Using the neutral red cytotoxicity assay, the IC50 of P. guajava and P. betle were determined
at 29.0±0.4 and 29.5±0.3 µg/ml, respectively, indicating both plant extracts equally potent for
the treatment of cancerous oral epidermal lesions. However, a less potent anti-proliferative
activity was recorded by P. guajava towards HeLa cell line with an IC50 of 51.0±0.6 µg/ml,
whereas P. betle extract did not affect the proliferation of HeLa.