Publications by authors named "Yee Ping Ho"

The different types of cell death occurring in HCT116 colorectal cancer cell after the treatment of cisplatin, carboplatin, oxaliplatin, DMC, Pt(NH3)2(demethylcantharidin:DMC) and Pt(R,R-1,2-diaminocyclohexane: DACH)(DMC) were examined. Pt(NH3)2(DMC) and Pt(R,R-DACH)(DMC) are the two DMC-integrated platinum complexes:Pt(R,R-DACH)(DMC) with the same Pt moiety as oxaliplatin and Pt(NH3)2(DMC) akin to carboplatin. Using the light scattering properties of cells combined with propidium iodide (PI) red fluorescence to distinguish between early apoptotic and necrotic cells, the results confirmed that apoptosis, which triggered by cisplatin, carboplatin and oxaliplatin, was the major type of cell death, while the major DMC-induced cell death type was necrosis.

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Amyloid β peptide (Aβ) induced toxicity is a well-established pathway of neuronal cell death which might play a role in Alzheimer's disease. In this regard, the toxic effect of Aβ on a cultured Aβ-sensitive neuronal cell line was used as a primary screening tool for potential anti-Alzheimer's therapeutic agents. The effects of nine pure compounds (vitamin E, α-asarone, salidroside, baicolin, magnolol, gastrodin, bilobalide, honokiol and β-asarone) from selected Chinese herbs on neuronal cell death induced by Aβ in NGF-differentiated PC12 cells were examined.

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Background: In vitro and animal studies have suggested that soy protein and isoflavones have favorable effects on glucose and insulin regulation, but intervention studies in humans are limited, and the results are controversial.

Objective: We investigated whether soy protein with isoflavones and soy isoflavone extracts could improve glycemic control and insulin sensitivity in postmenopausal women with early hyperglycemia.

Design: This was a randomized, double-blind, placebo-controlled trial that included 180 postmenopausal Hong Kong Chinese women with prediabetes or early untreated diabetes.

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Novel demethylcantharidin-platinum (DMC-Pt) complexes have been found to have superior in vitro anticancer activity against a number of human colon cancer cell lines when compared with oxaliplatin. One complex where the DMC-Pt moiety was integrated with trans-R,R-diamino-cyclohexane (DACH), exhibited the most pronounced cytotoxicity. To ascertain the mechanistic contribution of the DMC component, microarray analysis was conducted to compare the effect of the novel (R,R-DACH)-Pt-(DMC) complex and oxaliplatin, on the gene expression of human colorectal cancer (HCT116) cells.

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Oxaliplatin is a third generation platinum (Pt) drug with a diaminocyclohexane (DACH) entity, which has recently obtained worldwide approval for the clinical treatment of colon cancer, and apparently operates by a different mechanism of action to the classical cisplatin or carboplatin. Introducing a novel dual mechanism of action is one approach in designing a new platinum-based anticancer agent, whereby an appropriate ligand, such as demethylcantharidin (DMC), is released from the parent compound to exert a cytotoxic effect, in addition to that of the DNA-alkylating function of the platinum moiety. To investigate the likelihood of a novel dual mechanism of anticancer action, demethylcantharidin-integrated Pt complexes: Pt(R,R-DACH)(DMC) with the same Pt-DACH moiety as oxaliplatin, and Pt(NH(3))(2)(DMC) akin to carboplatin; were studied for their ability to induce DNA damage in HCT116 colorectal cancer cells by an alkaline comet assay.

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The pharmacokinetics and tissue distribution profiles of a novel series of traditional Chinese medicine-platinum (TCM-Pt) compounds [Pt(C(8)H(8)O(5))(NH(2)R)(2)]: 1 (where R=H), 3 (R=CH(3)) and 5 (R=C(6)H(10)), were studied in Sprague-Dawley rats following a single bolus intravenous (i.v.) injection.

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Objective: To investigate whether soy-derived isoflavone extract improves performance in cognitive function and quality of life in Chinese postmenopausal women.

Design: The study was a 6-month double-blind, randomized, placebo-controlled, parallel group trial. Participants were community-dwelling women aged 55 to 76 years; 191 eligible women were randomly assigned to receive a daily oral intake of 80 mg soy-derived isoflavones or an identical-appearing placebo for 6 months.

