Chemical profiling of unpolished pigmented chakhao amubi rice produced lipid-lowering and cardioprotective effects via reducing oxidative stress and improving digestibility behaviour.

Abstract

The current research work was designed to study the amylose content, total phenolic content (TPC), total flavonoid content (TFC), total anthocyanin content (TAC) and digestibility of unpolished chakhao amubi (CA) rice extract along with antioxidant, antihyperlipidemic activity. In addition, the profiling of the bioactive polyphenolic compounds present in unpolished CA rice flour was evaluated. Based on the results obtained from the in vitro antioxidant and hypolipidemic activities of all the rice extract, CA-EtOH (ethanol) was selected for in vivo study. Effect of CA-EtOH after 45 days treatment was evaluated in high-fat-high-sugar (HFHS) induced Wistar rats. The unpolished CA rice produces higher levels of TPC (346.53 mg GAE/100 g DW), TFC (634.22 mg QUE/100 G DW) and TAC (873.34 mg C-3-G/100 g DW) compared to polished rice and CA-EtOH extract showed strong antioxidant activity with the lowest IC₅₀ value in in vitro antioxidant assays. The unpolished CA black rice extracts exhibited significant HMG CoA reductase inhibitory activity. Sinapic acid (620.20 mg/100 gm), o-coumaric acid (200.80 mg/100 gm), rosamarinic acid (199.30 mg/100 gm) and p-coumaric acid (156.60 mg/100 gm) were present abundantly. The fraction of RDS, SDS and RS in unpolished CA rice flour was significantly different (p < 0.05) compared to standard corn starch. Both the lower (CA-EtOH-200 mg/kg) and higher (CA-EtOH-400 mg/kg) doses of unpolished CA rice extract significantly (p < 0.001) reduce the body weight in HFHS induced rats. Oral administration of unpolished CA rice extract reduced the level of TC, TG, LDL-C, VLDL-C, LDH, SGOT, SGPT, ALP, CK-NAC, ApoA1, ApoB, ApoB/ApoA1, CRP, LP(a), LPO, AIP, AC, CPI, CRR were significantly (p < 0.001) improved in hyperlipidemic rat model. In addition, HDL-C, GSH, CAT, SOD and GPx levels were elevated. Thus, our current results suggested that unpolished CA black rice could be effective against oxidative stress, dyslipidaemia and cardiovascular diseases due to availability of the numerous functional moieties such as phenolic compounds.