Displaying publications 61 - 80 of 426 in total

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  1. Use of UV-vis-NIR spectroscopy to monitor label-free interaction between molecular recognition elements and erythropoietin on a gold-coated polycarbonate platform
    Citartan M, Gopinath SC, Tominaga J, Chen Y, Tang TH
    Talanta, 2014 Aug;126:103-9.
    PMID: 24881539 DOI: 10.1016/j.talanta.2014.03.043
    Label-free-based detection is pivotal for real-time monitoring of biomolecular interactions and to eliminate the need for labeling with tags that can occupy important binding sites of biomolecules. One simplest form of label-free-based detection is ultraviolet-visible-near-infrared (UV-vis-NIR) spectroscopy, which measure changes in reflectivity as a means to monitor immobilization and interaction of biomolecules with their corresponding partners. In biosensor development, the platform used for the biomolecular interaction should be suitable for different molecular recognition elements. In this study, gold (Au)-coated polycarbonate was used as a platform and as a proof-of-concept, erythropoietin (EPO), a doping substance widely abused by the athletes was used as the target. The interaction of EPO with its corresponding molecular recognition elements (anti-EPO monoclonal antibody and anti-EPO DNA aptamer) is monitored by UV-vis-NIR spectroscopy. Prior to this, to show that UV-vis-NIR spectroscopy is a suitable method for measuring biomolecular interaction, the interaction between biotin and streptavidin was demonstrated via this strategy and reflectivity of this interaction decreased by 25%. Subsequent to this, interaction of the EPO with anti-EPO monoclonal antibody and anti-EPO DNA aptamer resulted in the decrease of reflectivity by 5% and 10%, respectively. The results indicated that Au-coated polycarbonate could be an ideal biosensor platform for monitoring biomolecular interactions using UV-vis-NIR spectroscopy. A smaller version of the Au-coated polycarbonate substrates can be derived from the recent set-up, to be applied towards detecting EPO abuse among atheletes.
  2. Current aspects in immunosensors
    Gopinath SC, Tang TH, Citartan M, Chen Y, Lakshmipriya T
    Biosens Bioelectron, 2014 Jul 15;57:292-302.
    PMID: 24607580 DOI: 10.1016/j.bios.2014.02.029
    Sensing applications can be used to report biomolecular interactions in order to elucidate the functions of molecules. The use of an analyte and a ligand is a common set-up in sensor development. For several decades, antibodies have been considered to be potential analytes or ligands for development of so-called "immunosensors." In an immunosensor, formation of the complex between antibody and antigen transduces the signal, which is measurable in various ways (e.g., both labeled and label-free based detection). Success of an immunosensor depends on various factors, including surface functionalization, antibody orientation, density of the antibody on the sensor platform, and configuration of the immunosensor. Careful optimization of these factors can generate clear-cut results for any immunosensor. Herein, current aspects, involved in the generated immunosensors, are discussed.
  3. Detection of host-specific immunogenic proteins in the saliva of patients with oral squamous cell carcinoma
    Mu AK, Chan YS, Kang SS, Azman SN, Zain RB, Chai WL, et al.
    J Immunoassay Immunochem, 2014;35(2):183-93.
    PMID: 24295181 DOI: 10.1080/15321819.2013.836535
    The main purpose of this article is to develop a new and reliable saliva-based clinical diagnostic method for the early detection of oral squamous cell carcinoma (OSCC). This study used an immunoproteomic approach which allowed the detection of immunogenic host proteins in patients' samples using pooled human antibodies. In an attempt to investigate potential biomarkers of OSCC, two-dimensional electrophoresis (2-DE) followed by immunoblotting of saliva from patients and controls were compared. The protein spots of interest were analyzed using 2-DE image analyzer and subsequently subjected to MALDI-TOF/TOF and then matched against NCBI database. The result showed that four protein clusters, namely Human Pancreatic Alpha-amylase (HPA), Human Salivary Amylase (sAA), keratin-10 (K-10), and Ga Module Complexed with Human Serum Albumin (GA-HSA), had exhibited immunoreactivity in western blot. The results are suggestive of the potential use of the differentially expressed saliva protein as tumor biomarkers for the detection of OSCC. However, further studies are recommended to validate this finding.
  4. Fulltext Antioxidant activity of methanol extracts of different parts of Lantana camara
    Mahdi-Pour B, Jothy SL, Latha LY, Chen Y, Sasidharan S
    Asian Pac J Trop Biomed, 2012 Dec;2(12):960-5.
    PMID: 23593576 DOI: 10.1016/S2221-1691(13)60007-6
    To investigate the antioxidant activity of methanolic extracts of Lantana camara (L. camara) various parts and the determination of their total phenolics content.
  5. In vitro antioxidant activity potential of lantadene A, a pentacyclic triterpenoid of Lantana plants
    Grace-Lynn C, Darah I, Chen Y, Latha LY, Jothy SL, Sasidharan S
    Molecules, 2012 Sep 19;17(9):11185-98.
    PMID: 22992785
    Lantadenes are pentacyclic triterpenoids present in the leaves of the plant Lantana camara. In the present study, in vitro antioxidant activity and free radical scavenging capacity of lantadene A was evaluated using established in vitro models such as ferric reducing antioxidant power (FRAP), 2,2-diphenyl-1-picryl-hydrazyl (DPPH•), hydroxyl radical (OH•), nitric oxide radical (NO•), superoxide anion scavenging activities and ferrous ion chelating assay. Interestingly, lantadene A showed considerable in vitro antioxidant, free radical scavenging capacity activities in a dose dependant manner when compared with the standard antioxidant in nitric oxide scavenging, superoxide anion radical scavenging and ferrous ion chelating assay. These findings show that the lantadene A possesses antioxidant activity with different mechanism of actions towards the different free radicals tested. Since lantadene A is a very popular drug in modern medicine, it is a promising candidate for use as an antioxidant and hepatoprotective agent.
  6. Fulltext Bioassay-directed isolation of active compounds with antiyeast activity from a Cassia fistula seed extract
    Jothy SL, Zakaria Z, Chen Y, Lau YL, Latha LY, Shin LN, et al.
    Molecules, 2011 Sep 05;16(9):7583-92.
    PMID: 21894090 DOI: 10.3390/molecules16097583
    BACKGROUND AND OBJECTIVE: Cassia fistula L belongs to the family Leguminosae, and it is one of the most popular herbal products in tropical countries. C. fistula seeds have been used as a herbal medicine and have pharmacological activity which includes anti-bacterial, anti-fungal, and antioxidant properties. The goal of this study was to identify compounds from C. fistula seeds which are responsible for anti-Candida albicans activity using bioassay-directed isolation.

