Double beam scanning uv vis model uv 1700

Folin–Ciocalteau method was executed using gallic acid as reference standard [57 ,58 (link)]. Each experiment was carried out in triplicate and results were described as mg equivalents of gallic acid (GA)/g of dried extract (mg eq GA/ g dried MECP extract). A calibration curve was performed using pure gallic acid as a standard diluted in deionized water, in a range of concentrations from 0.02 to 0.12 mg/mL (R² = 0.99, y = 13.398x + 0.0013). Sample MECP was evaluated using a stock solution of 0.2 mg/mL in deionized water to carry out the assay, using 250 μL and adding deionized water until a final volume of 1 mL, after which 500 μL of Folin–Ciocalteau and 1.5 mL of sodium carbonate was added. Then, the reaction was left to incubate at room temperature for two hours. All absorbance was measured with a spectrophotometer (Shimadzu Double Beam Scanning UV–Vis (Model UV-1700)) and all samples were measured at 750 nm.

Antioxidant potential of MECP was also evaluated using in vitro DPPH (2,2-Diphenyl-1-picrylhydrazyl, Sigma–Aldrich, No. cat D9132) scavenging assay [59 (link)]. Free radical MECP was dissolved in methanol, and the last two were evaluated at the same concentrations (from 4 to 40 µg/mL, R² = 0.99, y = 1.5967x + 21.187). Experiment was determined in triplicate, and inhibition potential was calculated with % inhibition = [AC-AS/AC] × 100, where AS: absorbance sample, AC: absorbance DPPH control. A calibration curve was performed using pure quercetin as a standard in a range of concentrations from 2 to 20 µg/mL (R² = 0.99, y = 3.9877x + 34.381). All of absorbance was measured with a spectrophotometer (Shimadzu Double Beam Scanning UV–Vis (Model UV-1700, SHIMADZU Corporation, Nishinokyo Kuwabara-cho, Nakagyo-ku, Kyoto 604-8511, Japan)) at 515 nm. Finally, median inhibitory concentration (IC₅₀) was calculated for MECP and quercetin. Results were reported as µg/mL after extrapolation on the calibration curve.