In Vitro Identification Of Hdl Receptor, Sr-B1 Regulator From Selected Natural Products
| dc.contributor.author | Nadarasan, Karthiyayini | |
| dc.date.accessioned | 2016-11-24T03:10:28Z | |
| dc.date.available | 2016-11-24T03:10:28Z | |
| dc.date.issued | 2015-08 | |
| dc.description.abstract | Atherosclerosis is a condition where the artery wall thickens as a result of the accumulation and retention of fatty materials due to an absent of adequate removal of fats and cholesterols by functional high density lipoprotein. SR-B1 is a cell surface receptor which plays a crucial role in cholesterol metabolism via reverse cholesterol transport (RCT) pathway. A reporter gene based assay was developed by implying the promoter region of SR-B1 gene as target gene to test extracts from natural products for the anti-atherosclerotic properties. Total of 16 plant extracts and 11 marine extracts were screened using the developed assay. Two extracts, namely Andrographis paniculata (Hempedu bumi) and Trochus niloticus (Giant top shell snail) showed an distinguished activity in preliminary screening. The subsequent work was unable to proceed for Trochus niloticus due to insufficient samples and also the samples variation between collected batches. Therefore, works were only carried out using Andrographis paniculata due to its samples availability. Four compounds were isolated from A.paniculata and subjected to screening. Utilising transient transfection approach, the potent activity of the compounds in elevating SR-B1 promoter activity was evaluated. The positive hit compound was identified as andrographolide based on NMR and mass spectroscopic analysis. Subsequently, semi-quantitative real time PCR and immunohistochemistry was employed to observe the effect of andrographolide on SR-B1 mRNA expression and its protein content in HepG2 cells respectively. These findings were further validated by performing Diotadecylindocarbocyanine-High Density Lipoprotein (Dil-HDL) uptake assay. The preliminary screening performed using transient transfection approach demonstrated that andrographolide mediated the trans-activation of SR-B1 promoter, thereby increased the transcriptional activity of SR-B1 in dose dependent manner. Subsequently, immunohistochemistry and mRNA expression study illustrated the mRNA and the protein expressions of the SR-B1 was up-regulated by andrographolide. Similarly, the Dil-HDL assay further confirmed the HDL cholesterol efflux was significantly improved in andrographolide-treated HepG2 cells. Conclusively, we have demonstrated andrographolide as a potential transcriptional up-regulator of SR-B1 in HepG2 cells and possesses anti-atherosclerotic activity. | en_US |
| dc.identifier.uri | http://hdl.handle.net/123456789/3205 | |
| dc.subject | Natural History | en_US |
| dc.title | In Vitro Identification Of Hdl Receptor, Sr-B1 Regulator From Selected Natural Products | en_US |
| dc.type | Thesis | en_US |
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