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Fulltext Intracellular stored calcium plays a minor role in Gq-coupled receptor-mediated contraction in rat airway smooth muscle

Govindaraju, Kayatri, Lee, Mei Kee, Mbaki, Yvonne, Ting, Kang Nee

Life Sciences, Medicine and Biomedicine, 2018;2(2):1-6.
MyJurnal

The general notion of activation of Gq-protein coupled receptors (GPCR) involves the mobilisation of stored and extracellular calcium and leads to smooth muscle tissue contraction. The aim of this study was to investigate the involvement of calcium mediated contractions in vascular and airway smooth muscles. Using standard organ bath procedures, aortic and tracheal rings were obtained from 6 to 8 week-old male Sprague Dawley rats. To activate the Gq protein receptors, phenylephrine (PE), an α1-adrenoceptor agonist, and carbachol, a M3 cholinoceptor agonist was added to baths containing the aortic and tracheal rings, respectively. The maximum response (Emax) to PE was reduced from 158.8 ± 11.8% (n=6) to 62.5 ± 12.4 % (n=8) upon removal of extracellular calcium in Krebs-Ringer solution. Maximal response to PE was also suppressed in the presence of nifedipine, a L-type Ca2+ channel inhibitor, (70.3 ± 11 %, n=8) and SKF96365, a canonical transient receptor potential cation channel inhibitor, (26.7 ± 13.2 %, n=5) when the influx of extracellular calcium was blocked. Removal of stored calcium also attenuated the PE contraction (p0.05). From these observations, we conclude that the role of stored and extracellular calcium in Gq protein activation is not the same across different types of smooth muscle tissues.
Fulltext Microplastics - an emerging silent menace to public health

Li-Yin Pang, Shola Sonagara, Oreoluwatomide Oduwole, Christopher Gibbins, Ting Kang Nee

Life Sciences, Medicine and Biomedicine, 2021;5(1):0-0.
MyJurnal

Over the past few decades, microplastics have become increasingly ubiquitous in the environment and now contaminate the bodies of many living organisms, including humans. Microplastics, as defined here, are plastics within the size range 0.1 μm and 5 mm and are a worrying form of pollution due to public health concerns. This mini-review aims to summarise the route of entry of microplastics into humans and explore the potential detrimental health effects of microplastics. Trophic transfer is an important pathway for microplastic to be transferred across different groups of organisms, with ingestion is regarded as one of the major routes of exposure for humans. Other pathways include inhalation and dermal contact. The health consequences of microplastics manifest because these materials can translocate into the circulatory system and accumulate in the lungs, liver, kidney, and even brain, regardless of the route of entry. Health effects include gastrointestinal disturbances such as inflammation and gut microbiota disruption, respiratory conditions, neurotoxicity and potential cancers. Overall, while it is apparent that microplastics are causing adverse effects on different biological groups and ecosystems, current research is largely focused on marine organisms and aquaculture. Therefore, more studies are needed to investigate specific effects in mammalian cells and tissues, with more long-term epidemiological studies needed on human population considered to be at high-risk due to socioeconomic or other circumstance. Knowledge of the toxicity and long-term health impacts of microplastics is currently limited and requires urgent attention.
Fulltext Ophiocordyceps sinensis: a prominent source of bioactive components for alleviating overactive bladder

Li-Yin Pang, Chon-Seng Tan, Szu-Ting Ng, Kuan-Hon Lim, Sue-Mian Then, Ting Kang Nee

