RCC II activity was measured in a buffer containing 25 mM K[H.sub.2]P[O.sub.4]/K2HP[O.sub.4]; 5 mM Mg[Cl.sub.2], pH 7.2, 20 mM sodium succinate (Sigma-Aldrich); 50 [micro]M 2,6-dichloroindophenol
sodium salt hydrate (Sigma-Aldrich); 2 mM KCN; 2 [micro]g/mL antimycin A; 2 [micro]g/mL rotenone; and 65 [micro]M ubiquinone 1.
Vitamin C Determination: This was determined using the 2,6-Dichloroindophenol
Titrimetric method .
The [V.sub.C] content was determined by using the 2,6-dichloroindophenol
titration method .
Twenty-five milliliter of the extract was then titrated with 0.025% of 2,6-dichloroindophenol
. Triplicate measurements were considered for statistical analysis.
Folin & Ciocalteu's phenol reagent, 1,1-diphenyl-2-picrylhydrazyl radical (DPPH), 2,4,6-tripyri-dyl-1,3,5-triazine (TPTZ), 2,2'-azinobis-(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS), 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid (Trolox), gallic acid monohydrate, 2,6-dichloroindophenol
, (+)-catechin hydrate, and vitamin C were purchased from Sigma-Aldrich (Shanghai, China).
 using the reaction in which complex I oxidizes NADH and the produced electrons reduce the artificial substrate decylubiquinone that subsequently delivers the electrons to 2,6-dichloroindophenol
(DCIP, Santa Cruz Biotechnology, CA).
Phenazine oxidoreductase (soluble succinate dehydrogenase - SDH) was measured in terms of the decrease in absorbance due to the reduction in 2,6-dichloroindophenol
(DCIP) at 600 nm as reference wavelength ([epsilon] = 19.1 [mM.sup.-1] x [cm.sup.-1]) in the presence of phenazine methosulphate (PMS).
The filtrate was added to 1 mL of 1.7 mM 2,6-dichloroindophenol
(2,6-DCPIP) in a 3 mL cuvette.
, measured by the following decrease in absorbance due to the reduction of 2,6-dichloroindophenol
(2,6-DCIP) at 600 nm with 700 nm as the reference wave length ([epsilon] = 19.1 [mM.sup.-1] [cm.sup.-1]) in the presence of phenazine methosulphate (PMS).
The NAD(P)H:quinone oxidoreductase 1 (NQ01) activity was measured as 2,6-dichloroindophenol
(DCIP) reduction in the cell cytosol.
Coenzyme [Q.sub.l], decylubiquinone, 2,6-dichloroindophenol
(DCIP),  rotenone, and antimycin-A were obtained from Sigma.
Total NADH dehydrogenase activity was measured on sonicated mitochondria in a 1-mL reaction medium containing 35 [micro]M 2,6-dichloroindophenol
(DCIP), 30 mM MOPS, 1 mM SHAM, 1 mM KCN, and 1 [micro]M antimycin A and was initiated with 1 mM NADH.