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Title: Traditionally used Thai medicinal plants : in vitro anti-inflammatory, anticancer and antioxidant activities
Author: Siriwatanametanon, Nisarat
ISNI:       0000 0004 2690 8674
Awarding Body: UCL (University College London)
Current Institution: University College London (University of London)
Date of Award: 2010
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INTRODUCTION: This thesis presents a panel of the anti-inflammatory, cytotoxic and antioxidant activities of nine plant species, which have been selected from Thai textbooks, in order to assess the traditional claims about the therapeutic potential and to select plants for further phytochemical research, of active compounds through bioassay-guided fractionation procedures. METHODS: Anti-inflammatory, Nuclear factor-kappa B (NF-κB) inhibitory effects on PMA-induced NF-κB activation in stably tranfected HeLa cells were determined by luciferase assay, and the effects on LPS-induced pro-inflammatory mediators prostaglandin E2 (PGE2), interleukin (IL)-6, IL-1β, and tumor necrosis factor (TNF)α in primary monocytes were assessed by ELISA. Cytotoxic activities were examined against cervix cancer HeLa cells, human leukaemia CCRF-CEM cells and the multidrug-resistant CEM/ADR5000 cells using the MTT and XTT tests. However, as redox status has been linked with both inflammation and cancer, antioxidant effects were also assessed using the DPPH, lipid-peroxidation, and Folin- Ciocalteau methods. Phytochemical investigation of active compounds from the methanol extract of G. pseudochina var. hispida was carried out using Sephadex LH-20 column chromatography, TLC and HPLC as well as NMR and MS spectroscopic techniques. RESULTS: Among the nine species, the methanol extract of Gynura pseudochina var. hispida and the ethylacetate extract of Oroxylum indicum showed the most promising NF-κB-inhibitory effects with the lowest IC50 values (41.96 and 47.45 μg/ml, respectively). The ethyl acetate and methanol extracts of Muehlenheckia platyclada did not inhibit the NF-κB activation but effectively inhibited the release of IL-6, IL-1β and TNF-α with IC50 values ranging between 0.28 and 8.67 μg/ml. The petroleum ether extract of Pouzolzia indica was the most cytotoxic against CCRF-CEM cells and the multidrug resistant CEM/ADR5000 cells (9.75% and 10.48% viability, at 10 μg/ml, respectively). The ethylacetate extract of Rhinacanthus nasutus showed the most potent cytotoxicity against HeLa cells (IC50 3.63 μg/ml) and the methanol extract of R. nasutus also showed specific cytotoxicity against the multidrug resistant CEM/ADR5000 cells (18.72% viability at 10 μg/ml, p< 0.0001 compared to its cytotoxicity against CCRF-CEM cells). Moreover, the ethylacetate extract of O. indicum showed a high level of antioxidant activity by inhibiting lipid-peroxidation (IC50=0.08 μg/ml). As the most active anti-inflammatory species via the NF-κB signaling pathway, G. pseudochina var. hispida was selected for further investigation of active compounds. Through bioassay guided fractionation and isolation procedures, flavonoid glycosides; quercetin-rutinoside (rutin), dicaffeoylquinic acid derivatives and caffeoylquinic acid were isolated as the active NF-κB inhibitors. CONCLUSIONS: This thesis provides in vitro evidence for the use of the Thai plants, most importantly Gynura pseudochina var. hispida, Oroxyhm indicum and Muehlenheckia platyclada as Thai anti-inflammatory remedies. The active compounds isolated from the methanol extract of G. pseudochina var. hispida: the most potent NF-κB inhibitory extract, were identified as the known compounds quercetin-rutinoside and dicaffeoylquinic acid. Some of the results obtained might support the uses of the plants and are in agreement with previously reported literature, but some are in need of further investigation of either active compounds or their pharmacology. This finding provides a new insight for understanding the anti-inflammatory activities of a panel of traditionally used anti-inflammatory plants. The active compounds isolated from the methanol extract of G. pseudochina var. hispida: the most potent NF-κB inhibitory extract, were identified as the known compounds quercetin-rutinoside, dicaffeoylquinic acid and caffeoylquinic acid derivatives. The active compounds are reported from this genus for the first time.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available