    RESULTS: The preliminary phytochemical screening of the plant seed revealed the presence of anthraquinones, flavonoids, saponins, tannins and terpenoids. The isolation of active compounds was carried out in four steps: multiple extractions, fractionation using column chromatography and purification using preparative thin-layer chromatography (TLC) and liquid chromatography/mass spectrometry (LC/MS). The structure of separated compounds was determined on the basis of mass spectrometry data. One compound was identified is roseanone.

    CONCLUSIONS: The MS analysis on the active fraction from seed extract of C. fistula confirmed the presence of roseanone with antiyeast activity.

  7. Fulltext Acute oral toxicity of methanolic seed extract of Cassia fistula in mice
    Jothy SL, Zakaria Z, Chen Y, Lau YL, Latha LY, Sasidharan S
    Molecules, 2011 Jun 23;16(6):5268-82.
    PMID: 21701437 DOI: 10.3390/molecules16065268
    BACKGROUND AND OBJECTIVE: Cassia fistula is widely used in traditional medicine to treat various types of ailments. The evaluation of toxic properties of C. fistula is crucial when considering public health protection because exposure to plant extracts can result in undesirable effects on consumers. Hence, in this study the acute oral toxicity of C. fistula seeds extract was investigated in mice.

    RESULTS: Oral administration of crude extract at the highest dose of 5000 mg/kg resulted in no mortalities or evidence of adverse effects, implying that C. fistula in nontoxic. Throughout 14 days of the treatment no changes in behavioural pattern, clinical sign and body weight of mice in both control and treatment groups. Also there were no any significant elevations observed in the biochemical analysis of the blood serum. Further, histopathological examination revealed normal architecture and no significant adverse effects observed on the kidney, heart, liver, lung and spleen.

    CONCLUSIONS: Overall, the results suggest that, the oral administration of C. fistula methanolic seeds extract did not produce any significant toxic effect in mice. Hence, the extract can be utilized for pharmaceutical formulations.

  8. Fulltext Hepatoprotective potential of Clitoria ternatea leaf extract against paracetamol induced damage in mice
    Nithianantham K, Shyamala M, Chen Y, Latha LY, Jothy SL, Sasidharan S
    Molecules, 2011 Dec 06;16(12):10134-45.
    PMID: 22146374 DOI: 10.3390/molecules161210134
    BACKGROUND AND AIM: Clitoria ternatea, a medicinal herb native to tropical equatorial Asia, is commonly used in folk medicine to treat various diseases. The aim of the present study is to evaluate the hepatoprotective and antioxidant activity of C. ternatea against experimentally induced liver injury.

