Characterization, components, and chemical structure of a novel natural pigments derived from Streptomyces tauricus

Microbial pigments have extensive applications in the food, cosmetic, and biopharmaceutical industries. In this study, a pigment-rich actinomycete identified as Streptomyces tauricus was isolated from soil, and the solubility and stability of its were investigated. The pigment was separated and purified through thin-layer chromatography (TLC), column chromatography, and high performance liquid chromatography (HPLC) to determine its components. The chemical structure of the pigment was characterized through infrared (IR) spectroscopy, gas chromatography-mass spectrometry (GC–MS), tandem mass spectrometry (MS/MS–MS), and nuclear magnetic resonance (NMR). Additionally, the antioxidant properties and safety profile of the pigment were assessed. The S. tauricus pigment was bright, vivid brownish-red, intracellular, and fat-soluble; it exhibited considerable photothermal stability and maintained its color below pH 7. The presence of Cu²⁺, Fe²⁺, and Fe³⁺ ions markedly influenced the pigment’s characteristics. The pigment comprised primarily purple and orange components. The purple component, which is relatively rare in microbial sources, was subjected to detailed study. The core structure of the purple component was identified as methylbenzanthracene dione, which has high antioxidant activity and no toxicity in brine shrimp assays. Due to its resilience to high temperatures and acidic environments, coupled with its bioactivity and lack of toxicity, this pigment may serve as a promising candidate for various industrial and food applications.