Life Sciences, Medicine and Biomedicine, 2020;4(1):0-0.
MyJurnal

Ophiocordyceps sinensis is one of the most sought-after medicinal fungi used to treat various medical conditions such as respiratory diseases, liver and kidney dysfunctions. In China, it is widely used for alleviation of frequent urination where patients treated with O. sinensis have shown improvement in nocturia, which is the most common symptom of overactive bladder (OAB). Many studies have reported its anticancer, anti-inflammatory, anti-oxidative, hypoglycaemic and vasorelaxation properties. These properties are attributable to the presence of bioactive components such as polysaccharides, proteins and nucleosides. This mini-review highlights the medicinal potential of O. sinensis in alleviating OAB, which is a debilitating condition with a profound impact on the quality of life in a high proportion of older people. Four possible mechanisms of action of O. sinensis are suggested. Firstly, the relaxation of bladder smooth muscle through calcium dynamic, production of nitric acid (NO) and adenosine triphosphate (ATP). A second mechanism proposed is through the suppression of micturition reflex. The unequivocal properties of O. sinensis as anti-inflammatory and anti-oxidant, are two other plausible explanations, as both chronic inflammation and accumulation of oxidative stress molecules are associated with OAB exacerbation. With the recent success in cultivation of O. sinensis and the positive results from toxicity studies, a better understanding of its pharmacological actions can be further substantiated, including its use for relieving OAB.
Community pharmacists' views on adverse drug reactions reporting in Malaysia: a pilot study

Ting KN, Stratton-Powell DM, Anderson C

Pharm World Sci, 2010 Jun;32(3):339-42.
PMID: 20336371 DOI: 10.1007/s11096-010-9382-0

OBJECTIVES: To investigate community pharmacists' knowledge, attitudes and views on adverse drug reaction (ADR) reporting. Setting Seven community pharmacies in Malaysia.
METHOD: Structured interviews with community pharmacists. Informed consent was obtained and interviews were audio-recorded and transcribed verbatim.
MAIN OUTCOME MEASURES: Content analysis of themes on awareness of ADR reporting, reporting activities, attitudes and views on patient reporting.
RESULTS: All pharmacists claimed to have some knowledge of a reporting system but only one had submitted a report directly to the regulatory authority. Despite the low level of reporting activities, all participants agreed that it was part of their professional obligation to report an ADR. Most participants were not aware of the direct patient reporting scheme and were skeptical about its success. Lack of awareness and patients' limited knowledge about their medications were viewed as barriers to patient reporting. Local attitudinal issues including pharmacists' attitude towards ADR reporting were described as possible contributing factors.
CONCLUSION: Community pharmacists have an important role in reporting ADRs. Many Malaysian patients are still perceived to be ill-informed of their medications, an important determinant to the success of patient reporting. There is a need for further training about ADRs and ADR reporting for health professionals and further education for patients.
Knowledge, attitude and practice of community pharmacists towards household pharmaceutical waste disposal

Low BY, Ting KN, Lee MK

Int J Pharm Pract, 2023 Apr 10;31(2):261-265.
PMID: 36534990 DOI: 10.1093/ijpp/riac101

OBJECTIVE: To assess the knowledge, attitude and practice of community pharmacists (CP) towards household pharmaceutical waste disposal.
METHODS: All pharmacists attending the Malaysian Community Pharmacy Guild event held in-person were invited to self-administer a web-based survey.
KEY FINDINGS: The response rate was 61% (168/276). Overall, community pharmacists have mixed knowledge (mean ± SD: 5.89 ± 1.38) and positive attitude (mean ± SD: 9.58 ± 0.81) towards household pharmaceutical waste disposal. However, few community pharmacists (18/168, 10.7%) have promotional materials encouraging safe medication disposal in their pharmacies.
CONCLUSIONS: Community pharmacists do not proactively promote safe household pharmaceutical waste disposal to mitigate pharmaceutical pollutants entering the environment although they have satisfactory knowledge and attitude.
Microplastic pollution in freshwater systems in Southeast Asia: contamination levels, sources, and ecological impacts

Chen HL, Selvam SB, Ting KN, Gibbins CN

Environ Sci Pollut Res Int, 2021 Oct;28(39):54222-54237.
PMID: 34386926 DOI: 10.1007/s11356-021-15826-x

