Xiu-Li Zhang

Isolation, 1H, 13C NMR Assignments, and crystal structure of chrodrimanin B from A marine fungus Aspergillus sp.

A terrestrial fungal metabolite, chrodrimanin B (1), has been isolated for the first time from the fermentation broth of a marine-derived fungus Aspergillus sp. collected from the South China Sea. Detailed assignments for the proton and carbon of 1 have been unambiguously elucidated by combined spectroscopic methods including 1D and 2D NMR spectral data, and the relative configurations were also confirmed by single- crystal X-ray data.

A new sesquiterpene from the Hainan gorgonian Menella kanisa Grassoff

Chemical investigation of the gorgonian Menella kanisa Grassoff collected from the South China Sea led to the isolation of a new sesquiterpene, menecubebane A (1), together with three known compounds, 8-methoxy-trans-calamenene (2), 8,9-dihydro-linderazulene (3) and (3β)-oleanan-3-ol (4). The structure of 1 was determined by detailed analysis of the spectroscopic data especially the NOESY spectrum. All the compounds were evaluated for their cytotoxic, brine shrimp lethal and antifouling activities.

Isoechinulin-Type Alkaloids from a Soft Coral-Derived Fungus Nigrospora oryzae

The large number of symbiotic microbes in corals is considered to be a promising source of novel drugs [1, 2]. To date, studies on secondary metabolites from coral epiphytic microbes are still limited. Fungi belonging to the genus Nigrospora have been found to be a rich source of bioactive secondary metabolites, such as plant growth-inhibiting nigrosporolide [3] and phomalactone [4], phytotoxic and antibacterial nigrosporins [5], and phytotoxic lactones [6]. In our ongoing research on the bioactive secondary metabolites from coral-derived fungi [7, 8], a soft coral-derived fungus Nigrospora oryzae (ZJ-2008005) obtained from a soft coral Dendronephthya sp. collected from the South China Sea attracted our attention. Seven isoechinulin-type alkaloids were isolated from the EtOAc extract of the fungal fermentation broth. Their structures were identified as neoechinulin A (1) [9], preechinulin (2) [10], isoechinulin A (3) [11], tardioxopiperazine A (4) [12] and variecolorin L (5) [13], dihydroxyisoechinulin A (6) [14], and L-alanyl-L-tryptophan anhydride (7) [15] on the basis of their spectral data and by comparison with those reported in the literature. All of these compounds were isolated for the first time from the genus Nigrospora. In previous reports, more than 30 isoechinulin-type alkaloids have been isolated from Aspergillus species. And the genus Aspergillus has proved to be a rich source of isoechinulin-type alkaloids [15]. These alkaloids usually contain three structural units: an indole, a diketopiperazine, and a 2-methyl-3-buten-2-yl unit. They were usually screened for pharmacological activities, most of which display radical scavenging, ultraviolet-A protecting, immunosuppressive, and antibacterial activities [9, 10]. In our study, the antifouling activity of isoechinulin-type alkaloids was evaluated for the first time. Compounds 1–3 and 6 and 7 were selected to evaluate their antifouling activity against the larval settlement of barnacle Balanus amphitrite. Compound 3 showed strong activity with an IC50 value of 5.92 g/mL, while 1 and 6 exhibited only weak activity with IC50 values of 30.0 g/mL and 50.0 g/mL, respectively. General Experimental Procedures. UV spectra were obtained using a Milton-Roy spectrophotometer. IR spectra were recorded on a Nicolet-Nexus-470 spectrophotometer. NMR spectra were recorded on a JEOL JEM-ECP NMR spectrometer. ESI-MS spectra were performed on a Micromass Q-TOF spectrometer. HPLC separation was performed in a Waters prep-HPLC system. Silica gel and GF254 were obtained from Qingdao Marine Chemical Factory, Qingdao, China. Sephadex LH-20 was from Pharmacia Co. Ltd.

Aspergivones A and B, two new flavones isolated from a gorgonian-derived Aspergillus candidus fungus

Abstract Two new flavones, aspergivones A (1) and B (2), were isolated from the fungus Aspergillus candidus cultured from the gorgonian coral Anthogorgia ochracea collected from the South China Sea. The structures of 1 and 2 were elucidated by NMR and MS methods and comparison with relatively known compounds. Only 2 showed slight inhibitory activity against alpha-glucosidase with an IC50 value of 244 μg/mL. Compounds 1 and 2 were also evaluated for their cytotoxic and antibacterial activities.

Bioactive Perylene Derivatives from a Soft Coral-Derived Fungus Alternaria sp. (ZJ-2008017)

