Isobenzofuranones and Isochromenones from the Deep-Sea Derived Fungus Leptosphaeria sp. SCSIO 41005

Abstract

Four new isobenzofuranones, leptosphaerins J–M (1–4), including an unusual naturally-occurring centrosymmetric dimer skeleton (1), and two new isochromenones, clearanols I–J (9–10), were obtained from a culture of a deep-sea sediment-derived fungus Leptosphaeria sp. SCSIO 41005, together with four known isobenzofuranones (5–8) and six known isochromenones (11–16). These structures were elucidated by extensive spectroscopic analyses, and absolute configurations were assigned on the basis of electronic circular dichroism and optical rotations data comparison. Additionally, the absolute configurations of the new compounds 1 and 9, together with the known one 7 with stereochemistry undetermined, were further confirmed by single crystal X-ray diffraction experiments. A plausible biosynthetic pathway of these isobenzofuranones and isochromenones was also proposed.

Nitrogenous Compounds Produced by the Deep Sea Derived Fungus Leptosphaeria sp. SCSIO 41005

“…SCSIO 41005 was isolated from a deep-sea sediment sample, which was identified as Leptosphaeria sp. by analysis of its ITS region of the rDNA as described in our previous research [4].…”

“…In the course of our studies on marine fungi, four new isobenzofuranones, leptosphaerins J-M and two new isochromenones, clearanols I-J, have been obtained from the culture extract of Leptosphaeria sp. SCSIO 41005, recently [4]. Further efforts on the remaining fractions of the fungus resulted in the isolation of four nitrogenous compounds (1-4), a bicyclic compound (5) and three known non-nitrogenous compounds (6)(7)(8).…”

“…All of the obtained compounds were tested for their cytotoxicity against K562, MCF-7 and SGC7901 cell lines, and antiviral activities towards H3N2, EV71 and HIV viruses, according to previously reported protocols [4]. However, no of them exhibited significant activity (IC 50 > 100 μM) in those assays.…”

Novel Natural Products from Extremophilic Fungi

“…SCSIO 41005 (depth 3614 m, the Indian Ocean). When evaluated for biological activity, no cytotoxicity (K562, MCF-7, and SGC7901 cell lines) or antiviral activity (H3N2, EV71, and HIV viruses) was detected [ 46 ].…”

A new naphthopyranone from the sponge‐associated fungus Penicillium sp. XWS02F62

“…During the course of our search for novel bioactive SMs from marine fungi, a series of structurally diverse and biologically significant SMs have been obtained . The sponge‐associated fungus Penicillium sp.…”