    METHODS: The antioxidant property of methanolic extract (ME) of C. ternatea leaf was investigated by employing an established in vitro antioxidant assay. The hepatoprotective effect against paracetamol-induced liver toxicity in mice of ME of C. ternatea leaf was also studied. Activity was measured by monitoring the levels of aspartate aminotransferase (AST), alanine aminotransferase (ALT) and billirubin along with histopathological analysis.

    RESULTS: The amount of total phenolics and flavonoids were estimated to be 358.99 ± 6.21 mg/g gallic acid equivalent and 123.75 ± 2.84 mg/g catechin equivalent, respectively. The antioxidant activity of C. ternatea leaf extract was 67.85% at a concentration of 1 mg/mL and was also concentration dependant, with an IC(50) value of 420.00 µg/mL. The results of the paracetamol-induced liver toxicity experiments showed that mice treated with the ME of C. ternatea leaf (200 mg/kg) showed a significant decrease in ALT, AST, and bilirubin levels, which were all elevated in the paracetamol group (p < 0.01). C. ternatea leaf extract therapy also protective effects against histopathological alterations. Histological studies supported the biochemical findings and a maximum improvement in the histoarchitecture was seen.

    CONCLUSIONS: The current study confirmed the hepatoprotective effect of C. ternatea leaf extract against the model hepatotoxicant paracetamol. The hepatoprotective action is likely related to its potent antioxidative activity.

