Papers by DR. MOHD HILMI ABU BAKAR
The International Arabic Journal of Antimicrobial Agents
Background: The study aims to evaluate the antibacterial activity of Trigona honey against S. pne... more Background: The study aims to evaluate the antibacterial activity of Trigona honey against S. pneumonia. Methods: The effect of Trigona honey on S. pneumonia investigated using agar well diffusion, MIC, MBC, biofilm formation and RT-qPCR. Results: Trigona honey samples showed the larger zones of inhibition against S. pneumonia, 22.2±0.4 at 100% concentration. Trigona honey possessed the lowest MIC, MBC, MIC50 and MIC90 against S. pneumoniae, 25%, 30%, 12.5% and 25% (w/v) respectively. Trigona honey permeated established biofilms of S. pneumonia, resulting in significant decreased the cells from the biofilm. RT-qPCR revealed that the expression of genes amiF, ftsY, mvaS, pnpA, argG, mvd1, purN, miaA and pbp2a were upregulated, glcK, marR, prmA and ccpA were downregulated after exposure to honey. Conclusion: Trigona honey demonstrated the highest antibacterial activity against S. pneumoniae. By limiting study in vitro on Trigona honey, we infer that Trigona honey impacts on S. pneu...
The International Arabic Journal of Antimicrobial Agents, 2021
Background: The purpose of this study was to investigate antibacterial activity of three varietie... more Background: The purpose of this study was to investigate antibacterial activity of three varieties of Malaysian honey; Tualang honey (TH), Gelam honey (GH), and Acacia honey (AH) against Escherichia coli. Methods: The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of the honey samples against E. coli were determined by the broth microdilution assay in the presence and absence of catalase enzyme. The mode of inhibition of honey samples against E. coli was investigated by the effect of time on viability. Impacts of the honeys on the expression profiles of the selected genes of E. coli were examined using RT-qPCR analysis. Results: The results showed that TH and GH honey possessed lowest MIC and MBC values against E. coli with 20% and 25% (w/v) respectively. Highest MIC and MBC values were observed by AH honey against E. coli with 25% (w/v) and 50% (w/v) values respectively. Among the tested honeys, TH and GH exhibited the highest total antibacteria...
Antibiotics
Honey is considered to be a functional food with health-promoting properties. However, its potent... more Honey is considered to be a functional food with health-promoting properties. However, its potential health benefits can be affected by individual composition that varies between honey types. Although studies describing the health benefits of Tualang honey (TH), Kelulut honey (KH), and Sidr honey (SH) are scarce, these honey types showed a comparable therapeutic efficacy to Manuka honey (MH). The purpose of this review is to characterise the physicochemical, biological, and therapeutic properties of TH, KH, and SH. Findings showed that these honeys have antibacterial, antifungal, antiviral, antioxidant, antidiabetic, antiobesity, anticancer, anti-inflammatory and wound-healing properties and effects on the cardiovascular system, nervous system, and respiratory system. The physicochemical characteristics of TH, KH, and SH were compared with MH and discussed, and results showed that they have high-quality contents and excellent biological activity sources. Flavonoids and polyphenols, ...
Physicochemical and Therapeutic Properties of Malaysian Stingless Bee Kelulut Honey in Comparison with Yemeni Sidr Honey
Anti-Infective Agents
: Kelulut and Yemeni Sidr honey has been documented to have various therapeutic properties. Inves... more : Kelulut and Yemeni Sidr honey has been documented to have various therapeutic properties. Investigations associated with the medicinal properties and physicochemical characteristics of Kelulut and Yemeni Sidr honey are growing broadly and receiving raised awareness. This study incorporated and analysed the findings on the biological and physicochemical properties of Kelulut and Yemeni Sidr honey. Kelulut and Yemeni Sidr honey was found to have a wide variety of biological effects attributed to their physicochemical characteristics. Findings showed that Kelulut and Yemeni Sidr honey have anti-bacterial, antibiofilm, anti-virulence, anti-oxidative, anti-cancer, anti-inflammatory, anti-diabetic, antiobesity and wound-healing properties. The physicochemical properties of Kelulut and Yemeni Sidr honey were compared and discussed and results revealed that they have high-quality contents and excellent antioxidant sources.
