Antioxidant Activity of a Novel Streptomyces Strain Eri12 Isolated from the Rhizosphere of Rhizoma curcumae Longae

There are rare reports about isolated streptomyces associated with the rhizosphere of Rhizoma Curcumae Longae. In the present study, the cultural characteristics, phylogenetic analysis of the streptomyces strain Eri12 isolated from the rhizosphere of Rhizoma Curcumae Longae and antioxidant activity of the ethyl acetate extract of mycelia of Eri12 were investigated. The Strain Eri12 was isolated from the rhizosphere of Rhizoma Curcumae Longae which was collected from Ya'an city of Sichuan province, southwest of China. The strain Eri12 was subjected to molecular identification which included DNA extraction, amplification of 16S rDNA, 16S rDNA gene sequencing, BLASTN search and construction of 16S rDNA phylogenetic tree using MEGA4.1. Simultaneously, the mycelia extract using ethyl acetate was tested for its antioxidant activity using ABTS (2,2-Azinobis-3-ethyl benzthiazoline-6-sulfonic acid) radicals scavenging test and DPPH [1,1-Diphenyl-2-picrylhydrazyl radical 2,2-Diphenyl-1-(2,4,6-trinitrophenyl) hydrazyl] radicals scavenging test. Analysis of 16S rDNA gene sequence demonstrated that the strains Eri12 was most closely related to representatives of the genera Streptomyces. The ethyl acetate extract showed the antioxidant activity against the ABTS (2,2-Azinobis-3-ethyl benzthiazoline-6-sulfonic acid) free radicals and DPPH(1,1-Diphenyl-2-picrylhydrazyl radical 2,2-Diphenyl-1-(2,4,6-trinitrophenyl) hydrazyl) free radicals with IC50 (The half-inhibitory concentration) of 172.4322.19 and 842.18161.24 g mL-1, respectively. So, it was suggested that the isolated streptomyces strain Eri12 could be a candidate for the nature resource of the antioxidants.