Model uv 1900i

DPPH radical scavenging property was determined by following the procedure of Mensor et al.^{50 (link)}. The dry seedling tissue were extracted through incubation in 80% methanol at 28 °C for 24 h in shaking incubator. After centrifugation at 3500 rpm for 20 min in cold, collected supernatant was filtered and used for DPPH radical scavenging activity mixed with DPPH solution (0.04 mg mL⁻¹ ethanol) in 1:3 ratios. Absorbance at 517 nm was observed after 30 min incubation in dark with the help of UV–VIS spectrophotometer (Shimadzu, Model UV-1900i). Finally total antioxidant capacity (TAC) was determined by the following formula: $$\text{TAC}\left(\%\right)=\left[1-\frac{\text{Ai}-\text{Aj}}{\text{Ac}}\right]\times 100$$ $$\begin{array}{c}[{\text{A}}_{\text{i}}=1\text{mL}\text{sample}+3\text{mL}\text{DPPH};\\ {\text{A}}_{\text{j}}=1\text{mL}\text{sample}+3\text{mL}\text{ethanol};{\text{A}}_{\text{c}}=1\text{mL}\text{ethanol}+3\text{mL}\text{DPPH}]\\ \end{array}$$

Lipoxygenase activity was determined according to Peterman and Siedow^{54 (link)}. 200 mg of tissue was homogenized with 5 mL of 50 mM Na-phosphate buffer (p^H-6.5) and centrifuged at 5000 rpm for 5 min. Supernatant was taken and re-centrifuged at 17,000 rpm for 10 min in cold. The reaction mixture contained 1 mL of 1.65 mM Na-phosphate buffer (P^H-6.5) and 1 mL of 1.3 mM linoleic acid. After 1 h of incubation at 25 °C, absorbance was read at 234 nm with the help of UV–VIS spectrophotometer (Shimadzu, Model UV-1900i).

To estimate membrane lipid peroxidation, test for thiobarbituric acid reactive substances (TBARS) was performed using the procedure of Heath and Packer^{53 (link)}. 200 mg of sample was homogenized in 5 mL 0.1% trichloroacetic acid (TCA) and then centrifuged at 10,000 rpm for 15 min and finally supernatant was taken. To 1 mL of supernatant, 3 mL of 5% TCA containing 1% thiobarbituric acid (TBA) was added and heated in a hot water bath for 30 min and cooled quickly in cold water bath. It was finally centrifuged at 10,000 rpm for 10 min. The absorbance of the supernatant was measured at 530 nm with the help of UV–VIS spectrophotometer (Shimadzu, Model UV-1900i). The concentration of TBARS was measured from its extinction coefficient of 155 µM cm^-1. The non-specific turbidity was corrected by subtracting A₆₀₀ from A₅₃₀ value. The formula employed as: $$\text{Conc}.\text{of}\text{unknown}=\frac{\text{Absorbance}\text{of}\text{unknown}\text{at}530\text{nm}\text{mols/l}}{\text{Diameter}\text{of}\text{cuvette}\times 155}$$
The TBARS content was finally expressed in n mol g^-1 dry mass of tissue.