Phenolic content and antioxidant activity of flowers and stems of Retama raetam and Retama monosperma
Description
Raw numerical data from phenolic content and antioxidant activity of flowers and stems of Retama raetam and Retama monosperma from which the graphs (Figure 1-6) and Tables (1-6) have been derived.
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Dosage of total polyphenols: The determination of polyphenols was carried out according to the protocol of Li et al. (2005), based on the use of the Folin-Ciocalteu reagent which colors polyphenols blue following their oxidation. A calibration curve was prepared using a dilution range of gallic acid. These solutions were treated according to the same protocol as the determination of total polyphenols. Then, the curve obtained was established according to the equation f(c)=DO and the results are expressed in (mg) gallic acid equivalent / (g) dry matter (EAG/g DM). Dosage of total flavonoids: The quantification of the flavonoid level was estimated by the colorimetric method using aluminum trichloride (AlCl3) and sodium hydroxide (NaOH). Aluminum trichloride forms a yellow complex with flavonoids (Vladimir et al. 2011). This coloring results from the fixation of Al+3 ions on the oxygen atoms present on carbons 4 and 5 of the flavonoids, while sodium hydroxide forms a pink-colored complex which absorbs in the visible at 510 nm (Vladimir et al. 2011).The quantitative determination of flavonoids in the extracts was carried out according to the protocol described by Kim et al. (2003). A calibration curve was established with standard solutions of catechins prepared at different concentrations. The absorbance of the mixture obtained was directly measured with a UV-visible spectrophotometer at 510 nm, and the results are expressed as (mg) catechin equivalent / (g) dry matter (EC/g DM). Determination of antioxidant power by the DPPH method: The 1,1-diphenyl-2-picrylhydrazyl (DPPH) molecule is a stable free radical, the solution of which exhibits a violet color and a characteristic absorption at 410 nm. When a solution of DPPH is mixed with a hydrogen-donating, antioxidant substance, the reduced form is formed. The reduction results in the loss of the violet color, transforming into a yellow color characterized by a visible absorption band at 410 nm (Brand-Williams 1995). The determination of the antioxidant power of the samples was carried out according to the method described by Hansraj et al. (2006). Three volumes of 1 ml were used for the analysis of the antioxidant activity of the extracts by the DPPH test. After 30 minutes of incubation in the dark and at room temperature, the absorbance is read at 517 nm. Phytochemical screening: -Flavonoids: The presence of flavonoids is indicated by the appearance of a pink, red, yellow-reddish, or red-purplish color (N'Guessan et al. 2009). -Tannins: The oxidation of tannins and their presence are indicated by a greenish or blue-blackish coloration (Karumi et al. 2004). -Saponins: The formation of a foam at least 1 cm high indicates the presence of saponins (N'Guessan et al. 2009). -Alkaloids: The appearance of a white or brown precipitate reveals the presence of alkaloids (Mojab et al. 2003). -Coumarins: The visualization of a fluorescent yellow color indicates the presence of coumarins (Bruneton 1999).