Displaying publications 1 - 20 of 67 in total

Abstract:
Sort:
  1. Isolation and characterization of the thrombin-like enzyme from Cryptelytrops albolabris (white-lipped tree viper) venom
    Tan NH, Fung SY, Yap YH
    Comp Biochem Physiol B Biochem Mol Biol, 2012 Jan;161(1):79-85.
    PMID: 21983189 DOI: 10.1016/j.cbpb.2011.09.009
    A thrombin-like enzyme (termed albolabrase) was isolated in purified form from the venom of Cryptelytrops albolabris (white-lipped tree viper) using high performance anion ion exchange and gel filtration chromatography. The molecular mass of albolabrase was 33.7 kDa as determined by SDS-PAGE and 35.8 kDa as determined by Superose gel filtration chromatography. The N-terminal sequence was determined to be VVGGDECNINE which is homologous to many snake venom thrombin-like enzymes. Albolabrase exhibits both arginine ester hydrolase and arginine amidase activities and the enzyme is fastidious towards tripeptide chromogenic anilide substrates. The fibrinogen clotting activity was optimum at 3mg/mL bovine fibrinogen, and showed distinct species differences in the following decreasing order: bovine fibrinogen>dog fibrinogen≈human fibrinogen>goat fibrinogen. The enzyme failed to clot both rabbit and cat fibrinogens. Reversed-phase HPLC analysis on the breakdown products of fibrinogenolytic action of albolabrase indicated that the enzyme belongs to the AB class of snake venom thrombin-like enzyme. In the indirect ELISA, IgG anti-albolabrase reacted extensively with most crotalid venoms, except with Tropidolaemus wagleri and Calloselasma rhodostoma venoms. The double sandwich ELISA, however, showed that anti-albolabrase reacted strongly only with venoms from the Trimeresurus complex, and that the results support the proposed new taxonomy changes concerning the Trimeresurus complex.
  2. Medicinal Mushrooms and Their Use to Strengthen Respiratory Health during and Post-COVID-19 Pandemic
    Booi HN, Lee MK, Fung SY, Ng ST, Tan CS, Lim KH, et al.
    Int J Med Mushrooms, 2022;24(10):1-14.
    PMID: 36374826 DOI: 10.1615/IntJMedMushrooms.2022045068
    COVID-19 infection has been a key threat to the public health system globally, with an estimated 248 million cases worldwide. COVID-19 patients are subject to a higher risk of developing chronic respiratory disorders that are closely associated with long-term disability, multi-morbidity, and premature mortality. Although there have been recent advancements in respiratory treatment regimens, there has also been increased interest in the use of medicinal mushrooms in bridging the unaddressed pathways of action within the treatment algorithms. In this review, we provide a collection of medicinal mushrooms that are beneficial in promoting respiratory health and potentially reducing COVID-19 symptoms in patients who are newly diagnosed and those who have recovered. While reviewing the use of immunomodulatory pathways, which have shown promising results in tackling side effects and post-COVID syndromes, we also provide insights into how the antioxidant elements present in medicinal mushrooms help to achieve the same results, especially in the prophylactic and therapeutic management of COVID-19 infection. To date, medicinal mushrooms are regarded as a functional food, which, however, need further quality, safety, and efficacy assessments. These requirements are also highlighted in the present review to promote the future development and application of medicinal mushrooms for better respiratory health.
  3. Unveiling the elusive and exotic: Venomics of the Malayan blue coral snake (Calliophis bivirgata flaviceps)
    Tan CH, Fung SY, Yap MK, Leong PK, Liew JL, Tan NH
    J Proteomics, 2016 Jan 30;132:1-12.
