2.7. Antioxidant activity
Homogenized tomato samples (1 g of fresh full ripe fruit) were
each extracted twice with acetone. DPPH (1.1-diphenyl-2-picrylhydrazyl)
radical scavenging activity was determined according to the
method of Livak and Schmittgen (2001). Equal volume (1 ml) of
tomato extract and DPPH solution (0.2 mM in ethanol) was kept at
room temperature for 30 min before the decrease of the solution absorbance was measured at 517 nm. The percentage of inhibition
was calculated by % inhibition¼[1−(absorbance of the solution
with extracts/ absorbance of the solution without extracts)] 100%.
Lipid peroxidation was determined by fluorescence according to the
method of Kang et al. (2006). Inhibiting rate (%) is calculated as
[fluorescence intensity (395ex/460em) of BSA adding with fatty
acid—flurescence intensity (395ex/460em) of BSA with fatty acid
and extract]/ fluorescence intensity (395ex/460em) of BSA adding
with fatty acid 100.
2.8. Data analysis
Carotenoid contents were analyzed by one-way ANOVA which
was carried out by a post hoc Tukey’s Honestly Significant
Difference (HSD) test for more than three group means or
Paired-Samples T test for two group means by software SPSS.
Quantitative data of real-time PCR, growth and photosynthesis
were analyzed by Paired-Samples T test.