Characterization of anti-BCG benz[α]anthraquinones and new siderophores from a Xinjiang desert-isolated rare actinomycete Nocardia sp. XJ31.

Zhang L, Zhang J, Ren B, Lu W, Hou C, Wang J, Ma X, Ma R, Liu M, Liu Z, Li JP, Ding K, Dai H, Zhang L, Liu X

Appl. Microbiol. Biotechnol. 104 (19) 8267-8278 [2020-10-00; online 2020-08-24]

The current global demand for novel anti-TB drugs has drawn urgent attention on the discovery of natural product compounds with anti-TB activity. Lots of efforts have emphasized on environmental samples from unexplored or underexplored natural habits and identified numerous rare actinomycete taxa producing structurally diverse bioactive natural products. Herein, we report a survey of the rare actinobacteria diversity in Xinjiang region together with the discovery of anti-TB active natural products from these strains. We have collected 17 soil samples at different sites with different environmental conditions, from which 39 rare actinobacteria were identified by using a selective isolation strategy with 5 media variations. Among those isolated strains, XJ31 was identified as a new Nocardia sp. based on 16S rRNA gene analysis. Through one strain-many compounds (OSMAC) strategy combined with anti-Bacillus Calmette-Guérin bioassay-guided isolation, two groups of compounds were identified. They were twelve siderophores (nocardimicins, 1-12) and two anthraquinones (brasiliquinones, 13 and 14) and ten of them were identified as new compounds. The structures of the purified compounds were elucidated using HR-ESI-MS, 1D NMR, and 2D NMR techniques. The anti-TB bioassays revealed that the two benz[α]anthraquinones have potent activity against BCG (MICs = 25 μM), which can be used as a promising start point for further anti-TB drug development. KEY POINTS: • Ten new natural products were identified from Nocardia sp. XJ31. • Brasiliquinones 13 and 14 showed moderate anti-BCG activity.

PubMed 32830291

DOI 10.1007/s00253-020-10842-2

Crossref 10.1007/s00253-020-10842-2

pmc: PMC7443361
pii: 10.1007/s00253-020-10842-2