    PMID: 26598790 DOI: 10.1016/j.jprot.2015.11.014
    The venom proteome of the Malayan blue coral snake, Calliophis bivirgata flaviceps from west Malaysia was investigated by 1D-SDS-PAGE and shotgun-LCMS/MS. A total of 23 proteins belonging to 11 protein families were detected from the venom proteome. For the toxin proteins, the venom consists mainly of phospholipase A2 (41.1%), cytotoxin (22.6%), SVMPs (18.7%) and vespryns (14.6%). However, in contrast to the venoms of New World coral snakes and most elapids, there was no post-synaptic α-neurotoxin detected. The proteome also revealed a relatively high level of phosphodiesterase (1.3%), which may be associated with the reported high level of adenosine in the venom. Also detected were 5'-nucleotidase (0.3%), hyaluronidase (0.1%) and cysteine-type endopeptide inhibitor (0.6%). Enzymatic studies confirmed the presence of phospholipase A2, phosphodiesterase, 5'-nucleotidase and acetylcholinesterase activities but not l-amino acid oxidase activity. The venom exhibited moderate cytotoxic activity against CRL-2648 fibroblast cell lines (IC50=62.14±0.87 μg/mL) and myotoxicity in mice, presumably due to the action of its cytotoxin or its synergistic action with phospholipase A2. Interestingly, the venom lethality could be cross-neutralized by a neurotoxic bivalent antivenom from Taiwan. Together, the findings provide insights into the composition and functions of the venom of this exotic oriental elapid snake.
  4. Fulltext Transcriptome Analysis Revealed Highly Expressed Genes Encoding Secondary Metabolite Pathways and Small Cysteine-Rich Proteins in the Sclerotium of Lignosus rhinocerotis
    Yap HY, Chooi YH, Fung SY, Ng ST, Tan CS, Tan NH
    PLoS One, 2015;10(11):e0143549.
    PMID: 26606395 DOI: 10.1371/journal.pone.0143549
    Lignosus rhinocerotis (Cooke) Ryvarden (tiger milk mushroom) has long been known for its nutritional and medicinal benefits among the local communities in Southeast Asia. However, the molecular and genetic basis of its medicinal and nutraceutical properties at transcriptional level have not been investigated. In this study, the transcriptome of L. rhinocerotis sclerotium, the part with medicinal value, was analyzed using high-throughput Illumina HiSeqTM platform with good sequencing quality and alignment results. A total of 3,673, 117, and 59,649 events of alternative splicing, novel transcripts, and SNP variation were found to enrich its current genome database. A large number of transcripts were expressed and involved in the processing of gene information and carbohydrate metabolism. A few highly expressed genes encoding the cysteine-rich cerato-platanin, hydrophobins, and sugar-binding lectins were identified and their possible roles in L. rhinocerotis were discussed. Genes encoding enzymes involved in the biosynthesis of glucans, six gene clusters encoding four terpene synthases and one each of non-ribosomal peptide synthetase and polyketide synthase, and 109 transcribed cytochrome P450 sequences were also identified in the transcriptome. The data from this study forms a valuable foundation for future research in the exploitation of this mushroom in pharmacological and industrial applications.
  5. Venomics, lethality and neutralization of Naja kaouthia (monocled cobra) venoms from three different geographical regions of Southeast Asia
    Tan KY, Tan CH, Fung SY, Tan NH
    J Proteomics, 2015 Apr 29;120:105-25.
    PMID: 25748141 DOI: 10.1016/j.jprot.2015.02.012
    Previous studies showed that venoms of the monocled cobra, Naja kaouthia from Thailand and Malaysia are substantially different in their median lethal doses. The intraspecific venom variations of N. kaouthia, however, have not been fully elucidated. Here we investigated the venom proteomes of N. kaouthia from Malaysia (NK-M), Thailand (NK-T) and Vietnam (NK-V) through reverse-phase HPLC, SDS-PAGE and tandem mass spectrometry. The venom proteins comprise 13 toxin families, with three-finger toxins being the most abundant (63-77%) and the most varied (11-18 isoforms) among the three populations. NK-T has the highest content of neurotoxins (50%, predominantly long neurotoxins), followed by NK-V (29%, predominantly weak neurotoxins and some short neurotoxins), while NK-M has the least (18%, some weak neurotoxins but less short and long neurotoxins). On the other hand, cytotoxins constitute the main bulk of toxins in NK-M and NK-V venoms (up to 45% each), but less in NK-T venom (27%). The three venoms show different lethal potencies that generally reflect the proteomic findings. Despite the proteomic variations, the use of Thai monovalent and Neuro polyvalent antivenoms for N. kaouthia envenomation in the three regions is appropriate as the different venoms were neutralized by the antivenoms albeit at different degrees of effectiveness.
