GC–MS metabolomics was used to discriminate the phytochemicals profile of Indonesian white, red, and black rice brans, and Japanese white rice brans. This technique was used for the first time to identify compounds in rice brans having cytotoxic activity against WiDr colon cancer cells. Orthogonal Projection to the Latent Structure (OPLS) analysis showed that protocatechuic acid (PA) was a discriminating factor found in black rice brans which strongly correlated with its cytotoxicity (IC₅₀ 8.53 ± 0.26 µM). Real time-PCR data demonstrated that PA cytotoxicity at different concentrations (1, 5, 10, 25 and 50 µg/mL) was mediated through different pathways. Bcl-2 expression was downregulated at all tested concentrations indicating apoptosis stimulation. At 1–10 ppm concentration, PA activated both intrinsic and extrinsic apoptosis pathways since the expression of p53, Bax, caspase-8, and caspase-9 were upregulated. At a higher dose (25 and 50 µg/mL), PA possibly involved in pyroptosis-mediated pro-inflammatory cell death by upregulating the expression of caspase-1 and caspase-7.

GC-MS代谢组学用于区分印尼白米糠，红米糠和黑米糠以及日本白米糠的植物化学成分。该技术首次用于鉴定米糠中对WiDr结肠癌细胞具有细胞毒活性的化合物。潜在结构的正交投影（OPLS）分析表明，原儿茶酸（PA）是黑米糠中的鉴别因子，与它的细胞毒性密切相关（IC ₅₀8.53±0.26 µM）。实时PCR数据表明，不同浓度（1、5、10、25和50 µg / mL）的PA细胞毒性是通过不同途径介导的。Bcl-2表达在所有测试浓度下调，表明细胞凋亡受到刺激。由于p53，Bax，caspase-8和caspase-9的表达上调，在1-10 ppm的浓度下，PA激活了内在和外在的凋亡途径。在较高剂量（25和50 µg / mL）下，PA可能通过上调caspase-1和caspase-7的表达而参与了热解介导的促炎细胞死亡。