Phytochemical investigation, antioxidant and antibacterial activities of Tanacetum parthenium L. aerial parts and root ethanolic extracts at different phenological stages

The amount of secondary metabolites in medicinal plants are changed during different stages of plant growth, so in order to determine the best time to harvest each medicinal herb, it is necessary to determine the amount of active substances and their biological activities in different phenological stages. Tanacetum parthenium L. is one of the important species of chicory genus that has many medicinal properties. This study investigated the content of total phenols, flavonoids, alkaloids, and anthocyanins and the antioxidant and antibacterial properties of Tanacetum parthenium L. aerial parts and root ethanolic extracts at different phenological stages (vegetative, flowering, and seeding). For this purpose, total phenols, flavonoids, alkaloids, and anthocyanins were measured spectrophotometrically in the aerial parts and root ethanolic extracts of T. parthenium. The antioxidant activity of the extracts was measured using 2,2-diphenyl-1-picrylhydrazyl (DPPH), and antibacterial activity was evaluated against Gram-positive bacteria (Staphylococcus aureus and Bacillus cereus) and Gram-negative bacteria (Escherichia coli and Salmonella typhimurium) by disk diffusion, minimum inhibitory concentration (MIC), and minimum bactericidal concentration (MBC) methods. The maximum levels of total phenol (62.3 ± 1.2 mg gallic acid equivalents (GAE)/g dry weight), flavonoids (35.7 ± 0.9 mg quercetin equivalents (QE).g-1 dry weight), alkaloids (73.2 ± 0.6 mg atropine equivalent.g-1 dry weight) and total anthocyanin (4.2 ± 0.3 mg cyaniding-3glicoside equivalents.g-1 dry weight) were measured in the shoot extract of the studied species at the flowering stage. Results of the antioxidant activity evaluation showed that the shoot extract at the flowering stage had the highest antioxidant activity (75.3 ± 0.7 %). The lowest antioxidant activity (16.5 ± 0.9 %) was measured for the root extract at the vegetative stage. According to the antibacterial investigation, the maximum inhibition zone (21 ± 0.3 mm) was observed for the shoot extract at the flowering stage against Staphylococcus aureus. The minimum inhibitory concentration (12.5 mg.mL-1) and the minimum bactericidal concentration (25 mg.mL-1) were recorded for shoot extracts at vegetative and flowering stages against the abovementioned bacteria. Based on the results, the studied species' extracts were more effective against gram-positive than gram-negative bacteria. According to the results of this study, it can be concluded that the flowering stage extract of T. parthenium had considerable phytochemical compounds with appropriate antioxidant and antibacterial properties. It can be used as a source of natural antioxidants and antibiotic agents.