Sq2800

The antioxidant activity of the extracts against DPPH radicals was evaluated according to the method previously described by Patro et al. [32 (link)] with slight modifications. Exactly 0.5 mL of each sample with a concentration between 0.05 and 1.00 mg/mL were mixed with 1.0 mL of 0.1 mM DPPH reagent (Sigma Aldrich, St. Louis, MO, USA). The reaction mixture was incubated in the dark at room temperature for 30 min. The absorbance of the reaction was then recorded at 517 nm using a UV-visible spectrophotometer (SQ2800, Unico, Dayton, NJ, USA). The antioxidant efficacy of all samples was compared to ascorbic acid at 25–200 µg/mL (Loba Chemie, Mumbai, India) as a positive control in triplicate using the following Equation (2):
where C is the absorbance value of the control and S is the absorbance value of the sample.

Nifedipine concentrations were measured in methanol on a UV spectrophotometer (Unico SQ-2800) at 348 nm. The linear range was 5–100 µg/mL (r² > 0.999). Values reported represent mean ± SD for triplicate measurements.