World Research Journal of Agricultural Sciences, vol.4, no.2, pp.126-131, 2017 (Refereed Journals of Other Institutions)
Six Rhododendron species, one of which (R. smirnowii) is endemic, are growing naturally in Turkey, especially in Northeastern Anatolia (Eastern Part of Black Sea Region). Total phenolic content and antioxidant activity of two Rhododendron species collected in Rize at different altitudes from their natural habitats were determined. Samples obtained from Rize province (Turkey) were screened for total phenolic content by the modified Folin–Ciocalteu method, for potential antioxidant activity using phospho-molybdenum assay and by the 1,1-diphenyl-2-picryl hydrazyl (DPPH) and FRAP method for antiradical activity. Total phenolic content and antioxidant activity of plant parts (flower, leaf) of two Rhododenron sepecies, namely R. luteum L. and R. ponticum L. were determined. The total phenolic content of leaves of R. luteum L. collected from different altitudes ranged between 112,363 and 219,071 mg GAE/gr DW. Total phenolic content of flower parts of the same species ranged between 82,275 and 201,642 mg GAE/gr DW. The total phenolic content of different parts of R. ponticum L. were higher compared with R. luteum L. On the other hand, the antioxidant activity values of leaf parts of R. luteum L. were lower compared with flower parts and like the phenolic content the antioxidant activity values of different plant parts of R. ponticum L. were higher compared with that of R. lutem L. İn the present study it was determined that leaf and flower parts of two Rhododendron species could be diffrentiated regarding their total phenolic content and antioxidant activity.