Effects of gamma radiation on phenolic composition, cytotoxicity, antibacterial and virucidal activities of two medicinal plants
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The authors are grateful to the Foundation for Science and Technology (FCT, Portugal) and FEDER under Programme PT2020 for financial support to CIMO (UID/AGR/00690/2013) and CTN (RECI/AAG-TEC/0400/2012). The authors are also grateful to FEDER-Interreg España-Portugal programme for financial support through the project 0377_Iberphenol_6_E.
The consumers' interest for a healthier diet and the use of natural products in the prevention and/or treatment of health problems has triggered an intensive search for bioactive plant compounds. Plants are a good source of phenolic compounds, terpenoids, alkaloids, quinones, carotenoids, sterols, glucosinolates and other compounds, which provide health benefits due to their wide range of biological properties.
This work aimed to evaluate the effects of gamma radiation on the phenolic composition, cytotoxicity, virucidal and antimicrobial properties of Aloysia citrodora L. and Mentha x piperita L. infusions. Gamma radiation treatment was performed in a 60Co chamber, applying the doses of 1 and 10 kGy and the results were compared with the control sample (0 kGy). The phenolic compounds profile was obtained by HPLC-DAD-ESI/MS and the cytotoxicity was evaluated in human tumour cell lines and in a primary cell culture. For virucidal efficacy evaluation, MNV-1 and HAdV-5 viral titers were determined by plaque assay in Raw264.7 and A549 cell lines, respectively. The antibacterial activity was evaluated against Gram-negative and Gram-positive bacteria. Radiation treatment has been shown to cause different effects on phenolic concentrations and virucidal efficacy, depending on the plant species studied, the virus and the absorbed dose. In cytotoxicity assay A. citrodora did not reveal significant statistically differences considering the different doses applied, however M. piperita at 10 kGy stood out with the highest cytotoxic potential in all tested cell lines. Regarding antibacterial assays, S. aureus was the only bacteria that was sensible to the infusions of non-irradiated and 1 kGy irradiated in both species. Thus, this study contribute to a wider knowledge of the effects of gamma irradiation on several relevant bioactive potentials of some aromatic and medicinal plants and showed that gamma radiation is a technique recommended for these matrices.
