Total phenolic, total flavonoids content and antioxidant activity from the aerial parts of Thalictrum minus L

Abstract

Background: The genus Thalictrum belongs to the family Ranunculaceae Juss. and comprises approximately 200 species distributed worldwide. Most species occur in temperate regions, although a few are also found in lowland areas. Approximately 43 species of Thalictrum have traditionally been used as medicinal raw materials due to their notable therapeutic properties and reported efÏcacy. These plants have traditionally been used to treat a wide range of conditions, including infectious diseases, nervous system disorders, joint diseases, intestinal inflammation, gingivitis, tumors, jaundice, pneumonia, and other pulmonary inflammatory conditions. They have also been used for wound healing, reducing fever, treating gastric and duodenal ulcers, managing eye disorders and headaches, restoring physical strength, promoting diuresis, alleviating digestive disturbances, stimulating intestinal peristalsis to facilitate bowel movements, supporting recovery after illness, and treating snakebites. Phytochemical investigations have revealed that Thalictrum species contain diverse bioactive constituents, including alkaloids, flavonoids, glycosides, terpenoids, fatty acids, and phenolic compounds. These compounds have been associated with various pharmacological properties, particularly antioxidant, anti-inflammatory, antimicrobial, cytotoxic, and antitumor activities. Therefore, Thalictrum minus, a species that is widely distributed in Mongolia but whose chemical composition and biological activities have not yet been comprehensively investigated, was selected for the present study. Aim: To determine total phenolic and flavonoid content of crude extracts of this plant. To investigate the antioxidant activity. Materials and Methods: Total phenolic compounds, total flavonoids and antioxidant activity were determined using spectrophotometer methods using extracts from the aerial parts of T. minus. Dried flowering plant material of Thalictrum minus, taxonomically identified by the Botanical Garden of the Mongolian Academy of Sciences, was obtained from the Department of Pharmaceutical Technology, Mongolian University of Pharmaceutical Sciences. Total phenolic content (TPC) was determined using the Folin–Ciocalteu method, with gallic acid as the reference standard, and absorbance was measured at 760 nm. Total flavonoid content (TFC) was determined using an aluminum chloride colorimetric assay, with rutin as the reference standard, and absorbance was measured at 500 nm. Antioxidant activity was evaluated using the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical-scavenging assay. Plant extracts at different concentrations were mixed with DPPH solution and incubated in the dark for 30 min. Absorbance was measured at 517 nm using an Agilent BioTek Epoch 2 microplate reader, with quercetin as the positive control. Radical-scavenging activity was calculated as a percentage, and IC₅₀ values were determined from concentration–response curves. All measurements were performed in triplicate or quadruplicate, and results were expressed as IC₅₀±standard deviation (SD). Results: The total phenolic, total flavonoid content and antioxidant activity of the aerial parts of T. minus, a plant species growing in Mongolia, were evaluated using spectrophotometric methods. The total phenolic content of the aerial parts of Thalictrum minus L. was determined using gallic acid as the reference standard. The absorbance was measured at 500 nm, and the content was calculated using the calibration equation (y=0.6947x + 0.0046, R2=0.9997), yielding a total phenolic content of 5.38±0.09%. The total flavonoid content was determined using rutin as the reference standard and calculated using the calibration equation (y=0.3089x +0.0112, R2=0.9960), yielding a content of 2.04±0.16%. The antioxidant activity of the aerial-part extract was evaluated using the DPPH free-radical scavenging assay, which yielded an IC₅₀ value of 66.09 µg/mL. Conclusion: The contents of selected bioactive secondary metabolites in the aerial parts of Thalictrum minus were determined. In addition, the antioxidant activity of the aerial-part extracts was evaluated in comparison with reference standards, demonstrating that the extracts possess antioxidant activity.