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SelectedWorks

2012

Articles 1 - 4 of 4

Full-Text Articles in Natural Products Chemistry and Pharmacognosy

Cytotoxic And Antioxidant Compounds From The Stem Bark Of Goniothalamus Tapisoides Mat Salleh, Kok Hoong Leong Dec 2012

Cytotoxic And Antioxidant Compounds From The Stem Bark Of Goniothalamus Tapisoides Mat Salleh, Kok Hoong Leong

Kok Hoong Leong

Eleven compounds:goniomicin A (1), goniomicin B (2), goniomicin C (3), goniomicin D (4), tapisoidin (5), goniothalamin (6), 9-deoxygoniopypyrone (7), pterodondiol (8), liriodenine (9), benzamide (10) and cinnamic acid (11), were isolated from the stem bark of Goniothalamus tapisoides. All compounds were identified by spectroscopic analysis and, for known compounds, by comparison with published data. Goniothalamin (6) exhibited mild cytotoxic activity towards a colon cancer cell line (HT-29), with an IC50value of 64.17 ± 5.60 μM. Goniomicin B (2) give the highest antioxidant activity in the DPPH assay among all compounds tested, with an IC50 of 0.207 μM.

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Triterpenes And Steroids From The Leaves Of Aglaia Exima (Meliaceae), Kok Hoong Leong Oct 2012

Triterpenes And Steroids From The Leaves Of Aglaia Exima (Meliaceae), Kok Hoong Leong

Kok Hoong Leong

A study on the leaves of Aglaia exima led to the isolation of one new and seven known compounds: six triterpenoids and two steroids. Their structures were elucidated and analyzed mainly by using spectroscopic methods; 1D and 2D NMR, mass spectrometry, UV spectrometry and X-ray. All the triterpenoids and steroids were measured in vitro for their cytotoxic activities against eight cancer cell lines; lung (A549), prostate (DU-145), skin (SK-MEL-5), pancreatic (BxPC-3), liver (Hep G2), colon (HT-29), breast (MCF-7) and (MDA-MB-231). The new cycloartane triterpenoid, 24(E)-cycloart-24-ene-26-ol-3-one 1, showed potent cytotoxic activity against colon (HT-29) cancer cell line (IC50 11.5 μM).

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Spectaflavoside A, A New Potent Iron Chelating Dimeric Flavonol Glycoside From The Rhizomes Of Zingiber Spectabile Griff, Kok Hoong Leong Mar 2012

Spectaflavoside A, A New Potent Iron Chelating Dimeric Flavonol Glycoside From The Rhizomes Of Zingiber Spectabile Griff, Kok Hoong Leong

Kok Hoong Leong

The rhizomes of Zingiber spectabile yielded a new dimeric flavonol glycoside for which the name kaempferol-3-O-(4″-O-acetyl)-α-l-rhamnopyranoside-(I-6,II-8)-kaempferol-3-O-(4″-O-acetyl)-α-l-rhamnopyranoside; spectaflavoside A (1) was proposed, along with kaempferol and its four acetylrhamnosides (2–6), demethoxycurcumin (7) and curcumin (8). The structure of spectaflavoside A was elucidated by spectroscopic methods including, 1D and 2D NMR techniques. This is the first report on the occurrence of a dimeric flavonol glycoside in the Zingiberaceae and the second in nature. Spectaflavoside A was found to be a potent iron chelating agent.

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Erectogenic Effects Of Clerodendron Capitatum: Involvement Of Phosphodiesterase Type-5 Inhibition, Dr Syam Mohan Jan 2012

Erectogenic Effects Of Clerodendron Capitatum: Involvement Of Phosphodiesterase Type-5 Inhibition, Dr Syam Mohan

Syam Mohan

No abstract provided.

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