Displaying publications 1 - 20 of 32 in total

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  1. Chuah CH, Goh SH, Prestwich GD, Tho YP
    J Chem Ecol, 1983 Mar;9(3):347-56.
    PMID: 24407404 DOI: 10.1007/BF00988454
    Trinervita-1(15),8(19)-dien-2β,3α-diol and the new trinervita-1(15),8(19)-dien-2β, 3α-diol 2-O-acetate constitute the major diterpene constituents of the soldier defense secretions of the NasutitermiteHospitalitermes umbrinus of Malaysian region. Studies on the intraspecific variations on sympatric and allopatric populations indicate two distinct patterns of chemical composition.
  2. Goh SH, Chuah CH, Tho YP, Prestwich GD
    J Chem Ecol, 1984 Jun;10(6):929-44.
    PMID: 24318785 DOI: 10.1007/BF00987974
    The chemical defense secretions of major and minor soldiers of over 18 colonies of the primitive glue-squirting nasute termiteLongipeditermes longipes (Isoptera, Termitidae, Nasutitermitinae) were analyzed chormatographically. The colonies, collected from four rainforest sites in peninsular Malaysia, showed monoterpene patterns rich in pinenes and limonene but with few quantitative differences between colonies. In marked contrast, the diterpene chemistry is high variable, and includes tricyclic (trinervitane), tetracyclic (rippertane), bicyclic (secotrinervitane), and a new spirotetracyclic (longipane) skeleton. Three new natural products are included in this remarkable and unprecedented example of structural diversity among different colonies of a single species.
  3. Chuah CH, Goh SH, Tho YP
    J Chem Ecol, 1986 Mar;12(3):701-12.
    PMID: 24306909 DOI: 10.1007/BF01012103
    Soldier defense secretions of the genus Hospitalitermes (Isoptera, Termitidae, Nasutitermitinae) were chemically analyzed by GC-MS and were found to contain volatile monoterpenes and polyoxygenated diterpenes. Interspecific and intraspecific chemical variations for H. umbrinus, H. hospitalis, H. flaviventris, and H. bicolor are described. Interspecific variations in monoterpene and diterpene structures and compositions were evident. A remarkable example of large intraspecific variation from a single species was observed inH. umbrinus, indicating that colonies of this species can be separable into two chemically distinct groups. The diterpenes found in one of these groups have unusually high molecular weights.
  4. Chuah CH, Goh SH, Tho YP
    J Chem Ecol, 1989 Feb;15(2):549-63.
    PMID: 24271798 DOI: 10.1007/BF01014700
    The defense secretions of five species of MalaysianNasutitermes,N. longinasus, N. matangensis, N, havilandi, N. johoricus, andNasutitermes species 01, are compared.N. longinasus andN. species 01 provide trinervitene alcohols,N. havilandi mainly tricyclic trinervitene and tetracyclic kempane alcohols and acetates, whereasN. matangensis furnish acetyl/propionyl derivatives of trinervita-11(12),15(17)-dien-3α,9β,13α-triol (XXI and XXII). A new diterpene, assigned as trinervita-11(12),15(17)-dien-3α,13α-diol-3,13-O-diacetate (XVII), is isolated fromN. havilandi. The mono- and diterpenoid compositions, being species-specific, are useful for chemotaxonomic and phylogenetic studies.
  5. Chang P, Koh YK, Geh SL, Soepadmo E, Goh SH, Wong AK
    J Ethnopharmacol, 1989 Apr;25(2):213-5.
    PMID: 2747255
  6. Goh SH, Chuah CH, Vadiveloo J, Tho YP
    J Chem Ecol, 1990 Feb;16(2):619-30.
    PMID: 24263517 DOI: 10.1007/BF01021792
    Soldiers of free-ranging termites of the genusLacessititermes (Isoptera, Nasutitermitinae) secrete from their frontal glands a mixture of monoterpenes, sesquiterpenes, and diterpenes.Lacessititermes ransoneti, L. laborator, andL. species A produce species-specific secretions, the composition being most complex forL. laborator. Apart from known mono- and dihydroxytrinervitadienes, the following new diterpenes were isolated and tentatively assigned as trinervita-1(15),8(19)-dien-2β,3α,9α,14α-tetraol 2,3,14-O-triacetate, trinervita-1(15),8(19)-dien-2β,3α,9β,14α-tetraol 2,3,14-O-triacetate, 2β,3α,9α, 14α-tetraacetoxy-1 (15), 8(19)-trinervitadiene, and 2β,3α,11α,13α-tetraacetoxy-1(15),8(19)-trinervitadiene. Data on intragenus chemical variations were subjected to canonical discriminant analysis and genetic distances among the species were calculated to depict intragenus identities and affinities.
