## 2 Materials and Methods
### Chemical Characterisation of Pinus spp. Bark Polar Extracts
#### 3.2.2 Quantitative UHPLC-UV Analysis of _Pinus_ spp. Bark Polar Extracts
[ENDFOOTNOTE] & 280 & 4.03 \(\pm\) 0.06 & 1.66 \(\pm\) 0.10 & 2.13 \(\pm\) 0.29 \\
12 & B-type (epilacthe trimer isomer 4 C [FOOTNOTE:]Footnote : The abundance is lower than the limit of quantification (JOB),’ the abundance of compounds 6 and 7 was determined at 280 nm, using the standard curve of citelbin. [ENDFOOTNOTE] & **0.35 \(\pm\) 0.01** & **0.39 \(\pm\) 0.06** & **1.66 \(\pm\) 0.10** & **2.13 \(\pm\) 0.29** \\
13 & B-type (epilacthe trimer isomer 1 C [FOOTNOTE:]Footnote : The abundance is lower than the limit of quantification (JOB),’ the abundance of compounds 6 and 7 was determined at 280 nm, using the standard curve of citelbin. [ENDFOOTNOTE] & **0.35 \(\pm\) 0.01** & **0.39 \(\pm\) 0.06** & **1.66 \(\pm\) 0.10** & **2.13 \(\pm\) 0.29** \\
12 & B-type (epilacthe trimer isomer 1 C [FOOTNOTE:]Footnote : The abundance is lower than the limit of quantification (JOB),’ the abundance of compounds 6 and 7 was determined at 280 nm, using the standard curve of citelbin. [ENDFOOTNOTE] & 280 & 4.03 \(\pm\) 0.06** & **1.66 \(\pm\) 0.10** & **2.13 \(\pm\) 0.29** \\
14 & & & & & & \\
15 & & & & & & \\
Flavan-3-ols constituted the major phenolic subclass detected in the studied pine bark polar extracts (Table 4), accounting for 47% and 48% (_w/w_) of the total identified content in the _P. pinaster_ Ait. and _P. pinea_ L. barks, respectively. Considering the abundance of flavan-3-ols expressed as mg of compound per g of extract, it was higher in the _P. pinea_ L. bark extract (48.66 mg g\({}^{-1}\) of extract) than in the _P. pinaster_ Ait. Bark extract (33.03 mg g\({}^{-1}\) of extract) (Table 4). Indeed, the flavan-3-ols contents of the _Pinus_ spp. bark extracts analysed in the present work are concordant with that detected in Pycogenol(r) [13] but lower than that reported by [PERSON] and colleagues [55] in a commercial pine bark extract (776.6 mg g\({}^{-1}\) powder). Moreover, catechin (**6**) and a B-type procyanidin dimer (**7**) were the main flava-3-ols present in both pine bark samples, representing 15% (_w/w_) of the total content of the identified compounds (Table 4). In particular, catechin and B-type procyanidin dimers accounted for 27.79 mg g\({}^{-1}\) of the _P. pinea_ L. extract and 20.06 mg g\({}^{-1}\) of the _P. pinaster_ Ait. extract, being slightly higher than that earlier evidenced for Pycogenol(r) (15.49 mg g\({}^{-1}\) of extract) [13]. Catechin (**6**) has also been detected in _P. pinea_ L. bark extracts, namely in an ethyl acetate fraction of HWE (35.8 mg g\({}^{-1}\) of extract) [17]. B-type procyanidin trimers (8, 10, and 11) were also abundant in both pine barks, accounting for 14.2% (_w/w_) and 12.6% (_w/w_) of the total identified content in the _P. pinea_ L. and _P. pinaster_ Ait. barks, respectively. Their abundances agreed with those described for a commercial extract of _P. martiima_ L. bark (21.1% (_w/w_) of total content) [55]. To the best of our knowledge, the abundances of procyanidins in _P. pinea_ L. bark are exhibited, for the first time, in this study. Flavanonols were also detected at considerable abundances in both pine barks, representing 9.8% (_w/w_) and 7.7% (_w/w_) of the total identified contents of the _P. pinaster_ Ait. and _P. pinea_ L. barks, respectively (Table 4). Taxifolin (**14**) was the major flavanonol, accounting for 7.66 mg g\({}^{-1}\) of the _P. pinea_ L. bark extract and 6.83 mg g\({}^{-1}\) of the _P. pinaster_ Ait. bark extract (Table 4). Taxifolin abundance in the _P. pinaster_ Ait. bark extract is within the range reported for commercial _P. pinaster_ Ait. bark extracts (1.20 mg g\({}^{-1}\) extract-33.1 mg g\({}^{-1}\) powder) [13; 55]. However, the taxifolin abundance in the _P. pinea_ L. bark polar extract was 4.2-fold lower than that reported for the ethyl fraction of HWE (28.7 mg g\({}^{-1}\) fraction) [17]. It is noteworthy that both pine barks contained much higher taxifolin abundances than the respective Spanish species (up to 12.5-fold) [18]. Regarding the taxifolin-\(O\)-hexoside (13) content, the _P.