Antimicrobial, antibiofilm, cytotoxicity, and anti-DNA topoisomerase activity of Streptomyces sp. 22SH with ADME and in silico study

The genus Streptomyces has been recently proven to be a valuable and rich source of producing several bioactive compounds with substantial biological activity and applications in many fields such as medicine, environmental science, food industries, and agronomy. This study highlights the importance of Streptomyces as an antimicrobial, antibiofilm, and anticancer. Out of the 75 actinobacteria isolated from both marine and soil habitats, one isolate, HG2, was selected based on its potent antimicrobial activity. The isolate has been identified morphologically by studying colony and spore chain morphology using TEM and genetically by sequencing their 16 sr RNA gene as Streptomyces sp. 22SH with Accession number OK326829.1. Bioassay-guided fractionation of the Streptomyces sp. 22SH crude extract led to the isolation and purification of Cis-9-Octadecenoic. Biological evaluation including antimicrobial and antibiofilm activity of the crude and purified compound was performed on four clinical microbes (S. aureus ATCC6538-P, B. subtilis ATCC6633, and P. aeruginosa ATCC27853). The compound showed the ability to eradicate the biofilm formation by the tested pathogens. Additionally, the antitumor activity was assessed, and the compound showed a cytotoxic effect against liver carcinoma and breast cancer cells, with IC50 values of 17.48 ± 0.94 and 88.73 ± 4.78 µg/ml, respectively. While it displayed anti-topoisomerase activity with an IC₅₀ of 0.65 ± 0.023 µg/ml. Furthermore, the compound's ADME-related physicochemical features and docking analysis were investigated.