  6. Fulltext Genome-based proteomic analysis of Lignosus rhinocerotis (Cooke) Ryvarden sclerotium
    Yap HY, Fung SY, Ng ST, Tan CS, Tan NH
    Int J Med Sci, 2015;12(1):23-31.
    PMID: 25552915 DOI: 10.7150/ijms.10019
    Lignosus rhinocerotis (Cooke) Ryvarden (Polyporales, Basidiomycota), also known as the tiger milk mushroom, has received much interest in recent years owing to its wide-range ethnobotanical uses and the recent success in its domestication. The sclerotium is the part with medicinal value. Using two-dimensional gel electrophoresis coupled with mass spectrometry analysis, a total of 16 non-redundant, major proteins were identified with high confidence level in L. rhinocerotis sclerotium based on its genome as custom mapping database. Some of these proteins, such as the putative lectins, immunomodulatory proteins, superoxide dismutase, and aegerolysin may have pharmaceutical potential; while others are involved in nutrient mobilization and the protective antioxidant mechanism in the sclerotium. The findings from this study provide a molecular basis for future research on potential pharmacologically active proteins of L. rhinocerotis.
  7. Fulltext The genome of the Tiger Milk mushroom, Lignosus rhinocerotis, provides insights into the genetic basis of its medicinal properties
    Yap HY, Chooi YH, Firdaus-Raih M, Fung SY, Ng ST, Tan CS, et al.
    BMC Genomics, 2014;15:635.
    PMID: 25073817 DOI: 10.1186/1471-2164-15-635
    The sclerotium of Lignosus rhinocerotis (Cooke) Ryvarden or Tiger milk mushroom (Polyporales, Basidiomycota) is a valuable folk medicine for indigenous peoples in Southeast Asia. Despite the increasing interest in this ethnobotanical mushroom, very little is known about the molecular and genetic basis of its medicinal and nutraceutical properties.
  8. Fulltext Energy and nutritional composition of Tiger milk mushroom (Lignosus tigris Chon S. Tan) sclerotia and the antioxidant activity of its extracts
    Yap HY, Aziz AA, Fung SY, Ng ST, Tan CS, Tan NH
    Int J Med Sci, 2014;11(6):602-7.
    PMID: 24782649 DOI: 10.7150/ijms.8341
    The Lignosus is a genus of fungi that have useful medicinal properties. In Southeast Asia, three species of Lignosus (locally known collectively as Tiger milk mushrooms) have been reported including L. tigris, L. rhinocerotis, and L. cameronensis. All three have been used as important medicinal mushrooms by the natives of Peninsular Malaysia. In this work, the nutritional composition and antioxidant activities of the wild type and a cultivated strain of L. tigris sclerotial extracts were investigated. The sclerotia are rich in carbohydrates with moderate amount of protein and low fat content. Free radical scavenging activities of L. tigris sclerotial extracts correlate with their phenolic content, which ranges from 6.25 to 45.42 mg GAE/g extract. The FRAP values ranged from 0.002 to 0.041 mmol/min/g extract, while the DPPH(•), ABTS(•+), and superoxide anion (SOA) scavenging activities ranged from 0.18 to 2.53, 0.01 to 0.36, and -4.53 to 10.05 mmol Trolox equivalents/g extract, respectively. L. tigris cultivar shows good prospect to be developed into functional food due to its good nutritional value and potent SOA scavenging activity.
  9. Fulltext King cobra (Ophiophagus hannah) venom L-amino acid oxidase induces apoptosis in PC-3 cells and suppresses PC-3 solid tumor growth in a tumor xenograft mouse model
    Lee ML, Fung SY, Chung I, Pailoor J, Cheah SH, Tan NH
    Int J Med Sci, 2014;11(6):593-601.
