A comparative study of essential oil profile, antibacterial and antioxidant activities of two cultivated Ziziphora species (Z. clinopodioides and Z. tenuior)

The genus Ziziphora belongs to Lamiaceae family being known as an aromatic medicinal plant. The Lamiaceae family has several species which are of great importance in pharmaceutical, food and cosmetic industry, as well as in traditional and modern medicine. In this manuscript we analyzed the chemical composition of the essential oils (EOs) isolated from the aerial flowering organs of cultivated Ziziphora clinopodioides Lam. and Z. tenuior L. using GC and GC–MS methods for the first time. In total, 17 and 21 compounds (comprising 99.7 % of total EO) were identified in Z. clinopodioides and Z. tenuior, respectively. The major identified compounds identified in essential oil analysis reported as pulegone (70.4 %) and menthone (11.5 %) for Z. clinopodioides, pulegone (55.1 %) and limonene (8.2 %) for Z. tenuior. Both Ziziphora species were rich in phenolic compounds (total phenol content: 30.3 ± 0.1 mg gallic acid/100 g EO and 49.0 ± 1.4 mg mg gallic acid/100 g EO; total flavonoids: 2.7 ± 0.3 mg quercetin/ 100 g EO and 6.6 ± 0.4 mg quercetin/ 100 g EO) and they contained high antioxidant properties with IC50: 147.2 ± 1.3 μg/mL and 111.4 ± 1.2 μg/mL in Z. tenuior and Z. clinopodioides, respectively. Furthermore, obtained results indicated that the reducing power of Z. tenuior was 7.5 ± 1.2 μg/mL while this number was 6.1 ± 0.7 μg/mL for Z. clinopodioides. We have also investigated the antibacterial activity of the EOs on seven current important foodborne pathogenic bacteria. Results showed that the EO of Z. clinopodioides and Z. tenuior possess an acceptable antimicrobial effect on the studied microbes. This research indicated that the EOs of two species of Ziziphora due to their main components such as pulegone, menthone and limonene as well as high phenolic content could be considered as good sources of natural antioxidant and antibacterial material in which have the high potential to use for food science as well as food preservative.