Metabolites of Streptomyces sp., an endophytic actinomycete from Alpinia oxyphylla.

Four known compounds had been isolated from the Streptomyces sp. YIM66017, and their structures were elucidated by spectral analysis as 2,6-dimethoxy terephthalic acid (1), yangjinhualine A (2), α-hydroxyacetovanillone (3) and cyclo(Gly-Trp) (4). Compound 1 was isolated from natural resources for the first time, and compounds 2-4 were isolated from streptomycetes for the first time. The 2,2-diphenyl-1-picrylhydrazyl radical-scavenging activity assays showed that 1 showed higher activity than rutin with IC50 of 4.61 μg/mL and 2 showed the activity with IC50 of 57.12 μg/mL.