Scopularides Revisited: Molecular Networking Guided Exploration of Lipodepsipeptides in Australian Marine Fish Gastrointestinal Tract-Derived Fungi.

Chemical analysis of a cultivation of an Australian Mugil mullet gastrointestinal tract (GIT) derived fungus, Scopulariopsis sp. CMB-F458, yielded the known lipodepsipeptides scopularides A (1) and B (2). A comparative global natural product social (GNPS) molecular networking analysis of ×63 co-isolated fungi, detected two additional fungi producing new scopularides, with Beauveria sp. CMB-F585 yielding scopularides C-G (3-7) and Scopulariopsis sp. CMB-F115 yielding scopularide H (8). Structures inclusive of absolute configurations were assigned by detailed spectroscopic and C3 Marfey's analysis, together with X-ray analyses of 3 and 8, and biosynthetic considerations. Scopularides A-H (1-8) did not exhibit significant growth inhibitory activity against a selection of Gram positive (+ve) and negative (-ve) bacteria, a fungus, or a panel of three human carcinoma cell lines.

Scopuquinolone B, a new monoterpenoid dihydroquinolin-2(1H)-one isolated from the coral-derived Scopulariopsis sp. fungus.

Further chemical investigation of the secondary metabolites of the fungus Scopulariopsis sp. led to the discovery of a new alkaloid, scopuquinolone B (1). The structure of compound 1 was elucidated by extensive NMR spectroscopic data, CD spectrum and analysis of its Dess-Martin oxidation derivative. Compound 1 was evaluated for antilarval settlement activity of barnacle Balanus amphitrite and showed promising antifouling activity with an EC50 value of 0.103 µM and a high therapeutic ratio of 222.

Two new triterpenoids and a new naphthoquinone derivative isolated from a hard coral-derived fungus Scopulariopsis sp.

Scopulariopsis sp. isolated from the Red Sea hard coral Stylophora sp. yielded two new triterpenoids (1-2) and a new naphthoquinone derivative (8) when cultured on white beans. In addition, fourteen known compounds including three triterpene analogues (3-5), two sesquiterpenoids (6-7), two polyketides (9-10) and seven nitrogenous compounds (11-17) were isolated. All structures were determined through extensive analysis of the NMR and MS data as well as by comparison with literature data. All isolated compounds were evaluated for their cytotoxic, antibacterial and antitubercular activities. However, none of them showed significant activity.

Potent Antifouling Marine Dihydroquinolin-2(1H)-one-Containing Alkaloids from the Gorgonian Coral-Derived Fungus Scopulariopsis sp.

Marine biofouling has a major economic impact, especially when it occurs on ship hulls or aquaculture facilities. Since the International Maritime Organization (IMO) treaty to ban the application of organotin-based paints to ships went into effect in 2008, there is an urgent demand for the development of efficient and environmentally friendly antifouling agents. Marine microorganisms have proved to be a potential source of antifouling natural compounds. In this study, six dihydroquinolin-2-one-containing alkaloids, three monoterpenoids combined with a 4-phenyl-3,4-dihydroquinolin-2(1H)-one (1-3) and three 4-phenyl-3,4-dihydroquinolin-2(1H)-one alkaloids (4-6), were isolated from the gorgonian coral-derived fungus Scopulariopsis sp. collected in the South China Sea. These dihydroquinolin-2-one-containing alkaloids were evaluated against the larval settlement of barnacle Balanus amphitrite, and antifouling activity was detected for the first time for this class of metabolites. All of them except 6 showed strong antifouling activity. Compounds 1 and 2 were discovered to be the most promising non-toxic antilarval settlement candidates. Especially, compound 1 is the strongest antifouling compound in nature until now which showed highly potent activity with picomolar level (EC50 17.5 pM) and a very safety and high therapeutic ratio (LC50/EC50 1200). This represents an effective non-toxic, anti-larval settlement structural class of promising antifouling lead compound.

Structure and absolute configuration of fumiquinazoline L, an alkaloid from a gorgonian-derived Scopulariopsis sp. fungus.

Fumiquinazoline L (1), an alkaloid with a heptacyclic skeleton formed via a bridging hemiaminal linkage, was isolated from a gorgonian-derived Scopulariopsis sp. fungus. The structure and absolute configuration of the new compound were identified by comprehensive spectroscopic data and X-ray diffraction analysis. During acid hydrolysis of 1, the isomerization of the valine residue was observed and also studied in different conditions. Fumiquinazoline L (1) showed no cytotoxic or antibacterial activities.

Two new naphthalene derivatives from an endolichenic fungal strain Scopulariopsis sp.

Chemical investigation on an endolichenic fungal strain Scopulariopsis sp. led to the isolation of two new naphthalene derivatives, 1-(4'-hydroxy-3',5'-dimethoxy-phenyl)-1,8-dimethoxynaphthalen-2(1H)-one (1) and 1,8-dimethoxynaphthalen-2-ol (2). Their structures were determined by spectroscopic techniques (UV, IR, MS, 1D, and 2D NMR).