectively, while the recoveries ranged from 82.0% to 105.7% (RSD < 7%, n = 3). The most probable structure of the inclusion complexes was proposed based on the findings from the molecular docking studies conducted using the PatchDock server.
  11. Fulltext A Bottom-Up Synthesis Approach to Silver Nanoparticles Induces Anti-Proliferative and Apoptotic Activities Against MCF-7, MCF-7/TAMR-1 and MCF-10A Human Breast Cell Lines
    Zulkifli NI, Muhamad M, Mohamad Zain NN, Tan WN, Yahaya N, Bustami Y, et al.
    Molecules, 2020 Sep 22;25(18).
    PMID: 32971740 DOI: 10.3390/molecules25184332
    A bottom-up approach for synthesizing silver nanoparticles (AgNPs-GA) phytomediated by Garcinia atroviridis leaf extract is described. Under optimized conditions, the AgNPs-GA were synthesized at a concentration of 0.1 M silver salt and 10% (w/v) leaf extract, 1:4 mixing ratio of reactants, pH 3, temperature 32 °C and 72 h reaction time. The AgNPs-GA were characterized by various analytical techniques and their size was determined to be 5-30 nm. FTIR spectroscopy indicates the role of phenolic functional groups in the reduction of silver ions into AgNPs-GA and in supporting their subsequent stability. The UV-Visible spectrum showed an absorption peak at 450 nm which reflects the surface plasmon resonance (SPR) of AgNPs-GA and further supports the stability of these biosynthesized nanoparticles. SEM, TEM and XRD diffractogram analyses indicate that AgNPs-GA were spherical and face-centered-cubic in shape. This study also describes the efficacy of biosynthesized AgNPs-GA as anti-proliferative agent against human breast cancer cell lines, MCF-7 and MCF-7/TAMR-1. Our findings indicate that AgNPs-GA possess significant anti-proliferative effects against both the MCF-7 and MCF-7/TAMR-1 cell lines, with inhibitory concentration at 50% (IC50 values) of 2.0 and 34.0 µg/mL, respectively, after 72 h of treatment. An induction of apoptosis was evidenced by flow cytometry using Annexin V-FITC and propidium iodide staining. Therefore, AgNPs-GA exhibited its anti-proliferative activity via apoptosis on MCF-7 and MCF-7/TAMR-1 breast cancer cells in vitro. Taken together, the leaf extract from Garcinia atroviridis was found to be highly capable of producing AgNPs-GA with favourable physicochemical and biological properties.
  12. Molecular docking and molecular dynamic simulations of apoptosis proteins with potential anticancer compounds present in Clinacanthus nutans extract using gas chromatography-mass spectrometry
    Ismail NZ, Mohamed WAS, Ab Rahim N, Hashim NM, Adebayo IA, Mohamad Zain NN, et al.
    J Biomol Struct Dyn, 2023;41(13):6104-6120.
    PMID: 35899385 DOI: 10.1080/07391102.2022.2101530
    Clinacanthus nutans is a medicinal plant recognised for its anticancer properties. We previously discovered that the C. nutans extract had the most potent inhibitory effect on MCF7 breast cancer cell and significantly induced apoptosis. However, there is a scarcity of studies demonstrating the molecular interactions of C. nutans-derived chemical compounds associated with apoptosis-related proteins. Therefore, the objective of this study was to determine the potential chemical compounds found in the C. nutans extract and examine their interactions with the targeted apoptotic proteins using molecular docking and molecular dynamic simulations. To address this objective, the compounds found in the SF2 extract of C. nutans were analysed using Gas Chromatography-Mass Spectrometry (GC-MS). The molecular interaction of the compounds with the targeted apoptotic proteins were determined using molecular docking and molecular dynamic simulations. GC-MS analysis revealed a total of 32 compounds in the SF2 extract. Molecular docking analysis showed that compound β-amyrenol had the highest binding affinity for MDM2-P53 (-7.26 kcal/mol), BCL2 (-11.14 kcal/mol), MCL1-BAX (-6.42 kcal/mol), MCL1-BID (-6.91 kcal/mol), and caspase-9 (-12.54 kcal/mol), whereas campesterol had the highest binding affinity for caspase-8 (-10.11 kcal/mol) and caspase-3 (-10.14 kcal/mol). These selected compounds were subjected to molecular dynamic simulation at 310 K for 100 ns. The results showed that the selected protein-ligand conformation complexes were stable, compact, and did not alter much when compared to the protein references. The findings indicate that β-amyrenol and campesterol are potentially significant compounds that might provide insight into the molecular interactions of the compounds with the apoptosis-related proteins.Communicated by Ramaswamy H. Sarma.
  13. A simple and efficient sequential electrokinetic and hydrodynamic injections in micellar electrokinetic chromatography method for quantification of anticancer drug 5-fluorouracil and its metabolite in human plasma
    Semail NF, Noordin SS, Keyon ASA, Waras MN, Saad B, Kamaruzaman S, et al.
    Biomed Chromatogr, 2021 May;35(5):e5050.
