Nano-Formulation of Sponge Associated-Cytobacillus gottheilii Extract for Cancer Treatment

Sponge-associated bacteria represent a potentially promising source for new bioactive compounds, including antimicrobial and anticancer agents. In the present study, the endosymbiotic bacteria present in the marine sponge, Amphimedon ochracea, and Hyrtios erecta sp. collected from Hurghada, Red Sea, Egypt, were screened for cytotoxic activities. Identification of Cytobacillus sp. strains utilized conventional techniques and DNA sequencing of the 16 S rRNA gene. Culture supernatants from Cytobacillus gottheilii MSB1 and MSB2 demonstrated growth inhibition against hepatocellular carcinoma (HepG2), breast cancer (MCF7), and colon cancer (HCT-116) cell lines. Cytobacillus gottheilii MSB1 showed the most promising strong cytotoxic activity against MCF7, HCT-116 and HepG2. The fractionation of culture supernatants of Cytobacillus gottheilii MSB1 by using organic solvents depending on the polarity of n-hexane, dichloromethane, ethyl acetate, and n-butanol yielded four cytotoxic-active fractions from CBG MSB1. The dichloromethane fraction showed the highest cytotoxic activity against HepG2, HCT-116 and MCF7, while the n-butanol fraction showed a weak effect. An emulsification-solvent evaporation method was used to prepare the dichloromethane fraction of Cytobacillus gottheilii MSB1 (Ex-DCM)-loaded PLGA nanoparticles (Ex-DCM-LNPs) to overcome its poor solubility. The average diameters and zeta potential of the developed drug-loaded PLGA nanoparticles were 226.8 ± 11.33 nm and − 14.9 ± 0.451 mV, respectively. Ex-DCM-LNPs were performed in vitro against the same three cell lines; it revealed promising strong cytotoxic activity against cancer cell lines, especially colon cancer, but exhibited a minor effect on the other cell lines, such as hepatocellular carcinoma and breast cancer.