Comparison of the partition coefficient and skin penetration of a marine algal toxin (lyngbyatoxin A).

Lyngbyatoxin A is produced by marine algae, and causes local cutaneous toxicity in swimmers. The purpose of this research was (1) to determine the partition coefficient of lyngbyatoxin A in octanol/water and (2) to use methods in vitro to measure the penetration and distribution of lyngbyatoxin A in guinea pig and human skin. Discs of excised guinea pig and human skin were mounted in diffusion chambers that exposed the epidermal surface to air and bathed the dermis with HEPES-buffered Hanks' balanced salt solution with gentamicin sulphate. The epidermal surfaces were dosed with 26 micrograms lyngbyatoxin A/cm2 dissolved in 13 microliters dimethyl sulphoxide/cm2. The diffusion chambers were incubated at 36 degrees C for varying periods (1.0-24 hr). HPLC was used to quantify lyngbyatoxin A. Skin penetration was calculated by summing the amount of lyngbyatoxin A recovered from the dermis and receptor fluid. The mean partition coefficient for lyngbyatoxin A was 1.53. Penetration of lyngbyatoxin A (expressed as a percentage of dose, n = 3) in guinea pig and human skin was 23 and 6.2 (respectively) after 1 hr of topical exposure. The amount of lyngbyatoxin A in the dermis and receptor fluid did not change significantly over time.