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Permatang Kuching, Malaysia

Rajasekaran D.,Swinburne University of Technology | Palombo E.A.,Swinburne University of Technology | Yeo T.C.,Sarawak Biodiversity Center | Ley D.L.S.,Sarawak Biodiversity Center | And 3 more authors.

The emergence of drug resistant variants of the influenza virus has led to a need to identify novel and effective antiviral agents. As an alternative to synthetic drugs, the consolidation of empirical knowledge with ethnopharmacological evidence of medicinal plants offers a novel platform for the development of antiviral drugs. The aim of this study was to identify plant extracts with proven activity against the influenza virus. Extracts of fifty medicinal plants, originating from the tropical rainforests of Borneo used as herbal medicines by traditional healers to treat flu-like symptoms, were tested against the H1N1 and H3N1 subtypes of the virus. In the initial phase, in vitro micro-inhibition assays along with cytotoxicity screening were performed on MDCK cells. Most plant extracts were found to be minimally cytotoxic, indicating that the compounds linked to an ethnomedical framework were relatively innocuous, and eleven crude extracts exhibited viral inhibition against both the strains. All extracts inhibited the enzymatic activity of viral neuraminidase and four extracts were also shown to act through the hemagglutination inhibition (HI) pathway. Moreover, the samples that acted through both HI and neuraminidase inhibition (NI) evidenced more than 90% reduction in virus adsorption and penetration, thereby indicating potent action in the early stages of viral replication. Concurrent studies involving Receptor Destroying Enzyme treatments of HI extracts indicated the presence of sialic acid-like component(s) that could be responsible for hemagglutination inhibition. The manifestation of both modes of viral inhibition in a single extract suggests that there may be a synergistic effect implicating more than one active component. Overall, our results provide substantive support for the use of Borneo traditional plants as promising sources of novel anti-influenza drug candidates. Furthermore, the pathways involving inhibition of hemagglutination could be a solution to the global occurrence of viral strains resistant to neuraminidase drugs. © 2013 Rajasekaran et al. Source

Daker M.,Institute for Medical Research | Yeo J.,Sarawak Biodiversity Center | Bakar N.,Institute for Medical Research | Abdul Rahman A.S.A.,Sarawak Biodiversity Center | And 3 more authors.
Experimental and Therapeutic Medicine

Nasopharyngeal carcinoma (NPC) is a type of tumour that arises from the epithelial cells that line the surface of the nasopharynx. NPC is treated with radiotherapy and cytotoxic chemotherapeutic drugs such as cisplatin and 5.fluorouracil. However, current strategies are often associated with potential toxicities. This has prompted efforts to identify alternative methods of treatment. The present study aimed to investigate silvestrol and episilvestrol.mediated inhibition of cell proliferation in human NPC cells. The growth kinetics of NPC cells treated with silvestrol or episilvestrol were monitored dynamically using a real.time, impedance.based cell analyzer, and dose.response profiles were generated using a colorimetric cell viability assay. Furthermore, apoptosis was evaluated using flow cytometry and high content analysis. In addition, flow cytometry was performed to determine cell cycle distribution. Finally, the effects of combining silvestrol or episilvestrol with cisplatin on NPC cells was examined. Apoptosis was not observed in silvestrol and episilvestrol.treated NPC cells, although cell cycle perturbation was evident. Treatment with both compounds induced a significant increase in the percentage of cells in the G2/M phase, as compared with the control. In vitro cultures combining silvestrol or episilvestrol with cisplatin showed synergistic effects against NPC cells. The results of the present study suggested that silvestrol and episilvestrol had an anti.tumour activity in NPC cells. Silvestrol and episilvestrol, particularly in combination with cisplatin, merit further investigation, so as to determine the cellular mechanisms underlying their action(s) as anti.NPC agents. © 2016, Spandidos Publications. All Rights Reserved. Source

Galappathie S.,Swinburne University of Technology | Palombo E.A.,Swinburne University of Technology | Yeo T.C.,Sarawak Biodiversity Center | Ley D.L.S.,Sarawak Biodiversity Center | And 3 more authors.
Journal of Herbal Medicine

Experimental assays were carried out to validate traditional claims about medicinal plants collected by the Traditional Knowledge Documentation Program at the Sarawak Biodiversity Centre on the island of Borneo. The majority of the medicinal plants are utilised as traditional therapies for various diseases, including diarrhoea, food poisoning, vaginomycosis, sexually transmitted infections (gonorrhoea) and furunculosis. Six medicinal plants used as indigenous herbal medicines were individually screened for antimicrobial and antifungal effects using their crude extracts and were found to inhibit a broad range of pathogenic microorganisms. Plant extracts derived from Fibraurea tinctoria, Polyalthia hookeriana, Pyrenaria sp., Baccaurea lanceolata, Goniothalamus tapisoides and Goniothalamus velutinus were demonstrated to have the highest antimicrobial activities. Pyrenaria sp. showed significant antifungal activity against Candida albicans with minimum inhibitory and minimum fungicidal concentrations of 25 μg/mL and 50 μg/mL, respectively. The evidence in this study has highlighted the effectiveness of using the traditional knowledge approach to screen for antimicrobial and antifungal activity in plants to evaluate their potential as herbal remedies for human and animal protection against pathogens. © 2014 Elsevier GmbH. All rights reserved. Source

Yeo T.C.,Sarawak Biodiversity Center | Naming M.,Sarawak Biodiversity Center | Manurung R.,Sarawak Biodiversity Center
Combinatorial Chemistry and High Throughput Screening

The Sarawak Biodiversity Centre (SBC) is a state government agency which regulates research and promotes the sustainable use of biodiversity. It has a program on documentation of traditional knowledge (TK) and is well-equipped with facilities for natural product research. SBC maintains a Natural Product Library (NPL) consisting of local plant and microbial extracts for bioprospecting. The NPL is a core discovery platform for screening of bioactive compounds by researchers through a formal agreement with clear benefit sharing obligations. SBC aims to develop partnerships with leading institutions and the industries to explore the benefits of biodiversity. © 2014 Bentham Science Publishers. Source

Kumarasingha R.,Swinburne University of Technology | Kumarasingha R.,Monash University | Palombo E.A.,Swinburne University of Technology | Bhave M.,Swinburne University of Technology | And 5 more authors.
International Journal for Parasitology

Traditional healers in Sarawak, Malaysia, use plants such as Picria fel-terrae, Linariantha bicolor and Lansium domesticum to treat gastrointestinal infections. This study aimed to test whether their nematocidal activities could be confirmed in vitro using highly standardised Caenorhabditis elegans models. We applied eight different ethanol solubilised plant extracts and two commercial anthelmintic drugs to larval and adult stages of C. elegans in vitro. Seven C. elegans strains were evaluated, one wild type and six strains with GFP-tagged stress response pathways to help characterise and compare the pathways affected by plant extracts. Our in vitro screen confirmed that both of the commercial anthelmintic drugs and five of the eight traditionally used plant extracts had significant nematocidal activity against both larval and adult C. elegans. The most effective extracts were from P. fel-terrae. The plant extracts triggered different stress response pathways from the commercial anthelmintic drugs. This study showed that using traditional knowledge of plant medicinal properties in combination with a C. elegans in vitro screen provided a rapid and economical test with a high hit rate compared with the random screening of plants for nematocidal activities. The use of transgenic C. elegans strains may allow this approach to be refined further to investigate the mode of action of active extracts. © 2014 Australian Society for Parasitology Inc. Source

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