  7. Chuah CH, Goh SH, Tho YP
    J Chem Ecol, 1990 Mar;16(3):685-92.
    PMID: 24263584 DOI: 10.1007/BF01016479
    The defense secretions of the soldiers of the Malaysian rhinotermitid,Parrhinotermes aequalis (Havilandi) andP. pygmaeus (John),Termitogeton planus (Havilandi) andSchedorhinotermes malaccensis (Holmgren) consist mainly of vinyl ketones, whereas that ofProrhinotermes flavus (Bugnion & Popoff) gives (E)-1-nitropentadecene. The chemistry of the defense secretions ofParrhinotermes andTermitogeton is documented and based on their chemical relationships;Termitogeton shows a closer affinity to the Rhinotermitinae than Heterotermitinae.
  8. Mok JS, Chang P, Lee KH, Kam TS, Goh SH
    J Ethnopharmacol, 1992 Jun;36(3):219-23.
    PMID: 1434680
    Among several alkaloids, including dimeric indoles, isolated from Uncaria callophylla, gambirine which is an alkaloid unique to this plant, has been found to be another hypotensive principle from the plant. Intravenous injections of gambirine in the dose range of 0.2 to 10.0 mg/kg caused a dose-related fall in both systolic and diastolic blood pressures as well as heart rate. At all doses gambirine showed a prompt onset of action and at the higher doses (5.0-10 mg/kg), marked persistence of hypotension accompanied by severe bradycardia were observed. In addition, higher doses of gambirine produced a more marked decrease in diastolic than systolic pressure while at lower doses both decreased equally. It is suggested that the hypotensive effect of gambirine may be peripheral in origin and is associated, at least in part, with a cardiac action.
  9. Goh SH, Hew NF, Norhanom AW, Yadav M
    Int J Cancer, 1994 May 15;57(4):529-31.
    PMID: 8181855
    Inhibition of tumour promotion by various vitamin E compounds (tocopherols and tocotrienols) and some of their dimers was examined by an in vitro assay utilizing the activation of Epstein-Barr virus (EBV) early antigen (EA) expression in EBV-genome-carrying human lymphoblastoid cells. The results reveal that gamma- and delta-tocotrienols derived from palm oil exhibit a strong activity against tumour promotion by inhibiting EBV EA expression in Raji cells induced by 12-O-tetradecanoylphorbol-13-acetate (TPA). However, alpha- and gamma-tocopherols and dimers of gamma-tocotrienol or gamma-tocopherol lack this activity.
  10. Yap SC, Choo YM, Hew NF, Yap SF, Khor HT, Ong AS, et al.
    Lipids, 1995 Dec;30(12):1145-50.
    PMID: 8614305
    The oxidative susceptibilities of low density lipoproteins (LDL) isolated from rabbits fed high-fat atherogenic diets containing coconut, palm, or soybean oil were investigated. New Zealand white rabbits were fed atherogenic semisynthetic diets containing 0.5% cholesterol and either (i) 13% coconut oil and 2% corn oil (CNO), (ii) 15% refined, bleached, and deodorized palm olein (RBDPO), (iii) 15% crude palm olein (CPO), (iv) 15% soybean oil (SO), or (v) 15% refined, bleached, and deodorized palm olein without cholesterol supplementation [RBDPO(wc)], for a period of twelve weeks. Total fatty acid compositions of the plasma and LDL were found to be modulated (but not too drastically) by the nature of the dietary fats. Cholesterol supplementation significantly increased the plasma level of vitamin E and effectively altered the plasma composition of long-chain fatty acids in favor of increasing oleic acid. Oxidative susceptibilities of LDL samples were determined by Cu2(+)-catalyzed oxidation which provide the lag times and lag-phase slopes. The plasma LDL from all palm oil diets [RBDPO, CPO, and RBDPO(wc)] were shown to be equally resistant to the oxidation, and the LDL from SO-fed rabbits were most susceptible, followed by the LDL from the CNO-fed rabbits. These results reflect a relationship between the oxidative susceptibility of LDL due to a combination of the levels of polyunsaturated fatty acids and vitamin E.
