4.3. Quantification of DAA and AA by HPLC-PDA Analysis

One gram of the f. noni powder was diluted with 50 mL of H₂O-MeOH (1:1) and mixed thoroughly, and the solution was collected into a 50 mL volumetric flask for HPLC-PDA analysis. The extracts were combined, filtered, and dried in a rotary evaporator under vacuum at 50 °C. The dried extracts were re-dissolved in MeOH for HPLC analysis. An HPLC system (Shimadzu Corporation, Kyoto, Japan) equipped with an LC-20AD series pumping system and an SPD-M20A photodiode array detector (PDA) was used to analyze Noni, F. noni, and the standard iridoid (DAA and AA). Separation was carried out on a symmetry column (250 × 4.6 mm, 5 μm). The binary mobile phase consisted of water containing 0.1% formic acid (solvent A) and acetonitrile (solvent B). The flow rate was kept constant at 1.0 mL/min for a total run time of 40 min. The mobile phase was run with a gradient program: 0–5 min, 0% B; 5–40 min, 35% B. The sample injection volume was 5 µL. The column temperature was maintained at 25 °C. Peaks of interest were monitored at 190–380 nm using a PDA detector, and the spectra were compared with that of the standard.