3.5.3. Marinoterpins

Marinoterpins A–C (**107**–**109**) (Figure 26) are linear merosesterterpenoids that were recently isolated (2021) by Winter and Fenical from the marine-derived actinomycete bacteria *Streptomyces* sp. AJS-327 and CNQ-253 [96]. Due to their similarity to the aurachin family of compounds, a marinoterpin biosynthetic cluster (*mrt*) was identified. Thus, a biosynthetic route for the 3-geranylfarnesyl-2-methylquinoline core was proposed, although the reactions that lead to the tetrahydrofuran rings as well as the N-oxidation still remain unknown.

**Figure 26.** Structure of marinoterpins A–C (**107**–**109**).

#### **4. Other Tetrahydrofuran Derivatives**

## *4.1. Substituted Tetrahydrofurans*

4.1.1. Pachastrissamine (Jaspine B)

Pachastrissamine (**110**) was first isolated by Higa and coworkers from a marine sponge of the genus *Pachastrissa* [97]. A year later, Debitus reported its isolation from another sponge *Jaspis* sp. and, thus, named the compound jaspine B [98]. Other related compounds were also isolated, including jaspine A (**111**) (Figure 27). Pachastrissamine is a sphingolipid—in particular, a derivative from anhydrophytosphingosine. Its biological activity and synthetic endeavors until 2016 were summarized by Martinková in a mini-review [99].

**Figure 27.** Structures of pachastrissamine (jaspine B, **110**) and jaspine A (**111**).