  11. Xu YJ, Wu XH, Tan BK, Lai YH, Vittal JJ, Imiyabir Z, et al.
    J Nat Prod, 2000 Apr;63(4):473-6.
    PMID: 10785416
    Leaf extracts of the Malaysian plant Aglaia laxiflora provided two cytotoxic compounds, a new rocaglaol rhamnoside (1), a known rocaglaol (2), new (but inactive) flavonol-cinnamaminopyrrolidine adducts (3-6), and their probable biosynthetic precursors (7 and trimethoxyflavonol). All structures were elucidated primarily by 2D NMR spectroscopy. The structure and stereochemistry of aglaxiflorin A (3) were confirmed by single-crystal X-ray crystallography.
  12. Xu J, Harrison LJ, Vittal JJ, Xu YJ, Goh SH
    J Nat Prod, 2000 Aug;63(8):1062-5.
    PMID: 10978198
    Leaf extracts of Callicarpa pentandra provided four new clerodane-type diterpenoids (1-4), of which 1, 2, and 4 have ring-A-contracted structures. Their structures and stereochemistry were established by spectral data interpretation, and for 3 also by single-crystal X-ray diffraction.
  13. Xu YJ, Chiang PY, Lai YH, Vittal JJ, Wu XH, Tan BK, et al.
    J Nat Prod, 2000 Oct;63(10):1361-3.
    PMID: 11076552
    Leaf extracts of Garcinia parvifolia provided relatively high yields of four novel, cytotoxic prenylated depsidones. The structures were determined mainly by detailed NMR spectral analysis and X-ray crystallography.
  14. Xu YJ, Lai YH, Imiyabir Z, Goh SH
    J Nat Prod, 2001 Sep;64(9):1191-5.
    PMID: 11575954
    Nine new xanthones, parvixanthones A-I (1-9), isolated from the dried bark of Garcinia parvifolia, were found to have a common 1,3,6,7-oxygenated pattern for their xanthone nucleus, but various oxygenated isoprenyl or geranyl substituent groups. The structures were determined by spectroscopic methods.
  15. Cao SG, Sim KY, Goh SH
    Nat Prod Lett, 2001;15(5):291-7.
    PMID: 11841112
    Two new biflavonoids, pyranoamentoflavone 7-methyl ether (1) and pyranoamentoflavone 4'-methyl ether (2), have been isolated from the leaves of Calophyllum venulosum. The structures of these two new compounds were elucidated by spectroscopic data.
  16. Ong AS, Goh SH
    Food Nutr Bull, 2002 Mar;23(1):11-22.
    PMID: 11975364
    Palm oil is an excellent choice for food manufacturers because of its nutritional benefits and versatility. The oil is highly structured to contain predominantly oleic acid at the sn2-position in the major triacylglycerols to account for the beneficial effects described in numerous nutritional studies. Oil quality and nutritional benefits have been assured for the variety of foods that can be manufactured from the oil directly or from blends with other oils while remaining trans-free. The oxidative stability coupled with the cost-effectiveness is unparalleled among cholesterol-free oils, and these values can be extended to blends of polyunsaturated oils to provide long shelf-life. Presently the supply of genetic-modification-free palm oil is assured at economic prices, since the oil palm is a perennial crop with unparalleled productivity. Numerous studies have confirmed the nutritional value of palm oil as a result of the high monounsaturation at the crucial 2-position of the oil's triacylglycerols, making the oil as healthful as olive oil. It is now recognized that the contribution of dietary fats to blood lipids and cholesterol modulation is a consequence of the digestion, absorption, and metabolism of the fats. Lipolytic hydrolysis of palm oil glycerides containing predominantly oleic acid at the 2 position and palmitic and stearic acids at the 1 and 3 positions allows for the ready absorption of the 2-monoacrylglycerols while the saturated free fatty acids remain poorly absorbed. Dietary palm oil in balanced diets generally reduced blood cholesterol, low-density lipoprotein (LDL) cholesterol, and triglycerides while raising the high-density lipoprotein (HDL) cholesterol. Improved lipoprotein(a) and apo-A1 levels were also demonstrated from palm oil diets; an important benefits also comes from the lowering of blood triglycerides (or reduced fat storage) as compared with those from polyunsaturated fat diets. Virgin palm oil also provides carotenes apart from tocotrienols and tocopherols that have been shown to be powerful antioxidants and potential mediators of cellular functions. These compounds can be antithrombotic, cause an increase of the prostacyclin/thromboxane ratio, reduce restenosis, and inhibit HMG-CoA-reductase (thus reducing) cholesterol biosynthesis). Red palm oil is a rich source of beta-carotene as well as of alpha-tocopherol and tocotrienols.