Plastics are synthetic polymers known for their outstanding durability and versatility, and have replaced traditional materials in many applications. Unfortunately, their unique traits ensure that they pose a major threat to the environment. While literature on freshwater microplastic contamination has grown over the recent years, research undertaken in rapidly developing countries, where plastic production and use are increasing dramatically, has lagged behind that in other parts of the world. In the South East Asia (SEA) region, basic information on levels of contamination is very limited and, as a consequence, the risk to human and ecological health remains hard to assess. This review synthesises what is currently known about microplastic contamination of freshwater ecosystems in SEA, with a particular focus on Malaysia. The review 1) summarises published studies that have assessed levels of contamination in freshwater systems in SEA, 2) discusses key sources and transport pathways of microplastic in freshwaters, 3) outlines what is known of the impacts of microplastic on freshwater organisms, and 4) identifies key knowledge gaps related to our understanding of the transport, fate and effects of microplastic.
Spatio-temporal variation of microplastic along a rural to urban transition in a tropical river

Chen HL, Gibbins CN, Selvam SB, Ting KN

Environ Pollut, 2021 Nov 15;289:117895.
PMID: 34364115 DOI: 10.1016/j.envpol.2021.117895

Microplastic pollution is widely recognised as a global issue, posing risks to natural ecosystems and human health. The combination of rapid industrial and urban development and relatively limited environmental regulation in many tropical countries may increase the amount of microplastic entering rivers, but basic data on contamination levels are lacking. This is especially the case in tropical South East Asian countries. In this paper, the abundance, composition and spatio-temporal variation of microplastic in the Langat River, Malaysia, were assessed, and the relationship between microplastic concentration and river discharge was investigated. Water samples were collected over a 12-month period from 8 sampling sites on the Langat, extending from forested to heavily urbanised and industrial areas. All 508 water samples collected over this period contained microplastic; mean concentration across all sites and times was 4.39 particles/L but extended up to 90.00 particles/L in some urban tributaries. Most microplastics were secondary in origin, and dominated by fibres. Microplastic counts correlated directly with river discharge, and counts increased and decreased in response to changes in flow. A time-integrated assessment of the microplastic load conveyed by the Langat suggested that the river is typically (50 % of the time) delivering around 5 billion particles per day to the ocean. The positive correlation between the concentration of microplastics and suspended sediments in the Langat suggested that continuously logging turbidity sensors could be used to provide better estimates of microplastic loads and improve assessment of human and ecological health risks.
Quinine interactions with tryptophan and tyrosine in malaria patients, and implications for quinine responses in the clinical setting

Islahudin F, Pleass RJ, Avery SV, Ting KN

J Antimicrob Chemother, 2012 Oct;67(10):2501-5.
PMID: 22763566 DOI: 10.1093/jac/dks253

OBJECTIVES: Recent work with the yeast model revealed that the antiprotozoal drug quinine competes with tryptophan for uptake via a common transport protein, causing cellular tryptophan starvation. In the present work, it was hypothesized that similar interactions may occur in malaria patients receiving quinine therapy.
PATIENTS AND METHODS: A direct observational study was conducted in which plasma levels of drug and amino acids (tryptophan, tyrosine and phenylalanine) were monitored during quinine treatment of malaria patients with Plasmodium falciparum infections.
RESULTS: Consistent with competition for uptake from plasma into cells, plasma tryptophan and tyrosine levels increased ≥2-fold during quinine therapy. Plasma quinine levels in individual plasma samples were significantly and positively correlated with tryptophan and tyrosine in the same samples. Control studies indicated no effect on phenylalanine. Chloroquine treatment of Plasmodium vivax-infected patients did not affect plasma tryptophan or tyrosine. During quinine treatment, plasma tryptophan was significantly lower (and quinine significantly higher) in patients experiencing adverse drug reactions.
CONCLUSIONS: Plasma quinine levels during therapy are related to patient tryptophan and tyrosine levels, and these interactions can determine patient responses to quinine. The study also highlights the potential for extrapolating insights directly from the yeast model to human malaria patients.
Fulltext High Correlation of 2,2-diphenyl-1-picrylhydrazyl (DPPH) Radical Scavenging, Ferric Reducing Activity Potential and Total Phenolics Content Indicates Redundancy in Use of All Three Assays to Screen for Antioxidant Activity of Extracts of Plants from the Malaysian Rainforest

