Abstract
Purpose: Dihydroxyacetone (DHA), the primary ingredient in most sunless tanning solutions, causes a reaction in the stratum corneum turning the skin a brown color lasting until the stratum corneum is shed. Lawsone, the primary component of red henna, is used in henna tattooing and in reverse tattooing. It is known that DHA reacts with Lawsone, and it is suggested that their combined use may provide extended UV protection.|Methods: Permeability across pig skin was demonstrated for freshly prepared DHA (3%w/v) and Lawsone (0.035%) alone and in combination (in pH 7.4 PBS) using a side-by-side diffusion apparatus at 37ºC over 48 hours. Prior to the study, pig skin was removed from the back of shaved and thawed previously frozen pig ears using a silvers skin graft knife set to 0.5mm depth. The skin was then cut to fit the diffusion chambers using a razor and scissors. An HPLC method consisting of a Zorbax C18 column, and mobile phase (0.1M Acetic acid: Acetonitrile 75:25(v/v)) at a flow rate of 0.8mL/min was developed for the detection and separation of Lawsone, DHA, and products of Lawsone:DHA interactions if any. Effluents were monitored from 250-500nm using a photodiode array detector.|Results: Permeability studies showed significant flux differences when solutions were used alone verses in combination. Lawsone showed a flux of 15.93±0.771 and 0.013±0.003mg/cm2/hour, alone and with DHA respectively. DHA showed a flux of 64.52±0.270 and 75.02±0.333mg/cm2/hour, alone and with Lawsone respectively. By 48 hours Lawsone in the donor chambers of the combination solutions had been reduced by 99.81±6.18. Visual inspection of skins displays darker coloration of skins exposed to the combined solution verses individual solutions.|Conclusion: Our current study suggests that used in combination DHA and Lawsone may be preferentially reacting within the dermis of the pig ear. When taken with prior work by our lab these findings suggest possible enhanced UV protection will be shown in these samples.