# Inhibition of Peroxidation Potential and Protein Oxidative Damage by Metal Mangifera Complexes
## 4 Discussion  
### Metal-Mangiferin Complexes  
One of the most complex problems in the synthesis of metal-organic complexes is the stoichiometric ratio that leads to the most stable complex. Said relationship will depend not only on the nature of the metal but also on the structure of the ligand. A 1:3 stoichiometric \begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multirow{2}{*}{**Sample**} & **Chromatop. Peak** & **PP (\(\mu\)M)** & **CO (\(\mu\)M)** & \multicolumn{2}{c}{**Inhibition (\%)**} \\ \cline{3-6}  & & **PP (\(\mu\)M)** & **CO (\(\mu\)M)** & \multicolumn{2}{c}{**Protein**} \\  & & & & **PP** & **Degradation** \\ \hline Control & & 16.4 \(\pm\) 1.1 a ** & 504.8 \(\pm\) 50.5 a  & - & - \\ \hline Mangiferin & 1 & 15.9 \(\pm\) 1.5 a  & 490.6 \(\pm\) 55.2 a  & 3.10 & 2.81 \\ \hline Cu (1:2) & 2 & 16.0 \(\pm\) 1.4 a  & 497.0 \(\pm\) 48.4 a  & 0.01 & NA \\ \cline{2-6}  & 3 & 16.2 \(\pm\) 1.6 a  & 501.4 \(\pm\) 49.7 a  & 0.02 & NA \\ \hline Zn (1:2) & 2 & 13.8 \(\pm\) 1.5 ab  & 456.8 \(\pm\) 50.5 a  & 13.21 & 6.94 \\ \cline{2-6}  & 3 & 14.4 \(\pm\) 1.5 ab  & 472.9 \(\pm\) 45.8 a  & 9.43 & 3.67 \\ \hline Zn (1:3) & 4 & 10.8 \(\pm\) 1.2 abc  & 419.0 \(\pm\) 56.8 ab  & 32.08 & 14.49 \\ \hline Se (1:2) & 3 & 12.6\(\pm\)1.4 abc  & 444.9\(\pm\)52.2 ab  & 20.75 & 12.24 \\ \hline Se (1:3) & 4 & 8.1\(\pm\)1.7 bcd  & 388.0\(\pm\)55.0 ab  & 49.06 & 20.81 \\ \hline \hline \end{tabular} RBC lysates were tested adding equivalent amounts of 20 mM for each tested compound. PP represents MDA values according to differential textures at 0 and 24 h (586 nm) after incubation of RBC lysates with tested compounds. CO values according to absorbance textures at 370-375 nm. Inhibition values as percentages against the control sample (for mangiferin) or mangiferin (complexes). Legend: Control, egg albumin; PP, peroxidation potential; CO, carbonyl groups. NA, Not Applied. Different letters mean significant variation (\(p>\) 0.05).  
\end{table} 
Table 4: Determination of the inhibition of the peroxidation potential and the protein degradation by metal–mangiferin complexes. Figure 3: Determination of the inhibition of the peroxidation potential and the protein degradation by metal–mangiferin complexes. (**A**). Percentage of inhibition of lipid peroxidation; (**B**). Percentage of inhibition of protein degradation. Inhibition values as percentages against the control sample (for mangiferin) or mangiferin (complexes). Legend: Cu (1:2) P2, copper complex 1:2 Chromatographic peak 2; Cu (1:2) P3, copper complex 1:2 Chromatographic peak 3; Zn (1:2) P2, zinc complex 1:2 Chromatographic peak 2; Zn (1:2) P3 zinc complex 1:2 Chromatographic peak 3; Zn (1:3) P4 zinc complex 1:3 Chromatographic peak 4; Se (1:2) P3, selenium complex 1:2 Chromatographic peak 3; Se (1:3) P4, selenium complex 1:3 Chromatographic peak 4. Different letters mean significant variation (\(p\)\(>\)0.05). ratio can give rise to complexes where several ligands may be attached to a metal nucleus, but a 1:2 ratio rendered a complex with two ligands attached to said nucleus [3]. It has been reported that the coordination sites can be two adjacent hydroxyl groups [2]. The metal-MF complex of Peak 2 is probably the result of the metal coordination to the quinolic oxygen (carbonyl group) and one adjacent hydroxyl group from two MF moieties, but that possible structure was only observed for Cu (II) and Zn (II) complexes (ratio 1:2). That Peak 2 was not observed for the reaction between sodium selenite and MF at the same ratio, probably due to a steric hindrance. These type of structures with Cu (II) and Fe (II), but with a different xanthone (\(\beta\)-mangostin), have been reported [23]. Similar Cu (II) and Zn (II) coordination complexes have been also reported, but with a different xanthone ligand (isoeuxanthone) [24]. Other metal-MF complexes with Cu (II) and Zn (II) have been reported, but only with one MF moiety attached to the metal nucleus [25], probably due to the basic reaction conditions (pH = 7.5), while our reactions were conducted in acidic medium (pH = 6.5).