Anticancer effect of Psidium guajava (Guava) leaf extracts against colorectal cancer through inhibition of angiogenesis

Objective: To evaluate the anti-angiogenic and anticancer activities of Psidium guajava leaf extracts against angiogenesis-dependent colorectal cancer. Methods: Three extracts were produced using distilled water, ethanol, and n-hexane as solvents. The extracts were physically characterised through gas chromatography-mass spectrometry, ultraviolet-visible spectroscopy, and Fourier transform infrared spectroscopy. Their antioxidant activity was evaluated using the 2,2-diphenyl-1-picrylhydrazyl, total phenolic content, and total flavonoid content assays. To assess their anti-angiogenic activity, cell viability and rat aortic ring assays were conducted, while cell migration, tube formation, colony formation, and VEGF ELISA assays were conducted to elucidate their effects on different aspects of angiogenesis. Molecular docking was used to assess the anti- angiogenic potential of some possible compounds in the extracts. Tumour spheroid assay was used to assess the extracts' potential as a treatment for colorectal cancer. Results: The ethanol extract showed the best antioxidant activity. The distilled water and ethanol extracts exhibited more inhibitory activity against EA.hy926 cell viability and aortic ring microvessel growth. In addition, the ethanol extract performed significantly better than the distilled water extract against cell migration and colony formation, and VEGF expression of the cells was suppressed by the ethanol extract. Both the distilled water and ethanol extracts showed significant inhibitory effect on EA.hy926 tube formation and tumour spheroids consisting of EA.hy926 and HCT116 cells. The ethanol extract contained beta-caryophyllene and beta-elemene by phytochemical analysis and subsequent docking studies, which may contribute to its anti-angiogenic activity. Conclusions: The ethanol extract of Psidium guajava has potential in the treatment of colorectal cancer through the inhibition of angiogenesis.