Study of Antioxidant Properties and Recognition of Chemical Compounds of Extracts from Adiantum Capillus-veneris Leaf

Regarding the antioxidant properties of Adiantum capillus-veneris, identification of phytochemical compounds, extraction of phenolic compounds, and determination of inhibitory activity of free radicals of this plant seem necessary. Therefore, in this study, the structure of fatty acids, tocopherols, sterols, and phenols was identified. Then, the effect of methanol and ethanol solvents on extraction of polyphenolic compounds and antioxidant activity of Adiantum capillus-veneris leaf extract were investigated. The results of identification of the chemical compounds of the extract showed that palmitic acid was the predominant saturated fatty acid, gamma and beta tocopherols were the most abundant tocopherols, cytosterol the most abundant sterol, and syringic acid and hydroxytyrosol the main phenol of the leaf extract. Measurement of phenolic compounds showed that by increasing the concentration of extract up to 1000 ppm, the amount of polyphenolic extracted in methanol and ethanol solvents increased to 240.65 and 142.4 mg GA/g, respectively, but the extraction percentage of these antioxidants by methanol was significantly higher than ethanol. In the next step, the inhibitory activity of free radicals was measured at different concentrations of methanol and ethanol and compared with the synthetic antioxidant BHT at 200 ppm; it was found that increasing the antioxidant properties of methanolic and ethanolic extracts depend on concentration, meaning that by increasing the concentration of extracts from 200 ppm to 1000 ppm, the antioxidant activity increased significantly and at a constant concentration, the methanol-extracted extract had more radical scavenging activity than the ethanol-extracted extract and both extracts had more antioxidant activity than synthetic antioxidant BHT. Generally, the results of this study showed that methanol is a more effective solvent in extraction of phenolic compounds from Adiantum capillus-veneris leaves. There was also a positive correlation between the amount of phenols and antioxidant activity.