Isolation and identification of two alkaloid structures with radical scavenging activity from Actinokineospora sp. UTMC 968, a new promising source of alkaloid compounds.

For decades, natural products from Actinomycetes have been recognized as one of the inestimable sources of therapeutic compounds. Presently, due to some challenges in the identification of novel compounds including the validation of novel natural products and their compatibility with the high throughput screening bioassays, evaluating new activity from known commercial ones would be an important designation. On the other hand, finding new sources of bioactive compounds from Actinomycetes can be promising in attaining pharmaceutical compounds with fewer purification steps and cost-effective production of the bioproducts. Here we describe the isolation and identification of two alkaloid compounds from a soil actinobacterium Actinokineospora sp. UTMC 968 including N-acetyltyramine (1) and N-acetyltryptamine (2) with revealing a new bioactivity for these molecules. The producer is a rare actinobacterium belonging to family Pseudonocardiaceae as the first alkaloid compounds producer genus in its family. The structures of alkaloid 1 and 2 were assigned on the basis of 1D and 2D NMR spectroscopy and MS analyses. Compound 1 and 2 are used commercially for their pharmaceutical activity but their radical scavenging activity has not previously been reported. The results of 1,1-diphenyl-2-picrylhydrazyl radical scavenging assay represented a remarkable DPPH radical scavenging capability with an IC50 value of 64.7 ± 0.5 and 131.3 ± 1.8 µg/mL for compound 1 and 2, respectively.