## 3 Results  
### Structural Identification of Compounds 1-3  
Compound **1** was obtained as a white powder, \(\{\left[\alpha\right]^{22}_{\text{D}}-54.47^{\circ}\) (\(c\) 0.14, CH\({}_{3}\)OH)}. The \({}^{13}\)C NMR spectrum of **1** in DMSO-\(d6\) showed distinctive 11 carbon signals including two amide carbonyls at \(\delta_{\text{C}}\) 170.32 and 166.51, three sp3 carbons with the attachment of N atom at \(\delta_{\text{C}}\) 58.44, 52.59, and 44.83, and six sp3 carbons without N attachment at \(\delta_{\text{C}}\) 37.76, 27.40, 24.04, 22.79, 22.44, and 21.88. The \({}^{1}\)H NMR spectrum of **1** in DMSO-\(d6\) showed a broad NH proton signal at \(\delta_{\text{H}}\) 8.00, signals for two \(\alpha\) protons at \(\delta_{\text{H}}\) 4.19, and 4.00, N-attached methylene protons at \(\delta_{\text{H}}\) 3.42-3.30, two doublet methyl signals at \(\delta_{\text{H}}\) 0.87 (\(J\) = 6.3 Hz) and 0.86 (\(J\) = 6.3 Hz), along with the residual seven protons at \(\delta_{\text{H}}\) 2.22-1.30. The ESI-MSspectrum (positive ion detection mode) showed a peak corresponding to a protonated molecule at \(m/z\) 211.4 [M + H]\({}^{+}\). These data indicated that the molecular formula of compound **1** was C\({}_{11}\)H\({}_{18}\)N\({}_{2}\)O\({}_{2}\). The 2D NMR data analysis led to the planar structure of **1** as a cyclic dipeptide, _cyclo_(Pro-Leu), as shown in Figure 1. The absolute configuration of **1** was determined to be _cyclo_(L-Pro-L-Leu) using [PERSON]'s method (Figure S8) [17]. Compound **2** [[\(\alpha\)]\({}^{22}\)\({}_{\rm D}\) - 48.65\({}^{\circ}\) (c 0.07, CH\({}_{3}\)OH)] showed a protonated ion at \(m/z\) 211.4 [M + H]\({}^{+}\) in the positive ion mode of the ESI-MS spectrum. The \({}^{1}\)H NMR spectrum of **2** showed structural features similar to those of compound **1**. However, compound **2** showed a distinctive methyl triplet and a methyl doublet, whereas compound **1** showed two methyl doublets. Based on a careful comparison of spectroscopic data, including \({}^{1}\)H and \({}^{13}\)C NMR data, compound **2** was identified as _cyclo_(Pro-Ile). In addition, [PERSON]'s analyses configured both constituting amino acids as \(L\) (Figure S9) [17]. Compound **3** was obtained as a white powder. Its molecular formula was assigned as C\({}_{10}\)H\({}_{13}\)NO based on 1D NMR spectra and the presence of a protonated ion at \(m/z\) 164.2 [M + H]\({}^{+}\) in the ESI-MS spectrum. The \({}^{1}\)H and \({}^{13}\)C NMR spectra of compound **3** in CDCl\({}_{3}\) showed five proton signals in the ranges of \(\delta_{\rm H}\) 7.15-7.35, and resonances for four sp2 methine carbons at \(\delta_{\rm C}\) 138.97, 128.80, 128.69, and 126.57, corresponding to a mono-substituted phenyl ring. Moreover, signals of two methylene units (\(\delta_{\rm C}\) 40.78, \(\delta_{\rm H}\) 2.80; \(\delta_{\rm C}\) 35.68, \(\delta_{\rm H}\) 3.49) and an acetyl unit (\(\delta_{\rm C}\) 170.35; \(\delta_{\rm C}\) 23.30, \(\delta_{\rm H}\) 1.92) were observed. By comparing the spectroscopic data with the values provided in the literature, the structure of compound **3** was confirmed to be N-phenethylacetamide [18]. Compounds **1-3** were isolated from microorganisms of the genus _Aquimarina_ for the first time. The Cell Viability Effect on Comparison of Compounds **1-3** on TGF-\(\beta\)-Induced EMT of A549 Cells  
First, we investigated the cytotoxic effects of compounds **1-3** with or without TGF-\(\beta\) on A549 cells using an EZ-Cytox assay. As presented in Figure 2, the cells were treated with various concentrations of compounds **1-3** (100, 50, 25, and 12.5 uM) for 24 h. The cell viability analysis showed that none of the components affected cell viability at concentrations below 50 uM; however, compound **2** showed a significant decrease cell viability at 100 uM concentration. Therefore, further assays were conducted at a concentration of 50 uM. Figure 1: Structures of compounds **1-3** from _Aquimarina_ sp. MC085.