Acid hydrolysis of the lentil samples was performed for the HPLC analysis of flavonoid aglycones according to a previous study, with minor modifications [19 (link)]. Briefly, 30 mg of lentil samples were mixed with 1 mL of 1.2 M HCl diluted with 50% aqueous methanol, and incubated at 90 °C for 2 h. Then, the mixtures were cooled in ice and were centrifuged at 12,800× g for 5 min. The supernatant was collected and filtered using a 0.45 μm PTFE filter (Futecs Co., Ltd., Daejeon, Republic of Korea) for HPLC analysis. Individual phenolic compounds analysis was performed with reversed-phase HPLC (Waters 2695 Alliance HPLC, Waters Inc., Milford, MA, USA) with an octadecylsilane column (Prontosil 120-5-C18 SH (5 μm, 250 × 4.6 mm), Bischoff, Leonberg, Germany). The gradient elution of mobile phases (0.1% formic acid in water and 0.1% formic acid in acetonitrile) followed the previously described method [19 (link)]. The injection volume was 10 μL. The flow rate was maintained at 1 mL/min. Peaks were detected at 360 nm using a Waters 996 photodiode array detector (Waters Inc.). Individual phenolics in lentil samples were quantified with kaempferol standard (Sigma-Aldrich Co., St. Louis, MO, USA).
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