Development and validation of a high-performance liquid chromatography method for the quantification of ursolic/oleanic acids mixture isolated from Plumeria obtusa.

Oleanolic acid (OA) and ursolic acid (UA) are ubiquitous pentacyclic triterpenes compounds in plants. These triterpenoids exhibit unique, important biological and pharmacological activities. For the investigation and development of topical drug delivery systems of triterpenoids in Plumeria obtusa is essential an adequate detection and quantification method for its application in skin permeation studies. The aim of this study was to develop a HPLC method for the determination of OA/UA from leaves of P. obtusa. Results showed that it was sensitive, repeatable, selective, accurate and precise. The detection limit was 0.93±0.21μg/mL and the quantification limit 2.81±0.65μg/mL. Determination coefficients were higher than 0.999 for concentrations between 3.62 and 116μg/mL. The intra and inter-day precision (relative standard deviation) was less than 1.50% and accuracy in terms of relative error ranged between -1.45 and 1.39%. The proposed HPLC method presented advantageous performance characteristics and it can be considered suitable for the evaluation of OA/UA in ex vivo permeation studies.