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A series of novel traditional Chinese medicine-platinum compounds has been found to be active against a number of murine and human cancers both in vitro and in vivo. Their high potency and the lack of cisplatin cross-resistance are believed to be due to the inclusion of the protein phosphatase 2A-inhibiting demethylcantharidin in the novel structures. A simple reversed-phase high-performance liquid chromatographic method was developed and validated as a stability-indicating assay for the platinum compounds.

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A series of platinum complexes derived from integrating demethylcantharidin (DMC) with different isomers of 1,2-diaminocyclohexane (DACH) has been synthesized and found to exhibit superior in vitro anticancer activity against colorectal and human hepatocellular cancer cell lines when compared with oxaliplatin, cisplatin, and carboplatin. Flow cytometric analysis revealed that the trans-DACH-Pt-DMC analogues showed similar behavior to oxaliplatin on affecting the cell cycle of the HCT116 colorectal cancer cell line, but distinct from that of cisplatin or carboplatin. The DACH component apparently dictates the trans-DACH-Pt-DMC complexes to behave mechanistically similar to oxaliplatin, whereas the DMC ligand appears to enhance the compounds' overall anticancer activity, probably by accelerating the cell cycle from G1 to S-phase with subsequent onset of G2/M arrest and accompanying apoptosis.

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Protein phosphatase 2A (PP2A) is a new target for platinum (Pt)-based cancer chemotherapeutic agents. A series of novel Pt complexes containing demethylcantharidin, a modified component of a traditional Chinese medicine (TCM), [Pt(C8H8O5)(NH2R)2] 1-5 have been shown to inhibit PP2A both in its purified form and in cell homogenates. In this study, the potential efficacy of compounds 1-5 in suppressing the growth of PP2A-highly expressed liver cancer was evaluated.

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A novel series of TCM-platinum complexes [Pt(C8H8O5)(NH2R)2] 1-5, designed from incorporating demethylcantharidin, a modified component from a traditional Chinese medicine (TCM) with a platinum moiety was found to circumvent cisplatin resistance in mouse leukemia and human hepatocellular carcinoma. These properties are most likely due to the inclusion of the protein phosphatase 2A (PP2A)-inhibiting demethylcantharidin in the novel compounds. We have investigated the potential synergistic effect of combining demethylcantharidin with a platinum-based antitumor agent, such as cisplatin, carboplatin, or oxaliplatin in vitro against L1210 mouse leukemia and SK-Hep-1 human hepatocellular carcinoma, and in vivo against a SK-Hep-1 subcutaneous-inoculated xenograft in nude mice, using median effect analysis.

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Novel TCM-platinum compounds [Pt(C(8)H(8)O(5))(NH(2)R)(2)] 1-5, derived from integrating demethylcantharidin, a modified component from a traditional Chinese medicine (TCM) with a platinum moiety, possess anticancer and protein phosphatase 2A inhibition properties. The compounds are able to circumvent cisplatin resistance by apparently targeting the DNA repair mechanism. Novel isosteric analogues [Pt(C(9)H(10)O(4))(NH(2)R)(2)] A and B, devoid of PP2A-inhibitory activity, were found to suffer from an enhanced DNA repair and were cross-resistant to cisplatin.

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The impact of cisplatin on cancer chemotherapy cannot be denied. Over the past 20 years, much effort has been dedicated to discover new platinum-based anticancer agents that are superior to cisplatin or its analogue, carboplatin. Most structural modifications are based on changing one or both of the ligand types coordinated to platinum.

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The present paper describes the development of a simple, accurate and reproducible gas chromatographic method for the determination of hydrolyzed demethylcantharidin release from a novel series of traditional Chinese medicine (TCM)-platinum compounds possessing potent anticancer and protein phosphatase 2A (PP2A)-inhibition properties. The salient features of the validated assay were a limit of detection (LOD) of 2 microg/mL, a limit of quantitation (LOQ) of 6 microg/mL, an intra- and inter-day precision of less than 11%, and an accuracy of more than 92%. The developed GC-flame ionization detection (FID) method was successfully utilized for the analysis of hydrolyzed demethylcantharidin, the TCM component that is slowly released from the novel compounds over 24 h, leading to PP2A inhibition.

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