Investigation of the volatile oils, lipid constituents and biological activity of Ballota andreuzziana, Teucrium zanonii and Verbena tenuisecta in Libya

Abstract

To determine the chemical composition of essential oils and lipid constituents of Ballota andreuzziana (B. andreuzziana), Teucrium zanonii (T. zanonii) and Verbena tenuisecta (V. tenuisecta) growing in Libya, and to test the antibacterial activity of different extracts of Teucrium zanonii. The volatile oils of all plants were extracted by hydrodistillation method and analyzed by GC/MS method. The lipid constituents of plants were obtained by extraction with petroleum ether and fractionated into fatty alcohols, fatty acids and unsapoinfiable matters. Antibacterial activity of T. zanonii extracts and antioxidant activity of different extracts of T. zanonii were also studied. The volate oil of B. andreuzziana was found to consists of 20 compounds in which caryophyllin is the main one (63.1%), the volatile oil of T. zanonii consists of 74 compounds in which germacrene-D was the main compound, while the volatile oil of V. tenuisecta consists of 13 compounds with 1-octen-3-ol as a major constituent (52.87%). The study of antimicrobial activity of different extracts of V. tenuisecta showed that, both methanol and butanol extracts exhibited the highest activity against Mycobactirium phlei (M. phlei) and Candida albicans (C. albicans) respectively, while petroleum ether, fatty alcohols and unsaponifiable fractions had no antimicrobial activity against all the tested microorganisms. Investigation of the antioxidant activity of different extracts of T. zanonii using DPPH method proved that, the ethyl acetate and butanol fractions showed the highest activity where the inhibition percentage (I%) are 93.6 and 92.1 respectively. This is the first report about the volatile oils of these plants where T. zanonii have the highest content and the highest number of the identified compounds. The study of antioxidant T. zanonii extracts proved that, the ethyl acetate, butanol and aqueous extracts have the highest antioxidant activity. Methanol and butanol extracts of V. tenuisecta exhibited the highest activity against M. phlei and C. albicans respectively.