Anwar Usman

Dr. Anwar Usman

Department of Chemistry, Faculty of Science, Universiti Brunei Darussalam, Jalan Tungku Link, Gadong BE1410, Brunei
orcid

Research Focus & Metrics

Academic Career Length

26Years (2001-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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19 September 2022 in Molecules
Verified
Journal Article
Open access
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Nadzirah ZullkifleeNadzirah Zullkiflee
Nadzirah Zullkiflee
HTHussein Taha
Hussein Taha
Anwar UsmanAnwar Usman
Anwar Usman
With technological advancements in the medicinal and pharmaceutical industries, numerous research studies have focused on the propolis produced by stingless bees (Meliponini tribe) and Apis mellifera honeybees as alternative complementary medicines for the potential treatment of various acute and chronic diseases. Propolis can be found in tropical and subtropical forests throughout the world. The composition of phytochemical constituents in propolis varies depending on the bee species, geographical location, botanical source, and environmental conditions. Typically, propolis contains lipid, beeswax, essential oils, pollen, and organic components. The latter include flavonoids, phenolic compounds, polyphenols, terpenes, terpenoids, coumarins, steroids, amino acids, and aromatic acids. The biologically active constituents of propolis, which include countless organic compounds such as artepillin C, caffeic acid, caffeic acid phenethyl ester, apigenin, chrysin, galangin, kaempferol, luteolin, genistein, naringin, pinocembrin, coumaric acid, and quercetin, have a broad spectrum of biological and therapeutic properties such as antidiabetic, anti-inflammatory, antioxidant, anticancer, rheumatoid arthritis, chronic obstruct pulmonary disorders, cardiovascular diseases, respiratory tract-related diseases, gastrointestinal disorders, as well as neuroprotective, immunomodulatory, and immuno-inflammatory agents. Therefore, this review aims to provide a summary of recent studies on the role of propolis, its constituents, its biologically active compounds, and their efficacy in the medicinal and pharmaceutical treatment of chronic diseases.

10 March 2024 in Catalysts
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Journal Article
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NRNur Nabaahah Roslan
Nur Nabaahah Roslan
HLHarry Lik Hock Lau
Harry Lik Hock Lau
NSNurul Amanina Afiqah Suhaimi
Nurul Amanina Afiqah Suhaimi
NSNurulizzatul Ningsheh Haji Awang Mohammad Shahri
Nurulizzatul Ningsheh Haji Awang Mohammad Shahri
SVSera Budi Verinda
Sera Budi Verinda
Anwar UsmanAnwar Usman
Anwar Usman
A large variety of pharmaceutical compounds have recently been detected in wastewater and natural water systems. This review highlighted the significance of removing pharmaceutical compounds, which are considered indispensable emerging contaminants, from wastewater and natural water systems. Various advanced oxidation processes (AOPs), including UV-H2O2, Fenton and photo-Fenton, ozone-based processes, photocatalysis, and physical processes, such as sonolysis, microwave, and electron beam irradiation, which are regarded as the most viable methods to eliminate different categories of pharmaceutical compounds, are discussed. All these AOPs exhibit great promising techniques, and the catalytic degradation process of the emerging contaminants, advantages, and disadvantages of each technique were deliberated. Heterogeneous photocatalysis employing metal oxides, particularly anatase TiO2 nanoparticles as catalysts activated by UV light irradiation, was reviewed in terms of the electron–hole separation, migration of the charge carriers to the catalyst surfaces, and redox potential of the charge carriers. This brief overview also emphasized that anatase TiO2 nanoparticles and TiO2-based nanomaterials are promising photocatalysts, and a combination of photocatalysis and other AOPs enhanced photocatalytic degradation efficiency. Finally, the challenges of applying anatase TiO2-based photocatalysis in environmental remediation and wastewater treatments to degrade pharmaceutical compounds, including mass spectroscopic analysis and a biological activity test of by-products of the emerging contaminants resulting from photocatalysis, are summarized.

1 September 2021 in Catalysis Today
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Journal Article
Closed access
IHIshaq Y. Habib
Ishaq Y. Habib
JBJasmine Burhan
Jasmine Burhan
FJFadhli Jaladi
Fadhli Jaladi
CLChee Ming Lim
Chee Ming Lim
Anwar UsmanAnwar Usman
Anwar Usman
AMAbdul Hanif Mahadi
Abdul Hanif Mahadi

