New Hybrids Derived from the Natural Compound (-)-β-Pinene and Amides or Acylthioureas as Antitumor Agents

Background: Plant-derived natural compounds have a unique molecular structure and rich biological activity, hence, they are treated as important raw materials for the development of drugs. Methods: A natural compound (-)-β-pinene was used as a raw material, and twenty-six novel derivatives with amide or acylthiourea groups were synthesized based on the molecular hybridization method. In vitro antitumor activity of these derivatives on human breast cancer cell line MCF7 and human colon cancer cell line SW1116 were tested by MTT method. The effects of the synthesized derivatives on the morphology of MCF7 and SW1116 were observed by fluorescent inverted microscope. Results: The preliminary structure-activity relationship analysis demonstrates that the position and species of substituents on the aromatic ring of derivatives have an effect on the antitumor activity of derivatives. Observation of the cell morphology reveals that derivatives with antitumor activity can lead to rounding of the cell morphology, a decrease in cell volume and cell density, and ultimately inhibition of the proliferation of MCF7 and SW1116 cells. The antitumor activity evaluation results show that among these derivatives, compounds 5c, 5e, 5h, 7c, 7b and 7e exhibit good antitumor activity against MCF7, and compounds 5c, 5e, 5h and 7j exert moderate antitumor activity against SW1116. Conclusion: This study hopes to promote the high value-added utilization of natural compounds β-pinene and the development of novel antitumor drugs.