  17. Tan WP, Goh SH, Cham GW, Chng SM
    Ann Acad Med Singap, 2002 May;31(3):375-81.
    PMID: 12061300
    INTRODUCTION: Acute pulmonary thromboembolism (PE) has been considered rare among Asians. We aim to describe the frequency and clinical features of this condition in a hospital in Singapore. Among patients admitted by the Emergency Department (ED), comparisons were made between those primarily diagnosed in the ED and those who were not.

    MATERIALS AND METHODS: Retrospective review of all cases of radiologically proven acute PE over a 20-month period.

    RESULTS: Sixty-two patients were identified. The mean age was 61.5 +/- 18.0 years with a female to male ratio of 1.8:1. There were more Malays compared to other races. There were also more Caucasians, given the proximity of the hospital to the airport and the inclusion of tourists. The commonest symptoms were dyspnoea and chest pain, while the commonest signs were tachycardia and tachypnoea. Prolonged immobilisation was the commonest risk factor. Electrocardiographic S1Q3T3 pattern was seen in more patients compared to Western studies. Cardiomegaly was the commonest chest X-ray finding. Thirty-two patients were identified to have a source of embolisation. Overall mortality rate was 21%. The ED diagnosed 36% of the cases. Alternative admitting diagnoses were predominantly ischaemic heart disease and pneumonia. The group diagnosed in the ED were notably female (P = 0.044), Caucasian (P = 0.002) and had prolonged immobilisation (P = 0.025) prior to the onset of PE.

    CONCLUSION: Acute PE is not as rare here as previously thought. Clinical features reveal more similarities than differences compared to other studies in the literature. We advocate a high index of suspicion for earlier diagnosis in the ED.

  18. Chung LY, Yap KF, Goh SH, Mustafa MR, Imiyabir Z
    Phytochemistry, 2008 May;69(7):1548-54.
    PMID: 18334259 DOI: 10.1016/j.phytochem.2008.01.024
    The bark extract of Melicope subunifoliolata (Stapf) T.G. Hartley showed competitive muscarinic receptor binding activity. Six polymethoxyflavones [melibentin (1); melisimplexin (3); 3,3',4',5,7-pentamethoxyflavone (4); meliternatin (5); 3,5,8-trimethoxy-3',4',6,7-bismethylenedioxyflavone (6); and isokanugin (7)] and one furanocoumarin [5-methoxy-8-geranyloxypsoralen (2)] were isolated from the bark extract. Compounds 2 and 6 were isolated for the first time from M. subunifoliolata. The methoxyflavones (compounds 1, 3, 4, 5, 6, and 7) show moderate inhibition in a muscarinic receptor binding assay, while the furanocoumarin (compound 2) is inactive. The potency of the methoxyflavones to inhibit [(3)H]NMS-muscarinic receptor binding is influenced by the position and number of methoxy substitution. The results suggest these compounds are probably muscarinic modulators, agonists or partial agonists/antagonists.
  19. Chung LY, Lo MW, Mustafa MR, Goh SH, Imiyabir Z
    Phytother Res, 2009 Mar;23(3):330-4.
    PMID: 18844258 DOI: 10.1002/ptr.2627
    A 96-well microplate filtration based 5-HT(2A) receptor-radioligand binding assay was optimized and adopted to carry out a bioassay-guided fractionation of the methanol extract of the leaves of Litsea sessilis. This purification led to the isolation of two compounds identified as (+)-boldine (1) and (+)-dehydrovomifoliol (2). (+)-Boldine binds to 5-HT(2A) receptors at high concentrations with a K(i) value of 2.16 microm. However, (+)-dehydrovomifoliol showed minimal competitive inhibition on the binding of [(3)H]ketanserin to the same receptor with a K(i) value of 2.06 mm. These results suggest that (+)-boldine influences the activity of 5-HT(2A) receptors through competitive binding as an agonist or antagonist.
  20. Goh SH, Alitheen NB, Yusoff FM, Yap SK, Loh SP
    Pharmacogn Mag, 2014 Jan;10(37):1-8.
    PMID: 24696543 DOI: 10.4103/0973-1296.126650
    Marine brown diatom Chaetoceros calcitrans and green microalga Nannochloropsis oculata are beneficial materials for various applications in the food, nutraceutical, pharmaceutical and cosmeceutical industries.
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