    PMID: 24782648 DOI: 10.7150/ijms.8096
    King cobra (Ophiophagus hannah) venom L-amino acid oxidase (OH-LAAO), a heat stable enzyme, has been shown to exhibit very potent anti-proliferative activity against human breast and lung tumorigenic cells but not in their non-tumorigenic counterparts. We further examine its in vitro and in vivo anti-tumor activity in a human prostate adenocarcinoma (PC-3) model. OH-LAAO demonstrated potent cytotoxicity against PC-3 cells with IC50 of 0.05 µg/mL after 72 h incubation in vitro. It induced apoptosis as evidenced with an increase in caspase-3/7 cleavages and an increase in annexin V-stained cells. To examine its in vivo anti-tumor activity, we treated PC-3 tumor xenograft implanted subcutaneously in immunodeficient NU/NU (nude) mice with 1 µg/g OH-LAAO given intraperitoneally (i.p.). After 8 weeks of treatment, OH-LAAO treated PC-3 tumors were markedly inhibited, when compared to the control group (P <0.05). TUNEL staining analysis on the tumor sections showed a significantly increase of apoptotic cells in the LAAO-treated animals. Histological examinations of the vital organs in these two groups showed no significant differences with normal tissues, indicating no obvious tissue damage. The treatment also did not cause any significant changes on the body weight of the mice during the duration of the study. These observations suggest that OH-LAAO cytotoxic effects may be specific to tumor xenografts and less to normal organs. Given its potent anti-tumor activities shown in vitro as well as in vivo, the king cobra venom LAAO can potentially be developed to treat prostate cancer and other solid tumors.
  10. Proteomic characterization of venom of the medically important Southeast Asian Naja sumatrana (Equatorial spitting cobra)
    Yap MK, Fung SY, Tan KY, Tan NH
    Acta Trop, 2014 May;133:15-25.
    PMID: 24508616 DOI: 10.1016/j.actatropica.2014.01.014
    The proteome of Naja sumatrana (Equatorial spitting cobra) venom was investigated by shotgun analysis and a combination of ion-exchange chromatography and reverse phase HPLC. Shotgun analysis revealed the presence of 39 proteins in the venom while the chromatographic approach identified 37 venom proteins. The results indicated that, like other Asiatic cobra venoms, N. sumatrana contains large number of three finger toxins and phospholipases A2, which together constitute 92.1% by weight of venom protein. However, only eight of the toxins can be considered as major venom toxins. These include two phospholipases A2, three neurotoxins (two long neurotoxins and a short neurotoxin) and three cardiotoxins. The eight major toxins have relative abundance of 1.6-27.2% venom proteins and together account for 89.8% (by weight) of total venom protein. Other venom proteins identified include Zn-metalloproteinase-disintegrin, Thaicobrin, CRISP, natriuretic peptide, complement depleting factors, cobra venom factors, venom nerve growth factor and cobra serum albumin. The proteome of N. sumatrana venom is similar to proteome of other Asiatic cobra venoms but differs from that of African spitting cobra venom. Our results confirm that the main toxic action of N. sumatrana venom is neurotoxic but the large amount of cardiotoxins and phospholipases A2 are likely to contribute significantly to the overall pathophysiological action of the venom. The differences in toxin distribution between N. sumatrana venom and African spitting cobra venoms suggest possible differences in the pathophysiological actions of N. sumatrana venom and the African spitting cobra venoms, and explain why antivenom raised against Asiatic cobra venom is not effective against African spitting cobra venoms.
  11. Cross neutralization of common Southeast Asian viperid venoms by a Thai polyvalent snake antivenom (Hemato Polyvalent Snake Antivenom)
    Leong PK, Tan CH, Sim SM, Fung SY, Sumana K, Sitprija V, et al.
    Acta Trop, 2014 Apr;132:7-14.
