## 2 Materials and Methods
### Assessment of Antioxidant Capacity of OM Extracts  
Reducing power and radical scavenging assays were conducted to assess the antioxidant activity of OM extracts, as established in our previous study [18]. The procedure demanded 100 \(\upmu\)L of properly diluted sample and 100 \(\upmu\)L of FeCl\({}_{3}\) solution (4 mM in 0.05 M HCl) in a 2-mL Eppendorf tube. Incubation of the mixture took place in a water bath at 37 \({}^{\circ}\)C for 30 min, in which 1800 \(\upmu\)L of TPTZ solution (1 mM in 0.05 M HCl) was immediately added to the mixture right after, with the absorbance (620 nm) being measured after 5 min. The ferric-reducing power (\(P_{\text{R}}\)) was conducted with molecule TPTZ as the ligand within a calibration curve of 50-500 \(\upmu\)M of ascorbic acid in 0.05 M HCl (R2 = 0.9997), with the results being expressed as \(\upmu\)mol ascorbic acid equivalents (AAE)/g dw, as indicated in Equation (2):  
\[P_{R}\left(\upmu\text{mol AAE/g dw}\right)=\frac{\text{C}_{\text{AA}}\times V }{w} \tag{2}\]  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**Phenolic Compound**} & **Linear Regression** & **LOD a** & **LOQ b** & \multirow{2}{*}{**R2 c**} \\  & **Equation** & **(mg/L)** & **(mg/L)** & & \\ \hline \(\beta\)-Resorylic acid & y = 73,173x \(-\) 374,752 & 6.38 & 19.35 & 0.9960 \\
4-Hydroxybenzoic acid & y = 82,756x \(-\) 322,848 & 4.30 & 13.02 & 0.9978 \\ Pyrogallol & y = 57,521x \(-\) 598,596 & 12.93 & 39.18 & 0.9919 \\ Pyrocatechuric acid & y = 189,392x \(-\) 143,080 & 9.92 & 30.06 & 0.9904 \\ Caffeic acid & y = 83,601x \(-\) 606,104 & 9.03 & 27.36 & 0.9942 \\ Homovanillic acid & y = 15,054x \(-\) 30,731 & 8.34 & 25.27 & 0.9951 \\ Syringic acid & y = 172,124x \(-\) 1,804,823 & 14.08 & 42.66 & 0.9881 \\ \(m\)-Coumaric acid & y = 110,557x \(-\) 583,252 & 7.37 & 22.34 & 0.9954 \\ \hline \hline \end{tabular} a
[FOOTNOTE:a]Footnote a: footnotetext: Limit of Detection; b
[FOOTNOTE:b]Footnote b: footnotetext: Limit of Quantification; c  
\end{table}
Table 3: Linear equation, detection limits of quantified polyphenols, and coefficient of determination (R2) in chromatographic quantification of individual polyphenols.  
In Equation (2), \(V\) (in L) and \(w\) (in g) indicate the volume of the extraction medium and the dried weight of the material, respectively.  
In addition, the DPPH* inhibition calibration curve ranged from 100-1000 uM of ascorbic acid in methanol (R\({}^{2}\) = 0.9926) and was calculated as umol AAE/g dw. The initial absorbance (515 nm) of a solution consisting of 50 uL of methanol and 1950 uL of a methanolic 100 uM DPPH* solution was measured immediately. Properly diluted sample volume of 50 uL was mixed with 1950 uL of the methanolic DPPH* solution, with the mixture being stored for 30 min in ambient temperature with the absence of light and the absorbance being recorded in the same wavelength. The percentage of inhibition calculation was done using Equation (3):  
\[\text{Inhibition}\;(\%)=\frac{A_{\text{515(i)}}\;-A_{\text{515(f)}}}{A_{ \text{515(i)}}}\times 100 \tag{3}\]  
Antiradical activity (\(A_{\text{AR}}\)) was evaluated using an ascorbic acid calibration curve which was expressed as umol AAE per gram of dw, as shown in Equation (4):  
\[A_{\text{AR}}(\upmu\text{mol AAE/g dw})=\frac{C_{\text{AA}}\times V}{w} \tag{4}\]  
where \(V\) (expressed in L) and \(w\) (expressed in g) denote the volume of the extraction medium and the dry weight of the sample, respectively.