Cytotoxic Activity of Parotid Gland Toxins from Ingerophrynus philippinicus (Philippine Toad) Against Human Colorectal Carcinoma (HCT-116).

BACKGROUND

Colorectal cancer is the third most prevalent cancer and the second leading cause of cancer-related deaths worldwide. Limitations of current treatments include adverse effects and drug resistance, highlighting the need for new chemotherapeutic agents. This study evaluated the cytotoxic activity of crude methanolic extract of the parotid gland secretions of Ingerophrynus philippinicus (PGSE), a toad endemic to the Philippines, against human colorectal carcinoma cell line (HCT-116) and identified its bioactive compounds.

METHODS

Crude methanolic extract of parotid gland secretions was prepared and evaluated for antiproliferative activity using the MTT assay. An Annexin V/PI assay was used to assess apoptosis and necrosis. The presence of bufadienolides was determined using Ultra Performance Liquid Chromatography-Quadrupole Time-of-Flight Double Tandem Mass Spectrometry (UPLC-QTOF-MS/MS).

RESULTS

The extract exhibited cytotoxic activity against HCT-116 cells in a dose-dependent manner with an IC50 of 4.462 ± 2.141 μg/mL. The Annexin V/PI assay revealed that treated cells predominantly underwent late apoptosis (89.52% ± 2.25%), with smaller proportions of early apoptosis (6.16% ± 2.49%), and necrosis (4.32% ± 0.29%). The UPLC-QTOF-MS/MS analysis identified three bufadienolides (bufalin, bufotalin, and bufotalinin) in the PGSE.

CONCLUSION

PGSE demonstrates potent cytotoxic activity against colorectal cancer cells, primarily through apoptosis, and contains bufadienolides with known antineoplastic activity. These findings support its potential as a source of bioactive compounds for anticancer research.