A novel reverse phase high performance liquid chrom atographic method with photodiode detection was dev eloped and validated to qualitatively and quantitatively a nalyze the extracts and products of Allamanda catha rtica flowers. The gradient method was carried out with a C18 colu mn using acetonitrile and acidified water as the mo bile phase, at a flow rate of 1.0 mL min -1 and a total time of 25 min. Plumieride, an iridoide glycoside present in Allamanda species, was used as a marker in the method validat ion. Four flavonoids also were identified and quant ified. Plumieride was detected at 230 nm at a retention ti me of 9.58 min. Flavonoids peaks were detected at 3 55 nm and at 10 to 13 min. Samples of extract and nanoemulsions were analyzed. The method was shown to be simple, f ast, selective, precise and accurate for A. cathartica f lower extracts and nanoemulsions. This method shoul d be useful for the pharmaceutical and cosmetic industry in the analysis of phytoderivatives and products from A. cathartica flowers and may be further adapted to other product s containing herbal drug derivatives.