Penispirozines A–H, Three Classes of Dioxopiperazine Alkaloids with Spirocyclic Skeletons Isolated from the Mangrove-Derived <i>Penicillium janthinellum</i>
Meilin Zhu, Zhen Yang, Haotian Wang, Qi Gan, Guojian Zhang, Qian Che, Tianjiao Zhu, Qianqun Gu, Bingnan Han, Dehai Li
Abstract
Eight new dioxopiperazine alkaloids, penispirozines A–H (1–8), were discovered from the mangrove-derived fungus Penicillium janthinellum HDN13-309. Their structures were elucidated by spectroscopic analysis, TDDFT-ECD calculations, and X-ray diffraction. Compound 1 had an unusual pyrazino[1,2]oxazadecaline coupled with a thiophane ring system, and compound 2 possessed a 6/5/6/5/6 pentacyclic ring system with two rare spirocyclic centers. Interestingly, compounds 3–8 were distinguished by not only the existence of a spiro-thiophane or spiro-furan ring system but also the chirality of the pentacyclic moiety. Compounds 3 and 4 increased the expression of the two relevant phase II detoxifying enzymes SOD2 and HO-1 at 10 μM.