    PMID: 24384454 DOI: 10.1016/j.actatropica.2013.12.015
    Snake envenomation is a serious public health threat in many rural areas of Asia and Africa. Antivenom has hitherto been the definite treatment for snake envenomation. Owing to a lack of local production of specific antivenom, most countries in these regions fully depend on foreign supplies of antivenoms. Often, the effectiveness of the imported antivenoms against local medically important species has not been validated. This study aimed to assess cross-neutralizing capacity of a recently developed polyvalent antivenom, Hemato Polyvalent Snake Antivenom (HPAV), against venoms of a common viper and some pit vipers from Southeast Asia. Neutralisation assays showed that HPAV was able to effectively neutralize lethality of the common Southeast Asian viperid venoms examined (Calloselasma, Crytelytrops, Popeia, and Daboia sp.) except for Tropidolaemus wagleri venom. HPAV also effectively neutralized the procoagulant and hemorrhagic activities of all the venoms examined, corroboratively supporting the capability of HPAV in neutralizing viperid venoms which are principally hematoxic. The study also indicated that HPAV fully prevented the occurrence of hematuria and proteinuria in mice envenomed with Thai Daboia siamensis venom but was only partially effective against venoms of Myanmar D. siamensis. Thus, HPAV appears to be useful against its homologous venoms and venoms from Southeast Asian viperids including several medically important pit vipers belonging to the Trimeresurus complex. Nevertheless, the effectiveness of HPAV as a paraspecific antivenom for treatment of viperid envenomation in Southeast Asian region requires further assessment from future clinical trials.
  12. Cross neutralization of Hypnale hypnale (hump-nosed pit viper) venom by polyvalent and monovalent Malayan pit viper antivenoms in vitro and in a rodent model
    Tan CH, Leong PK, Fung SY, Sim SM, Ponnudurai G, Ariaratnam C, et al.
    Acta Trop, 2011 Feb;117(2):119-24.
    PMID: 21073851 DOI: 10.1016/j.actatropica.2010.11.001
    Hypnale hypnale (hump-nosed pit viper) is a medically important venomous snake in Sri Lanka and Southwestern India. Bite of this snake may result in hemostatic dysfunction, acute kidney injury and death. Clinical studies indicated that the locally available polyvalent antivenoms produced in India are not effective against hump-nosed pit viper envenoming. Hence, there is an urgent need to search for effective antivenom. In this paper, we examined the ability of Calloselasma rhodostoma (Malayan pit viper) monovalent antivenom and the Hemato polyvalent antivenom (both produced by Thai Red Cross Society, TRCS) to neutralize the lethality and toxic effects of H. hypnale venom, as C. rhodostoma is considered a sister taxon of H. hypnale. In vitro neutralization studies showed that the Hemato polyvalent antivenom effectively neutralized the lethality of H. hypnale venom (1.52mgvenom/mL antivenom) as well as the hemorrhagic, procoagulant and necrotic activities of the venom. The monovalent C. rhodostoma antivenom could also neutralize the lethality and toxic activities of the venom, but the potency was lower. The Hemato polyvalent antivenom also effectively protected mice from the lethal and local effects of H. hypnale venom in an in vivo rodent model of envenoming. Furthermore, the polyvalent antivenom could also effectively neutralize the venom of Daboia russelii (2.50mgvenom/mL antivenom), another common cause of snake bites in Sri Lanka and South India. These findings suggested that the Hemato polyvalent antivenom may be beneficial in the antivenom treatment of H. hypnale envenoming.
  13. Fulltext Venom-gland transcriptome and venom proteome of the Malaysian king cobra (Ophiophagus hannah)
    Tan CH, Tan KY, Fung SY, Tan NH
    BMC Genomics, 2015;16:687.
    PMID: 26358635 DOI: 10.1186/s12864-015-1828-2
    The king cobra (Ophiophagus hannah) is widely distributed throughout many parts of Asia. This study aims to investigate the complexity of Malaysian Ophiophagus hannah (MOh) venom for a better understanding of king cobra venom variation and its envenoming pathophysiology. The venom gland transcriptome was investigated using the Illumina HiSeq™ platform, while the venom proteome was profiled by 1D-SDS-PAGE-nano-ESI-LCMS/MS.
  14. Shotgun proteomic analysis of tiger milk mushroom (Lignosus rhinocerotis) and the isolation of a cytotoxic fungal serine protease from its sclerotium
    Yap HY, Fung SY, Ng ST, Tan CS, Tan NH
    J Ethnopharmacol, 2015 Nov 4;174:437-51.
    PMID: 26320692 DOI: 10.1016/j.jep.2015.08.042
    The sclerotium of Lignosus rhinocerotis (Cooke) Ryvarden (tiger milk mushroom) has been traditionally used as a complementary and alternative medicine for cancer treatment by the local communities of Southeast Asia. Despite the continuous research interest in its antiproliferative activity, the identity of the bioactive compound(s) responsible has yet to be determined. This study aims to bridge the gap in existing research literature by using proteomics approach for investigation of the nature of the anticancer substance of L. rhinocerotis.