Clarke G, Ting KN, Wiart C, Fry J

Antioxidants (Basel), 2013;2(1):1-10.
PMID: 26787618 DOI: 10.3390/antiox2010001

Extracts of plants from the Malaysian rainforest and other fragile habitats are being researched intensively for identification of beneficial biological actions, with assessment of antioxidant behavior being a common component of such assessments. A number of tests for antioxidant behavior are used, with the 2,2-diphenyl-1-picrylhydrazyl (DPPH) and ferric reduction activity potential (FRAP) assays often being used in parallel, and also with measurement of total phenolics content (TPC) as a surrogate marker for antioxidant capacity. The present study investigated the possible redundancy in using all three assays to determine antioxidant capacity in 92 extracts obtained from 27 plants from the Malaysian rainforest. The results demonstrated that the assays displayed a high (R ≥ 0.82) and significant (P < 0.0001) correlation with one another, indicating a high level of redundancy if all three assays are used in parallel. This appears to be a waste of potentially valuable plant extracts. Because of problems with the FRAP assay relating to color interference and variable rates of reaction point, the DPPH assay is the preferred assay in preliminary screening of extracts of plants from the Malaysian rainforest.
Fulltext Inhibitory effect of Duabanga grandiflora on MRSA biofilm formation via prevention of cell-surface attachment and PBP2a production

Santiago C, Lim KH, Loh HS, Ting KN

Molecules, 2015 Mar 10;20(3):4473-82.
PMID: 25764489 DOI: 10.3390/molecules20034473

Formation of biofilms is a major factor for nosocomial infections associated with methicillin-resistance Staphylococcus aureus (MRSA). This study was carried out to determine the ability of a fraction, F-10, derived from the plant Duabanga grandiflora to inhibit MRSA biofilm formation. Inhibition of biofilm production and microtiter attachment assays were employed to study the anti-biofilm activity of F-10, while latex agglutination test was performed to study the influence of F-10 on penicillin-binding protein 2a (PBP2a) level in MRSA biofilm. PBP2a is a protein that confers resistance to beta-lactam antibiotics. The results showed that, F-10 at minimum inhibitory concentration (MIC, 0.75 mg/mL) inhibited biofilm production by 66.10%; inhibited cell-surface attachment by more than 95%; and a reduced PBP2a level in the MRSA biofilm was observed. Although ampicilin was more effective in inhibiting biofilm production (MIC of 0.05 mg/mL, 84.49%) compared to F-10, the antibiotic was less effective in preventing cell-surface attachment. A higher level of PBP2a was detected in ampicillin-treated MRSA showing the development of further resistance in these colonies. This study has shown that F-10 possesses anti-biofilm activity, which can be attributed to its ability to reduce cell-surface attachment and attenuate the level of PBP2a that we postulated to play a crucial role in mediating biofilm formation.
Fulltext Prevention of cell-surface attachment and reduction of penicillin-binding protein 2a (PBP2a) level in methicillin-resistant Staphylococcus aureus biofilms by Acalypha wilkesiana

Santiago C, Lim KH, Loh HS, Ting KN

BMC Complement Altern Med, 2015;15:79.
PMID: 25880167 DOI: 10.1186/s12906-015-0615-6

Formation of biofilm is known to enhance the virulence of methicillin-resistance Staphylococcus aureus (MRSA), which is associated with persistent infections in hospital settings. The biofilm layer essentially forms a protective barrier encapsulating the bacterial colony and thus reduces the effectiveness of chemotherapeutics. We have isolated 9EA-FC-B bioactive fraction from Acalypha wilkesiana Müll. Arg. that reverses ampicillin resistant in MRSA through inhibition of the antibiotic resistant protein, penicillin-binding protein 2a (PBP2a). In this study, we aimed to investigate the effects of 9EA-FC-B on MRSA biofilm forming capacity.
Fulltext Reply to "chloroquine, an antifungal but also a fertility drug"

Islahudin F, Ting KN, Pleass RJ, Avery SV

Antimicrob Agents Chemother, 2013 Nov;57(11):5787.
PMID: 24123347 DOI: 10.1128/AAC.01688-13
Microplastic concentrations in river water and bed sediments in a tropical river: implications for water quality monitoring

