In Thailand, Acanthus ebracteatus Vahl and Clerodendrum petasites S. Moore have been prescribed to treat skin diseases, such as rash, abscess, and urticaria, for at least 30 years. However, there is limited scientific support and no clinical trials that identify and verify the compounds that elicit useful pharmacological effects following their topical delivery.Vanillic acid was identified for the first time in A. ebracteatus together with verbascoside; furthermore, nine phenolic compounds, vanillic acid, 4-coumaric acid, ferulic acid, verbascoside, nepetin, luteolin, chrysin, naringenin, and hesperetin, and two reported, apigenin and hispidulin, were found in C. petasites. C. petasites (CP) was therefore chosen as the principal plant to be studied in this thesis. Hispidulin was quantified as a predominant compound, being present at 39 μmol/g (1.2% w/w) in a dried ethanolic extract.Various formulations of CP extracts were examined (a) in in vitro skin penetration experiments using Franz diffusion cells, and (b) in vivo using the tape-stripping method. Hispidulin penetrated through the skin within 3 hours; vanillic acid and nepetin were absorbed after 6 hours. In contrast, verbascoside was only taken up into the superficial layers of SC. There was no difference in the permeation of hispidulin, nepetin and vanillic acid from 10% w/w CP cream and lotion formulations. Hispidulin was percutaneously absorbed through the skin and taken up into the stratum corneum in the greatest amount, followed by vanillic acid and nepetin. It was found that the in vitro model was useful for preliminary formulation development, and that the tape-stripping method was robust and effective.Verbascoside, although a poor penetrant, was well released from the formulations in an in vitro release test, suggesting that it might be a potential skin surface-active compound, such as an antimicrobial. Hispidulin, nepetin and vanillic acid, based on their uptake and penetration into the skin, together with their known biological activities, may be considered as feasible candidates for the development of novel and effective antimicrobial, anti-inflammatory, and antioxidant formulations.
|Date of Award||19 Jun 2013|
|Supervisor||Richard Guy (Supervisor) & Michael Rowan (Supervisor)|
- clerodendrum petasites
- Thai traditional medicines
- topical delivery system