Heat-Assisted Extraction and Bioactivity Evaluation of a Dinactin-Associated Compound from Streptomyces UP Strains

Streptomyces is a versatile genus widely used in drug production and biotechnological applications. This study aimed to identify and characterize bioactive compounds produced by Streptomyces UP-AC4 and UP-3.2 strains and evaluate their antibacterial and anticancer activities. The strains were identified as Streptomyces californicus and Streptomyces purpurascens via chemotaxonomy, 16S rRNA sequencing, amplified ribosomal DNA restriction analysis, and phylogenetic analysis. Bioactive compounds were extracted using heat treatments at 63 °C for 30 min or 73–110 °C for 10 min. Antibacterial activity against Staphylococcus aureus, Bacillus cereus, and Escherichia coli was assessed by agar disc assay, with MICs of 0.024–0.195 mg/mL and MBCs of 0.098–0.391 mg/mL for the most effective extracts. Anticancer activity against A549, H1299, and Lu99 lung cancer cells was evaluated using the MTT assay, showing IC50 values of 0.23 ± 0.06 to 4.85 ± 0.64 mg/mL, while exhibiting no toxicity to normal fibroblast cells. HPLC analysis indicated that heat-assisted extraction of UP-AC4 at 73 °C for 10 min enriched a dinactin-associated compound as a predominant metabolite with antibiotic and anticancer activities. In conclusion, Streptomyces UP-AC4 and UP-3.2 produce promising low-cost bioactive compounds with strong potential for pharmaceutical and healthcare applications.