Chen HL, Selvam SB, Ting KN, Gibbins CN

Environ Monit Assess, 2023 Jan 18;195(2):307.
PMID: 36652034 DOI: 10.1007/s10661-022-10856-5

Recent increase in awareness of the extent of microplastic contamination in marine and freshwater systems has heightened concerns over the ecological and human health risks of this ubiquitous material. Assessing risks posed by microplastic in freshwater systems requires sampling to establish contamination levels, but standard sampling protocols have yet to be established. An important question is whether sampling and assessment should focus on microplastic concentrations in the water or the amount deposited on the bed. On three dates, five replicated water and bed sediment samples were collected from each of the eight sites along the upper reach of the Semenyih River, Malaysia. Microplastics were found in all 160 samples, with mean concentrations of 3.12 ± 2.49 particles/L in river water and 6027.39 ± 16,585.87 particles/m2 deposited on the surface of riverbed sediments. Fibres were the dominant type of microplastic in all samples, but fragments made up a greater proportion of the material on the bed than in the water. Within-site variability in microplastic abundance was high for both water and bed sediments, and very often greater than between-site variability. Patterns suggest that microplastic accumulation on the bed is spatially variable, and single samples are therefore inadequate for assessing bed contamination levels at a site. Sites with the highest mean concentrations in samples of water were not those with the highest concentrations on the bed, indicating that monitoring based only on water samples may not provide a good picture of either relative or absolute bed contamination levels, nor the risks posed to benthic organisms.
Fulltext Heterologous Expression of a Novel Drug Transporter from the Malaria Parasite Alters Resistance to Quinoline Antimalarials

Tindall SM, Vallières C, Lakhani DH, Islahudin F, Ting KN, Avery SV

Sci Rep, 2018 02 06;8(1):2464.
PMID: 29410428 DOI: 10.1038/s41598-018-20816-0

Antimalarial drug resistance hampers effective malaria treatment. Critical SNPs in a particular, putative amino acid transporter were recently linked to chloroquine (CQ) resistance in malaria parasites. Here, we show that this conserved protein (PF3D7_0629500 in Plasmodium falciparum; AAT1 in P. chabaudi) is a structural homologue of the yeast amino acid transporter Tat2p, which is known to mediate quinine uptake and toxicity. Heterologous expression of PF3D7_0629500 in yeast produced CQ hypersensitivity, coincident with increased CQ uptake. PF3D7_0629500-expressing cultures were also sensitized to related antimalarials; amodiaquine, mefloquine and particularly quinine. Drug sensitivity was reversed by introducing a SNP linked to CQ resistance in the parasite. Like Tat2p, PF3D7_0629500-dependent quinine hypersensitivity was suppressible with tryptophan, consistent with a common transport mechanism. A four-fold increase in quinine uptake by PF3D7_0629500 expressing cells was abolished by the resistance SNP. The parasite protein localised primarily to the yeast plasma membrane. Its expression varied between cells and this heterogeneity was used to show that high-expressing cell subpopulations were the most drug sensitive. The results reveal that the PF3D7_0629500 protein can determine the level of sensitivity to several major quinine-related antimalarials through an amino acid-inhibitable drug transport function. The potential clinical relevance is discussed.
Cis-9, Trans-11 Conjugated Linoleic Acid Reduces Phosphoenolpyruvate Carboxykinase Expression and Hepatic Glucose Production in HepG2 Cells

Chai BK, Al-Shagga M, Pan Y, Then SM, Ting KN, Loh HS, et al.

