MyMedR

Interaction of Aqueous Solutions of a Surface Active Copper(II) Complex with Several Common Surfactants

Lim YY, Lim KH

J Colloid Interface Sci, 1997 Dec 01;196(1):116-9.

Micellar properties of binary mixed surfactants of a surface active mixed copper(II) chelate, [Cu(C12-tmed)(acac)Cl] (where C12-tmed is N,N,N'-trimethyl-N'-dodecylethylenediamine) with three common surfactants, viz. sodium dodecyl sulfate (SDS), cetyltrimethylammonium bromide (CTAB), and octaethylene glycol monododecyl ether (C12E8), were investigated by surface tensiometry, ESR, and UV-visible absorption techniques. The surface tension data were treated with Rubingh's method for mixed micelle formation and Rosen's method for mixed monolayer formation at the aqueous solution/air interface. It was found that in the mixed micelle there is strong attractive interaction between cationic copper surfactant and anonic dodecyl sulfate while there is almost ideal mixing between copper surfactant and CTAB and C12E8. From the ESR and UV-visible studies, a mixed block-type arrangement of head groups is proposed. Copyright 1997 Academic Press. Copyright 1997Academic Press

Effects of Aminocarboxylate Ligands of Surface Active Copper(II) Complexes on the Hydrolysis of p-Nitrophenyldiphenylphosphate

Ship CP, Zainudin A, Lim YY

J Colloid Interface Sci, 1999 Sep 1;217(1):211-213.

PMID: 10441432

The rate of hydrolysis of p-nitrophenyldiphenylphosphate in the presence of micellized [Cu(C(12)tmed)(L)](+) where C(12)tmed is N,N,N'-trimethyl-N'-dodecylethylenediamine and L is the anion part of the amino acid has been investigated. It was found that the observed maximum rate obtained under the excess surfactant over the substrate condition depends very much on the ability of the amino acid ligand to form a mixed-chelate complex with the [Cu(C(12)tmed)](2+) moiety. In general, a chelating ligand with better coordination ability gives a slower rate because of the reduction in the supply of Cu-OH nucleophile in the micelle. Copyright 1999 Academic Press.

Effects of aminoacids on the autooxidation of 3,5-di-tert-butylcatechol in the presence of surface-active copper(II) complexes

Lim YY, Liew LP

J Colloid Interface Sci, 2002 Nov 15;255(2):425-7.

PMID: 12505092

The rate of autooxidation of 3,5-di-tert-butylcatechol (3,5-DTBC) in the presence of micelles formed from mixing equal concentrations of [Cu(C(12)-tmed)Br(2)] (where C(12)-tmed is N,N,N'-trimethyl-N'-dodecylethylenediamine) and several amino acids has been investigated. It was found that the rate in air-saturated solution is very much dependent on pH, which affects the availability of copper(II) coordination site for the catechol and the degree of micellization. At a given pH, the rates in [Cu(C(12)-tmed)Br(2)] micellar media are greatly enhanced in the presence sodium halide.

Antioxidative, tyrosinase inhibiting and antibacterial activities of leaf extracts from medicinal ferns

Lai HY, Lim YY, Tan SP

Biosci Biotechnol Biochem, 2009 Jun;73(6):1362-6.

PMID: 19502733

Leaf extracts of five medicinal ferns, Acrostichum aureum L. (Pteridaceae), Asplenium nidus L. (Aspleniaceae), Blechnum orientale L. (Blechnaceae), Cibotium barometz (L.) J. Sm. (Cyatheaceae) and Dicranopteris linearis (Burm.) underwood var. linearis (Gleicheniaceae), were investigated for their total phenolic content (TPC), and antioxidative, tyrosinase inhibiting and antibacterial activities. The antioxidative activity was measured by assays for radical scavenging against 1,1-diphenyl-2-picrylhydrazyl (DPPH), ferric ion reducing power (FRP), beta-carotene bleaching (BCB) and ferrous ion chelating (FIC). The results revealed B. orientale to possess the highest amount of total polyphenols and strongest potential as a natural antioxidative, tyrosinase inhibiting and antibacterial agent as demonstrated by its strong activities in all related bioassays. The other ferns with antioxidative potential were C. barometz and D. linearis. Except for A. aureum, all ferns showed antibacterial activity which may justify their usage in traditional medicines.

A method for cross-cultural adaptation of a verbal memory assessment

Lim YY, Prang KH, Cysique L, Pietrzak RH, Snyder PJ, Maruff P

Behav Res Methods, 2009 Nov;41(4):1190-200.