Iranian Journal of Biotechnology, 2020
Background: Honey has been known as a traditional medicine for centuries with its antibacterial p... more Background: Honey has been known as a traditional medicine for centuries with its antibacterial properties. It is considered one of the most enduring substances used in wound management. Objectives: This study aimed to: (i) evaluate the effects of Malaysian Trigona honey on bacterial structure and (ii) assess the anti-virulence potential of this honey by examining their impacts on the expression of selected genes (involved in stress survival and biofilm formation) in a test organism. Materials and Methods: Trigona honey’s impacts on the bacterial structure (cell morphology) and the expression profiles of select Pseudomonas Aeruginosa and Streptococcus Pyogenes genes were examined using scanning electron microscopy (SEM) and real-time PCR (RT-qPCR) analysis, respectively. Results: SEM showed that the decreased cell density deformed, disrupted, and damaged cells for both bacteria. RT-qPCR showed that the expression of fleN, fleQ, and fleR genes of P.aeruginosa were decreased, 4.26-fol...
Aim: This study was designed to assess the effectiveness of Trigona honey in blocking the biofilm... more Aim: This study was designed to assess the effectiveness of Trigona honey in blocking the biofilm formation by E. coli. Methods: Biofilms were cultivated in microtiter plates with varying concentrations (10, 20, 30, 40 and 50%) of honey for specific incubation time (24, 48 and 72 hours). The extent of biofilm biomass was estimated by staining with crystal violet. Results: It was found that the mean values of biofilms were significantly different (F = 425.42, P < 0.001) within groups based upon time of incubation. The mean biofilm values were significantly different among groups (F = 121.82, P = 0.029). It was also observed that a difference of 10% between the treatments was found to be nonsignificant. Overall it was found that 30% Trigona honey application significantly reduce the formation of biofilms during first 24 hours of incubation. Conclusion: This study has shown that Trigona honey has significantly inhibited biofilm formation by E. coli in vitro. Hence Trigona honey can ...
Biomedical and Pharmacology Journal, 2017
Cancer is a disease with marked heterogeneity in both response to therapy and survival. Malignant... more Cancer is a disease with marked heterogeneity in both response to therapy and survival. Malignant neoplasm or cancer is a type of genetic disease in which a group of cells display uncontrolled growth, invasion and sometimes metastasis. Cancer progression is not only associated with changes in the cell cycle that inactivate pathways leading to cell death or senescence but also enhanced cell proliferation. Usually, these changes are associated with alterations in Ca 2+ homeostasis in cells. The transient receptor potential (TRP) channels play a role as cell sensors and are involved in a plethora of Ca 2+-mediated cell functions. TRP vanilloid 4 (TRPV4) is a member of the TRPV ion channel family which is permeable to both Ca 2+ and Na +. TRPV4 is expressed in various types of tissues such as kidneys, airway smooth muscle and lungs. As other TRPV channels, TRPV4 may also be involved in cancer cell proliferation, apoptosis, angiogenesis, migration and invasion. Previous studies have demonstrated that TRPV4 plays a role in the proliferation of several types of cancer cells. Moreover, TRPV4 also contributes to cancer cell angiogenesis via arachidonic acid-induced migration of breast tumour-derived endothelial cells. TRPV4 is also able to regulate angiogenesis via mechanotransduction. Recent studies have also reported a significant role of TRPV4 in breast cancer metastasis and induction of breast cancer cell death. In this review, the emerging roles of TRPV4 in cancer will be discussed which further supports the potential of TRPV4 as a promising drug target for cancer therapy.
