Purpose: To develop topical formulations of Clerodendrum petasites S. Moore (CP), and to optimize the skin
permeability and topical bioavailability of the active phenolic compounds therein.
Methods: The skin uptake and delivery of active compounds from two formulations, an oil-in-water
cream and a lotion (both containing 10% w/w CP extracts), were examined (a) in vitro using pig skin, and
(b) in vivo in human volunteers. Stratum corneum (SC) was collected by tape stripping and the
compounds were detected and quantified by high performance liquid chromatography coupled with
either mass spectrometry (HPLC–MS) or ultraviolet and photodiode array (HPLC–UV–PDA) detection.
Results: From the in vitro results, vanillic acid, verbascoside, nepetin and hispidulin, were chosen as
potential phenolic actives for topical delivery optimization from the formulations. In vivo, vanillic acid,
nepetin and hispidulin were appreciably taken up into the SC within 6 h, while verbascoside did not
penetrate beyond the most superficial layers. No significant differences in delivery were observed
between the two formulations, both of which were well tolerated.
Conclusions: The detected topical absorption of hispidulin, nepetin, and vanillic acid, from the cream and
lotion vehicles investigated, suggest that these compounds are potentially active compounds in Thai
traditional medicine for the treatment of a wide range of skin diseases