Tin-Yan Cheng

The Chinese University of Hong Kong, Hong Kong, Hong Kong

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Publications (4)11.44 Total impact

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    ABSTRACT: Protostemonamide ( 1), a new protostemonine-type alkaloid, and 12 known compounds were isolated from the roots of Stemona sessilifolia. Their structures were elucidated by 1 D and 2 D NMR spectral and other spectroscopic studies. The main alkaloidal constituents, protostemonine ( 2), stemospironine ( 4), and maistemonine ( 7), showed significant antitussive activity in a citric acid-induced guinea pig cough model following peripheral administration; stemonamine ( 11) had antitussive activity following i. c. v. administration.
    No preview · Article · Dec 2008 · Planta Medica
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    Sunny Sun-Kin Chan · Tin-Yan Cheng · Ge Lin
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    ABSTRACT: Ligusticum chuanxiong Hort. (Umbelliferae) is a widely prescribed traditional Chinese medicinal herb for cardiovascular diseases in China. However, the cardiovascular actions of ligustilide and senkyunolide A, two of the most abundant Ligusticum chuanxiong constituents, have yet to be examined. The objective of the present study was to investigate the vasorelaxation effects of ligustilide and senkyunolide A and their underlying mechanisms in rat isolated aorta. Both constituents had similar relaxation potencies against contractions to 9,11-dideoxy-9alpha,11alpha-methanoepoxyprostaglandin F(2alpha), phenylephrine, 5-hydroxytryptamine and KCl. Their vasorelaxation effects were not affected by endothelium removal, the adenylate cyclase inhibitor 9-(tetrahydro-2-furanyl)-9H-purin-6-amine, the soluble guanylate cyclase inhibitor 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one, or the non-selective K+ channel blocker tetraethylammonium. This is the first report to demonstrate the vasorelaxation activities of ligustilide and senkyunolide A in contractions to various contractile agents in rat isolated aorta. The underlying mechanisms await further investigations.
    Full-text · Article · Jun 2007 · Journal of Ethnopharmacology
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    ABSTRACT: Five new stemoninine-type alkaloids, bisdehydrostemoninine (1), isobisdehydrostemoninine (2), bisdehydroneostemoninine (3), and bisdehydrostemoninines A (4) and B (5), were isolated from the crude-alkaloid extract of the roots of Stemona tuberosa. Their structures were elucidated on the basis of one- and two-dimensional NMR and other spectroscopic studies. The relative configuration of 4 was determined by X-ray diffraction. Alkaloid 1 displayed significant antitussive activity in the citric acid-induced guinea pig cough model.
    No preview · Article · Aug 2006 · Journal of Natural Products
  • Ge Lin · Ivo P Nnane · Tin-Yan Cheng
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    ABSTRACT: A wide variety of medicinal herbs contain hepatotoxic pyrrolizidine alkaloids (PAs), and often cause acute and chronic liver damages in man. Liquorice, a known antihepatitis, is commonly used with PA-containing herbs concurrently, and hepatotoxicity induced by such combined uses was not pronounced. The present study is to investigate effects of glycyrrhizin (GL) and 18β-glycyrrhetinic acid (GA), the major biologically active ingredients of liquorice, against PA-induced hepatotoxicity in rats.Single dose (35 mg/kg, i.p.) of retrorsine (RET), a typical potent hepatotoxic PA, was given to rats to induce liver injury. A single dose pretreatment with GL or GA prior to retrorsine challenge did not show hepatoprotection. However, when rats were pretreated with either GL (200 mg/kg/day, i.p.) or GA (10 mg/kg/day, i.p.) for three consecutive days prior to retrorsine exposure, the elevated serum GOT and GPT levels induced by retrorsine were significantly reduced. Serum levels of transaminases almost returned to normal (GOT: 56±2 (control), 104±5 (RET), 64±3 (GL+RET) and 59±3 (GA+RET). GPT: 40±2 (control), 90±7 (RET), 45±2 (GL+RET) and 45±4 (GA+RET) SF units/ml). Furthermore, no extensive hepatocellular damages were observed. The results demonstrated that a three-day pretreatment with either GL or GA exhibited protective effect on retrorsine-induced liver damage in rats.
    No preview · Article · Oct 1999 · Toxicon