In vitro antioxidant activity, total phenolic content and phenolic composition of Inula heterolepis

Inula heterolepis Boiss., a perennial herbaceous plant (15 – 40 cm) widespread throughout the Eastern Mediterranean region, is used topically in folk medicine against loss of appetite, headaches and hemorrhoids. To the best of our knowledge, a few studies were performed on I. heterolepis and in this study, total phenolic content, antioxidant capacity and phenolic composition of the plant were investigated for the first time (1 – 3). Total phenolic content of methanol extracts of aerial parts and roots of the plant was estimated by Folin Ciocalteu method. The aerial parts of the plant was seemed to contain higher amount of total phenolics compared to roots. Antioxidant activities of methanol extracts of flowers, leaves and roots of the plant were evaluated by DPPH radical scavenging and ABTS assays. All the investigated parts of the plant exhibited antioxidant activity in different concentrations. Flower and leaf extracts expressed higher antioxidant activities compared to root extract with lower IC₅₀ values. With regard to the total phenolic content and antioxidant activity results, phenolic composition of the plant was investigated. Some phenolic compounds such as chlorogenic acid, caffeic acid, rutin, myricetin, quercetin, luteolin and kaempferol were analyzed qualitatively and quantitatively in different parts of the plant by RP-HPLC. Various amounts of phenolics in different parts of the plant could be the main occasion for the determined antioxidant potential.

References:

[1] Davis, P.H. (1982) Flora of Turkey and The East Aegean Islands, Edinburgh University Press, Edinburgh.

[2] Bohlmann, F. et al. (1982) Phytochemistry, 21(5):1166 – 1168.

[3] Baytop, T. (1999) Therapy with Medicinal Plants in Turkey (Past and Present), 2^nd Edition, Nobel Tıp Kitabevleri, Istanbul.