Lipids, 2019 06;54(6-7):369-379.
PMID: 31124166 DOI: 10.1002/lipd.12154

Dysregulated hepatic gluconeogenesis is a hallmark of insulin resistance and type 2 diabetes mellitus (T2DM). Although existing drugs have been proven to improve gluconeogenesis, achieving this objective with functional food is of interest, especially using conjugated linoleic acid (CLA) found in dairy products. Both cis-9, trans-11 (c9,t11) and trans-10, cis-12 (t10,c12) isomers of CLA were tested in human (HepG2) and rat (H4IIE) hepatocytes for their potential effects on gluconeogenesis. The hepatocytes exposed for 24 h with 20 μM of c9,t11-CLA had attenuated the gluconeogenesis in both HepG2 and H4IIE by 62.5% and 80.1%, respectively. In contrast, t10,c12-CLA had no effect. Of note, in HepG2 cells, the exposure of c9,t11-CLA decreased the transcription of gluconeogenic enzymes, cytosolic phosphoenolpyruvate carboxykinase (PCK1) by 87.7%, and glucose-6-phosphatase catalytic subunit (G6PC) by 38.0%, while t10,c12-CLA increased the expression of G6PC, suggesting the isomer-specific effects of CLA on hepatic glucose production. In HepG2, the peroxisome proliferator-activated receptor (PPAR) agonist, rosiglitazone, reduced the glucose production by 72.9%. However, co-administration of c9,t11-CLA and rosiglitazone neither exacerbated nor attenuated the efficacy of rosiglitazone to inhibit glucose production; meanwhile, t10,c12-CLA abrogated the efficacy of rosiglitazone. Paradoxically, PPARγ antagonist GW 9662 also led to 70.2% reduction of glucose production and near undetectable PCK1 expression by abrogating CLA actions. Together, while the precise mechanisms by which CLA isomers modulate hepatic gluconeogenesis directly or via PPAR warrant further investigation, our findings establish that c9,t11-CLA suppresses gluconeogenesis by decreasing PEPCK on hepatocytes.
Fulltext Virucidal activity of Garcinia parvifolia leaf extracts in animal cell culture

Adnan A, Allaudin ZN, Hani H, Loh HS, Khoo TJ, Ting KN, et al.

BMC Complement Altern Med, 2019 Jul 10;19(1):169.
PMID: 31291936 DOI: 10.1186/s12906-019-2586-5

BACKGROUND: Garcinia species contain bioactive compounds such as flavonoids, xanthones, triterpernoids, and benzophenones with antibacterial, antifungal, anti-inflammatory, and antioxidant activities. In addition, many of these compounds show interesting biological properties such as anti-human immunodeficiency virus activity. Garcinia parvifolia is used in traditional medicine. Currently, the antiviral activity of G. parvifolia is not known.
METHODS: This study was conducted to determine the effects of ethyl acetate (45 L Ea), ethanol (45 L Et), and hexane (45 L H) leaf extracts of G. parvifolia on the infectivity of pseudorabies virus (PrV) in Vero cells. The antiviral effects of the extracts were determined by cytopathic effect (CPE), inhibition, attachment, and virucidal assays.
RESULTS: The 50% cytotoxicity concentration (CC50) values obtained were 237.5, 555.0, and
Concise synthesis of the vasorelaxant alkaloids schwarzinicines A and B

Lee FK, Krishnan P, Muhamad A, Low YY, Kam TS, Ting KN, et al.

Nat Prod Res, 2021 Mar 22.
PMID: 33749454 DOI: 10.1080/14786419.2021.1903005

A concise synthesis of the 1,4-diarylbutanoid-phenethylamine alkaloids, schwarzinicines A (1) and B (2), recently isolated from Ficus schwarzii, is reported. Key steps include a Claisen condensation to assemble the 1,4-diaryl-2-butanone intermediate, followed by a reductive amination to furnish the core skeleton of the target compounds. The overall synthetic yields of 1 and 2 were 9.1% and 3.5%, respectively. Synthetic (-)-1, (+)-1 and (±)-1 exhibited comparable vasorelaxation as natural schwarzinicine A on rat isolated aortic rings, suggesting that the observed vasorelaxant effects were not influenced by the chirality at C-2.
Fulltext Reversal of ampicillin resistance in MRSA via inhibition of penicillin-binding protein 2a by Acalypha wilkesiana

