In this study, the antioxidant activities of different parts of lotus (Nelumbo nuficera Gaertn) rhizome were compared. The total phenolic content of lotus rhizome was determined, and Ferric reducing antioxidant power (FRAP) assay, 1,1-diphenyl-2-picrylhydrazyl hydrate (DPPH) radical-scavenging assay and β-carotene-linoleic acid assay were performed to assess the antioxidant activity of lotus rhizome. Results showed that there was a significant difference in total phenolic content and antioxidant activity between any two of four parts of lotus rhizome. The order of total phenolic content and antioxidant activity in different parts of lotus rhizome was as follows: peel of old lotus rhizome > peel of young lotus rhizome > flesh of old lotus rhizome > flesh of young lotus rhizome. The total phenol content is significantly positive correlated with the antioxidant activity in different parts of lotus rhizome. This study has provided a basis for further exploring the antioxidant components in lotus rhizome.

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Rice bran, the industry byproduct, contains high levels of phenolic compounds. Based on glycerol, a green recovery of phenolics from rice bran was proposed. Extraction temperature (X 1 ), glycerol concentration (X 2 ) and liquid-to-solid ratio (X 3 ) were optimised by response surface methodology. Basic physical properties, that is, viscosity, conductivity, density were analysed and UPLC-Triple-TOF/MS method was applied for phenolic identification. Results showed the optimum conditions were X 1 = 66.76°C, X 2 = 19.47% and X 3 = 32.92 mL g À1 . Under these conditions, the recovery yield in total polyphenols was 708.58 AE 12.36 mg GAE/100 g DW. Moreover, the recovery capacity of phenolic compounds was significantly correlated with viscosity, conductivity and density of glycerol solution. Under the optimal conditions, totals of thirteen phenolic compounds were identified and phenolic acids (4-hydroxybenzoic acid, vanillic acid, syringic acid, 4-coumaric acid, ferulic acid and salicylic acid) were quantified. These results demonstrate glycerol can serve as an ideal green solvent to recover phenolic compounds from rice bran.

In vitro antioxidant activity of extracts of lotus rhizome with different solvent by gradient extraction was determined. The extraction yield and total phenolic content of extracts were determined. 1,1-diphenyl-2-picrylhydrazyl hydrate (DPPH) radical scavenging assay and β-carotene-linoleic acid assay were conducted to assess the antioxidant activity of the extracts. Results showed that the yield of butanol extract was the highest. The order of total phenolic content in different extracts was as follows: water extract < petroleum ether extract < chloroform extract < butanol extract < ethyl acetate extract, the same with that of the DPPH scavenging activity. The total phenolic content was significantly correlated with DPPH scavenging activity (R 2 = 0.9363). All extracts, except water extract with too poor antioxidant activity, showed obvious antioxidant activity against β-carotene-linoleic acid, and the antioxidant activity of butanol extract was significantly lower than others. There was no significant correlation between the antioxidant activity against β-carotene-linoleic acid and the total phenolic content (R 2 =0.1995).