Conclusion
In this study, it was found that the extraction temperature had a huge effect on the bioactive components of S. cusia . Indoxyl formed in this extraction process inhibited cell growth and metabolism by disrupting EM formation and altering intracellular redox, and its inhibitory effect was much higher than the traditionally recognized bioactives in banlangen, such as indigo and indirubin. Moreover, the precursor of indoxyl, indican, did not have any antimicrobial activity. Simulating the hydrolysis of indican by β-glucosidase in plants, a novel antibacterial mode with indican could be formed, improving the medicinal properties of antimicrobial agents.