Table 3.

Methodology of estimation of free radical generation in serum and tissue

The leukoplakic tissue sample and serum were homogenized (5%) in ice cold 0.9% saline with a potter–Elvehjem glass homogenizer for 30 s. The homogenate was centrifuged at 800×g for 10 min followed by centrifugation of the supernatant at 12000×g for 15 min and the obtained mitochondrial fraction was used for following estimation:

Superoxide dismutase (SOD)

The inhibition of reduction of nitro blue tetrazolium to blue coloured formazan in presence of phenazine metha sulphate and NADH was measured at 560 nm using n-butanol as blank. One unit of enzyme activity was defined as the amount of enzyme that inhibits rate of reaction by 50% in 1 min under the defined assay conditions and the results have been expressed as units (U) of SOD activity/g wet tissue [11].

Catalase activity (CAT)

Decomposition of H2O2 in presence of catalase was followed at 240 nm. One unit of (U) CAT was defined as the amount of enzyme required to decompose 1 μmol of H2O2 per min, at 25°C and pH 7.0. Results are expressed as units (U) of CAT activity/g wet tissue [12].

Lipid peroxidation (LPO)

LPO product malodialdehyde was estimated using 1,1,3,3 tetraethoxypropane as the standard and is expressed in nmol/mg protein [13].