## 3 Results and Discussion
### Polyphenolic Profile  
To illustrate the effect of ultrasonication pretreatment on the analytical polyphenolic profile, LC-MS was undertaken for the samples obtained after 180 min of extraction, at 80 \({}^{\circ}\)C, under optimal conditions. A typical chromatogram is given in Figure 7, showing the principal substances detected at both 320 and 360 nm. It should be noted that for both ultrasonication-pretreated and non-pretreated samples,  
Figure 6: Arrhenius plot for the extractions with no pretreatment (No US) and ultrasonication pretreatment (US). the chromatograms recorded were identical (data not shown), evidencing no effect of ultrasonication on the polyphenolic profile. Peak #1 showed a pseudo-molecular ion at \(m\)/z = 355 and a derivative ion at \(m\)/z = 163. Considering the UV-vis characteristics, this structure was assigned to neochlorogenic acid. The identity of this peak was further confirmed by comparing the UV-vis spectrum and retention time (Rt) with an original standard. Likewise, peaks 2 and 3 were tentatively identified as chlorogenic acid and a chlorogenate isomer, respectively (Table 7). Peak #4 displayed a pseudo-molecular ion at \(m\)/z = 595, a sodium adduct at \(m\)/z = 617, and a diagnostic fragment (aglycone) at \(m\)/z = 287. This compound was tentatively assigned to multiforin B (kaempferol 3-\(O\)-Hammosylglucose). Similarly, peaks 7 and 8 were assigned to a kaempferol glucoside and kaempferol malonylglucose. Peaks 5 and 6, which exhibited typical quercetin glycoside UV-vis pattern and diagnostic fragment at \(m\)/z = 303, were tentatively identified as quercetin glucoside and quercetin malonylglycoside derivative, respectively [39]. All these compounds have been previously reported in _M. oleifera_ leaf extracts [13]; however, the presence of a quercetin rhamnide derivative claimed in an earlier study [40] was not confirmed. The information emerged from the quantitative data (Table 8) showed that ultrasonication pretreatment afforded changes in the recovery of major polyphenols, but not all substances were equally affected. \begin{table}
\begin{tabular}{c c c c c c} \hline
**No** & **Rt (min)** & **UV-Vis** & **[M + H]\({}^{+}\) (\(m\)/z)** & **Fragment Ions (\(m\)/z)** & **Tentative Identity** \\ \hline
1 & 17.24 & 244, 318 & 355 & 163 & Neochlorogenic acid \\
2 & 22.48 & 246, 318 & 355 & 377, 163 & Chlorogenic acid \\
3 & 23.07 & 246, 318 & 355 & 377, 163 & Chlorogenic acid isomer \\
4 & 27.19 & 270, 3205, 340 & 595 & 617[M + Na]\({}^{+}\), 287 & Multiforin B \\
5 & 35.62 & 256, 318(s), 354 & 465 & 487[M + Na]\({}^{+}\), 303 & Quercetin glucoside \\
6 & 37.89 & 256, 316(s), 360 & 833 & 609, 573, 551, 303 & Quercetin malonylglycoside derivative \\
7 & 39.34 & 264, 318(s), 348 & 449 & 471[M + Na]\({}^{+}\), 287 & Kaempferol glucoside \\
8 & 42.30 & 264, 348 & 535 & 557[M + Na]\({}^{+}\), 287 & Kaempferol malonylglucose \\ \hline \end{tabular}
\end{table} 
Table 7: Analytical spectrometric data of the major polyphenolic phytochemicals detected in the extracts of _M. oleifera_ leaves. Figure 7: HPLC traces of the sample extracted under optimal conditions, at 80 \({}^{\circ}\)C, with ultrasonication pretreatment, recorded at 320 and 360 nm. Peak assignment: 1, neochlorogenic acid; 2, chlorogenic acid; 3, chlorogenic acid isomer; 4, multiforin B; 5, quercetin glucoside; 6, quercetin manonylglycoside derivative; 7, kaempferol glucoside; 8, kaempferol malonylglucose. For neochlorogenic acid and chlorogenic acid, ultrasonication pretreatment brought about an increase by 3.1% and 9.1%, but for the chlorogenic acid isomer, a decrease by almost 1.9% was observed. Overall, total chlorogenate content was by 1.1% increased, a difference that falls within the limits of statistical error. Thus, ultrasonication pretreatment had practically no effect on chlorogenate extractability. On the other hand, all flavonoid glycosides had higher content in the ultrasonication-pretreated sample, the increases varying from 0.65% (quercetin glucoside) to 14.6% (quercetin nanolyglycoside derivative).