Development of a High-Performance Liquid Chromatographic Method for Asiaticoside Quantification in Different Skin Layers after Topical Application of a Centella asiatica Extract.

The topical application of extract has been commonly used for many different purposes but especially for cosmetic use in the treatment of gynoid lipodystrophy. Asiaticoside, the most active component in this extract, is responsible for its therapeutic activities. However, little is known to date about asiaticoside skin penetration. Thus, an analytical method for asiaticoside quantification in different skin layers after the topical application of extract was developed and skin permeation studies were performed with the plant extract to apply the analytical method developed. An extraction procedure to recover asiaticoside from the biological matrix was also developed. Asiaticoside was assayed by HPLC/UV (high-performance liquid chromatography-ultraviolet detection) using a gradient of ACN (acetonitrile) and 0.2% phosphoric acid (flow rate of 1.0 mL/min). The analytical procedure was validated according to U. S. Food and Drug Administration guidelines. Selectivity was shown, as endogenous skin components did not interfere with the asiaticoside peak. Analytical curve was linear (3 to 60 µg/mL) and the lower limit of quantification was determined (3 µg/mL). Asiaticoside recoveries from skin samples were 95.1% and 66.7% for the stratum corneum and remaining skin, respectively. After 48 h of permeation studies, a substantial amount of asiaticoside was quantified in the skin layers. The presence of asiaticoside was also detected in the receptor solution of Franz diffusion cells after 48 h (5.81 ± 1.00 µg/mL). The method was reliable and reproducible for asiaticoside quantification in skin samples, thereby making it possible to determine the cutaneous penetration profile of this drug in permeation studies.