Bioactive constituents and antioxidant activity of some traditional medicinal herbs extracts
Phenolic compounds are natural antioxidants that may give a defence against oxidative stress from endogenous reactive oxygen species and free radicals. Phenolics show various biological properties, such as antioxidative, antiproliferative, antibacterial, antiinflammatory and antiallergic effects . In this study, the content of bioactive constituents and free radical scavenging activity of Calendula officinalis, Hypericum perforatum, Galium verum, and Origanum vulgare extracts were determined and compared. These plants have been used in our country not only in traditional medicine but also as dyeing agents. Aqueous and hydroalcoholic extracts (30%, 50%, 70%) of the four plants (1:10 w/v) were examined for the content of total phenolics using Folin-Ciocalteu procedure  and individual compounds content by developing an analytical RP HPLC method. The free radical scavenging activity was evaluated using DPPH and ABTS scavenging methods and expressed as Trolox equivalent antioxidant capacity (TEAC) . Data obtained from our study show that the highest content of total polyphenols (9.9±0.02mg GAE/mL extract) was found in Origanum vulgare (50%) extract. This result was confirmed by those obtained for antioxidant activity, 20901µmM/L TEAC by DPPH method and 307507.8µmM/L TEAC by ABTS method. The samples were analysed on a RP C18 column gradiently eluted with two-phase system consisting of acetic acid, water and acetonitrile; detection was made on a diode array detector set between 320–370nm. Polyphenolic compounds (chlorogenic acid, caffeic acid, ferulic acid, coumaric acid, rosmarinic acid, rutoside, luteolin, quercetol, apigenin and kaempherol) were quantified in our samples using RP HPLC method. A very good peak-to-peak separation efficiency and a good linearity for all the analytes (R2>0.9978) was obtained.
This work was financially supported by Romanian Project PN 06–400101
References: 1. Heo, H.J., Kim et al. (2007)J. Food Chem. 104: 87–92
2. Waterhouse, A.L. (2002) Current Protocols in Food Analytical Chemistry, John Wiley & Sons, New York
3. Litescu, S.C. et al (2001) Electroanal. 13:804:806