Quantifying Piceid and Resveratrol in Rice

To determine the piceid and resveratrol content in rice grains, a fine powder of each sample was mixed with 80% methanol (300 mg fine powder: 900 µL of 80% methanol). The mixture was sonicated for 30 min at room temperature. The tube was centrifuged at 10,000× g at 4 °C for 5 min. After centrifugation, the supernatant was collected and filtered through a 0.2 m nylon membrane filter. The filtered supernatant (1 µL) was used for HPLC analysis of piceid and resveratrol amounts on a Waters e2695 (Waters, Milford, MA, USA). HPLC was performed as previously described [53 (link)]. Piceid and resveratrol contents were quantified by comparing them to the calibration standard curve (Figure 6).