A novel Umezawaea tangerina endophyte reveals anti-colorectal cancer activity and a rich biosynthetic landscape.

Colorectal cancer is the second leading cause of cancer-related mortality worldwide, highlighting the need for novel anticancer agents with fewer side effects. Endophytic actinobacteria (EA) are recognized as prolific producers of bioactive natural products. This study evaluated the anticancer potential of fractionated extracts from a novel endophytic actinobacterial strain, IKBG05 (genus Umezawaea), isolated from Cerasus microcarpa. Ethyl acetate extracts of submerged cultures were fractionated, and their cytotoxic effects were assessed against SW480 and HCT116 colorectal cancer cell lines. Among six fractions, F2 and F3' showed moderate cytotoxic effects consistent with early-stage screening of semi-purified fractions, with IC₅₀ values ranging from 188 to 416 µg/mL. At the tested concentration, fraction F2 produced 2.48- and 2.67-fold higher growth inhibition in SW480 and HCT116 cells, respectively, compared with normal fibroblasts. F2 treatment was also associated with increased intracellular ROS levels and induction of apoptosis, particularly in HCT116 cells, comparable to the reference drug 5-fluorouracil.In parallel, genome mining of three available Umezawaea genomes identified 85 putative biosynthetic gene clusters (BGCs), suggesting considerable biosynthetic potential. This study provides the first genome-wide prediction of BGCs across currently available Umezawaea genomes and reports preliminary evidence of anticancer activity in extracts from strain IKBG05. These findings support further purification and characterization of the bioactive constituents.