## 2 Results and Discussion  
Aspermonoterpenoid A (**1**), colorless oil, has the molecular formula of C\({}_{10}\)H\({}_{14}\)O\({}_{4}\) as determined by the \({}^{13}\)C NMR data and the HRESIMS spectrum (\(m\)/\(z\) 221.0784, [M + Na]\({}^{+}\)), indicating four degrees of unsaturation. The \({}^{1}\)H NMR spectrum showed two olefinic protons (\(\delta_{\rm H}\) 5.77, 6.66), a methine (\(\delta_{\rm H}\) 3.36), and three methyls (\(\delta_{\rm H}\) 1.24, 1.88, 2.14) (Table 1), while the \({}^{13}\)C NMR and HSQC spectra exhibited four sp\({}^{2}\) carbons (\(\delta_{\rm C}\) 117.0, 130.2, 144.5, 162.0) for two double bonds, two ester carbonyl carbons (\(\delta_{\rm C}\) 170.4, 171.5), one methine (\(\delta_{\rm C}\) 43.8), and three methyls (\(\delta_{\rm C}\) 12.8, 17.0, 19.0) (Table 1). As all degrees of unsaturation were accounted for by two carbonyl carbons and two double bonds, an acyclic structure was required in **1**. The COSY data of H-4 (\(\delta_{\rm H}\) 3.36)/H\({}_{3}\)-9 (\(\delta_{\rm H}\) 1.24) and the HMBC cross-peaks from H\({}_{3}\)-8 (\(\delta_{\rm H}\) 1.88) to C-5 (\(\delta_{\rm C}\) 144.5)/C-6 (\(\delta_{\rm C}\) 130.2)/C-7 (\(\delta_{\rm C}\) 171.5), H\({}_{3}\)-9 to C-3 (\(\delta_{\rm C}\) 162.0)/C-4 (\(\delta_{\rm C}\) 43.8)/C-5, H\({}_{3}\)-10 (\(\delta_{\rm H}\) 2.14) to C-2 (\(\delta_{\rm C}\) 117.0)/C-3/C-4, and from H-2 (\(\delta_{\rm H}\) 5.77) to C-1 (\(\delta_{\rm C}\) 170.4)/C-4/C-10 (\(\delta_{\rm C}\) 17.0) established the planar structure of **1** as 2,4,5-trimethylhepta-2,5-dienedioic acid (Figure 2). The \(E\) geometries at \(\Delta^{2}\) and \(\Delta^{5}\) were resolved on the basis of the NOESY cross-peaks from H-2 to  
Figure 1: Chemical structures of **1–11** from _Aspergillus Sydowii_ MCCC 3A00324. H-4 and from H\({}_{3}\)-8 to H-4 (Figure 2), which were further corroborated by the chemical shifts of Me-8 (\(\delta_{\rm C}\) 12.8) and Me-10 (\(\delta_{\rm C}\) 17.0). The sole chiral center of C-4 in **1** was resolved by the calculation of the specific rotation data using Gaussian 09 [38]. The specific rotation data of (45\({}^{\circ}\))-**1** was calculated at the B3 LYP/6-311+G(2d,p) level with the CPCM model in methanol, which has the same sign ([\(\alpha\)]\({}_{\rm D}\) +138) as that of the experimental data ([\(\alpha\)]\({}_{\rm D}^{25}\) +54), revealing the 4S configuration. Therefore, the structure of **1** was determined to be (2E,5E,4S)-2,4,5-trimethylhepta-2,5-dienedioic acid, which was named aspermonoterpenoid A. Noteworthily, **1** possessed a novel chained monoperenoid skeleton, biogenetically probably derived from the osname-type monoperpenoid after the cyclopentane ring cleavage and oxidation reactions [39; 40]. The molecular formula of aspermonoterpenoid B (**2**) was established to be C\({}_{10}\)H\({}_{14}\)O\({}_{3}\) on the basis of the HRESIMS spectrum at the sodium adduct ion peak at \(m\)/z 205.0845 (calcd for C\({}_{10}\)H\({}_{14}\)O\({}_{3}\)Na, 205.0841), requiring four degrees of hydrogen deficiency. The \({}^{1}\)H NMR spectrum showed one olefinic proton (\(\delta_{\rm H}\) 5.89), three methines (\(\delta_{\rm H}\) 2.21, 2.76, 2.94), and three methyls (\(\delta_{\rm H}\) 1.28, 1.29, 2.13). Analyses of the \({}^{13}\)C NMR spectrum, with the aid of the HSQC spectrum, revealed ten carbon signals attributable to two olefinic carbons (\(\delta_{\rm C}\) 130.1, 184.4) for a double bond, two carbonyl carbons for a keto (\(\delta_{\rm C}\) 211.6) and a carboxylic (\(\delta_{\rm C}\) 178.5) functionalities, three methines (\(\delta_{\rm C}\) 41.2, 44.8, 58.4), and three methyls (\(\delta_{\rm C}\) 15.3, 17.1, 18.9), which accounted for three degrees of unsaturation. The remaining one double bond equivalent indicated that a monocyclic skeleton was required in **2**. The COSY cross-peaks of H-4 (\(\delta_{\rm H}\)