  15. Immunological cross-reactivity and neutralization of the principal toxins of Naja sumatrana and related cobra venoms by a Thai polyvalent antivenom (Neuro Polyvalent Snake Antivenom)
    Leong PK, Fung SY, Tan CH, Sim SM, Tan NH
    Acta Trop, 2015 Sep;149:86-93.
    PMID: 26026717 DOI: 10.1016/j.actatropica.2015.05.020
    The low potency of cobra antivenom has been an area of concern in immunotherapy for cobra envenomation. This study sought to investigate factors limiting the neutralizing potency of cobra antivenom, using a murine model. We examined the immunological reactivity and neutralizing potency of a Thai polyvalent antivenom against the principal toxins of Naja sumatrana (Equatorial spitting cobra) venom and two related Asiatic cobra venom α-neurotoxins. The antivenom possesses moderate neutralizing potency against phospholipases A2 (P, potency of 0.98mg/mL) and moderately weak neutralizing potency against long-chain α-neurotoxins (0.26-0.42mg/mL) but was only weakly effective in neutralizing the short-chain α-neurotoxins and cardiotoxins (0.05-0.08mg/mL). The poor neutralizing potency of the antivenom on the low molecular mass short-chain neurotoxins and cardiotoxins is presumably the main limiting factor of the efficacy of the cobra antivenom. Our results also showed that phospholipase A2, which exhibited the highest ELISA reactivity and avidity, was most effectively neutralized, whereas N. sumatrana short-chain neurotoxin, which exhibited the lowest ELISA reactivity and avidity, was least effectively neutralized by the antivenom. These observations suggest that low immunoreactivity (low ELISA reactivity and avidity) is one of the reasons for poor neutralization of the cobra venom low molecular mass toxins. Nevertheless, the overall results show that there is a lack of congruence between the immunological reactivity of the toxins toward antivenom and the effectiveness of toxin neutralization by the antivenom, indicating that there are other factors that also contribute to the weak neutralization capacity of the antivenom. Several suggestions have been put forward to overcome the low efficacy of the cobra antivenom. The use of a 'proper-mix' formulation of cobra venoms as immunogen, whereby the immunogen mixture used for hyperimmunization contains a mix of various types of α-neurotoxins and cardiotoxins in sufficient amount, may also help to improve the efficacy and broaden the neutralization spectrum of the antivenom.
  16. Geographical venom variations of the Southeast Asian monocled cobra (Naja kaouthia): venom-induced neuromuscular depression and antivenom neutralization
    Tan KY, Tan CH, Sim SM, Fung SY, Tan NH
    Comp Biochem Physiol C Toxicol Pharmacol, 2016 Jul-Aug;185-186:77-86.
    PMID: 26972756 DOI: 10.1016/j.cbpc.2016.03.005
    The Southeast Asian monocled cobras (Naja kaouthia) exhibit geographical variations in their venom proteomes, especially on the composition of neurotoxins. This study compared the neuromuscular depressant activity of the venoms of N. kaouthia from Malaysia (NK-M), Thailand (NK-T) and Vietnam (NK-V), and the neutralization of neurotoxicity by a monospecific antivenom. On chick biventer cervicis nerve-muscle preparation, all venoms abolished the indirect twitches, with NK-T venom being the most potent (shortest t90, time to 90% twitch inhibition), followed by NK-V and NK-M. Acetylcholine and carbachol failed to reverse the blockade, indicating irreversible/pseudo-irreversible post-synaptic neuromuscular blockade. KCl restored the twitches variably (NK-M preparation being the least responsive), consistent with different degree of muscle damage. The findings support that NK-T venom has the most abundant curarimimetic alpha-neurotoxins, while NK-M venom contains more tissue-damaging cytotoxins. Pre-incubation of tissue with N. kaouthia monovalent antivenom (NKMAV) prevented venom-induced twitch depression, with the NK-T preparation needing the largest antivenom dose. NKMAV added after the onset of neuromuscular depression could only halt the inhibitory progression but failed to restore full contraction. The findings highlight the urgency of early antivenom administration to sequester as much circulating neurotoxins as possible, thereby hastening toxin elimination from the circulation. In envenomed mice, NKMAV administered upon the first neurological sign neutralized the neurotoxic effect, with the slowest full recovery noticed in the NK-T group. This is consistent with the high abundance of neurotoxins in the NK-T venom, implying that a larger amount or repeated dosing of NKMAV may be required in NK-T envenomation.