    PMID: 33314228 DOI: 10.1002/bmc.5050
    A simple and sensitive preconcentration strategy using sequential electrokinetic and hydrodynamic injection modes in micellar electrokinetic chromatography with diode array detection was developed and applied for the separation and determination of anticancer agent, 5-fluorouracil and its metabolite, 5-fluoro-2'-deoxyuridine, in human plasma. Sequential injection modes with increased analyte loading capacity using the anionic pseudo-stationary phase facilitated collection of the dispersed neutral and charged analytes into narrow zones and improved sensitivity. Several important parameters affecting sample enrichment performance were evaluated and optimized in this study. Under the optimized experimental conditions, 614- and 643-fold and 782- and 803-fold sensitivity improvement were obtained for 5-fluorouracil and its metabolite when compared with normal hydrodynamic and electrokinetic injection, respectively. The method has good linearity (1-1,000 ng/ml) with acceptable coefficient of determination (r2  > 0.993), low limits of detection (0.11-0.14 ng/ml) and satisfactory analyte relative recovery (97.4-99.7%) with relative standard deviations of 4.6-9.3% (n = 6). Validation results as well as the application to analysis of human plasma samples from cancer patients demonstrate the applicability of the proposed method to clinical studies.
  14. Fulltext Magnetic nanoparticles assisted dispersive liquid-liquid microextraction of chloramphenicol in water samples
    Saad SM, Aling NA, Miskam M, Saaid M, Mohamad Zain NN, Kamaruzaman S, et al.
    R Soc Open Sci, 2020 Apr;7(4):200143.
    PMID: 32431904 DOI: 10.1098/rsos.200143
    This work describes the development of a new methodology based on magnetic nanoparticles assisted dispersive liquid-liquid microextraction (DLLME-MNPs) for preconcentration and extraction of chloramphenicol (CAP) antibiotic residues in water. The approach is based on the use of decanoic acid as the extraction solvent followed by the application of MNPs to magnetically retrieve the extraction solvent containing the extracted CAP. The coated MNPs were then desorbed with methanol, and the clean extract was analysed using ultraviolet-visible spectrophotometry. Several important parameters, such as the amount of decanoic acid, extraction time, stirring rate, amount of MNPs, type of desorption solvent, salt addition and sample pH, were evaluated and optimized. Optimum parameters were as follows: amount of decanoic acid: 200 mg; extraction time: 10 min; stirring rate: 800 rpm; amount of MNPs: 60 mg; desorption solvent: methanol; salt: 10%; and sample pH, 8. Under the optimum conditions, the method demonstrated acceptable linearity (R2 = 0.9933) over a concentration range of 50-1000 µg l-1. Limit of detection and limit of quantification were 16.5 and 50.0 µg l-1, respectively. Good analyte recovery (91-92.7%) and acceptable precision with good relative standard deviations (0.45-6.29%, n = 3) were obtained. The method was successfully applied to tap water and lake water samples. The proposed method is rapid, simple, reliable and environmentally friendly for the detection of CAP.
  15. Simultaneous preconcentration and determination of sulfonamide antibiotics in milk and yoghurt by dynamic pH junction focusing coupled with capillary electrophoresis
    Semail NF, Abdul Keyon AS, Saad B, Kamaruzaman S, Mohamad Zain NN, Lim V, et al.
    Talanta, 2022 Jan 01;236:122833.
    PMID: 34635223 DOI: 10.1016/j.talanta.2021.122833
    A dynamic pH junction was used in capillary electrophoresis (CE-DAD) to on-line preconcentrate, separate, and determine trace amounts of sulfonamide antibiotics (SAs) in milk and yoghurt samples in this study. A sample matrix with 0.15% acetic acid and 10% methanol (MeOH) at a pH of 4.0, and a background electrolyte (BGE) that contained 35 mM sodium citrate with 10% MeOH at a pH of 8.5, and an acidic barrage of 0.4% acetic acid with 10% MeOH at a pH of 2.5 were utilised to achieve a stacking effect for SAs through a dynamic pH junction. Under optimised conditions, the proposed preconcentration method showed good linearity (30-500 ng/mL, r2 ≥ 0.9940), low limits of detection (LODs) of 4.1-6.3 ng/mL, and acceptable analytes recovery (81.2-106.9%) with relative standard deviations (RSDs) within 5.3-13.7 (n = 9). The limits of quantification (LOQs) were below the maximum residue limit approved by the European Union (EU) in this type of matrices. Sensitivity enhancement factors of up to 129 were reached with the optimised dynamic pH junction using CE with a diode array detector (DAD). The method was used to determine SAs in fresh milk, low-fat milk, full-cream milk, and yoghurt samples.
  16. Fulltext Biogenic Silver Nanoparticles of Clinacanthus nutans as Antioxidant with Antimicrobial and Cytotoxic Effects
    Chiu HI, Che Mood CNA, Mohamad Zain NN, Ramachandran MR, Yahaya N, Nik Mohamed Kamal NNS, et al.
    Bioinorg Chem Appl, 2021;2021:9920890.
    PMID: 34093698 DOI: 10.1155/2021/9920890
    Silver nanoparticles (AgNPs) previously synthesised using leaf (AgNP-L) and stem (AgNP-S) extracts of Clinacanthus nutans (C. nutans) were tested to evaluate antimicrobial, antioxidant, and cytotoxicity activities. The AgNPs showed good inhibition against bacteria, but not fungi. The inhibition results showed the highest activity against Staphylococcus aureus (S. aureus) with 11.35 mm (AgNP-L) and 11.52 mm (AgNP-S), while the lowest inhibition was against Escherichia coli (E. coli) with 9.22 mm (AgNP-L) and 9.25 mm (AgNP-S) in the disc diffusion method. The same trend of results was noted in the well diffusion method. The IC50 of AgNP-L and AgNP-S in 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2'-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) assays was 417.05 μg/mL and 434.60 μg/mL, as well as 304.31 μg/mL and 326.83 μg/mL, respectively. Ferric reducing power (FRAP) assay showed that AgNP-L [872.389 μmol/L Fe(II)] and AgNP-S [612.770 μmol/L Fe(II)] exhibited significantly (p 
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