Rice panicles: New promising unconventional cereal product for health benefits

• Rice panicle of 3 varieties was studied. PL was nutritionally (p < 0.05) higher.
• PL_EtOAc_Direct (Ins) was greater in FRAP as well as anti-tyrosinase effect (p < 0.05).
• The extracts were non-cytotoxic in fibroblast and neuron cultured cells.
• Neuro-activities were significant in PL_50% EtOH_EtOAc (Ins).
• The mainly phenolics were p-coumaric, ferulic and caffeic acids.

Historically, rice has been served as a food and as an herbal remedy. The claimed therapeutic properties of rice-derived products have attracted a considerable amount of attention, but these therapeutic properties are currently underestimated. Rice panicles of Phitsanulok 2 (PL), Suphan Buri 1 (SP) and San Pa Tong 1 (ST) varieties were compared based on their antioxidant activities and total phenolic content (TPC). The crude fiber, fat and mineral contents of PL were significantly (p < 0.05) greater than those of SP and ST. Phenolics were particularly found in PL, including insoluble phenolics in the PL_50%EtOH_EtOAc (Ins), PL_EtOAc_Direct (Ins) and PL_EtOAc (Ins) extracts. These extracts were comparable in their TPC, and ABTS and DPPH scavenging activities. The FRAP reducing power of PL_EtOAc_Direct (Ins) was significantly (p < 0.05) greater than those of the others, and it was similar to the anti-tyrosinase effect. All of the extracts were non-cytotoxic in fibroblasts and cultured neurons. The neuroprotective and neuritogenic activities were significant (p < 0.05) in PL_50%EtOH_EtOAc (Ins). The extracts contained health-promoting phenolics, particularly p-coumaric (2477–3153 μg/ml), ferulic (329–347 μg/ml) and caffeic (387–413 μg/ml) acids. Rice panicle extracts are therefore highlighted as potential antioxidants for health promotion products.