Antibacterial and Anticancer Properties of Anthraquinone Derivatives from Streptomyces kunmingensis BH111, an Isolate from Beehive

Background and Objective: The persistent global threats of antimicrobial resistance and cancer necessitate the discovery of novel chemical entities, a search where actinomycetes from unique environments are critical. To discover new therapeutics, this study investigated actinomycetes from the Apis florea beehive environment, aiming to identify a promising strain and structurally characterize its antibacterial and anticancer metabolites. Materials and Methods: Actinomycetes were isolated from five Apis florea beehives. Strain identification was performed using morphological, chemotaxonomic and dual-gene sequencing (16S rRNA and gyrB). Metabolites were purified and biological activity was assessed using MIC/MBC (antibacterial) and MTT cytotoxicity assays. The mechanism was explored via molecular docking against Topoisomerase II, complemented by ADMET prediction. Results: The most active isolate, BH111, was identified as Streptomyces kunmingensis. It produced two anthraquinone derivatives: Resistomycin (Compound 1) and tetracenomycin D (Compound 2). These compounds demonstrated selective, potent antibacterial activity against Gram-positive strains (MIC and MBC values ranged from 16 to 32 and 128 to 256 μg/mL, respectively) and significant cytotoxicity against tested cancer lines (IC₅₀ values ranged from 10.72 to 27.57 μg/mL). Docking results supported Topoisomerase II inhibition. However, low selectivity indices and ADMET flags (CYP450, hepatotoxicity) were noted. Conclusion: Streptomyces kunmingensis BH111 is the first strain of this species reported to produce resistomycin and tetracenomycin D from a beehive source. While these anthraquinone derivatives are promising drug scaffolds due to their potent antibacterial and topoisomerase-inhibiting anticancer activities, significant therapeutic optimization is required to enhance selectivity and mitigate predicted toxicological risks.