  9. A phone-counseling smoking-cessation intervention for male Chinese restaurant workers
    Burton D, Zeng XX, Chiu CH, Sun J, Sze NL, Chen Y, et al.
    J Community Health, 2010 Dec;35(6):579-85.
    PMID: 20186474 DOI: 10.1007/s10900-010-9244-7
    We sought to develop a smoking-cessation intervention for male Chinese restaurant workers in New York City that required no seeking out by participants; provided support over a relatively long period of time; and was responsive to participants' cultural backgrounds and daily lives. The resulting intervention consisted of a minimum of 9 proactive phone counseling sessions within a 6-month period for each participant recruited at his worksite. All activities were conducted in Chinese languages. The efficacy of this proactive phone-counseling intervention was assessed in a pretest/posttest design comparing baseline smoking with smoking 6 months after the intervention ended. Of 137 male employees recruited at their restaurants, 101 (median age 40.5) participated in the phone-counseling intervention in 2007-2008, with 75 completing the program with at least 9 counseling calls. We found a linear increase in smoking cessation from 0% at Call 1 to 50.7% at Call 9 for 75 men who completed the program, and we found for all 101 participants a 32.7% intent-to-treat cessation rate for 6 months post-end of program, adjusted to 30.8% by saliva cotinine assessments. The results indicate that combining field outreach with phone counseling over an extended period of time can facilitate smoking cessation for population groups whose environments do not support efforts to quit smoking.
  10. Fulltext Profiling of serum and tissue high abundance acute-phase proteins of patients with epithelial and germ line ovarian carcinoma
    Chen Y, Lim BK, Peh SC, Abdul-Rahman PS, Hashim OH
    Proteome Sci, 2008;6:20.
    PMID: 18637207 DOI: 10.1186/1477-5956-6-20
    Acute-phase response involves the simultaneous altered expression of serum proteins in association to inflammation, infection, injury or malignancy. Studies of the acute-phase response usually involve determination of the levels of individual acute-phase serum proteins. In the present study, the acute-phase response of patients with epithelial (EOCa) and germ-line (GOCa) ovarian carcinoma was investigated using the gel-based proteomic approach, a technique which allowed the simultaneous assessment of the levels of the acute-phase serum high abundance proteins. Data obtained were validated using ELISA and immunostaining of biopsy samples.
  11. Fulltext Evaluation of the hepatoprotective Effects of Lantadene A, a pentacyclic triterpenoid of Lantana plants against acetaminophen-induced liver damage
    Grace-Lynn C, Chen Y, Latha LY, Kanwar JR, Jothy SL, Vijayarathna S, et al.
    Molecules, 2012 Nov 23;17(12):13937-47.
    PMID: 23178309 DOI: 10.3390/molecules171213937
    The aim of the present study was to evaluate the hepatoprotective activity of lantadene A against acetaminophen-induced liver toxicity in mice was studied. Activity was measured by monitoring the levels of aspartate aminotransferase (AST), alanine aminotransferase (ALT), alkaline phosphatase (ALP) and bilirubin, along with histo-pathological analysis. Silymarin was used as positive control. A bimodal pattern of behavioural toxicity was exhibited by the lantadene A-treated group at the beginning of the treatment. However, treatment with lantadene A and silymarin resulted in an increase in the liver weight compared with the acetaminophen treated group. The results of the acetaminophen-induced liver toxicity experiments showed that mice treated with lantadene A (500 mg/kg) showed a significant decrease in the activity of ALT, AST and ALP and the level of bilirubin, which were all elevated in the acetaminophen treated group (p < 0.05). Histological studies supported the biochemical findings and a maximum improvement in the histoarchitecture was seen. The lantadene A-treated group showed remarkable protective effects against histopathological alterations, with comparable results to the silymarin treated group. The current study confirmed the hepatoprotective effects of lantadene A against the model hepatotoxicant acetaminophen, which is likely related to its potent antioxidative activity.
  12. Fulltext Decreased expression of alpha-2-HS glycoprotein in the sera of rats treated with Eurycoma longifolia extract
    Chen Y, Phang WM, Mu AK, Chan CK, Low BS, Sasidharan S, et al.
    Front Pharmacol, 2015;6:211.
    PMID: 26441666 DOI: 10.3389/fphar.2015.00211
    Eurycoma longifolia is a Malaysian native herb that has been widely used as an aphrodisiac and a remedy for andropause. Although the physiological effects of the plant extract were predicted as a result of the alterations in protein expression, the key protein(s) involved in these alterations are still unclear. In the present study, we have investigated the effect of standardized E. longifolia extract on serum protein expression up to 28 days following oral administration in rats. Serum protein profiles were analyzed by 2-dimensional electrophoresis, and altered proteins were identified via mass spectrometry. We observed that alpha-2-HS glycoprotein (AHS) was significantly decreased in the serum of experimentally treated rats compared to pre-treated animals. Moreover, reduction in AHS was confirmed using competitive enzyme-linked immunosorbent assay. AHS expression is known to be associated with insulin resistance and diabetes. Our data indicated that serum AHS was reduced in rats treated with standardized E. longifolia extract, and therefore form a prelude for further investigation into the effects of this natural extract in animal models involving infertility and diabetes.
