Further mechanistic studies demonstrated that both Radix Rubiae and realgar were capable of inducing cellular apoptosis on HaCaT cells in a dose- and time-dependent manner as shown by morphological inspection, DNA fragmentation, TUNEL assay, cell cycle analysis, annexin V---PI staining and Western blot analysis. HPLC fingerprintings were constructed for quality control of the Radix Rubiae extract using mollugin as the chemical marker. Further phytochemical study found that ethyl acetate fraction of this herb possessed potent growth inhibition on HaCaT cells, with IC50 of 0.9 microg/ml. However, the chemical compounds obtained from commercial sources including mollugin, alizarin, purpurin, and quinizarin failed to induce growth inhibition. Meanwhile, arsenic trioxide, arsenic pentoxide and arsenic iodide, three arsenic salts presented in realgar, had significant anti-proliferative effect on HaCaT cells, with IC50 values of 2.4, 16 and 6.8 microM, respectively; and cellular apoptosis was found to be the underlying mechanism for the observed growth inhibitory activity. Furthermore, Radix Rubiae, realgar and arsenic compounds were also revealed to possess growth inhibition when evaluated in a PHA-activated PBMC model, and all of the substances except arsenic pentoxide significantly attenuated the release of inflammatory cytokines such as IFN-y, TNF-alpha and IL-2 in PBMC, indicating an anti-inflammatory effect. The in vivo mouse tail model experiments demonstrated that arsenic trioxide, arsenic pentoxide and arsenic iodide were able to markedly induce mouse tail keratinocyte differentiation, while such differentiation-modulating effect observed in the fraction of Radix Rubiae was only marginal. / In summary, Radix Rubiae and realgar extracts and three arsenic compounds have been identified and characterized as potential anti-psoriatic agents. The discoveries from the present PhD project not only help put the traditional use of these medicinal substances for psoriasis treatment on a scientific footing, but also open up new opportunities for their development into novel anti-psoriatic therapies. / Psoriasis, a chronic inflammatory skin disorder affecting approximately 2-3% of the population worldwide, is characterized histologically by hyperproliferation and aberrant differentiation of epidermal keratinocytes. Many conventional therapies are offered for psoriasis treatment but there exist problems such as unsatisfactory efficacy, side effects and drug resistance. Many patients therefore turn to alternative and complementary medicines for help. Traditionally, Chinese herbal medicine has been extensively used to treat psoriasis and produced promising clinical results. The present PhD study was conducted to investigate psoriasis-treating Chinese herbal medicines with an aim to identify effective anti-psoriatic agents. Sixty Chinese medicinal materials were selected for the screening project based on their ethnomedical use in psoriasis. The ethanolic extracts of these medicinal substances were evaluated for their anti-proliferative action on cultured HaCaT human keratinocytes using microplate SRB and MTT assays. Among them, the root of Rubia cordifolia L. (Radix Rubiae) and realgar were found to have significant anti-proliferative effects, with IC50 values of 1.4 and 6.6 microg/ml, respectively as measured by MTT assay, while they exerted mild significant cytotoxicity on the human fibroblast Hs-68 cell line. / Tse, Wai Pui. / Advisers: C. T. Che; Z. X. Lin. / Source: Dissertation Abstracts International, Volume: 70-09, Section: B, page: . / Thesis submitted in: October 2008. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2009. / Includes bibliographical references (leaves 298-340). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts in English and Chinese. / School code: 1307.
| Identifer | oai:union.ndltd.org:cuhk.edu.hk/oai:cuhk-dr:cuhk_344410 |
| Date | January 2009 |
| Contributors | Tse, Wai Pui., Chinese University of Hong Kong Graduate School. Division of Chinese Medicine. |
| Source Sets | The Chinese University of Hong Kong |
| Language | English, Chinese |
| Detected Language | English |
| Type | Text, theses |
| Format | electronic resource, microform, microfiche, 1 online resource (xxxiv, 340 leaves : ill.) |
| Coverage | China, China |
| Rights | Use of this resource is governed by the terms and conditions of the Creative Commons “Attribution-NonCommercial-NoDerivatives 4.0 International” License (http://creativecommons.org/licenses/by-nc-nd/4.0/) |
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