Antibacterial and Anticancer Properties of Sapogenols from Streptomyces globisporus LL096, an Endophyte in Leucaena leucocephala (Lam.) de Wit.

Abstract

<b>Background and Objective:</b> Endophytic <i>Streptomyces globisporus</i> LL096, a bacterial strain isolated from the roots of <i>Leucaena leucocephala</i> (Lam.) de Wit, has been the subject of limited research, highlighting a significant knowledge gap regarding its potential applications in secondary metabolite production. The primary objectives of this study were to isolate and characterize the major bioactive compounds produced by <i>S. globisporus</i> LL096 and to evaluate their antibacterial and anticancer activities. <b>Materials and Methods:</b> The bioactive compounds produced by <i>S. globisporus</i> LL096 were isolated and purified using a combination of chromatographic techniques, including column chromatography and thin-layer chromatography (TLC). The chemical structures of the isolated compounds were elucidated by Nuclear Magnetic Resonance (NMR) spectroscopy and mass spectrometry (MS). The purified compounds were identified as soyasapogenol A (compound <b>1</b>) and soyasapogenol B (compound <b>2</b>). Subsequently, the antibacterial and anticancer activities of soyasapogenol A and soyasapogenol B were evaluated. Treatment effects were analyzed using one-way ANOVA with Tukey's <i>post hoc</i> test, considering p<0.05 as statistically significant. <b>Results:</b> Soyasapogenol A and B exhibited antibacterial activity against Gram-positive bacteria, including <i>Staphylococcus aureus</i> TISTR885, <i>Staphylococcus epidermidis</i> TISTR518, <i>Bacillus cereus</i> TISTR687 and <i>Bacillus subtilis</i> TISTR008. The minimum inhibitory concentrations (MICs) of the compounds against these bacterial strains ranged from 128 to 256 μg/mL. The compounds demonstrated significant cytotoxicity against these cancer cell lines, with IC₅₀ values ranging from 321.90 to 369.90 μg/mL for HeLa, 434.03 to 475.42 μg/mL for HepG2 and 282.96 to 362.17 μg/mL for MDA-MB-231 cells. However, moderate cytotoxicity against the non-cancerous Vero cell line was also observed, with IC₅₀ values ranging from 729.81 to 811.14 μg/mL. <b>Conclusion:</b> This study demonstrates that <i>Streptomyces globisporus</i> strain LL096 produces bioactive compounds, including soyasapogenol A and B, which exhibit antibacterial activity against Gram-positive bacteria and demonstrate cytotoxic effects against various human cancer cell lines.