PMID: 19897828 DOI: 10.3758/BRM.41.4.1190

Verbal memory tests-although important to the neuropsychological assessment of memory-are biased to many cultures. In the present article, we highlighted the limitations associated with the direct translation of tests and word matching, as well as the lack of ecological validity and cultural appropriateness when tests developed in one culture are used in another. To overcome these limitations, a verbal memory paradigm was developed that framed the memory assessment with a shopping-list format, but that developed culturally specific stimuli for the different language groups. The aim of the present study was to determine the equivalence of this shopping list memory test in different cultural and language groups. Eighty-three adults from English-, French-, Malay-, and Chinese-speaking cultures participated in four experiments. The results of all the experiments indicated that performance of verbal list learning is equivalent, irrespective of the language used. These results support the use of this methodology for minimizing cross-cultural test bias, and have important implications for testing culturally and linguistically diverse individuals.

Fulltext Factors associated with poor academic achievement among urban primary school children in Malaysia

Ong LC, Chandran V, Lim YY, Chen AH, Poh BK

Singapore Med J, 2010 Mar;51(3):247-52.

PMID: 20428748

The aim of this study was to identify factors associated with poor academic achievement during the early school years.

Fulltext Blechnum orientale Linn - a fern with potential as antioxidant, anticancer and antibacterial agent

Lai HY, Lim YY, Kim KH

BMC Complement Altern Med, 2010;10:15.

PMID: 20429956 DOI: 10.1186/1472-6882-10-15

Blechnum orientale Linn. (Blechnaceae) is used ethnomedicinally for the treatment of various skin diseases, stomach pain, urinary bladder complaints and sterilization of women. The aim of the study was to evaluate antioxidant, anticancer and antibacterial activity of five solvent fractions obtained from the methanol extract of the leaves of Blechnum orientale Linn.

Fulltext Antiproliferative and phytochemical analyses of leaf extracts of ten Apocynaceae species

Wong SK, Lim YY, Abdullah NR, Nordin FJ

Pharmacognosy Res, 2011 Apr;3(2):100-6.

PMID: 21772753 DOI: 10.4103/0974-8490.81957

The anticancer properties of Apocynaceae species are well known in barks and roots but less so in leaves.

Relating vision status to academic achievement among year-2 school children in Malaysia

Chen AH, Bleything W, Lim YY

Optometry, 2011 May;82(5):267-73.

PMID: 21524597 DOI: 10.1016/j.optm.2011.02.004

Vision affects daily activities, but of particular importance is the impact upon the learning process. Many studies have been conducted to establish the relationship between vision problems and academic performance. The results are varied, however, and suggest additional research is needed with particular care given to study design.

Fulltext Standardised herbal extract of chlorogenic acid from leaves of Etlingera elatior (Zingiberaceae)

Chan EW, Lim YY, Tan SP

Pharmacognosy Res, 2011 Jul;3(3):178-84.

PMID: 22022166 DOI: 10.4103/0974-8490.85003

Chlorogenic acid (CGA) or 5-caffeoylquinic acid, was found to be the dominant phenolic compound in leaves of Etlingera elatior (Zingiberaceae). The CGA content of E. elatior leaves was significantly higher than flowers of Lonicera japonica (honeysuckle), the commercial source. In this study, a protocol to produce a standardised herbal CGA extract from leaves of E. elatior using column chromatography was developed.

Fulltext Potential dermal wound healing agent in Blechnum orientale Linn

Lai HY, Lim YY, Kim KH

BMC Complement Altern Med, 2011 Aug 12;11:62.

PMID: 21835039 DOI: 10.1186/1472-6882-11-62

BACKGROUND: Blechnum orientale Linn. (Blechnaceae) is used ethnomedicinally to treat wounds, boils, blisters or abscesses and sores, stomach pain and urinary bladder complaints. The aim of the study was to validate the ethnotherapeutic claim and to evaluate the effects of B. orientale water extract on wound healing activity.

METHODS: Water extract of B. orientale was used. Excision wound healing activity was examined on Sprague-Dawley rats, dressed with 1% and 2% of the water extract. Control groups were dressed with the base cream (vehicle group, negative control) and 10% povidone-iodine (positive control) respectively. Healing was assessed based on contraction of wound size, mean epithelisation time, hydroxyproline content and histopathological examinations. Statistical analyses were performed using one way ANOVA followed by Tukey HSD test.

