The extraction yield was measured and expressed as a percentage (%). All extracts were dissolved in 10% dimethyl sulfoxide (DMSO) Tariquidar and stored at −20 °C for further analyses. Total polyphenol content (TPC) was determined according to the method of Singleton and Rossi (1965) with some modifications. An appropriately diluted sample (50 μl) was mixed with 25 μl of 1 N Folin–Ciocalteau reagent. The mixture was allowed to stand at room temperature for 5 min. Then, 100 μl of a saturated sodium carbonate (Na2CO3)
solution (0.57 M) was added to the mixture. The mixture was subsequently brought to a final volume of 250 μl, using distilled water. The absorbance was read at 760 nm (Bio-Rad Model 680 microplate reader, California, USA) after a 2 h reaction time. A standard calibration curve of gallic acid (0–0.2 mg/ml) was plotted.
Results were expressed as mg gallic acid equivalents (GAE)/g dried extract. Total flavonoid content (TFC) was measured by a modified aluminium chloride colorimetric assay, described by Liu et al. (2008). Sample (100 μl) was mixed with 10 μl of 5% sodium nitrite (NaNO2), and incubated for 5 min before the addition of 10 μl of 10% aluminium chloride (AlCl3). After 6 min, 100 μl of 1 M sodium hydroxide (NaOH) were added to the mixture. The reaction mixture was subsequently diluted to a volume of 250 μl, using distilled water. The absorbance of the mixture was read at 510 nm. A standard calibration curve of rutin (0–0.2 mg/ml) was plotted. The results were expressed as see more mg rutin equivalents (RE)/g dried extract. Total carotenoid content (TCC) was measured spectrophotometrically, as described by Khoo, Ismail, Mohd-Esa, and Idris (2008). It is recommended that a wavelength 5-Fluoracil research buy of 450 nm be utilised
for the measurement of carotenoids in fruit and vegetables (Khoo et al., 2008). No prior sample preparation was required and the absorbance of appropriately diluted sample was measured at 450 nm. A standard calibration curve of β-carotene (0–0.2 mg/ml) was plotted. All results were expressed in terms of mg of β-carotene equivalents (BE)/g dried extract. The ascorbic acid content (AA) was measured according to the method of Amin and Cheah (2003). Five hundred microgrammes of the extract were dissolved in 50% acetonitrile and then filtered through a 0.45 μm nylon membrane filter prior to analyses in the HPLC system (Series 1100, Agilent Technologies, Santa Clara, USA). Separation of ascorbic acid was achieved on a reverse phase Zorbax Eclipse XDB-C18 column (5 μm × 250 mm × 4.6 mm I.D), using acetonitrile:water (50:50) as the mobile phase at a flow rate of 1 ml/min. Sample injection volume was 20 μl. The compound was detected through a diode array detector at 254 nm. Results were calculated, based on a calibration curve of l-ascorbic acid (0–1 mg/ml).