Application of oleanane type triterpenoid in preparation of anti-tumor medicament, and rhodomyrtus tomentosa extract containing triterpenoid

The invention relates to the technical field of biological medicines, and particularly discloses an application of an oleanane type triterpenoid in preparation of an anti-tumor medicament, and a rhodomyrtus tomentosa extract containing the triterpenoid. The oleanane type triterpenoid has a structure shown in a formula I. The invention discloses pharmacological action of the oleanane type triterpenoid with the structure shown in the formula I for the first time. Experiments show that the oleanane type triterpenoid has the effects of resisting gastric cancer, liver cancer and melanoma. Further experimental research shows that by increasing ROS of cells, the oleanane type triterpenoid with the structure shown in the formula I can induce DNA damage and activate an ATM-Chk2-p53-p21 signal pathway so as to cause cell arrest in G2 phase. Further experimental research shows that by activating an ERS signal path, the oleanane type triterpenoid with the structure shown in the formula I can inhibit expression of Stat3 a