## 3 Results
### Structural Elucidation of Major Compounds
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Endophytic Fungi** & **Plant Organ** & \begin{tabular}{c} **Polyphenols** \\ **(mg QAE/g)** \\ \end{tabular} & \begin{tabular}{c} **Flavonoids** \\ **(mg QE/g)** \\ \end{tabular} & \
\begin{tabular}{c} **The Free-Radical Scavenging Activity (\%)** \\ **DPPH** \\ \end{tabular} &
\begin{tabular}{c} **Hydroxyl** \\ **(H-1)** \\ \end{tabular} \\ \hline AQF1 & Stem & 71.36 \(\pm\) 0.55 \({}^{\rm c}\) & 47.92 \(\pm\) 0.9 \({}^{\rm a}\) & 45.43 \(\pm\) 2.88 \({}^{\rm a}\) & 62.45 \(\pm\) 2.20 \({}^{\rm c}\) \\ AQF2 & Leaf & 84.27 \(\pm\) 0.34 \({}^{\rm d}\) & 65.21 \({}^{\rm b}\)\(\pm\) 1.67 \({}^{\rm b}\) & 61.43 \(\pm\) 2.68 \({}^{\rm c}\) & 37.18 \(\pm\) 2.22 \({}^{\rm a}\) \\ AQF3 & Root & - & - & - & - \\ AQF4 & Root & 87.53 \(\pm\) 0.23 \({}^{\rm d}\) & 81.25 \(\pm\) 1.88 \({}^{\rm d}\) & 58.55 \(\pm\) 1.93 \({}^{\rm c}\) & 43.59 \(\pm\) 2.67 \({}^{\rm b}\) \\ AQF5 & Root & - & - & - & - & - \\ AQF6 & Root & 117.76 \(\pm\) 0.94 \({}^{\rm h}\) & 169.01 \(\pm\) 2.09 \({}^{\rm f}\) & 95.75 \(\pm\) 1.06 \({}^{\rm f}\) & 85.66 \(\pm\) 1.91 \({}^{\rm e}\) \\ AQF7 & Root & - & - & - & - & - \\ AQF8 & Root & 101.84 \(\pm\) 5.5 \({}^{\rm f}\) & 101.44 \(\pm\) 2.70 \({}^{\rm e}\) & 84.85 \(\pm\) 2.2 \({}^{\rm e}\) & 72.41 \(\pm\) 1.43 \({}^{\rm d}\) \\ AQF9 & Root & - & - & - & - & - \\ AQF13 & Stem & 106.67 \(\pm\) 1.28 \({}^{\rm g}\) & 73.46 \(\pm\) 1.89 \({}^{\rm c}\) & 93.51 \(\pm\) 1.31 \({}^{\rm f}\) & 45.18 \(\pm\) 1.52 \({}^{\rm b}\) \\ AQF15 & Stem & - & - & - & - \\ AQF16 & Stem & - & - & - & - \\ AQF18 & Stem & 57.68 \(\pm\) 1.16 \({}^{\rm a}\) & 47.19 \(\pm\) 0.36 \({}^{\rm a}\) & 76.66 \(\pm\) 1.33 \({}^{\rm d}\) & 63.07 \({}^{\rm c}\)\({}^{\rm d}\) \(\leq\) 1.60 \({}^{\rm c}\) \\ AQF19 & Stem & 67.06 \(\pm\) 0.54 \({}^{\rm b}\) & 70.63 \(\pm\) 1.56 \({}^{\rm c}\) & 54.08 \(\pm\) 1.50 \({}^{\rm b}\) & 84.86 \(\pm\) 2.15 \({}^{\rm e}\) \\ AQF21 & Leaf & - & - & - & - & - \\ AQF23 & Leaf & 94.82 \(\pm\) 0.78 \({}^{\rm e}\) & 64.84 \(\pm\) 1.46 \({}^{\rm b}\) & 93.72 \(\pm\) 3.12 \({}^{\rm f}\) & 74.09 \(\pm\) 2.22 \({}^{\rm d}\) \\ Ascorbic acid & & & 96.32 \(\pm\) 3.97 \({}^{\rm f}\) & 99.19 \(\pm\) 0.23 \({}^{\rm f}\) \\ \hline \hline \end{tabular} Note: (-), no activity/not determined. The final concentration of each fungal extract was applied at 400 ug/mL and 10 ug/mL ascorbic acid was used as a positive control. Values with different superscripts are significantly different according to LSD test (\(p<\) 0.05).  
\end{table} 
Table 1: Determination of polyphenols, flavonoids, and antioxidant activity of 16 endophytic fungi isolated from _Amentotaxus yunnamensis_. and C-15 and from H-15 to C-9 and C-10, suggested the presence of a 2-methylpent-2-en-1-ol substituent (Figure 2). Additionally, observations of COSY correlations suggested the existence of a 1,2,3,4-tetrasubstituted cyclohexane ring (Figures S5-S7). These suppositions were supported by comparison with the NMR data of **1** with those of the previously reported bisabolane-type sesquiterpene, citrantifidiol, showing a good agreement, except for a methyl group in citrantifidiol, which was replaced by an oxymethylene group at C-10 in **1** [\(\delta_{\rm H}\) 3.94 (br s)/ \(\delta_{\rm C}\) 69.0 (C-15)] [28]. The planar structure of **1** was further confirmed by analyzing its 1D and 2D NMR spectra acquired in DMSO-\(d_{6}\) (Figures S8 and S9), which showed HMBC correlations from \(\delta_{\rm H}\) 3.76 (br s, 1-OH) to C-1, C-2, C-6, and C-13 and from \(\delta_{\rm H}\) 3.82 (br s, 3-OH) to C-3, C-4, and C-14 (Figures S10 and S11). The relative configuration of 1 was determined by detailed analysis of the NOESY spectrum (Figure 2). H-9 was shown to have NOE correlations with H-7 and H-15, while H-11 correlating with H-8 indicated \(E\) geometry for the 9,10-double bond. Furthermore, NOE correlations observed between H-4/H-13, H-4/H-14, and H-13/H-12 suggested that axial protons H-4 and H-13 and equatorial H-12 and H-14 are co-facial (Figure 2).