Biomedical and Pharmacology Journal, 2019
The transient receptor potential vanilloid member 4 (TRPV4) is a non-selective calcium (Ca2+)-per... more The transient receptor potential vanilloid member 4 (TRPV4) is a non-selective calcium (Ca2+)-permeable channel which is widely expressed in different types of tissues including the lungs, liver, kidneys and salivary gland. TRPV4 has been shown to serve as a cellular sensor where it is involved in processes such as osmoregulation, cell volume regulation and thermoregulation. Emerging evidence suggests that TRPV4 also plays important roles in several aspects of cancer progression. Despite the reported roles of TRPV4 in several forms of cancers, the role of TRPV4 in human colorectal cancer remains largely unexplored. In the present study, we sought to establish the potential role of TRPV4 in colorectal cancer by assessing TRPV4 expression levels and investigating whether TRPV4 pharmacological modulation may alter cell proliferation, cell cycle and cell death in colorectal cancer cells. Quantitative real-time PCR analysis revealed that TRPV4 mRNA levels were significantly lower in HT-2...
Bulletin of the National Research Centre, 2019
Pseudomonas aeruginosa and Streptococcus pyogenes are the most common pathogens to humans and are... more Pseudomonas aeruginosa and Streptococcus pyogenes are the most common pathogens to humans and are able to form a biofilm following ineffective precautionary approach. Biofilm is defined as a surface-attached community of bacterium embedded in an extracellular matrix which leads to tremendous problems in the environment, among humans and animals. This study aims to investigate the ability of P. aeruginosa and S. pyogenes to form biofilms in 96-well plate before further study in antibiofilm will be done. Initially, the 96-well plate was added with 100 μl of overnight P. aeruginosa culture with optical density (OD) 0.1 and S. pyogenes culture with OD 0.05. The cultures were incubated for 7 days at 37°C to justify the formation of biofilm. Subsequently, stained blue biofilm was detached from the plate by using 95% ethanol. Biofilms were finally measured using a micro plate reader at 570 nm and were classified based on the adherence strength formula. P. aeruginosa and S. pyogenes biofilms strongly adhered to the plates on days three, four, five and six. Interestingly on day three, biofilms showed the highest formation. However, moderate biofilm formation onto the plates by both P. aeruginosa and S. pyogenes were observed on day two, but non-adherence was observed on days one and seven. Day three is the optimum cultivation period for P. aeruginosa and S. pyogenes to switch into a strong biofilm in microtiter plate and could be beneficial for antibiofilm experiments.
Iranian Journal of Microbiology, 2020
Background and Objectives: Tualang honey (TH) is a Malaysian multifloral jungle honey. In recent ... more Background and Objectives: Tualang honey (TH) is a Malaysian multifloral jungle honey. In recent years, there has been a marked increase in the number of studies published in medical databases regarding its potential health benefits. The study aimed to investigate the effect of TH against Pseudomonas aeruginosa and Streptococcus pyogenes. Materials and Methods: The effect of TH on both bacteria was investigated using MIC, MBC, growth curve, time-kill curve, scanning electron microscopy (SEM) and RT-qPCR. Results: The MIC of TH against P. aeruginosa and S. pyogenes was 18.5% (w/v) and 13% (w/v) respectively and MBC 90 was 25% (w/v) for both bacteria. Spectrophotometric readings of at least 90% inhibition yielded MIC values of TH, 18.5% (w/v) and 15% (w/v) for P. aeruginosa and S. pyogenes respectively. A time–kill curve demonstrated a bactericidal with a 4-log reduction estimated within 8 hours. Using SEM, loss of structural integrity and marked changes in cell shape were observed. R...
