Phytochemical Screenings and Pharmacological Activities of two Medicinal Plants (Alchemilla arvensis and Taraxacum syriacum )
An-Najah National University
Background: Oxidative stress, obesity problems and multidrug-resistant microorganisms represent major challenges for pharmaceutical industries. These problems have prompted scientists to screen for alternative substances that act as strong antioxidant, antilipase and antimicrobial agents with maximum efficacy and few side effects. From the beginning of human history, different herbal remedies and other natural products have become important as biological sources of antioxidant, antilipase and antimicrobial agents. Therefore, the aims of this study were to investigate the antioxidant, antilipase and antimicrobial activities of two plant species, Alchemilla arvensis and Taraxacum syriacum. In addition, plants were screened for phytochemicals, specifically the total content of phenols and flavonoids. Methods: Antioxidant activity was examined by preparing a stock solution of plant extract at a concentration of 0.1mg/ml in methanol. A similar stock solution of 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid (Trolox), the reference substance, was also prepared. Solutions of different concentrations were prepared from the stock solutions by serial dilutions using methanol. The 2,2-diphenyl-picrylhydrazyl (DPPH) solution was mixed with methanol and the previously mentioned concentrations. The percent of antioxidant activity of the plant extracts and the trolox standard was calculated using the following formula: DPPH activity (%) = (A-B)/A ×100% A: Optical density of blank, B: Optical density of sample. Antilipase activity was examined by preparing a stock solution of p-nitrophenyl butyrate (PNPB). Pancreatic lipase activity was determined by measuring the hydrolysis of p-nitrophenolate to p-nitrophenol at 405 nm using a spectrophotometer. The same procedure was repeated for Orlistat ( is a drug designed to treat obesity.) which was used as a reference compound. The antimicrobial activities were examined using micro-broth dilution, agar dilution and agar-well diffusion methods. The tested strains, which were obtained from the American Type Culture Collection (ATCC), included Pseudomonas aeruginosa, Escherichia coli, Shigella sonnie, Staphylococcus aureus, Candida albicans, and Epidermophyton floccosum. Results: Trolox was used as reference drug in the detection of antioxidant activity and showed that the aqueous extract of Taraxacum syriacum was a more potent antioxidant (95.49µg/ml) than the methanol extract (281.83µg/ml). The acetone extract of Alchemilla arvensis was more potent antioxidant (4.86µg/ml) than the hexane extract (11.22µg/ml). Orlistat drug was used as reference to detect antilipase activity and showed that aqueous extract of Taraxacum syriacum more potent (154.88µg/ml) than the hexane extract (218.77µg/ml). The aqueous extract of Alchemilla arvensis was more potent(21.37µg/ml) then the methanol extract (30.90µg/ml). With regard to antimicrobial activity against bacteria and fungi, Taraxacum syriacum was evaluated against Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, and Shigella sonnie using aqueous and acetone extracts. The same were noticed against Candida albicans and Epidermophyton floccosum, in all extracts were used. Alchemilla arvensis was assessed against Staphylococcus aureus, Pseudomonas aeruginosa, Shigella sonnie, and Escherichia coli in aqueous and methanol extracts. Alchemilla arvensis was only potent against Epidermophyton floccosum fungus for all extracts were used. Conclusion: Extracts of Alchemilla arvensis and Taraxacum syriacum were tested for antioxidant, antilipase and antimicrobial activities. This study recommends that these plants could be used as cancer treatment drugs, also for obesity, in addition to used as antibacterial and antifungal drugs, or could be used as prevention against these diseases.