*Article* **Immunosuppressive Sesquiterpenoids from the Edible Mushroom** *Craterellus odoratus*

**Quan Dai 1,2, Fa-Lei Zhang 1,2 , Zheng-Hui Li 1,2, Juan He 1,2,\* and Tao Feng 1,2,\***


**Abstract:** The aim of this work was to comprehensively understand the chemical constituents of the edible mushroom *Craterellus ordoratus* and their bioactivity. A chemical investigation on this mushroom led to the isolation of 23 sesquiterpenoids including eighteen previously undescribed bergamotane sesquiterpenes, craterodoratins A–R (**1**–**18**), and one new victoxinine derivative, craterodoratin S (**19**). The new structures were elucidated by detailed interpretation of spectrometric data, theoretical nuclear magnetic resonance (NMR) and electronic circular dichroism (ECD) calculations, and single-crystal X-ray crystallographic analysis. Compounds **1** and **2** possess a ring-rearranged carbon skeleton. Compounds **3**, **10**, **12**–**15**, **19**, **20** and **23** exhibit potent inhibitory activity against the lipopolysaccharide (LPS)-induced proliferation of B lymphocyte cells with the IC<sup>50</sup> values ranging from 0.67 to 22.68 µM. Compounds **17** and **20** inhibit the concanavalin A (ConA)-induced proliferation of T lymphocyte cell with IC<sup>50</sup> values of 31.50 and 0.98 µM, respectively. It is suggested that *C. ordoratus* is a good source for bergamotane sesquiterpenoids, and their immunosuppressive activity was reported for the first time. This research is conducive to the further development and utilization of *C. ordoratus*.

**Keywords:** *Craterellus ordoratus*; sesquiterpenoids; isolation and structural elucidation; immunosuppressive activity
