Cytoprotectivity of plant extracts on doxorubicin and irinotecan-treated human peripheral blood lymphocytes

Growing clinical, toxicological and biochemical evidence supports the use of different herbs in chemopreventive strategies. It is particularly important in conventional cancer chemotherapy, since majority of antineoplastic drugs are detrimental to non-tumor cells and tissues too. In this study possible cytoprotective and genoprotective effects of plant extracts on doxorubicin and irinotecan-treated human peripheral blood lymphocytes in vitro were investigated. The water extracts examined were lemon balm (Melissae folium), green and black tea (Camelliae sinensis folium) and water and ethanolic extracts of purple coneflower (Echinaceae purpureae herba). Total polyphenols was determined using pharmacopoeial Folin-Ciocalteau method. Concentrations of plant extracts were adjusted to 1 and 0.1mg/mL of crude lyophilized extracts. After 1-hour of pre-treatment, lymphocytes were exposed to doxorubicin and irinotecan in their therapeutic concentrations for 2 hours. Assessment of cell viability, apoptosis and necrosis was performed using the fluorescent dye exclusion method. The levels of primary DNA damage were studied simultaneously by the alkaline comet assay. Corresponding negative controls were also included. All plant extracts possess low cytotoxicity and showed cytoprotective potential in vitro. The extracts did not induce significant increase of the single strand breaks or alkali-labile sites in pre-treated lymphocytes compared with negative control. Present findings confirm that polyphenolic compounds, as main constituents of extracts tested, are capable to prevent and/or significantly diminish DNA damage produced either directly or indirectly following exposure to both antineoplastic drugs. These preliminary results support further investigations on the possible application of plant extracts as food additives during chemotherapy.