Cultivar affects the phenolic composition and antioxidant properties of commercially available lemon balm (Melissa officinalis L.) varieties

Although agronomic factors affecting essential oil composition within lemon balm (Melissa officinalis L.) are well documented, much less is known about conditions that influence foliar phenolic levels. Therefore in this study, the effect of cultivar and seed company on the phenolic composition and antioxidant properties of five commercially available lemon balm varieties was determined. Cultivar (p = 0.009) and seed company (p = 0.020) had a significant effect on total phenolic concentrations. Analysis of individual phenolic acid levels by high-performance liquid chromatography showed substantial variations in the phenolic acid composition among cultivars. Rosmarinic (p = 0.001), gentisic (p = 0.014), chicoric (p < 0.001), protocatechuic (p = 0.018), and p-coumaric (p < 0.001) acid concentrations were affected by cultivar, although caftaric, caffeic and gallic acids were not. Seed company was a significant factor influencing rosmarinic (p = 0.007), gentisic (p = 0.002), chicoric (p = 0.034) and p-coumaric (p = 0.024) acid content. Cultivar also had a significant influence on FRAP (ferric reducing antioxidant power, p = 0.028) and DPPH (2,2-diphenyl-1-picrylhydrazyl, p = 0.002) antioxidant capacities. These results suggest that both the selection of cultivar and seed origin are important factors influencing the concentration of phenolic compounds and the resulting antioxidant properties within lemon balm.