Santiago C, Pang EL, Lim KH, Loh HS, Ting KN

Biomed Res Int, 2014;2014:965348.
PMID: 25101303 DOI: 10.1155/2014/965348

The inhibitory activity of a semipure fraction from the plant, Acalypha wilkesiana assigned as 9EA-FC-B, alone and in combination with ampicillin, was studied against methicillin-resistant Staphylococcus aureus (MRSA). In addition, effects of the combination treatment on PBP2a expression were investigated. Microdilution assay was used to determine the minimal inhibitory concentrations (MIC). Synergistic effects of 9EA-FC-B with ampicillin were determined using the fractional inhibitory concentration (FIC) index and kinetic growth curve assay. Western blot experiments were carried out to study the PBP2a expression in treated MRSA cultures. The results showed a synergistic effect between ampicillin and 9EA-FC-B treatment with the lowest FIC index of 0.19 (synergism ≤ 0.5). The presence of 9EA-FC-B reduced the MIC of ampicillin from 50 to 1.56 μg mL(-1). When ampicillin and 9EA-FC-B were combined at subinhibitory level, the kinetic growth curves were suppressed. The antibacterial effect of 9EA-FC-B and ampicillin was shown to be synergistic. The synergism is due the ability of 9EA-FC-B to suppress the activity of PBP2a, thus restoring the susceptibility of MRSA to ampicillin. Corilagin was postulated to be the constituent responsible for the synergistic activity showed by 9EA-FC-B.
Fulltext Crude Ethanol Extract of Pithecellobium ellipticum as a Potential Lipid-Lowering Treatment for Hypercholesterolaemia

Wong JP, Wijaya S, Ting KN, Wiart C, Mustafa K, Shipton F, et al.

Evid Based Complement Alternat Med, 2014;2014:492703.
PMID: 24839451 DOI: 10.1155/2014/492703

If left untreated, hypercholesterolaemia can lead to atherosclerosis, given time. Plants from the Fabaceae family have shown the ability to significantly suppress atherosclerosis progression. We selected four extracts from Pithecellobium ellipticum, from the Fabaceae family, to be screened in a 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMG-CoA reductase) assay. The ethanol extract, at a concentration of 500 μ g/mL, exhibited superior inhibition properties over the other extracts by demonstrating 80.9% inhibition, while 0.223 μ g/mL of pravastatin (control) showed 78.1% inhibition towards enzymatic activity. These findings led to the fractionation of the ethanol extract using ethyl acetate : methanol (95 : 5), gradually increasing polarity and produced seven fractions (1A to 7A). Fraction 7A at 150 μ g/mL emerged as being the most promising bioactive fraction with 78.7% inhibition. FRAP, beta carotene, and DPPH assays supported the findings from the ethanol extract as it exhibited good overall antioxidant activity. The antioxidant properties have been said to reduce free radicals that are able to oxidize lipoproteins which are the cause of atherosclerosis. Phytochemical screenings revealed the presence of terpenoid, steroid, flavonoid, and phenolic compounds as the responsible group of compound(s), working individually or synergistically, within the extract to prevent binding of HMG-CoA to HMG-CoA reductase.
Optimal methods for evaluating antimicrobial activities from plant extracts

Othman M, Loh HS, Wiart C, Khoo TJ, Lim KH, Ting KN

J Microbiol Methods, 2011 Feb;84(2):161-6.
PMID: 21094190 DOI: 10.1016/j.mimet.2010.11.008

The search for antimicrobial agents from plants has been a growing interest in the last few decades. However, results generated from many of these studies cannot be directly compared due to the absence of standardization in particular antimicrobial methods employed. The need for established methods with consistent results for the evaluation of antimicrobial activities from plant extracts has been proposed by many researchers. Nevertheless, there are still many studies reported in the literature describing different methodologies. The aim of this study was to find optimal methods to give consistent quantitative antimicrobial results for studying plant extracts. Three different agar-based assays (pour plate disc diffusion (PPDD), streak plate disc diffusion (SPDD) and well-in agar (WA)) and one broth-based (turbidometric (TB)) assay were used in this study. Extracts from two plant species (Duabanga grandiflora and Acalypha wilkesiana) were tested on two bacterial species, namely Escherichia coli and Staphylococcus aureus. Amongst the agar-based assays, PPDD produced the most reproducible results. TB was able to show the inhibitory effects of the test samples on the growth kinetic of the bacteria including plant extracts with low polarity. We propose that both agar- (i.e PPDD) and broth-based assays should be employed when assessing the antimicrobial activity of plant crude extracts.

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