Anti-proliferative Effect of Melissa officinalis on Human Colon Cancer Cell Line

摘要

Melissa officinalis L. (Lamiaceae) is consumed as a traditional herbal tea in the Mediterranean region. The cytotoxic effect of the 50% ethanolic and aqueous extract, determined by the MTT and NR assays, was evaluated in vitro on Human Colon Cancer Cell Line (HCT-116), using Triton 10% as positive control. The 50% ethanolic extract showed significant differences after 72 h of treatment, reducing cell proliferation to values close to 40%, even the lowest dose tested (5 μg/ml). In the MTT assay, the same extract caused the lowest cell viability with 13% at a concentration of 1,000 μg/ml after 72 h of treatment, being a value lower than Triton 10%. The antioxidant activity was also confirmed evaluating the capacity of the extracts to scavenge ABTS and DPPH radicals, and IC₅₀ values were highly correlated with the total phenolic and flavonoid content. Bioassay guided fractionation led to the isolation of an anti-proliferative compound, rosmarinic acid. Its structural elucidation was performed by HPLC/DAD/ESI/MS analysis. High dose of rosmarinic acid (1,000 μg/ml) was clearly cytotoxic against HCT-116 cells, with a significant decrease in cell number since the earliest time point (24 h).