  13. Radioprotective activity of Polyalthia longifolia standardized extract against X-ray radiation injury in mice
    Jothy SL, Saito T, Kanwar JR, Chen Y, Aziz A, Yin-Hui L, et al.
    Phys Med, 2016 Jan;32(1):150-61.
    PMID: 26526749 DOI: 10.1016/j.ejmp.2015.10.090
    The radioprotective effect of Polyalthia longifolia was studied in mice. P. longifolia treatment showed improvement in mice survival compared to 100% mortality in the irradiated mice. Significant increases in hemoglobin concentration, and red blood cell, white blood cell and platelet counts were observed in the animals pretreated with leaf extract. Pre-irradiation administration of P. longifolia leaf extract also increased the CFU counts of the spleen colony and increased the relative spleen size. A dose-dependent decrease in lipid peroxidation levels was observed in the animals pretreated with P. longifolia. However, although the animals pretreated with P. longifolia exhibited a significant increase in superoxide dismutase and catalase activity, the values remained below normal in both liver and the intestine. Pre-irradiation administration of P. longifolia also resulted in the regeneration of the mucosal crypts and villi of the intestine. Moreover, pretreatment with P. longifolia leaf extract also showed restoration of the normal liver cell structure and a significant reduction in the elevated levels of ALT, AST and bilirubin. These results suggested the radioprotective ability of P. longifolia leaf extract, which is significant for future investigation for human applications in developing efficient, economically viable, non-toxic natural and clinically acceptable novel radioprotectors.
  14. Fulltext Biopolymers Regulate Silver Nanoparticle under Microwave Irradiation for Effective Antibacterial and Antibiofilm Activities
    Velusamy P, Su CH, Venkat Kumar G, Adhikary S, Pandian K, Gopinath SC, et al.
    PLoS One, 2016;11(6):e0157612.
    PMID: 27304672 DOI: 10.1371/journal.pone.0157612
    In the current study, facile synthesis of carboxymethyl cellulose (CMC) and sodium alginate capped silver nanoparticles (AgNPs) was examined using microwave radiation and aniline as a reducing agent. The biopolymer matrix embedded nanoparticles were synthesized under various experimental conditions using different concentrations of biopolymer (0.5, 1, 1.5, 2%), volumes of reducing agent (50, 100, 150 μL), and duration of heat treatment (30 s to 240 s). The synthesized nanoparticles were analyzed by scanning electron microscopy, UV-Vis spectroscopy, X-ray diffraction, and Fourier transform infrared spectroscopy for identification of AgNPs synthesis, crystal nature, shape, size, and type of capping action. In addition, the significant antibacterial efficacy and antibiofilm activity of biopolymer capped AgNPs were demonstrated against different bacterial strains, Staphylococcus aureus MTCC 740 and Escherichia coli MTCC 9492. These results confirmed the potential for production of biopolymer capped AgNPs grown under microwave irradiation, which can be used for industrial and biomedical applications.
  15. Fulltext Secretion of N- and O-linked Glycoproteins from 4T1 Murine Mammary Carcinoma Cells
    Phang WM, Tan AA, Gopinath SC, Hashim OH, Kiew LV, Chen Y
    Int J Med Sci, 2016;13(5):330-9.
    PMID: 27226773 DOI: 10.7150/ijms.14341
    Breast cancer is one of the most common cancers that affect women globally and accounts for ~23% of all cancers diagnosed in women. Breast cancer is also one of the leading causes of death primarily due to late stage diagnoses and a lack of effective treatments. Therefore, discovering protein expression biomarkers is mandatory for early detection and thus, critical for successful therapy. Two-dimensional electrophoresis (2D-E) coupled with lectin-based analysis followed by mass spectrometry were applied to identify potential biomarkers in the secretions of a murine mammary carcinoma cell line. Comparisons of the protein profiles of the murine 4T1 mammary carcinoma cell line and a normal murine MM3MG mammary cell line indicated that cadherin-1 (CDH), collagenase 3 (MMP-13), Viral envelope protein G7e (VEP), Gag protein (GAG) and Hypothetical protein LOC433182 (LOC) were uniquely expressed by the 4T1 cells, and pigment epithelium-derived factor (PEDF) was exclusively secreted by the MM3MG cells. Further analysis by a lectin-based study revealed that aberrant O-glycosylated CDH, N-glycosylated MMP-13 and LOC were present in the 4T1 medium. These differentially expressed N- and O-linked glycoprotein candidates, which were identified by combining lectin-based analysis with 2D-E, could serve as potential diagnostic and prognostic markers for breast cancer.
  16. Aptamer-based 'point-of-care testing'
    Gopinath SC, Lakshmipriya T, Chen Y, Phang WM, Hashim U
    Biotechnol Adv, 2016 May-Jun;34(3):198-208.
    PMID: 26876017 DOI: 10.1016/j.biotechadv.2016.02.003
    Aptamers are single-stranded oligonucleotides that can be artificially generated by a method called Systematic evolution of ligands by exponential enrichment (SELEX). The generated aptamers have been assessed for high-performance sensing applications due to their appealing characteristics. With either aptamers alone or complementing with antibodies, several high sensitive and portable sensors have been demonstrated for use in 'point-of-care testing'. Due to their high suitability and flexibility, aptamers are conjugated with nanostructures and utilized in field applications. Moreover, aptamers are more amenable to chemical modifications, making them capable of utilization with most developed sensors. In this overview, we discuss novel, portable, and aptamer-based sensing strategies that are suitable for 'point-of-care testing'.
