**1. Introduction**

Polyketides are a representative class of fungal metabolites [1,2]. These compounds possess a vast range of structural diversity resulting in several subgroups such as anthraquinones, naphthoquinones, benzophenones, xanthones, flavonoids, macrolides, and tropolones [3,4]. Among these, anthraquinones are biosynthetically derived from an octaketide chain formed by the incorporation of one acetyl-CoA and seven malonyl-CoA units [5–7]. Although widely distributed in fungi, anthraquinone derivatives occur far frequently in the genera of *Alternaria*, *Aspergillus*, *Fusarium*, *Stemphylium*, and *Trichoderma* [8]. Anthraquinones typically contain various substituents (methyl, hydroxyl, methoxyl, or more complex substituents), often attributed to characteristic colors by their properties and positions at the aromatic core moiety [9,10].

A frequently encountered structural variation of fungal anthraquinones is the dimerization through a C–C bond formation between two similar units [3]. The dimerization patterns for these bianthraquinones are also diversified through both homo- and hetero- bond formation, providing additional structural variation to the anthraquinones. To date, a vast number of fungal examples were reported including alterporriols, icterinoidin, rubellin, and skyrin [3,11]. In addition to their monomeric precursors, bianthraquinones often co-occur with biosynthetically related compounds of the polyketide pathway [4,12]. Wide structural diversity, in conjunction with significant bioactivities such as antibacterial, anti-inflammatory, antituberculosis, and cytotoxic activities, designates bianthraquinones as an important group of fungal polyketides [3,8,11,13].

Meanwhile, tricycloalternarenes (TCAs) are a structural class of fungal meroterpenoids [14]. Structurally, these are closely related to the ACTG toxins with differences at the isoprenoid side chain and the substitution pattern at the C-ring of TCAs [15]. Biosynthetically, these meroterpenoids are proposed to be generated from a hybrid shikimate–isoprenoid route [16]. Exclusively found in *Alternaria* and *Guignardia*, tricycloalternarene-type meroterpenoids are regarded as one of the key chemical characteristics of these fungal genera [17,18]. These compounds were also reported to exhibit diverse bioactivities, including antimicrobial, cytotoxic, and NF-κB-inhibitory [19,20].

During the course of a search for bioactive compounds from marine-derived fungi, we isolated a strain (strain number FJJ006) of *Stemphylium* sp. from an unidentified sponge specimen collected off the coast of the island of Jeju-do, Korea. LC-ESIMS and LC-UV analyses of the culture broth of this strain showed the presence of several compounds with various profiles, prompting extensive chemical investigation. The large-scale cultivation, sequentially followed by extraction, solvent-partitioning, and chromatographic separations, afforded six new and three known compounds (Figure 1). Here, we report the structures of bianthraquinone alterporriols Z1–Z3 (**1**–**3**) and meroterpenoid tricycloalterfurenes E–G (**7**–**9**). This is first time isolating not only the tricycloalternarene-type meroterpenoids but also their co-occurrence with polyketide-derived anthracenes from the fungus *Stemphylium.* Compounds **1** and **2** exhibited moderate anti-inflammatory activity in LPS-stimulated RAW 264.7 cells.

**Figure 1.** Structures of **1**–**9**.