Marine-derived fungi have proved to be a promising source of structurally novel and biologically active secondary metabolites that have become interesting and significant resources for drug discovery [1, 2]. Perylene derivatives have been isolated from the marine-derived fungi of the genera of Alternaria and Stemphylium [3, 4]. They are of ten were found to have a partially reduced perylene quinone skeleton, and such perylene derivatives sometimes show a variety of phytotoxins and mutagenic activities [4]. As part of our ongoing investigation into new natural products, a series of antibacterial, antifouling, and cytotoxic compounds have been isolated from marine-derived fungi from the South China Sea [5–11]. Chemically-induced teratogenicity is preventable with proactive reproductive safety evaluations. The developing zebrafish (Daniorerio) is an in vivo developmental model with a number of advantages over in vitro systems and provides a simple, inexpensive, and rapid assay to screen for teratogenicity [10, 11]. From a zebrafish embryo teratogenicity assay, five perylene derivatives were isolated from the EtOAc extract of the marine-derived fungus Alternaria sp. ZJ-2008017. The fungus was isolated from a soft coral, Sarcophyton sp., collected from Weizhou Island in the South China Sea. The isolated structures were identified as 7-epi-8-hydroxyaltertoxin I (1) [4], stemphytriol (2) [14], altertoxin I (3) [15], stemphyltoxin II (4) [16], and stemphyperylenol (5) [17] on the basis of their spectroscopic data and by comparison with those previously reported in the literature. All compounds were isolated for the first time from the soft coral-derived fungi. Compounds 1–5 represent a class of perylene derivatives with a partially reduced perylene quinone skeleton. Their biosynthesis occurs probably via a phenol coupling of two pentaketide-derived moieties, followed by reduction and hydroxylation or epoxidation in different positions [15, 16, 18, 19]. To the best of our knowledge, most of the perylenequinones appear to derive from a head-to-head linkage such as 1–4; however, 5 seems to be a head-to-tail linkage of these moieties. Previous research revealed that some of these derivatives are phytotoxins and mutagens [4]. In our study, the zebrafish embryo teratogenicity and antifouling activity were evaluated for perylene derivatives for the first time. Compound 3 showed strong zebrafish embryo teratogenicity on Daniorerio with LC50 value of 4.54 g/mL on lethality of zebrafish embryo, and with EC50 values of 4.21 and 4.47 g/mL on inhibiting the incubation and deformity of zebrafish embryo, respectively. Compound 3 also exhibited potent antifouling activity against the barnacle Balanusamphitrite with an IC50 value of 0.27 g/mL, suggesting that 3 might be useful as a potential antifouling agent.

New briarane-type diterpenoids from gorgonian Ellisella dollfusi from the South China Sea.

Two new briarane-type diterpenoids, dollfusilin A (1) and dollfusilin B (2), along with five known briarane-type diterpenoids (3–7), were isolated from the gorgonian Ellisella dollfusi collected from the South China Sea. The structures of the two new compounds (1 and 2) were elucidated through a comprehensive analysis of spectroscopic data, especially 2D NMR. The bioactivities of the isolated compounds were evaluated using the zebrafish toxicity model.

Cytotoxic 19-oxygenated steroids from the South China Sea gorgonian, Pacifigorgia senta

Abstract Bioassay guided chemical investigation of the gorgonian Pacifigorgia senta led to the discovery of a new 19-oxygenated steroid, cholesta-5,24-diene-3β,7β,19-triol (1), as well as three known steroids (2–4). The structure of 1 was determined by extensive spectroscopic analysis, including NMR and MS spectra. All of the compounds exhibited cytotoxicities against HepG2, Hep3B, MCF-7/ADR, PC-3 and HCT-116 cell lines, with the IC50 values ranging from 7.0 to 29.7 μM. It is the first report on the chemical constituents of the coral species P. senta. Graphical abstract

Antibacterial Δ1‐3‐Ketosteroids from the South China Sea Gorgonian Coral Subergorgia rubra

Three new Δ1‐3‐ketosteroids characterized with a 9‐OH, subergosterones A–C (1–3), together with five known analogs 4–8, were obtained from the gorgonian coral Subergorgia rubra collected from the South China Sea. The structures of 1–3, including their absolute configurations, were determined by comprehensive spectroscopic methods and electronic circular dichroism (ECD) experiments. Compounds 2 and 3 exhibited inhibitory antibacterial activities against Bacillus cereus with MIC values of 1.56 μM.

Crystal structure of 1,3-bis(hydroxymethyl)-2-methyl-5-nitrobenzene, C9H11NO4

C9H11NO4, triclinic, P1 (no. 2), a = 7.845(1) Å, b = 8.517(2) Å, c = 14.468(3) Å, 0 = 88.441(3)°, . = 83.235(3)°, = 70.919(3)°, V = 907.1 Å, Z = 4, Rgt(F) = 0.044, wRref(F) = 0.144, T = 273 K. Source of material 1,3-Bis(hydroxymethyl)-2-methyl-5-nitrobenzene, a nitrophenyl compound was isolated from the fermentation broth of the endophytic fungus (no. B60) from the mangrove tree Acanthus ilicifolius Linn. on the South China Sea coast. A strain of fungus (no. B60) was deposited in the School of Chemistry and Chemical Engineering, Sun Yat-Sen University, Guangzhou, P. R. China. Culture conditions: GYT medium (glucose 10 g/l, peptone 2 g /l, yeast extract 1 g /l, NaCl 2.5 g /l) and incubation with shaking at 298 K for 15 d. For the extraction and separation of the metabolite, the cultures (100 l) of the title molecules were filtered through cheesecloth. The filtrate was concentrated to 3 l below 323 K, then extracted three times by shaking with an equal volume of ethyl acetate. The extract was evaporated under reduced pressure. The combined organic extracts were subjected to silica-gel column chromatography, eluting with petroleum ether/ethyl acetate, to yield the title compound. Colorless crystals were obtained through evaporation of a methanol solution.

Methyl 3-hydr-oxy-4-(3-methyl-but-2-en-yloxy)benzoate.

The title compound, C13H16O4, was isolated from culture extracts of the endophytic fungus Cephalosporium sp. The ester and ether substituents are twisted only slightly out of the benzene ring plane, making dihedral angles of 2.16 (2) and 3.63 (5)°, respectively. The non-H atoms of all three substituents are almost coplanar with the benzene ring, with an r.m.s. deviation of 0.0284 Å from the mean plane through all non-H atoms in the structure. A weak intramolecular O—H⋯O hydrogen bond contributes to this conformation. In the crystal structure, molecules are linked into a one-dimensional chain by intermolecular O—H⋯O hydrogen bonds. Weak non-classical C—H⋯π contacts are also observed in the structure.