Background: Oral squamous cell carcinoma (OSCC) is one of the most prevalent oral cancers, 
despite rapid improvement in chemotherapy, radiotherapy, and targeted gene therapy used in 
conjunction with mainstay surgery, the OSCC prognosis remains low. Previous studies have 
demonstrated anti-proliferative activity of polyphenols in cancer cells, Pyrogallol (PG) one of natural 
polyphenols, with cytotoxicity and apoptogenic effects on neoplastic and transformed cells, but not in 
normal cells. Objective: This study aims to investigate the effect of PG on tongue squamous cell 
carcinoma SCC-25 cells and evaluate possible apoptotic pathways on SCC-25 cells. Methods:
Cytotoxicity was measured by MTT assay. Mode of cell death was determined using Image 
morphometric analysis and Estimation of caspase-3 by Real Time PCR. Results: MTT results showed
that SCC-25 cells were sensitive to PG with an IC50 value of 19.17 ug/ml. Image morphometric 
analysis showed a decrease in the mean values of Nuclear Area Factor (NAF) of SCC-25 cells treated 
with Different concentrations of PG when compared to control cells. In addition, PG induced 
apoptosis by simultaneous up-regulation of capase-3.Conclusions: Different concentrations of PG 
have a cytotoxic effect on SCC-25 cells. PG was also found to be an effective anti-carcinogenic agent 
with less toxicity.