Isoquinoline alkaloid fractions of Fumaria officinalis: Characterization and evaluation of their antioxidant and antibacterial activities
Résumé
Crude alkaloid extracts of Fumaria officinalis (Fumariaceae), used in Algerian traditional medicine for hepatobiliary diseases, were subjected to fractionation and GC–MS analysis. The total alkaloid (TA) content was 630mg/100g of dry weight. Fractionation led to three fractions: neutral (NF), acidic (AF) and basic (BF) with alkaloid levels of 300, 240 and 180mg/100g of dry weight, respectively. Eleven isoquinoline alkaloids were identified. The main component in all fractions was protopine, especially in the acidic fraction (AF) (51.75%). F. officinalis is usually classified by authors in the second chemotaxonomic group of Fumaria sp., while our results showing the presence of stylopine, especially in the basic fraction (2.08%), suggest it should be classified in the first chemotaxonomic group. The crude extract and fractions showed high antioxidant activity against the free radical DPPH (IC50 NF (15.74±0.04μg/mL)), the ABTS radical (IC50 BF (70.71±0.04μg/mL)), and the hypochlorous acid radical (IC50 NF (304.19±0.29μg/mL)), Total Antioxidant Capacity (TA (14.23±0.04mg eq ascorbic acid/g DM)), lipid peroxidation inhibition (IC50 TA (41.67±0.17μg/mL)) and ferric reducing power (FRP) (BF (3.49±0.11mg eq ascorbic acid/g DM)). Antibacterial activity was evaluated using liquid medium against Acinetobacter calcoaceticus, Propionibacterium acnes and Corynebacterium xerosis. Evaluation of minimum inhibitory concentration (MIC) showed low values, indicating an interesting antibacterial capacity. The MIC of 0.33mg/mL recorded against Propionibacterium acnes with alkaloid extracts showed the effectiveness of this plant as an antibacterial agent. The greater effectiveness of the acid fraction (AF) and the total alkaloid extract (TA) against the three strains tested was correlated to their richness in protopine with levels of 51.75% and 34.48%, respectively.