Antioxidant activity of different varieties of lotus (Nelumbo nuficera Gaertn) rhizome
The antioxidant activity of different representative varieties of lotus (Nelumbo nuficera Gaertn) rhizome (Na ma, E lian si hao, Dong he zao ou and E lian wu hao) was carried out. 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 conducted to assess the antioxidant activity of lotus rhizome. Results showed that there was no significant difference in the total phenolic content between any two of four varieties of lotus rhizome, expect E lian wu hao of which the total phenolic content, extracted with 80 percent ethanol aqueous solution (Abbr. 80 percent ethanol), was significantly lower. The average total phenolic content in four varieties was 146 mg GAE/100g lotus rhizome and 117mg GAE/100g lotus rhizome, extracted with 80 percent ethanol and water, respectively. The order of FRAP value and DPPH scavenging activity in four varieties of lotus rhizome was as follows: Na ma > E lian si hao > Dong he zao ou > E lian wu hao, and the FRAP value and DPPH scavenging activity of four varieties of lotus rhizome extracted with 80 percent ethanol are higher than that with water. There was no significant difference in the antioxidant activity against β-carotene-linoleic acid in four varieties, and the antioxidant activity of lotus rhizome extracted with water is higher than that with 80 percent ethanol.
Lotus (Nelumbo nucifera Gaertn, N. nuficera) is a perennial aquatic plant growing and consumed throughout Asia (1). All parts of lotus are used for various medicinal purposes in oriental medicine (2). The seed of lotus is used in folk remedies as diuretic, cooling agent, antiemetic and antidote in the treatment of tissue inflammation, cancer, skin disease, leprosy and poisoning (3, 4). The leaf of lotus is considered best for “over-coming body heat”, and stopping bleeding (5). The extract of lotus stalk shows anti-pyretic effect (6), while the extract of lotus leaf and stamen shows anti-oxidant effect and strong radical scavenging activity (7, 8).
In China, lotus rhizome can be cooked into different dishes or eaten raw as a common vegetable. Especially, it has been applied in Chinese herbal prescriptions to alleviate tissue inflammation, cancer, and liver cirrhosis for a long time (9). It is reported that the aqueous ethanol extracts of lotus rhizome exhibit high antioxidant capacity (10), and the mian antioxidative compositions in lotus rhizome are phenolics including dopa, catechol, gallic acid, D-(+)-catechin and L-(-)-epicate ...