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Nor N.A.M.,Universiti Sains Malaysia | Nor N.A.M.,Darul Iman University, Malaysia | Halim A.S.,Universiti Sains Malaysia | Shamsuddin S.,Universiti Sains Malaysia | And 3 more authors.
Journal of Sustainability Science and Management | Year: 2013

Wound healing is a natural restorative response to tissue injury. Nowadays, wound healing study has become an active area for many researchers and the development of biomaterials as wound management product has been increased. Biocompatibility is one of the most important criteria in biomaterials selection. The objective of this study is to examine the cytotoxicity effect of newly developed chitosan derivatives film on fibroblasts growth and its proliferationin-vitro. The effect of oligochitosan on the secretion of interleukin 8 (IL-8) and transforming growth factor beta (TGF-β) also is being evaluated. The cytotoxicity of these chitosan products were compared by measuring cell survival with the tetrazolium salt reduction (MTT) assay which measured the mitochondrial activity of active living cells. The determination of fibroblasts proliferation was done by using CellTiter 96® Aqueous Non- Radioactive Cell Proliferation Assay. The results demonstrated that oligochitosan film was non-toxic. Low molecular weight chitosan derivatives have the ability to induce the proliferation of fibroblasts and stimulation of proliferation increased with time exposure. However, no fibroblasts proliferation detected in the presence of high molecular weight chitosan derivatives during the 5 days of incubation. The secretion of IL-8 by fibroblasts was also detected at low concentration of chitosan derivatives. However, none of TGF-β was detected. This study clearly demonstrated the growth modulating effects of chitosan on fibroblasts in-vitro. Thus, further study should be developed in order to clarify the effect of biomedical grade chitosan for wound management applications. © Penerbit UMT. Source


Alehashem M.S.,University of Malaya | Lim C.-G.,Environmental and Bioprocess Technology Center | Thomas N.F.,University of Malaya
RSC Advances | Year: 2016

The landmark synthesis of vinblastine (and analogues) by Boger et al. involves a tandem [4 + 2]/[3 + 2] cycloaddition that resulted in the construction of vindoline followed by FeCl3 promoted, radical cation mediated, catharanthine fragmentation/vindoline coupling that yields anhydrovinblastine (after NaBH4 reduction of the iminium ion) or vinblastine directly (by virtue of exposure of the first formed anhydrovinblastine to ferric oxalate-NaBH4, air, 0 °C). It is important to emphasise that this inspired and versatile innovation is essentially a one-pot vinblastine synthesis resulting from exposure of catharanthine/vindoline to a FeCl3/Fe2 (oxalate)3 combination. The mechanistic hypothesis of Kutney, in which the C(16)-C(21) cleavage in catharanthine leading to the azabenzfulvene is triggered by tertiary amine oxidation to the radical cation, has been subjected to a formidable challenge by Boger who has suggested, based on careful experimentation involving a number of judiciously selected simplified analogues, that indole C(2)-C(3) oxidative radical cation generation rather than tertiary amine radical cation formation is the key event that renders fragmentation/coupling possible. This review will attempt to assess the evidence for this novel and intriguing alternative mechanistic proposal and the practical implications of this FeCl3/Fe2 (oxalate)3 combination. A concise history of the azabenzfulvene intermediate will first be presented by way of introduction. © The Royal Society of Chemistry 2016. Source


Kee C.H.,University of Malaya | Ariffin A.,University of Malaya | Awang K.,University of Malaya | Noorbatcha I.,International Islamic University Malaysia | And 4 more authors.
Molecules | Year: 2011

The n-butyramido, isobutyramido, benzamido, and furancarboxamido functions profoundly modulate the electronics of the stilbene olefinic and NH groups and the corresponding radical cations in ways that influence the efficiency of the cyclization due presumably to conformational and stereoelectronic factors. For example, isobutyramidostilbene undergoes FeCl 3 promoted cyclization to produce only indoline, while n-butyramidostilbene, under the same conditions, produces both indoline and bisindoline. © 2011 by The Authors. Source


Kee C.H.,University of Malaya | Ariffin A.,University of Malaya | Awang K.,University of Malaya | Takeya K.,Tokyo University of Science | And 9 more authors.
Organic and Biomolecular Chemistry | Year: 2010

The syntheses of fourteen unusual o-carboxamido stilbenes by the Heck protocol revealed surprising complexity related to intriguing substituent effects with mechanistic implications. The unexpected cytotoxic and chemopreventive properties also seem to be substituent dependent. For example, although stilbene 15d (with a 4-methoxy substituent) showed cytotoxicity on HT29 colon cancer cells with an IC50 of 4.9 μM, the 3,4-dimethoxy derivative (15c) is inactive. It is interesting to observe that the 3,5-dimethoxy derivative (15e) showed remarkable chemopreventive activity in WRL-68 fetal hepatocytes, surpassing the gold standard, resveratrol. The resveratrol concentration needed to be 5 times higher than that of 15e to produce comparable elevation of NQO1. © 2010 The Royal Society of Chemistry. Source

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