Assessment of Total Phenolic and Flavonoid Content of Medicinal Plant Extracts from Kosovo

Background and objectives: Phenols and flavonoids are the most common phytoconstituents of medicinal and aromatic plants, and responsible for antioxidant activities. This study aimed to determine the content of phenolics and flavonoids in water and methanolic extracts of six selected medicinal plants (Betula pendula Roth, Betula pubescens Ehrh., Trifolium pratense L., Verbascum thapsus L., Equisetum arvense L., and Sambucus nigra L.) collected from various locations in Kosovo. Methods: The total phenolic content (TPC) was estimated spectrophotometrically using the Folin-Ciocalteu method and expressed as mg of gallic acid equivalents per gram of dry weight sample (mgGAE/gDW). The total flavonoid content (TFC) was measured by the aluminum chloride colorimetric assay and expressed as mg of catechin equivalents per gram of dry weight sample (mgCE/gDW). Results: The TPC of the water extracts ranged from 5.26±0.05 mgGAE/gDW (Equisetum arvense L.) to 33.14 ± 0.13 mgGAE/gDW (Sambucus nigra L.), while that of the methanolic extracts ranged from 16.85 ± 0.27 mgGAE/gDW (Equisetum arvense) to 38.95 ± 0.15 mgGAE/gDW (Betula pendula). The TFC of the water extracts ranged from 0.09 ± 0.01 mgCE/gDW (Verbascum thapsus) to 1.57 ± 0.01 mg CE/gDW (Trifolium pratense), while that of the methanolic extracts ranged from 0.25 ± 0.02 mgCE/gDW (Verbascum thapsus) to 1.36±0.02 mgCE/gDW (Trifolium pratense). Equisetum arvense herba showed the largest difference in TPC and TFC between the water and methanolic extracts, with 8.26 ± 0.05 mgGAE/gDW and 0.25 ± 0.01 mgCE/gDW in water extract and 16.85 ± 0.27 mgGAE/gDW and 1.15 ± 0.08 mgCE/gDW in methanolic extract, respectively. Conclusions: Results shows varying levels of phenolics and flavonoids, with some plants exhibiting higher levels in methanolic extracts than in water extracts. These findings may have important implications for the potential use of these plants in traditional medicine and as sources of natural antioxidants.