Effects of Melissa officinalis hydromethanolic extract on DNA damage induced by bleomycin in normal human dermal fibroblasts

Abstract

Natural plant antioxidants can protect cells against oxidative damage caused by various agents or pathological conditions. Melissa officinalis L., lemon balm, is a valuable aromatic and medicinal plant used in the food, pharmaceutical and cosmetic industries [1]. In this study, a hydromethanolic extract (MOE) obtained from lemon balm leaves was investigated for its ability to protect against DNA damage induced by bleomycin (BLM) in normal human dermal fibroblasts (NHDF). The chemical analysis of MOE was carried out using RP-HPLC-DAD. DNA damage was monitored by the comet and cytokinesis-block micronucleus assays. An increase in the comet parameters (tail moment, olive tail moment, %DNA in tail) was noticed following exposure of NHDF to MOE (25, 100 and 200 mg/mL) as well as to BLM (10 mg/mL). The treatment with MOE (200 mg/mL) produced the most pronounced effect: tail moment increased from 2.21 ± 0.17 to 56.63 ± 1.59, olive tail moment from 3.79 ± 0.17 to 45.93 ± 0.94 and %DNA in tail from 7.65 ± 0.35 to 52.18 ± 0.98. The exposure of NHDF to MOE (25 and 100 mg/mL) after preincubation with BLM resulted in an insignificant decrease of comet attributes. Conversely, MOE (200 mg/mL) exhibited a potentiating effect; thus, %DNA in tail in BLM-treated cells was 46.79 ± 1.27 whereas in BLM+MOE 200-treated group it increased to 61.47 ± 1.97. At 200 mg/mL, MOE caused an increase in the micronuclei frequency (18.56%) compared with the control. MOE did not protect against BLM-induced DNA damage. Moreover, MOE itself exhibited, in a concentration-dependent manner, some degree of genotoxicity.