Total phenolic contents and antioxidant activities of Michauxia L'Hérit (Campanulaceae) species growing in Turkey

The genus Michauxia L'Hérit (Campanulaceae) is represented by five species in Turkey, namely Michauxia campanuloides L'Hérit ex Aiton, M. laevigata Vent., M. tchihatchewii Fisch. et Mey. (E); M. thyrsoidea Boiss. & Heldr. (E), and M. nuda A.DC. The fresh stem and roots of M. campanuloides and M. tchihatchewii have been used as a vegetable.In the present study, the phenolic contents and antioxidant activities of the water, methanol (MeOH), dichlormethane (DCM), Ethyl acetate (EtOAc) and butanol (BuOH) extracts obtained from the root and herb of 5 species of Michauxia collected in different parts of Turkey were compared. The phenolic contents of the samples were determined using Folin-Ciocalteu's phenol reagent. Antioxidant activities of the extracts were studied by qualitative and quantitative DPPH· (1,1-diphenyl-2-picrylhydrazyl radical) assay to detect the free radical scavenging activity and by thiobarbituric acid (TBA) assay to detect their liposome lipid peroxidation. The total phenolic contents of extracts in the five different polarity were found the EtOAc extracts ranged from 108.1 to 439.1mg/g in dry weight expressed as gallic acid equivalents (GAE). All extracts showed a moderately antioxidant activity with the qualitative DPPH· test. In the quantitative DPPH· method the highest activity were determinated in EtOAc extracts of five plants. High activity was observed in the herb EtOAc extracts of M. tchihatchewii (IC₅₀=4.94±6,46) and the MeOH extracts of M. campanuloides herb (IC₅₀=97.58±6,03) when compared to the other extracts in the TBA test. Propyl gallate (IC₅₀=0.09±0,18) is used as a positive control.

Keywords: Michauxia campanuloides; M. laevigata; M. tchihatchewii; M. thyrsoidea; M. nuda; Antioxidant activity