Phytochemical profiling and antioxidant activity of rice (Oryza sativa L. cv. KDML105) tissues at different developmental stages

ABSTRACT This study investigated the phytochemical profile and antioxidant activity of most well-known aromatic Thai rice ( Oryza sativa L. cv. Khao Dawk Mali 105; KDML105) tissues at three development stages (milk, dough and maturity). Leaves, straw and grain were analyzed for total chlorophyll content (TCC), total phenolic content (TPC), and antioxidant capacity using 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging and ferric reducing antioxidant power (FRAP) assays. Phenolic acids and flavonoids were identified and quantified by HPLC. Among tissues, dough-stage leaves showed the highest chlorophylls, TPC, and antioxidant activity, surpassing straw and grain. Principal component analysis (PCA) revealed cinnamic acid, apigenin, and hydroxybenzoic/hydroxycinnamic acid derivatives as major contributors to antioxidant capacity. These findings indicate that rice leaves, particularly at the dough stage, are an underutilized source of natural antioxidants with potential for functional food applications. KDML105 serves as a representative model of Indica aromatic rice, though further studies across cultivars and tissues are needed.