**4. Conclusions**

In summary, four new metabolites, including one new asperchalasine I (**1**), dibefurin B (**2**), two epicoccine derivatives (**3**,**4**) and seven known compounds were isolated from the fungus *Mycosphaerella* sp. SYSU-DZG01. The structures of **1**–**11** were established by spectroscopic data and the absolute configuration of compounds **1**–**3** was determined in this research. Compound **1** possesses a unique T-shaped skeleton. All of the compounds were tested for their biological activities. Compounds **1**, **8** and **9** exhibited inhibitory effects against α-glucosidase with IC50 values of 17.1, 26.7 and 15.7 μM, respectively while compounds **1**, **4**, **6** and **8** showed antioxidant activity by scavenging DPPH· with EC50 values of 77.8, 85.8, 59.1 and 16.3 μM. These results suggested that the asperchalasine I may be a potential candidate for α-glucosidase inhibitor.

**Supplementary Materials:** The following are available online at http://www.mdpi.com/1660-3397/17/8/483/s1, Figure S1: 1H NMR spectrum of compound **1** (500 MHz, CDCl3), Figure S2: 13C NMR spectrum of compound **1** (125 MHz, CDCl3), Figure S3: DEPT 135, DEPT 90 and 13C NMR spectrum of compound **1** (125 MHz, CDCl3), Figure S4: 1H-1H COSY spectrum of compound **1** (CDCl3), Figure S5: HSQC spectrum of compound **1** (CDCl3), Figure S6: HMBC spectrum of compound **1** (CDCl3), Figure S7: NOESY spectrum of compound **1** (CDCl3), Figure S8: HRESIMS spectrum of compound **1**, Figure S9: Experiment ECD spectrum of **1**, Figure S10: 1H NMR spectrum of compound **2** (400 MHz, DMSO-*d*6), Figure S11: 13C NMR spectrum of compound **2** (100 MHz, DMSO-*d*6), Figure S12: 1H-1H COSY spectrum of compound **2** (DMSO-*d*6), Figure S13: HSQC spectrum of compound **2** (DMSO-*d*6), Figure S14: HMBC spectrum of compound **2** (DMSO-*d*6), Figure S15: HRESIMS spectrum of compound **2**, Figure S16: 1H NMR spectrum of compound **3** (500 MHz, MeOH-*d*4), Figure S17: 13C NMR spectrum of compound **3** (125 MHz, MeOH-*d*4), Figure S18: 1H-1H COSY spectrum of compound **3** (MeOH-*d*4), Figure S19: HSQC spectrum of compound **3** (MeOH-*d*4), Figure S20: HMBC spectrum of compound **3** (MeOH-*d*4), Figure S21: NOESY spectrum of compound **3** (MeOH-*d*4), Figure S22: HRESIMS spectrum of compound **3**, Figure S23: 1H NMR spectrum of compound **4** (400 MHz, MeOH-*d*4), Figure S24: 13C NMR spectrum of compound **4** (100 MHz, MeOH-*d*4), Figure S25: 1H-1H COSY spectrum of compound **4** (MeOH-*d*4), Figure S26: HSQC spectrum of compound **4** (MeOH-*d*4), Figure S27: HMBC spectrum of compound **4** (MeOH-*d*4), Figure S28: HRESIMS spectrum of compound **4**. Figure S29: The LC-HRESIMS analysis profile of crude extract.

**Author Contributions:** P.Q. contributed to isolation, structure elucidation and wrote the paper; Z.L. contributed to the analysis of the NMR data and structure elucidation. Y.C. contributed to the analysis of the NMR data and biological tests. R.C. contributed to the spectral analysis. Z.S. and G.C. guided the whole experiment and revised the manuscript.

**Funding:** This research was funded by the Guangdong Special Fund for Marine Economic Development (GDME-2018C004), Guangdong MEPP Fund (GDOE-2019A21), the National Natural Science Foundation of China (2187713, 21472251), the Key Project of Natural Science Foundation of Guangdong Province (2016A040403091), the Special Promotion Program for Guangdong Provincial Ocean and Fishery Technology (A201701C06) and the open foundation of Key Laboratory of Tropical Medicinal Resource Chemistry of Ministry of Education (rdyw2018001).

**Acknowledgments:** We thank all the funding assistance mentioned above for their generous support and the Sun Yat-Sen University Instrumental Analysis and Research Center.

**Conflicts of Interest:** The authors declare no conflict of interest.
