abstract
Thymus herba-barona, Thymus pseudolanuginosus, and Thymus caespititius decoctions were screened for their phenolic constituents, along with their potential antioxidant, anti-inflammatory, and antibacterial activities. The total phenolic compounds in the extracts of the three plants ranged from 236.0 +/- 26.6 mgGAE/g (T. caespititus) to 293.0 +/- 30.5 mgGAE/g of extract (T. pseudolanuginosus), being particularly rich in caffeic acid derivatives, namely rosmarinic acid and its structural isomers, as well as flavones, such as luteolin-O-glucuronide. The T. pseudolanuginosus extract presented the best DPPH radical scavenging ability (EC50 = 10.9 +/- 0.7 mu g/mL), a high reducing power (EC50 = 32.2 +/- 8.2 mu g/mL), and effectively inhibited the oxidation of -carotene (EC50 = 2.4 +/- 0.2 mu g/mL). The extracts also showed NO. scavenging activity close to that of ascorbic acid, and thus might be useful as anti-inflammatory agents. In addition, they exhibited antibacterial activity against gram-negative and gram-positive bacteria. Staphylococcus aureus strains were the most sensitive bacteria to thyme extracts, with minimum inhibitory concentration and minimum bactericidal concentration values in the range of 0.6-3.5 mg/mL. Overall, this work is an important contribution for the phytochemical characterization and the potential antioxidant, anti-inflammatory, and antimicrobial activities of these three Thymus species, which have been poorly explored.
keywords
ANTIOXIDANT CAPACITY; PHENOLIC-COMPOUNDS; ANTIBACTERIAL ACTIVITY; ANTIMICROBIAL ACTIVITY; BIOLOGICAL-ACTIVITIES; CHEMICAL-COMPOSITION; EXTRACTS; PLANTS; IDENTIFICATION; CONSTITUENTS
subject category
Biochemistry & Molecular Biology; Chemistry
authors
Afonso, AF; Pereira, OR; Neto, RT; Silva, AMS; Cardoso, SM
our authors
Rodrigo de Sousa Trêpa Alves Neto
PhD Studentacknowledgements
The authors acknowledge to the Foundation for Science and Technology (FCT), the European Union, the National Strategic Reference Framework (QREN), the European Regional Development Fund (FEDER), and Operational Programme Competitiveness Factors (COMPETE), for funding the Organic Chemistry Research Unit (QOPNA) (project PEst-C/QUI/UI0062/2013; FCOMP-01-0124-FEDER-037296).