mohammadmehdi nemat shahi

In this study, first extraction from the C. dactylon rhizomes was performed with methanol solvent using maceration method, and total phenolic compounds in the extract were identified and determined. Then the antioxidant effects of the extract in different concentrations (0, 100, 200, 400, 800 and 1000 ppm) on the oxidative stability factors of soybean oil including peroxide value, acidity value, thiobarbituric acid index (TBA) and rancimat value during kept of oil in an oven at 60 °C for 72 hours was evaluated and compared with the synthetic antioxidant BHT (200 ppm). The identification results of phenolic compounds by GC/MS showed that the total amount of phenolic compounds in the C. dactylon rhizomes extract was measured as 917.08 mg/kg and the major phenolic compounds of the extract including Hydroquinone (66.89%), Thymol (1.23%), Levoglucosenone (2.48%) and Vanillic acid (1.35%) were identified. With increasing the concentration of the extract, the amount of polyphenolic compounds and as a result, the free radical scavenging activity of the extract increased. Evaluation of soybean oil stability against oxidation also showed that among the studied concentrations of methanolic extract, the concentration of 1000 ppm due to having the highest amount of phenolic compounds and therefore the highest antioxidant activity, was determined as the most effective concentration level of the extract in increasing the oxidative stability of soybean oil, so that better results were obtained than BHT synthetic antioxidant at a concentration of 200 ppm. Thus, the methanolic extract of the C. dactylon rhizomes can be used as a cheap and available antioxidant source in the edible oils industry.

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.