*Article* **Viridicatol Isolated from Deep-Sea** *Penicillium Griseofulvum* **Alleviates Anaphylaxis and Repairs the Intestinal Barrier in Mice by Suppressing Mast Cell Activation**

**Zhendan Shu 1, Qingmei Liu 1, Cuiping Xing 2, Yafen Zhang 1, Yu Zhou 1, Jun Zhang 1, Hong Liu 1, Minjie Cao 1, Xianwen Yang 2,\* and Guangming Liu 1,\***


Received: 18 September 2020; Accepted: 14 October 2020; Published: 16 October 2020

**Abstract:** Viridicatol is a quinoline alkaloid isolated from the deep-sea-derived fungus *Penicillium griseofulvum.* The structure of viridicatol was unambiguously established by X-ray diffraction analysis. In this study, a mouse model of ovalbumin-induced food allergy and the rat basophil leukemia (RBL)-2H3 cell model were established to explore the anti-allergic properties of viridicatol. On the basis of the mouse model, we found viridicatol to alleviate the allergy symptoms; decrease the levels of specific immunoglobulin E, mast cell protease-1, histamine, and tumor necrosis factorα; and promote the production of interleukin-10 in the serum. The treatment of viridicatol also downregulated the population of B cells and mast cells (MCs), as well as upregulated the population of regulatory T cells in the spleen. Moreover, viridicatol alleviated intestinal villi injury and inhibited the degranulation of intestinal MCs to promote intestinal barrier repair in mice. Furthermore, the accumulation of Ca2+ in RBL-2H3 cells was significantly suppressed by viridicatol, which could block the activation of MCs. Taken together, these data indicated that deep-sea viridicatol may represent a novel therapeutic for allergic diseases.

**Keywords:** food allergy; deep-sea-derived viridicatol; X-ray single crystal; intestinal barrier; mast cell; calcium influx