RESULTS: Wound healing study revealed significant reduction in wound size and mean epithelisation time, and higher collagen synthesis in the 2% extract-treated group compared to the vehicle group. These findings were supported by histolopathological examinations of healed wound sections which showed greater tissue regeneration, more fibroblasts and angiogenesis in the 2% extract-treated group.

CONCLUSIONS: The ethnotherapeutic use of this fern is validated. The water extract of B. orientale is a potential candidate for the treatment of dermal wounds. Synergistic effects of both strong antioxidant and antibacterial activities in the extract are deduced to have accelerated the wound repair at the proliferative phase of the healing process.

Fulltext Assessment of phytochemical content, polyphenolic composition, antioxidant and antibacterial activities of Leguminosae medicinal plants in Peninsular Malaysia

Chew YL, Chan EW, Tan PL, Lim YY, Stanslas J, Goh JK

BMC Complement Altern Med, 2011;11:12.

PMID: 21306653 DOI: 10.1186/1472-6882-11-12

Many medicinal plants from Leguminosae family can be found easily in Malaysia. These plants have been used as traditional medicines by local ethnic groups, where they are prepared as decoction, pastes for wound infections, and some have been eaten as salad. This paper focused on the assessment of antioxidant potential, antibacterial activity and classes of phytochemicals of nine plants from the Leguminosae family.

Fulltext Assessment of antiproliferative and antiplasmodial activities of five selected Apocynaceae species

Wong SK, Lim YY, Abdullah NR, Nordin FJ

BMC Complement Altern Med, 2011;11:3.

PMID: 21232161 DOI: 10.1186/1472-6882-11-3

Studies have shown that the barks and roots of some Apocynaceae species have anticancer and antimalarial properties. In this study, leaf extracts of five selected species of Apocynaceae used in traditional medicine (Alstonia angustiloba, Calotropis gigantea, Dyera costulata, Kopsia fruticosa and Vallaris glabra) were assessed for antiproliferative (APF) and antiplasmodial (APM) activities, and analysed for total alkaloid content (TAC), total phenolic content (TPC) and radical-scavenging activity (RSA). As V. glabra leaf extracts showed wide spectrum APF and APM activities, they were further screened for saponins, tannins, cardenolides and terpenoids.

Fulltext Caffeoylquinic acids in leaves of selected Apocynaceae species: Their isolation and content

Wong SK, Lim YY, Ling SK, Chan EW

Pharmacognosy Res, 2014 Jan;6(1):67-72.

PMID: 24497746 DOI: 10.4103/0974-8490.122921

Three compounds isolated from the methanol (MeOH) leaf extract of Vallaris glabra (Apocynaceae) were those of caffeoylquinic acids (CQAs). This prompted a quantitative analysis of their contents in leaves of V. glabra in comparison with those of five other Apocynaceae species (Alstonia angustiloba, Dyera costulata, Kopsia fruticosa, Nerium oleander, and Plumeria obtusa), including flowers of Lonicera japonica (Japanese honeysuckle), the commercial source of chlorogenic acid (CGA).

Fulltext Antiproliferative activity of Vallaris glabra Kuntze (Apocynaceae)

Wong SK, Lim YY, Ling SK, Chiang Chan EW

Pharmacogn Mag, 2014 Apr;10(Suppl 2):S232-9.

PMID: 24991097 DOI: 10.4103/0973-1296.133238

Our earlier study on the antiproliferative (APF) activity of leaf extracts of ten Apocynaceae species showed that leaves of Vallaris glabra possessed strong and broad-spectrum properties.

Fulltext Antioxidant Content, Antioxidant Activity, and Antibacterial Activity of Five Plants from the Commelinaceae Family

Tan JB, Yap WJ, Tan SY, Lim YY, Lee SM

Antioxidants (Basel), 2014 Nov 17;3(4):758-69.

PMID: 26785239 DOI: 10.3390/antiox3040758

Commelinaceae is a family of herbaceous flowering plants with many species used in ethnobotany, particularly in South America. However, thus far reports of their bioactivity are few and far between. The primary aim of this study was to quantify the antioxidant and antibacterial activity of five Commelinaceae methanolic leaf extracts. The antioxidant content was evaluated by the total phenolic content (TPC), total tannin content (TTC), and total flavonoid content (TFC) assays. The antioxidant activities measured were DPPH free radical scavenging (FRS), ferric reducing power (FRP), and ferrous ion chelating (FIC); of the five plants, the methanolic leaf extract of Tradescantia zebrina showed the highest antioxidant content and activity, and exhibited antibacterial activity against six species of Gram-positive and two species of Gram-negative bacteria in a range of 5-10 mg/mL based on the broth microdilution method.