23 May 2018 in Food Science & Nutrition
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Journal Article
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NGNurul Aqilah A. Ghani
Nurul Aqilah A. Ghani
ACAmy‐Arniza Channip
Amy‐Arniza Channip
PHPhoebe Chok Hwee Hwa
Phoebe Chok Hwee Hwa
FJFairuzeta Ja'afar
Fairuzeta Ja'afar
HYHartini Mohd Yasin
Hartini Mohd Yasin
Anwar UsmanAnwar Usman
Anwar Usman
Different from cooking oils which contain long‐chain fatty acids, virgin coconut oil (VCO) has high medium‐chain fatty acids, making it a potential functional food which can provide some health benefits. In this study, our objective is to investigate the physicochemical properties, antioxidant capacity, and metal contents of the VCO extracted through four different processing methods: chilling and centrifugation; fermentation; direct micro expelling‐oven dried; and direct micro expelling‐sun‐dried processes. We found that the physicochemical properties, including moisture content, refractive index, viscosity, iodine value, saponification value, peroxide value, free fatty acid, and fatty acid content, of all the VCO conform to the Asian and Pacific Coconut Community (APCC) standard. All of the VCO predominantly contains lauric acid which is in the range of 48.40%–52.84% of the fatty acid content. The total phenolic content and DPPH radical‐scavenging activity (IC50) of the VCO was obtained to be in the range of 1.16–12.54 mg gallic acid equivalents (GAE)/g and 7.49–104.52 mg/ml, respectively, and the metal contents in the VCO were within the acceptable range of the recommended APCC limit. These findings ensure good quality and safety assurance of the VCO produced from the coconut grown in Brunei Darussalam through the different processing methods.

1 November 2020 in Saudi Journal of Biological Sciences
Verified
Journal Article
Open access
NANurul Aliah Abdullah
Nurul Aliah Abdullah
Nadzirah ZullkifleeNadzirah Zullkiflee
Nadzirah Zullkiflee
SZSiti Nurul Zahirah Zaini
Siti Nurul Zahirah Zaini
HTHussein Taha
Hussein Taha
FHFatimah Hashim
Fatimah Hashim
Anwar UsmanAnwar Usman
Anwar Usman
The present study focused on the evaluation of phytochemical properties, essential mineral elements, and heavy metals contained in raw propolis produced by stingless bees Geniotrigona thoracica, Heterotrigona itama, and Tetrigona binghami found in the same ecological conditions and environment in Brunei Darussalam. The results indicated that propolis of the three stingless bee species mainly consisted of lipids (45.60–47.86%) and very low carbohydrate (0.17–0.48%) and protein contents (0.18–1.18%). The propolis was rich in mineral elements, thus good sources of minerals, while they contained low concentrations of all heavy metals. Propolis of the different bee species could be distinguished based on their mineral compositions. The vibrational and absorption spectra suggested that propolis contains π-conjugated aliphatic and aromatic compounds as well as aromatic acids having amine, ester, carbonyl, alkyl, and hydroxyl functional groups which might be attributed to the presence of phenolic and flavonoid compounds. The antioxidant capacity of the propolis, based on radical scavenging activity of their ethanol extract, was in line with their total phenolic content. The ethanol extract of the propolis also showed antimicrobial activities against four bacterial strains (Bacillus subtilis, Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa). The propolis showed slightly higher antibacterial activity against Gram-positive (B. subtilis and S. aureus) bacteria, indicating that the antimicrobial active compounds could be associated with flavonoids, which were quantified to be approximately comparable in all the propolis.

1 September 2019 in Heliyon
Verified
Journal Article
Open access
NANurul Aliah Abdullah
Nurul Aliah Abdullah
FJFairuzeta Ja'afar
Fairuzeta Ja'afar
HYHartini M. Yasin
Hartini M. Yasin
HTHussein Taha
Hussein Taha
MPMark Ihrwell Remollo Petalcorin
Mark Ihrwell Remollo Petalcorin
Anwar UsmanAnwar Usman
Anwar Usman
In this study, the physicochemical, antioxidant, antibacterial properties, and the toxicity of propolis particles produced by stingless bee Heterotrigona itama found in Brunei Darussalam were investigated. Propolis particles of different sizes were extracted from raw propolis using various volume fractions of ethanol in water. Spectroscopic analyses were utilized to characterize the chemical structures, functional groups, as well as absorbance and fluorescence properties. The total antioxidant capacity of propolis particles, which was assessed using DPPH (2,2-diphenyl-1-picrylhydrazyl) assay, was found to increase with volume fraction of ethanol. The maximum antioxidant capacity was as high as 317.65 mg ascorbic acid equivalent per gram of propolis particles. All of the propolis particles showed antibacterial activity against Gram-positive (Bacillus subtilis and Staphylococcus aureus) and Gram-negative bacteria (Escherichia coli and Pseudomonas aeruginosa). The diameters of the inhibition zone were either significantly higher or equivalent to those of two standard antibiotics (rifampicin and streptomycin), suggesting strong antibacterial activity. The toxicity studies of propolis particles against Caenorhabditis elegans revealed that they are non-toxic after 24 h exposure. Overall findings suggest that H. itama propolis particles are not only an important source of natural antioxidants that could be beneficial for human health, but they have potentials as antimicrobial against bacteria.