Regenerative Research 1(2) 2012 8-13 ISOLATION OF HAIR FOLLICLE STEM CELL AND ITS THREE-DIMENSIONAL PROLIFERATION ON POROUS CHITOSAN SCAFFOLD
International Journal on Advanced Science, Engineering and Information Technology, 2017
Hair follicles repeatedly regress and reconstitute themselves, suggesting the presence of intrins... more Hair follicles repeatedly regress and reconstitute themselves, suggesting the presence of intrinsic tissue stem cells. Among the unique characteristics of adult stem cells isolated from hair follicles is their ability to differentiate into keratinocytes. Study on chitosan skin-engineered templates (SETs) as scaffolds for the proliferation of human fibroblasts have shown the promise of SETs in facilitating skin cell growth in three-dimensional culture. High proliferation in three-dimensional culture using human cells allows the researcher to extensively evaluate the cultivation of desirable cell types on chitosan SETs. Therefore, this study aimed to evaluate the in vitro attachment, proliferation and differentiation of hair follicle stem cells (HFSCs) on a chitosan SETs. HFSCs were isolated from human scalp tissues using collagenase type I prior to propagation in supplemented CnT-07 media. The phenotype of the HFSCs was verified using the markers keratin-15 (K15) and CD200, as detected by immunocytochemical staining. The attachment and proliferation of the HFSCs on the chitosan SETs were evaluated using scanning electron microscopy (SEM), an alamar blue assay and a live/dead assay. Subsequently, the HFSCs were differentiated using CnT-2D differentiation media. The cells' differentiation was verified using the markers involucrin and keratin-6 (K6), as detected by immunofluorescence staining. The HFSCs were successfully isolated, proliferated and differentiated according to staining positivity and microscopy imaging. HFSCs are able to proliferate and directly differentiate into keratinocytes on a chitosan SETs, which may facilitate their use in regenerative medicine.
The aim of this study was to determine the physicochemical, phytochemical content and antimicrobi... more The aim of this study was to determine the physicochemical, phytochemical content and antimicrobial properties of selected honey of Sabah, Malaysian Borneo. Methods: A standardized protocols were used to evaluate the physicochemical properties of selected honey of Sabah while the phytochemicals content (phenolics and flavonoids) were determined using Folin-Ciocalteau and aluminium colorimetric methods. Antimicrobial properties were evaluated using disc diffusion assay. Results: For 80% methanol extract, old Upper Mountain honey contained the highest free acidity, conductivity, total phenolic and flavonoid contents with the values 23.84 ± 0.42 ml/g, 0.61 ± 0.01 mS/cm, 9.71 ± 0.01 mg gallic acid equivalent (GAE)/g and 7.76 ± 0.02 mg rutin equivalent (RU)/g, respectively. Antimicrobial activity showed strong inhibition by old Upper Mountain honey extract (80% methanol extract) with the value of 6.00 ± 0.01 mm at concentration of 100% against gram-positive bacteria (Staphylococcus aureus and Bacillus subtilis). The same trend of phytochemicals content and antimicrobial activity was also observed in absolute methanol extracts. Conclusion: The present results suggested that wild raw honey collected at mangrove and mountain area in Sabah contained a wide range of phytochemical compounds which has the potential for human health.
Antibacterial properties of honey from Malaysian stingless bee
Introduction: Stingless bee honey or known as madu kelulut has significant contribution in antimi... more Introduction: Stingless bee honey or known as madu kelulut has significant contribution in antimicrobial activity. Naturally, bees from the genus Apis forage on one floral source thus producing monofloral honey. Most honey are monofloral and named according to their respective plant species. Manuka honey the well-known New Zealand medical-grade honey is named in respect to the Manuka tree, Leptospermum scoparium. Contrarily, bees from the genus Trigona or known as stingless honey bees forage on diverse floral sources to produce polyfloral or multifloral honey, and thus to name the honey according to a tree species is not applicable. Therefore, honey produced multiflorally is named according to the forager bee species such as Trigona itama honey or Trigona thoracica honey. Nevertheless, the efficacy of monofloral and multifloral honey on the treatment of human diseases and to claim which honey is superior to another is still under investigation. Objective: To explore the efficacy of ...
