Evaluation of anticancer and antimicrobial activities of the Polygonum maritimum ethanol extract

Polygonum maritimum is a traditional herbal remedy that produces abundant flavonoid secondary metabolites. The ethanol extract of P. maritimum aerial parts (POM) was chemically characterized and tested for antimicrobial properties and cytotoxicity. Results of LC-MS/MS analysis showed high contents of gallic acid, epigallocatechin gallate and catechin, and significant amounts of quercetin-3-O-galactoside and quercetin-3-O-glucoside. Evaluation of the antifungal properties revealed that POM induced notable growth inhibition of Alternaria alternata (34.3%), Penicillium spp. (30.6%), Fusarium semitectum (20.2%) and Aspergillus spp. (19.6%). Evaluation of cytotoxicity against human hepatoma HepG2 cells included monitoring the effects of both POM alone and its combination with cytostatic doxorubicin (Dox). Cell viability, apoptosis and cell cycle distribution and the expression of antioxidant enzymes (superoxide-dismutases SOD1 and SOD2 and catalase) were determined. A dose-dependent decrease in cell viability was detected, but a remarkably stronger effect was obtained when POM and Dox were applied in combination as compared to individual treatments. IC50 values were determined to be 393 μg/mL (POM) and 2.24 μg/mL (Dox) in combination, but 1153 μg/mL (POM) and 12.56 μg/mL (Dox) in a single treatment. The value of the Loewe index, determined for IC50, was notably lower than 1 (LI=0.51), clearly indicating synergism of POM and Dox. Additionally, POM and POM +Dox induced early/late apoptosis and G2/M cell cycle arrest. Furthermore, POM increased, while Dox decreased the expression levels of SODs and catalase. The obtained results encourage further examination of the potential use of POM in modern phytotherapy. [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. 172058]