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Rosmarinic acid - biologically active compound of Lamiaceae plants

In the food industry there is a great demand for ingredients that effectively inhibit oxidation of food components. It is already well known that plants from the Lamiaceae family possess strong antioxidant activity which exceeds many of currently used synthetic preservatives. In the current study, the contribution of rosmarinic acid content on the antioxidant properties of four mint plant extracts (Satureja montana L., Thymus vulgaris L., Melissa officinalis L. and Origanum majorana L.) was evaluated. The content of rosmarinic acid was determined using HPLC, direct UV method and complexation method with Zr4+. Total phenols, flavonoids and non-flavonoids were determined by spectrophotometric methods. The antioxidant properties of plant extracts were evaluated by ferric reducing/antioxidant power (FRAP), Briggs-Rauscher oscillating reaction and Rancimat method. All analysed extracts contained rosmarinic acid as a dominant compound. The highest concentration of RA detected using HPLC method was in M. officinalis extract. The concentrations determined by spectrophotometric methods were significantly higher. The highest content of total phenolics and flavonoids was detected in O. majorana and M. officinalis. extract. Due to their high phenolic content, O. majorana and M. officinalis were shown to possess extremely good reducing and free radical scavenging activity, while in lipid medium T. vulgaris extract was superior. Highly positive linear relationships were obtained between antioxidant activity of investigated plant extracts and rosmarinic acid content, so it safe to conclude that rosmarinic acid contributed to their biological properties.

rosmarinic acid; Lamiaceae; HPLC; antioxidant activity

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