## 4 Discussion  
Sprouts of black (cv. BGR) and white (cv. RD6) glutinous rice with the different harvest ages (5-7, 10-15, and 20-25 days or young, middle and old age) showed different degree of antioxidant capacity. The _in vitro_ antioxidant capacity of BGR is higher than RD6 based on TPC, TAC, DPPH, and FRAP assays. The hydroxyl group of phenolic compounds and anthocyanin has been reportedly responsible for antioxidant activity [41; 42; 43; 44]. DPPH yields a stable free radical of unpaired electron delocalized over the entire molecule. The scavenging activity of BGR and RD6 resulted in a decrease in DPPH radical  
Figure 3: (**a**). % Apoptotic cell of Jurkat cells after 24 h incubation with rice sprouts (BGR) at different harvest ages using annexin V staining and flow cytometry analysis. Docetaxel 100 \(\upmu\)M was used as a positive control. (**b**). Caspase 3/7 activity in Jurkat cells treated with 100 and 200 \(\upmu\)g/mL of BGR at different harvest ages at 24 h. Docetaxel at 10 \(\upmu\)M was used as a positive control. Data are expressed as the mean \(\pm\) SD of four replicates. (*) Value is significantly different (\(p<0.05\)) from untreated group (100%). (#) \(p<0.05\) when compared in the same extract at different concentrations. absorption proportional to the concentration of radicals that were scavenged. The lowest IC\({}_{50}\) from DPPH assay of middle and old age of BGR showed the greatest scavenging activity among harvest ages and cultivars (\(p<0.05\)). Moreover, the single-electron transfer mechanism based on the ferric ion reducing capability of BGR and RD6 was evident. Interestingly, BGR at middle and old age exhibited greater ferric reducing antioxidant power (FRAP) than RD6. A previous study reported on the antioxidant activity of the rice grass juices of various rice cultivars based on DPPH and FRAP assays [27]. The colored grass juice can prevent oxidative damage of supercoiled pBR322 DNA in a dose-dependent DNA protective effect. Their results showed that the colored rice (cv. Kum) possessed higher TPC than the white rice cultivar (cv. RD6). Moreover, TAC was also high in colored rice grass juices. The colored grass juice of Kum Doisaket (cv. C-KDS) contained TAC higher than the other colored rice. These results are in agreement with our study regarding the higher TPC, DPPH scavenging activity, and ferric reducing antioxidant power of colored rice (BGR) than that of white-colored rice (RD6). Different harvest ages of BGR exhibited cytotoxic effects on Jurkat and HCT116 at 24 h and at 48 h and on HepG2 cells at 48 h. BGR at 5-7 days and 10-15 days showed high selective cytotoxic (with SI \(>\) 3) against Jurkat cells at 24 h and 48 h (\(p<0.05\)) when compared to RD6. At 48 h, BGR at 5-7 days and 20-25 days displayed high selectivity (SI \(\geq\) 3) against HepG2. Notably, the Vero cells were not sensitive to any compounds, indicating the safety of BGR and RD6 in the noncancerous cells. Cytotoxicity results of BGR are well correlated with the _in vitro_ antioxidant activity, which is higher than RD6. A further anticancer effect of BGR extract on the Jurkat cells was directly examined. In the present study, the causes of high cytotoxic effects of BGR in Jurkat cells were investigated vis-a-vis intracellular ROS (e.g., H\({}_{2}\)O\({}_{2}\)) and endogenous glutathione levels. BGR at middle and old age effectively decreased the ROS level in Jurkat cells at 12 h in a concentration-dependent manner. Moreover, a decrease in cellular ROS level corresponded with an increase in endogenous GSH in cells treated with BGR at 12 h. BGR increased GSH to circumvent oxidative damage caused by ROS in Jurkat cells. During a high level of intracellular ROS such as H\({}_{2}\)O\({}_{2}\), GSH cleaves H\({}_{2}\)O\({}_{2}\) via GSH reductase to convert ROS to H\({}_{2}\)O [1; 45]. The middle and old age of BGR demonstrated the greatest antioxidant activity in Jurkat cells as a ROS reducer and GSH activator.