# Phenolic and Volatile Composition of a Dry Spearmint (_Mentha spicata_ L.) Extract
## Results and Discussion
### Characterization of the Phenolic Profile
Among this group of molecules, salvianolic acid A was the most abundant (7.79 \(\pm\) 0.52 mg/g), followed by salvianolic acid B (1.35 \(\pm\) 0.16 mg/g). Both were identified by means of reference compounds and served to identify their respective derivatives and isomers. Salvianolic acid D and F (dimers of caffeic acids), salvianolic acid J (a trimer of caffeic acid), and salvianolic acid E (a tetramer of caffeic acid), were all recognised by comparing the obtained fragmentations with those observed following analysis of extracts from _Salvia milliorrhiza_ roots [14]. All of these compounds displayed the characteristic mass spectra of salvianolic acids: neutral losses of one caffeic acid molecule (\(m/z\) 180) and a danshensu unit (\(m/z\) 198). Salvianolic acids have been reported in other members of the Lamaciae family although inconsistent between species. Within the _Mentha_ species, data on salvianolic acid concentrations within water extracts is limited, with \begin{table}
\begin{tabular}{c c c} \hline
**ID a [FOOTNOTE:a]Footnote a: See Table 1 for peak assignment; b Quantified by comparison with its corresponding standard; \({}^{\text{c}}\) hydroxybenzoic acids include compound **5** and **7**; hydroxycinamic acids, compounds **8**, **14**, **16**, and **18**; \\  & & \\  & & \\  & & \\  & & \\  & & \\ \end{tabular}
\end{table} 
Table 2: _Cont._concentrations of less than 1% observed in some instances and slightly lower than the currently evaluated extract [6]. Danshensu (dyhydroxyphenyllactic acid), another caffe acid derivative, as well as other danshensu-like compounds (peaks 53, 54, and 55) were identified on the basis of its molecular ion [M - H]\({}^{-}\) (\(m/z\) 197) and its MS\({}^{2}\) and MS\({}^{3}\) fragments (\(m/z\) 179, 153 and 135) [14]. Moreover, a considerable amount of lithospermic acid (3.81 \(\pm\) 0.26 mg/g), a caffeine trimer, was identified using a reference standard. The presence of different hydroxycinnamic acids was observed in the first part of the chromatogram. This category was mainly represented by cafratic acid (2.18 \(\pm\) 0.30 mg/g), followed by caffe acid (0.71 \(\pm\) 0.06 mg/g) and other minor components, such as dicaffeic acid and coumaric acid. The phenolic profile contained some compounds in the cafeoylquinic acid family, identified by their respective commercial standards (chlorogenic acid and neochlorogenic acid) or its characteristic fragmentation patterns (feruloylquinic acid). Small amounts of hydroxybenzoic acids were detected (0.57 \(\pm\) 0.07 mg/g) and the presence of salicylic acid (peak 27) was also observed. Hydroxycinnaminic, hydroxybenzoic, and cafeoylquinic acids have been previously reported to be present in _Mentha_ species with concentrations frequently below 1%, as observed for the current water-extracted spearmint [31]. Small amounts of flavones, flavonoids, and flavanones were detected. Among the flavones, the most representative compound, in terms of quantity, was apigenin (0.19 mg/g) which was identified by comparing the obtained mass spectra with those reported in the literature [26]. Rutin, narirutin, and orientin were recognised using their respective commercial standards, while other compounds, such as luteolin-rutinoside, luteolin-hexoside, and luteolin-glucuron, were identified by comparison of their relative mass spectra to those reported for other vegetables or natural extracts [20; 24]. Rutin, luteolin, and several additional flavones have been reported previously in commercially available spearmint at levels similar to those reported for the current extract. However, the apigenin levels reported for the extract was four-fold greater than that previously reported, although less than 1% in both cases [7].