  17. Molecular mechanism of cell death induced by king cobra (Ophiophagus hannah) venom l-amino acid oxidase
    Fung SY, Lee ML, Tan NH
    Toxicon, 2015 Mar;96:38-45.
    PMID: 25615711 DOI: 10.1016/j.toxicon.2015.01.012
    Snake venom LAAOs have been reported to exhibit a wide range of pharmacological activities, including cytotoxic, edema-inducing, platelet aggregation-inducing/platelet aggregation-inhibiting, bactericidal and antiviral activities. A heat-stable form of l-amino acid oxidase isolated from king cobra (Ophiophagus hannah) venom (OH-LAAO) has been shown to exhibit very potent cytotoxicity against human tumorigenic cells but not in their non-tumorigenic counterparts, and the cytotoxicity was due to the apoptosis-inducing effect of the enzyme. In this work, the molecular mechanism of cell death induced by OH-LAAO was investigated. The enzyme exerts its apoptosis-inducing effect presumably via both intrinsic and extrinsic pathways as suggested by the increase in caspase-8 and -9 activities. Oligonucleotide microarray analysis showed that the expression of a total of 178 genes was significantly altered as a result of oxidative stress induced by the hydrogen peroxide generated by the enzyme. Of the 178 genes, at least 27 genes are involved in apoptosis and cell death. These alterations of gene expression was presumably caused by the direct cytotoxic effect of H2O2 generated during the enzymatic reaction, as well as the non-specific oxidative modifications of signaling molecules that eventually lead to apoptosis and cell death. The very substantial up-regulation of cytochrome P450 genes may also contribute to the potent cytotoxic action of OH-LAAO by producing excessive reactive oxygen species (ROS). In conclusion, the potent apoptosis inducing activity of OH-LAAO was likely due to the direct cytotoxic effect of H2O2 generated during the enzymatic reaction, as well as the non-specific oxidation of signalling molecules.
  18. Pharmacokinetics of the Sri Lankan hump-nosed pit viper (Hypnale hypnale) venom following intravenous and intramuscular injections of the venom into rabbits
    Tan CH, Sim SM, Gnanathasan CA, Fung SY, Tan NH
    Toxicon, 2014 Mar;79:37-44.
    PMID: 24412778 DOI: 10.1016/j.toxicon.2013.12.011
    The knowledge of venom pharmacokinetics is essential to improve the understanding of envenomation pathophysiology. Using a double-sandwich ELISA, this study investigated the pharmacokinetics of the venom of hump-nosed pit viper (Hypnale hypnale) following intravenous and intramuscular injections into rabbits. The pharmacokinetics of the venom injected intravenously fitted a three-compartment model. There is a rapid (t1/2π = 0.4 h) and a slow (t1/2α = 0.8 h) distribution phase, followed by a long elimination phase (t1/2β = 19.3 h) with a systemic clearance of 6.8 mL h(-1) kg(-1), consistent with the prolonged abnormal hemostasis reported in H. hypnale envenomation. On intramuscular route, multiple peak concentrations observed in the beginning implied a more complex venom absorption and/or distribution pattern. The terminal half-life, volume of distribution by area and systemic clearance of the venom injected intramuscularly were nevertheless not significantly different (p > 0.05) from that of the venom injected intravenously. The intramuscular bioavailability was exceptionally low (Fi.m. = 4%), accountable for the highly varied median lethal doses between intravenous and intramuscular envenomations in animals. The findings indicate that the intramuscular route of administration does not significantly alter the pharmacokinetics of H. hypnale venom although it significantly reduces the systemic bioavailability of the venom.
  19. Venomics of Calloselasma rhodostoma, the Malayan pit viper: A complex toxin arsenal unraveled
    Tang EL, Tan CH, Fung SY, Tan NH
    J Proteomics, 2016 10 04;148:44-56.
