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Title: Topical delivery and effects of Harpagophytum procumbens
Author: Abdelouahab Ouitas, Nassima
ISNI:       0000 0004 2747 7204
Awarding Body: Cardiff University
Current Institution: Cardiff University
Date of Award: 2009
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Inflammation is a general term that is related to diseases such as rheumatoid arthritis and psoriasis. Harpagophytum procumbens (H. procumbens), commonly known as Devil's Claw, is a popular natural anti-inflammatory product. Relatively high proportions of active glycosides in its secondary tubers are of particular interest. Therefore, in this thesis four of the major glycosides of H. procumbens (harpagoside, harpagide, verbascoside and S-O-p-coumaroyl harpagide) were analysed for their topical and trans-cutaneous delivery, anti-inflammatory and virucidal effects. The delivery depended on their physiochemical characteristics and the vehicles used. They were all successfully delivered across the skin layers into subcutaneous compartments and achieved steady state flux of (20.0, 129.7, 30.6, 26.7 x 10" umol cm" hr") in water. H. procumbens and three glycosides showed decreased amounts of expressed inflammatory components using western blotting, immunocytochemistry and ELISA assays. Interestingly, harpagide was discovered to be pro-inflammatory. Amounts of H. procumbens delivered trans-cutaneously (receptor phase) were re-applied on ex-vivo porcine skin. Despite the low amounts of permeated glycosides, they successfully inhibited the expression and pathway of the inflammatory enzyme COX-2. The amounts of the active glycosides were determined in different formulations and very low amounts were found. Hence, standardizing the proportional amounts of active components is important in order to optimise the effects of H. procumbens. The delivery of H. procumbens into ex-vivo joint capsule led to undetectable amounts of glycosides. This was expected due to the multi layers the polar compounds had to cross before reaching the synovial fluid. Finally, cytotoxic and plaque assays were carried out for H. procumbens and its glycosides. The data obtained showed significant virucidal effects towards Herpes simplex virus (HSV-1). H. procumbens used trans-cutaneously proved to be effective in-vitro and a new mechanism proposed whereby active glycosides can work either synergistically or antagonistically within the extract towards inflammation and infection (eg. cold sores).
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available