Antioxidant and antibacterial activities of Thymus vulgaris L.

Thyme (Thymus vulgaris) belongs to the Lamiaceae family, and has been used since antiquity in traditional medicine. It is recognized by its therapeutic virtues. In this context, the objective of the present paper is to perform the extraction, quantification and separation of different phases containing the major flavonoids, and an evaluation of their antioxidant and antibacterial activities. We used the method of Folin Ciocalteu and AlCl3, respectively, to estimate the total of polyphenols and flavonoids. The main phases containing flavonoids have been obtained following confrontations realized by solvents of increasing polarity. The antioxidant capacity of the majority of flavonoids contained in this plant is evaluated in vitro by the method of trapping of free radical DPPH°. The same flavonoids are subjected to screening for their possible antibacterial activities against some human pathogenic bacteria. The content of polyphenols and flavonoids in T. vulgaris is 9.07 ± 0.002 mg/g Tannic Acid Equivalent of dry extract for polyphenols and 8.56 ±0.001 mg/g Quercetin Equivalent of dry extract for flavonoids. The chromatographic and spectral identification of extracts of thyme revealed the presence of six flavonoids characterized by their antioxidant activity in the order of 70, 58, 52, 51, 50 and 5%, respectively, for quercetin (3OR', 7OR'') (were R' and R'' are unknown radicals), luteolin, luteolin (7OR'), apignin (5OR', 7OR''), kaempfrol (3OR', 7OR''), chrysine (7OR') compared to quercetin standard characterized by its percentage of scavenging DPPH° equivalent to 93.05%. The microbiological results showed that the flavonoids isolated act differently on the bacterial species tested. In conclusion, this work shows that the flavonoids of the selected plants have good antioxidant and antibacterial activity, and can be used for medicinal and therapeutic applications.