Exploring the mechanisms and mode of action of bioactive compounds from marine Streptomyces albidoflavus against breast carcinoma cells

Breast cancer remains one of the most lethal diseases for women worldwide. Marine populations are considered a vast reservoir for novel bioactive metabolites, particularly marine Actinomycetes, which are known to produce various bioactive compounds with antitumour, antibacterial, and antifungal properties. A promising new marine strain was isolated and identified as Streptomyces albidoflavus strain EgyAB2 (16 S rRNA gene sequence accession number ON680945.1). The anticancer activity of the extracted compounds was tested in the MCF7 cell line using a sulforhodamine B (SRB) bioassay, which revealed an IC₅₀ of 0.36 µg/ml compared to the chemotherapeutic drug 5-fluorouracil (0.35 µg/ml). Additionally, the anticancer activity was confirmed by a dimethyl-thiazol-diphenyl-tetrazolium bromide (MTT) bioassay, which showed an IC₅₀ of 17.46 µg/ml. The mode of action of the treated breast carcinoma (apoptotic effect) was studied via qRT-PCR, revealing a significant role in anticancer treatment. Although the extracted compounds exhibited high antioxidant activity in the diphenyl-2-picrylhydrazyl (DPPH) radical-scavenging assay, they presented an IC₅₀ of 8.92 µg/ml and an inhibition percentage of 56.08%. Chemical characterisation was performed via GC‒MS, 1 H-NMR, and FTIR spectroscopy analyses, revealing the presence of 2-D N-methyl imidazole, 2-nonadecene, 1-D-2-methyl imidazole, and propane dinitrile, all of which exhibit antitumour activity.