**4. Conclusions**

In summary, we identified four unpublished drimane sesquiterpenoids (**1**–**4**) and three published analogues (**5**–**7**) from the mangrove-derived fungus *Aspergillus ustus* 094102. Their structures including absolute configurations of **1**–**7** were determined by spectroscopic analysis, chemical reaction, and ECD spectra. Compound **5,** containing four stereoisomers of the chiral *ortho*-diol in the side chain, was further purified as the pure isomers **5a**–**5d** for the first time, among which the absolute configuration of the *threo*-6,7-diol (**5c** and **5d**) in the side chain was also determined by a dimolybdenum ECD method for the first time. In addition, the absolute configurations of the published compounds **6** and **7** were also resolved in this paper. Unresolved compound **5** displayed selective antiproliferation against CAL-62 and MG-63 tumor cells with the IC50 values of 16.3 and 10.1 μM, respectively, while the purified compounds **5a**–**5d** didn't show activity.

**Supplementary Materials:** The following supporting information can be downloaded at https: //www.mdpi.com/article/10.3390/md20070408/s1, the HRESIMS of compounds **1**–**5** and the NMR spectra of compounds **1**–**7**, the analysis for the bacteriostatic activities and the cytotoxic activities, the HPLC separation, and purification profiles of **5a**–**5d**.

**Author Contributions:** P.G. purified and determined the stereo configurations of the compounds and prepared the draft of the manuscript. J.F. isolated and identified the constitution of the compounds. T.Z. performed the cultivation and extraction of *A*. *ustus* 094102. P.F. tested the cytotoxic and antimicrobial activity. K.H. isolated and identified the fungus *A*. *ustus* 094102. W.Z. designed the research, checked the data and revised the manuscript. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research was funded by NSFC-Shandong Union Foundation (No. U1906213) and NSFC (No. 41876172).

**Institutional Review Board Statement:** This research is not involving humans or animals.

**Informed Consent Statement:** This research is not involving humans or animals.

**Data Availability Statement:** This research is not involving humans or animals.

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