# Inhibition of Peroxidation Potential and Protein Oxidative Damage by Metal Mangifera Complexes
## 4 Discussion
### Evaluation of Antioxidant and Oxidative Damage Protection Properties of Metal-Mangiferin Complexes  
Adjuvant antioxidant therapies have been claimed to improve standard therapies for neurodegenerative diseases and cardiovascular disorders [28], but it seems that more important than the antioxidant effect, which means the reduction of ROS and/or the stimulation of the endogenous antioxidant defense mechanism, is the protection to oxidative damage thus maintaining the integrity of DNA within the organism [29]. Products having both antioxidant and protective effect against oxidative damage would be the best choice to those adjuvant therapies [30]. Antioxidants and pro-oxidants cannot be seen only in terms of cell damage/protection, but they play an important role in cell signal transduction pathways, both in physiological and pathological conditions [31]. For instance, the redox modulation \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Metal** & **Peak** & \begin{tabular}{c} **Stoichiometric** \\ **Ratio** \\ \end{tabular} & \
\begin{tabular}{c} **Predicted Complex** \\ **Molecular Formula** \\ \end{tabular} &
\begin{tabular}{c} **Estimated Complex** \\ **Molecular Mass** \\ \end{tabular} \\ \hline \multirow{3}{*}{Copper (II)} & 2 & 1:2 & C\({}_{38}\)H\({}_{34}\)O\({}_{22}\)Cu.2H\({}_{2}\)O & 942.22 \\ \cline{2-5}  & 3 & 1:2 & C\({}_{38}\)H\({}_{32}\)O\({}_{22}\)Cu.2H\({}_{2}\)O & 940.21 \\ \hline \multirow{3}{*}{Zinc (II)} & 2 & 1:2 & C\({}_{38}\)H\({}_{34}\)O\({}_{22}\)Zn.2H\({}_{2}\)O & 944.06 \\ \cline{2-5}  & 3 & 1:2 & C\({}_{38}\)H\({}_{32}\)O\({}_{22}\)Zn.2H\({}_{2}\)O & 942.04 \\ \cline{2-5}  & 4 & 1:3 & C\({}_{57}\)H\({}_{46}\)O\({}_{33}\)Zn\({}_{2}\).4H\({}_{2}\)O & 1461.76 \\ \hline \multirow{3}{*}{Selenium (IV)} & 3 & 1:2 & C\({}_{38}\)H\({}_{34}\)O\({}_{25}\)Se & 937.61 \\ \cline{2-5}  & 4 & 1:3 & C\({}_{57}\)H\({}_{46}\)O\({}_{33}\)Se\({}_{2}\) & 1448.85 \\ \hline \hline \end{tabular} Legend: Peak as per Table 1. Molecular formulae and masses were estimated as per Table 2.  
\end{table} 
Table 5: Molecular formulae and molecular masses of metal–MF complexes. o HIF1\(\alpha\) (hypoxia-inducible factor 1 alpha), named \"pseudob hypoxia\" is frequently used by cancer cells to promote glycolytic metabolism to support biomass synthesis for cell growth and proliferation [32]. MF inhibits the expression of HIF-1\(\alpha\)[33]; however, even when MF has shown promising chemotherapeutic and chemopre potential, its bioavailability is limited [34]. MF derivates as metal complexes, or other structural modification as metal complexes with glucoside-sulfate conjugates or phospholipid complexes, may increase the bioavailability of MF and thus its potential use for prophylactics and/or therapeutics. All previous research work about antioxidant and/or protection against protein oxidative damage of metal-polyphenols complexes has demonstrated that such coordination complexes had higher antioxidant and/protective effects than the isolated ligand. However, it cannot be generally assumed either for all metal nucleus or all polyphenic ligands. Our results demonstrated that Cu (II)-MF complexes had similar peroxidation potential to MF, but protein oxidative damage was increased as compared to MF. Biomolecules damage by Cu-mediated hydroxyl radical production may be acting as a drawback for these Cu (II)-MF coordination complexes [35]. Se (IV)-MF (peak 4) showed the best inhibition values for both peroxidation potential (49.06%) and protection against protein oxidative damage (20.81%), followed by the same complex type of Zn (II)-MF with 32.08% and 14.49%, respectively. Further structure-activity relationships with accurate crystallographic data for this complex type would be recommended. However, the inhibition of the peroxidation potential for both Zn (II)-MF complexes (Peaks 2 and 3) and the protection against protein oxidative damage were not significantly different as compared to MF.