Stylopeptide 1 synthesized and isolated from different sources exhibits a large activity difference in inhibitory effect on the growth of a cancer cell.Based on the different amounts of methanol and water during synthesis,isolation and purification of the cyclic peptides,molecular dynamics(MD) was employed to simulate the conformation of stylopeptide 1 in methanol and aqueous environments.The comparative results show that the backbone ring was more rigid in methanol than in water.In methanol,two β-turns and three hydrogen bonds were well conserved throughout the simulation,whereas no hydrogen bonds or turns were preserved in water.The activity difference of stylopeptide 1 seemed to be attributed to the solvent effect on its conformation. Stylopeptide 1 synthesized and isolated from different sources exhibits a large activity difference in inhibitory effect on the growth of a cancer cell.Based on the different amounts of methanol and water during synthesis, isolation and purification of the cyclic peptides, molecular dynamics (MD) was employed to simulate the conformation of stylopeptide 1 in methanol and aqueous environments. The comparative results show that the backbone ring was more rigid in methanol than in water. In methanol, two beta-turns and three hydrogen bonds were well conserved throughout the simulation. no hydrogen bonds or turns were preserved in water. The activity difference of stylopeptide 1 seemed to be attributed to the solvent effect on its conformation.