Chemical composition, and antibacterial and antioxidant activities of essential oils from Laggeratomentosa Sch. Bip. ex Oliv. et Hiern (Asteraceae) (original) (raw)

2020, Turkish Journal of Chemistry

Introduction The genus Laggera Sch. Bip. ex Benth. & Hook., belonging to the Asteraceae (Compositae) plant family, has about 20 species, distributed mainly in sub-Saharan Africa and southeastern Asia [1]. Most of its species are often used in folk and traditional medicines for the treatment of inflammation, jaundice, leukemia, bronchitis, removing phlegm, and bacterial diseases, and their leaves, as well as aerial parts, have been reported to have antiinflammatory, antibacterial, antiviral, antioxidant, hepatoprotective, insecticidal, antifungal, anthelmintic, sedative, antituberculosis, and antidiarrheal properties [2]. The essential oils (EOs) of Laggera species have also been reported to exhibit antibacterial, antifungal, antioxidant, larvicidal, and insecticidal activities [3-5]. To date, the chemical constituents of the extracts and/or EOs of only 8 plants of the genus Laggera have been reported from 13 countries [2]. However, many bioactive compounds with many-sided activities have been identified from these plants, which has drawn researchers to further investigate Laggera species [1,2]. The genus is rich in flavonoids, cyclitols, monoterpenes, and sesquiterpenes (eremophilanes and eudesmanes). Flavones, fatty acids, and their derivatives, sterols (stigmasterol and β-sitosterol), phenolic acids like 2-hydroxybenzoic acid, and phytotoxic thymol derivatives, such as 3-hydroxythymoquinone and 5-acetoxy-2hydroxythymol, have also been reported from extracts of the plants of the genus Laggera [1,2,6,7]. 2,5-dimethoxy-pcymene, α-humulene, β-caryophyllene, γ-eudesmol, 10-epi-γ-eudesmol, and juniper camphor are the most frequent chemical compounds in the EOs of these plants, and the former (oxygenated monoterpene) is the most abundant, as well as the most dominant constituent of many of the EOs [2]. Laggera tomentosa Sch. Bip. ex Oliv. et Hiern, an annual fragrant subshrub or bushy herb, is an endemic medicinal plant of Ethiopia. Its leaves are used to treat various diseases, including the common cold, cough, flu, rabies, leech infestation, dysentery, and febrile illness and headaches, while the aerial parts are used for the treatment of toothache, swelling, and