In vitro evaluation of the amount of flavonoids, flavanols, and total phenolic compounds in 10 medicinal plants used in Iran; focus on diabetes and kidney diseases

Introduction: Free radicals and reactive oxygen species (ROS) as oxidants are important concerns in medicine due to their adversative effects and risk of carcinogenicity. Antioxidants can neutralize free radicals and ROS thus possesses protective effect on the body. Plants are rich sources of natural antioxidants and phenolic compounds are among the most important antioxidants in the plants; therefore, many studies have investigated their protective effects. Objectives: This study was conducted to evaluate and compare the number of flavonoids, flavonols, and total phenolic compounds in 10 commonly used medicinal plants in Iran. Materials and Methods: Extraction was performed using 70% ethanol solvent. The extracts were concentrated by rotary evaporator at 40°C. Folin-Ciocalteu method was used to measure the amount of phenol. The amount of flavonol was measured using 2% aluminum chloride and 5% sodium acetate. In addition, to determine the flavonoid compounds, 2% aluminum chloride and 5% potassium acetate was used. Results: The outcomes of this study disclosed that the studied plants had reasonably high quantities of flavonoid and phenolic compounds. The uppermost amount of phenolic compounds was detected in the myrtle plant (62.7 mg/g), and the lowermost amounts were detected in fig leaves and lemon balm. Moreover, the highest amount of flavonoid compounds was detected in ginger, myrobalan, and myrtle; the measured amounts of flavonoid compounds in the mentioned plants were 42.49, 32.15, and 34.38 mg/g, respectively. The highest amount of phenolic compound was detected in hydroalcoholic extract of barberry. Conclusion: Hydroalcoholic extract of ginger, barberry, fig leaves, rhubarb, myrobalan, walnut diaphragm, pomegranate peel, lemon balm, cardamom, and myrtle had great quantities of phenolic, flavonol, and flavonoid compounds. As a result, these herbal plants can be considered and used as an important source of natural antioxidants.