Journal of Cell Science & Therapy, 2013
N eurodegeneration and cancer are fast becoming the leading causes of age-associated disability, ... more N eurodegeneration and cancer are fast becoming the leading causes of age-associated disability, dementia and ultimately death worldwide. Although oxidative stress has been intensely studied, little analysis has been done in chronic oxidative stress-induced mitochondrial models and cell signaling pathway. Moreover, DNA-overproliferation and/or deletion initiate mitochondrial deregulation causing energy failure, which has been implicated in the pathogenesis of Alzheimer's disease (AD), tumor growth, and metastasis. In addition, the overexpression of the cascades initiates the formation and release of large amounts of reactive free radicals [mainly nitric oxide (NO) via the overexpression of NO synthases], which cause the oxidative stress, cellular alterations, and concomitant mitochondrial lesions and decline in normal organ function. One of the key features of tumors is the deficiency in tissue energy that accompanies mitochondrial lesions and formation of the hypoxic smaller sized mitochondria with ultrastructural abnormalities. We theorize that mitochondrial involvement may play a significant role in the etiopathogenesis of cancer. Recently, we demonstrate a potential link between AD and cancer, and anticancer drugs are being explored for the inhibition of AD-like pathology in transgenic mice. Severity of the cancer growth, metastasis, and brain pathology in AD correlate with the degree of mitochondrial ultrastructural abnormalities. Recent advances in the cell-cycle reentry of the terminally differentiated neuronal cells indicate that NO-dependent mitochondrial abnormal activities and mitotic cell division are not the only important pathogenic factors in pathogenesis of cancer and AD, but open a new window for the development of novel treatment strategies for these devastating diseases. The present study explores the intimate, i.e., direct relationship between chronic oxidative stress and mitochondrial damage as a vital life-supporter for cells and/or the microcirculatory systems whose damage occurs before the development of human AD. Further extension of this approach will enable us not only for the better understanding of the blood brain barrier (BBB) homeostasis, which most likely plays a key role in the development of AD and some of forms of the cancer, but also for the development of new and more specific treatment strategies.
Tobacco Induced Diseases, 2004
A cross-sectional study was conducted to identify the factors related to smoking habits of adoles... more A cross-sectional study was conducted to identify the factors related to smoking habits of adolescents among secondary school boys in Kelantan state, Malaysia. A total of 451 upper secondary male students from day, boarding and vocational schools were investigated using a structured questionnaire. Cluster sampling was applied to achieve the required sample size. The significant findings included: 1) the highest prevalence of smoking was found among schoolboys from the vocational school; 2) mean duration of smoking was 2.5 years; 3) there were significant associations between smoking status and parents' smoking history, academic performance, perception of the health hazards of smoking, and type of school attended. Peer influence was the major reason students gave for taking up the habit. Religion was most often indicated by non-smokers as their reason for not smoking. Approximately 3/5 of the smokers had considered quitting and 45% of them had tried at least once to stop smoking. Mass media was indicated as the best information source for the students to acquire knowledge about negative aspects of the smoking habit. The authors believe an epidemic of tobacco use is imminent if drastic action is not taken, and recommend that anti-smoking campaigns with an emphasis on the religious aspect should start as early as in primary school. Intervention programs to encourage behavior modification of adolescents are also recommended.
Archives of Microbiology, 2003
Pseudomonas aeruginosa is a severe opportunistic pathogen and is one of the major causes of hard ... more Pseudomonas aeruginosa is a severe opportunistic pathogen and is one of the major causes of hard to treat burn wound infections. Herein we have used an RNA-seq transcriptomic approach to study the behavior of P. aeruginosa PAO1 growing directly on human burn wound exudate. A chemical analysis of compounds used by this bacterium, coupled with kinetics expression of central genes has allowed us to obtain a global view of P. aeruginosa physiological and metabolic changes occurring while growing on human burn wound exudate. In addition to the numerous virulence factors and their secretion systems, we have found that all iron acquisition mechanisms were overexpressed. Deletion and complementation with pyoverdine demonstrated that iron availability was a major limiting factor in burn wound exudate. The quorum sensing systems, known to be important for the virulence of P. aeruginosa, although moderately induced, were activated even at low cell density. Analysis of bacterial metabolism emphasized importance of lactate, lipid and collagen degradation pathways. Overall, this work allowed to designate, for the first time, a global view of P. aeruginosa characteristics while growing in human burn wound exudate and highlight the possible therapeutic approaches to combat P. aeruginosa burn wound infections.
