Validation of an UV spectrophotometric method for determining diffractaic acid from Usnea sp. in inclusion complexes with hydroxypropyl-β-cyclodextrin

Abstract

Diffractaic acid (DA) presents several biological activities. The goal of this study was to develop and validate a UV spectrophotometric method for determining diffractaic acid in inclusion complexes with hydroxypropyl-β-cyclodextrin. Validation parameters were determined according to international guidelines for standardization. The linearity range of analytical curve was from 1 to 5 μg/mL and the regression equation: CDA = (Area - 0.0053)/0.1541 (r2 = 0.99998; n = 3). The intermediate precision indicated that the difference between the means was statistically insignificant (p < 0.05). Accuracy revealed a mean recovery percentage of diffractaic acid in inclusion complexes of 100.1 %. The method was robust and the formulation excipients did not interfere on diffractaic acid quantification. Limits of detection and quantification of diffractaic acid were 0.03 and 0.08 μg/mL, respectively. The proposed method proved to be accurate, precise and reproducible, thus being able to quantify diffractaic acid in raw material and inclusion complexes.