Objective: Lysin specific demethylase 1 (LSD1) inhibits the tumor suppressor activity of p53 and facilitates the progress of tumor. In order to check the tumor growth, the activity of LSD1 enzyme is to be blunted. Methods:Phytochemicals from naturally occurring plant-based anticancer compound-activity-target (NPACT) database are screened with LSD1 as target applying genetic algorithm (GA) method to study best ligand poses and free energy of binding using Argus Lab. The prediction of drug-likeness and oral toxicity of the ligands are performed by the online tools Molsoft and ProTox respectively. Results:Calyxin H shows optimum binding affinity to both the substrate and FAD binding sites of LSD1. The LD 50 value (median lethal dose) of calyxin H is more than 1000 mg/kg body weight and the toxicity class is 4. Conclusions:Calyxin H is the inhibitor of choice against target LSD1. The lead molecule may be the future potential herbal drug for cancer treatment.