PloS one, 2011
Rapidly regenerating tissues need sufficient polyamine synthesis. Since the hair follicle (HF) is... more Rapidly regenerating tissues need sufficient polyamine synthesis. Since the hair follicle (HF) is a highly proliferative mini-organ, polyamines may also be important for normal hair growth. However, the role of polyamines in human HF biology and their effect on HF epithelial stem cells in situ remains largely unknown. We have studied the effects of the prototypic polyamine, spermidine (0.1-1 µM), on human scalp HFs and human HF epithelial stem cells in serum-free organ culture. Under these conditions, spermidine promoted hair shaft elongation and prolonged hair growth (anagen). Spermidine also upregulated expression of the epithelial stem cell-associated keratins K15 and K19, and dose-dependently modulated K15 promoter activity in situ and the colony forming efficiency, proliferation and K15 expression of isolated human K15-GFP+ cells in vitro. Inhibiting the rate-limiting enzyme of polyamine synthesis, ornithine decarboyxlase (ODC), downregulated intrafollicular K15 expression. In ...
BioMed Research International, 2013
Wounds with full-thickness skin loss are commonly managed by skin grafting. In the absence of a g... more Wounds with full-thickness skin loss are commonly managed by skin grafting. In the absence of a graft, reepithelialization is imperfect and leads to increased scar formation. Biomaterials can alter wound healing so that it produces more regenerative tissue and fewer scars. This current study use the new chitosan based biomaterial in full-thickness wound with impaired healing on rat model. Wounds were evaluated after being treated with a chitosan dermal substitute, a chitosan skin substitute, or duoderm CGF. Wounds treated with the chitosan skin substitute showed the most re-epithelialization (33.2 ± 2.8%), longest epithelial tongue (1.62 ± 0.13 mm), and shortest migratory tongue distance (7.11 ± 0.25 mm). The scar size of wounds treated with the chitosan dermal substitute (0.13 ± 0.02 cm) and chitosan skin substitute (0.16 ± 0.05 cm) were significantly decreased (P<0.05) compared with duoderm (0.45 ± 0.11 cm). Human leukocyte antigen (HLA) expression on days 7, 14, and 21 reveale...
Central European Journal of Biology, 2013
The challenge arises among researchers when hair follicle stem cells (HFSCs) derived from a human... more The challenge arises among researchers when hair follicle stem cells (HFSCs) derived from a human hair follicle remain poorly expanded in defined culture medium. In this study, we isolated the HFSCs and they became confluent after 10 days of cultivation. Comparing the viability of HFSCs cultured in defined keratinocytes serum free medium (KSFM) in a coated plate and CnT07 medium in an uncoated plate, the number of HFSCs cultured in CnT07 was significantly higher at days 2, 4, 6 and 8 (P=0.004). The population doubling time of HFSCs was 21.48±0.44 hours in non-coated plates with CnT07 and 30.73±0.75 hours in coated plates with KSFM. Our primary HFSC cultures were positive for CD200 and K15 with brownish color. Flow cytometry analysis showed that the percentage of HFSCs expressing CD200 and K15 were 65.20±3.16 and 72.07±6.62 respectively. After reaching 100% confluence, the HFSCs were differentiated into an epidermal layer in vitro using CnT02-3D defined media. HFSCs were differentiat...
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Papers by DR. MOHD HILMI ABU BAKAR