Bioactivity-guided isolation of anticancer agents from Bauhinia kockiana Korth

Chew YL, Lim YY, Stanslas J, Ee GC, Goh JK

Afr J Tradit Complement Altern Med, 2014;11(3):291-9.

PMID: 25371595

BACKGROUND: Flowers of Bauhinia kockiana were investigated for their anticancer properties.

METHODS: Gallic acid (1), and methyl gallate (2), were isolated via bioassay-directed isolation, and they exhibited anticancer properties towards several cancer cell lines, examined using MTT cell viability assay. Pyrogallol (3) was examined against the same cancer cell lines to deduce the bioactive functional group of the phenolic compounds.

RESULTS: The results showed that the phenolic compounds could exhibit moderate to weak cytotoxicity towards certain cell lines (GI50 30 - 86 µM), but were inactive towards DU145 prostate cancer cell (GI50 > 100 µM).

CONCLUSION: It was observed that pyrogallol moiety was one of the essential functional structures of the phenolic compounds in exhibiting anticancer activity. Also, the carboxyl group of compound 1 was also important in anticancer activity. Examination of the PC-3 cells treated with compound 1 using fluorescence microscopy showed that PC-3 cells were killed by apoptosis.

Fulltext Inhibition of euchromatic histone methyltransferase 1 and 2 sensitizes chronic myeloid leukemia cells to interferon treatment

Loh SW, Ng WL, Yeo KS, Lim YY, Ea CK

PLoS One, 2014;9(7):e103915.

PMID: 25079219 DOI: 10.1371/journal.pone.0103915

H3K9 methylation is one of the essential histone post-translational modifications for heterochromatin formation and transcriptional repression. Recently, several studies have demonstrated that H3K9 methylation negatively regulates the type I interferon response.

Analysis of interleukin-10 promoter single nucleotide polymorphisms and risk of non-Hodgkin lymphoma in a Malaysian population

Lim YY, Chin YM, Tai MC, Fani S, Chang KM, Ong TC, et al.

Leuk Lymphoma, 2015 Jan;56(1):163-8.

PMID: 24684230 DOI: 10.3109/10428194.2014.907895

We evaluated the association of two IL10 single nucleotide polymorphisms (SNPs) (rs1800896 and rs1800871) with non-Hodgkin lymphoma (NHL) risk in the three major races of the Malaysian population (Malay, Chinese and Indian; 317 cases and 330 controls). Our initial screening demonstrated that rs1800871 but not rs1800896 was significantly associated with increased NHL risk in Malays (pMalay-Rec = 0.007) and Chinese only (pChinese-Rec = 0.039). Subsequent combined analysis of the Malay and Chinese revealed significant association of rs1800871 with all (ALL) NHL subtypes (pMeta-ALL-NHL-Rec = 0.001), ALL B-cell subtypes (pMeta-ALL-B-cell-Rec = 0.003), diffuse large B-cell lymphoma (DLBCL) subtype (pMeta-DLBCL-Rec = 0.002) and ALL T-cell subtypes (pMeta-ALL-T-cell-Rec = 0.031). SNP rs1800896 showed increased risk only in follicular lymphoma (FL) (pMeta-FL-Dom = 0.0004). We also detected a male-specific association of rs1800871 with increased NHL risk (pMeta-Male-ALL-NHL-Rec = 0.006) in the combined analysis. To our knowledge, this is the first report on the association of IL10 promoter SNPs with NHL susceptibility in the three major races of Malaysia.

Critical analysis of current methods for assessing the in vitro antioxidant and antibacterial activity of plant extracts

Tan JB, Lim YY

Food Chem, 2015 Apr 1;172:814-22.

PMID: 25442625 DOI: 10.1016/j.foodchem.2014.09.141

Natural product research is an active branch of science, driven by the increased value placed on individual health and well-being. Many naturally-occurring phytochemicals in plants, fruits and vegetables have been reported to exhibit antioxidant and antibacterial activity; often touted as being beneficial for human health. In vitro screening is a common practice in many research laboratories as a means of rapidly assessing these properties. However, the methods used by many are not necessarily optimal; a result of poor standardization, redundant assays and/or outdated methodology. This review primarily aims to give a better understanding in the selection of in vitro assays, with emphasis placed on some common assays such as the total phenolic content assay, free radical scavenging activity, disc-diffusion and broth microdilution. This includes a discussion on the reasons for choosing a particular assay, its strengths and weaknesses, ways to improve the accuracy of results and alternative assays.

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