  17. Fulltext Revealing Glycoproteins in the Secretome of MCF-7 Human Breast Cancer Cells
    Tan AA, Phang WM, Gopinath SC, Hashim OH, Kiew LV, Chen Y
    Biomed Res Int, 2015;2015:453289.
    PMID: 26167486 DOI: 10.1155/2015/453289
    Breast cancer is one of the major issues in the field of oncology, reported with a higher prevalence rate in women worldwide. In attempt to reveal the potential biomarkers for breast cancer, the findings of differentially glycosylated haptoglobin and osteonectin in previous study have drawn our attention towards glycoproteins of secretome from the MCF-7 cancer cell line. In the present study, further analyses were performed on the medium of MCF-7 cells by subjecting it to two-dimensional analyses followed by image analysis in contrast to the medium of human mammary epithelial cells (HMEpC) as a negative control. Carboxypeptidase A4 (CPA4), alpha-1-antitrypsin (AAT), haptoglobin (HP), and HSC70 were detected in the medium of MCF-7, while only CPA4 and osteonectin (ON) were detected in HMEpC medium. In addition, CPA4 was detected as upregulated in the MCF-7 medium. Further analysis by lectin showed that CPA4, AAT, HP, and HSC70 were secreted as N-glycan in the medium of MCF-7, with HP also showing differentially N-glycosylated isoforms. For the HMEpC, only CPA4 was detected as N-glycan. No O-glycan was detected in the medium of HMEpC but MCF-7 expressed O-glycosylated CPA4 and HSC70. All these revealed that glycoproteins could be used as glycan-based biomarkers for the prognosis of breast cancer.
  18. Fulltext Cochlear Implant and Its Related Science
    Hwang CF, Chen Y, Lin HC, Narayanan P, Oh SH, Truy E
    Biomed Res Int, 2015;2015:683967.
    PMID: 26240825 DOI: 10.1155/2015/683967
  19. Phylogeography of Kandelia candel in East Asiatic mangroves based on nucleotide variation of chloroplast and mitochondrial DNAs
    Chiang TY, Chiang YC, Chen YJ, Chou CH, Havanond S, Hong TN, et al.
    Mol Ecol, 2001 Nov;10(11):2697-710.
    PMID: 11883883
    Vivipary with precocious seedlings in mangrove plants was thought to be a hindrance to long-range dispersal. To examine the extent of seedling dispersal across oceans, we investigated the phylogeny and genetic structure among East Asiatic populations of Kandelia candel based on organelle DNAs. In total, three, 28 and seven haplotypes of the chloroplast DNA (cpDNA) atpB-rbcL spacer, cpDNA trnL-trnF spacer, and mitochondrial DNA (mtDNA) internal transcribed spacer (ITS) were identified, respectively, from 202 individuals. Three data sets suggested consistent phylogenies recovering two differentiated lineages corresponding to geographical regions, i.e. northern South-China-Sea + East-China-Sea region and southern South-China-Sea region (Sarawak). Phylogenetically, the Sarawak population was closely related to the Ranong population of western Peninsula Malaysia instead of other South-China-Sea populations, indicating its possible origin from the Indian Ocean Rim. No geographical subdivision was detected within the northern geographical region. An analysis of molecular variance (AMOVA) revealed low levels of genetic differentiation between and within mainland and island populations (phiCT = 0.015, phiSC = 0.037), indicating conspicuous long-distance seedling dispersal across oceans. Significant linkage disequilibrium excluded the possibility of recurrent homoplasious mutations as the major force causing phylogenetic discrepancy between mtDNA and the trnL-trnF spacer within the northern region. Instead, relative ages of alleles contributed to non-random chlorotype-mitotype associations and tree inconsistency. Widespread distribution and random associations (chi2 = 0.822, P = 0.189) of eight hypothetical ancestral cytotypes indicated the panmixis of populations of the northern geographical region as a whole. In contrast, rare and recently evolved alleles were restricted to marginal populations, revealing some preferential directional migration.
  20. Differential expression and geographic variation of the venom phospholipases A2 of Calloselasma rhodostoma and Trimeresurus mucrosquamatus
    Tsai IH, Chen YH, Wang YM, Liau MY, Lu PJ
    Arch Biochem Biophys, 2001 Mar 15;387(2):257-64.
    PMID: 11370849
    To investigate the geographic variations in venoms of two medically important pitvipers, we have purified and characterized the phospholipases A2 (PLA2s) from the pooled venoms of Calloselasma rhodostoma from Malaysia, Thailand, Indonesia, and Vietnam, as well as the individual venom of Trimeresurus mucrosquamatus collected from both North and South Taiwan. Enzymatic and pharmacological activities of the purified PLA2s were also investigated. The complete amino acid sequences of the purified PLA2s were determined by sequencing the corresponding cDNAs from the venom gland and shown to be consistent with their molecular weight data and the N-terminal sequences. All the geographic venom samples of C. rhodostoma contain a major noncatalytic basic PLA2-homolog and two or three acidic PLA2s in different proportions. These acidic PLA2s contain Glu6-substitutions and show distinct inhibiting specificities toward the platelets from human and rabbit. We also found that the T. mucrosquamatus venoms from North Taiwan but not those from South Taiwan contain an Arg6-PLA2 designated as TmPL-III. Its amino acid sequence is reported for the first time. This enzyme is structurally almost identical to the low- or nonexpressed Arg6-PLA2 from C. rhodostoma venom gland, and thus appears to be a regressing venom component in both of the Asian pitvipers.
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