    PMID: 27418434 DOI: 10.1016/j.jprot.2016.07.006
    The venom of Malayan pit viper (Calloselasma rhodostoma) is highly toxic but also valuable in drug discovery. However, a comprehensive proteome of the venom that details its toxin composition and abundance is lacking. This study aimed to unravel the venom complexity through a multi-step venomic approach. At least 96 distinct proteins (29 basic, 67 acidic) in 11 families were identified from the venom. The venom consists of mainly snake venom metalloproteinases (SVMP, 41.17% of total venom proteins), within which the P-I (kistomin, 20.4%) and P-II (rhodostoxin, 19.8%) classes predominate. This is followed by C-type lectins (snaclec, 26.3%), snake venom serine protease (SVSP, 14.9%), L-amino acid oxidase (7.0%), phospholipase A2 (4.4%), cysteine-rich secretory protein (2.5%), and five minor toxins (nerve growth factor, neurotrophin, phospholipase B, 5' nucleotidase and phosphodiesterase, totaling 2.6%) not reported in the proteome hitherto. Importantly, all principal hemotoxins unveiled correlate with the syndrome: SVSP ancrod causes venom-induced consumptive coagulopathy, aggravated by thrombocytopenia caused by snaclec rhodocytin, a platelet aggregation inducer, while P-II rhodostoxin mediates hemorrhage, exacerbated by P-I kistomin and snaclec rhodocetin that inhibit platelet plug formation. These toxins exist in multiple isoforms and/or complex subunits, deserving further characterization for the development of an effective, polyspecific regional antivenom.

    BIOLOGICAL SIGNIFICANCE: Advents in proteomics and bioinformatics have vigorously propelled the scientific discoveries of toxins from various lineages of venomous snakes. The Malayan pit viper, Calloselasma rhodostoma, is a medically important species in Southeast Asia as its bite can cause envenomation, while the venom is also a source of bioactive compounds for drug discovery. Detailed profiling of the venom, however, is inadequate possibly due to the complex nature of the venom and technical limitation in separating the constituents into details. Integrating a multi-step fractionation method, this study successfully revealed a comprehensive and quantitative profile of the composition of the venom of this medically important venomous snake. The relative abundance of the various venom proteins is determined in a global profile, providing useful information for understanding the pathogenic roles of the different toxins in C. rhodostoma envenomation. Notably, the principal hemotoxins were identified in great details, including the variety of toxin subunits and isoforms. The findings indicate that these toxins are the principal targets for effective antivenom neutralization, and should be addressed in the production of a pan-regional polyspecific antivenom. In addition, minor toxin components not reported previously in the venom were also detected in this study, enriching the current toxin database for the venomous snakes.

  20. Isolation, characterization and antigenic cross-reactivities of the major hemorrhagin from Cryptelytrops purpureomaculatus venom
    Fung SY, Tan NH
    Indian J Exp Biol, 2013 Dec;51(12):1063-9.
    PMID: 24579371
    The major hemorrhagin from C. purpureomaculatus (mangrove pit viper) venom was purified to homogeneity and termed Maculatoxin. Maculatoxin has a molecular weight of 38 kDa as determined by SDS-PAGE. It is an acidic protein (pI= 4.2) and exhibited proteolytic and hemorrhagic activities (MHD10 = 0.84 microg in mice) but was not lethal to mice at a dose of 1 microg/g. The hemorrhagic activity of Maculatoxin was completely inactivated by EDTA and partially inhibited by ATP and citrate. The N-terminal sequence of Maculatoxin (TPEQQRFPPTYIDLGIFVDHGMYAT) shares a significant degree of homology with the metalloprotease domain of other venom hemorrhagins. Indirect ELISA showed anti-Maculatoxin cross reacted with protein components of many snake venoms. In the double-sandwich ELISA, however, anti-Maculatoxin cross-reacted only with venoms of certain species of the Trimeresurus (Asia lance-head viper) complex, and the results support the recent proposed taxonomy changes concerning the Trimeresurus complex.
Related Terms
Filters
Contact Us

Please provide feedback to Administrator (afdal@afpm.org.my)

External Links