Sponge Phakellia Fusca Research Articles

Discovery of cycloheptapeptides phakefusins A−E from the marine sponge Phakellia fusca based on molecular networking

Guided by a probe-based molecular networking strategy, five undescribed cycloheptapeptides, phakefusins A−E (1−5), were isolated from the marine sponge Phakellia fusca. Compounds 1 and 2 contain the nonproteinogenic amino acid residues of dioxindolyalanine (Dioia) and β-3-oxindolylalanine (Oia), respectively. Compound 3 possesses a unique methionine sulfoxide, whereas compound 5 includes a glutamic acid ethyl ester unit. Their structures were elucidated through NMR spectroscopy, HR-MS/MS analysis, and the advanced Marfey's method. By synthesizing the (S, S/R)-Oia standard through tryptophan oxidation, we determined the configuration of this amino acid in compound 2 using the advanced Marfey's method. These cycloheptapeptides were evaluated for their antitumor, antibacterial, and antioxidant activities. Compound 1 showed moderate cytotoxicity against MCF-7 and PC9 cells, with IC50 values of 6.8 and 9.6 μM, respectively, while compounds 2−5 demonstrated potential antioxidant effects by upregulating HO-1, NQO1, and SOD2 levels, as well as inducing Nrf2 activation.

Pyrrololactam alkaloids with IL-6 inhibitory activities from the sponge Phakellia fusca collected in the South China Sea

Sixteen undescribed pyrrololactam alkaloids, including five 2-bromopyrrole-ε-lactam (1a, 1b, 4a, 4b and 5), two 3-bromopyrrole-ε-lactam (9 and 10), eight pyrrole-ε-lactam (2a-3 and 6a-8), and one pyrrole-δ-lactam alkaloids (11), along with three previously reported compounds (12–14) were isolated from the marine sponge Phakellia fusca collected in the South China Sea. The planar structures were determined by NMR and MS analyses, while the absolute configurations were clearly elucidated by comparing the experimental and calculated ECD spectra. Compounds 2a, 2b, 4a-7b, 10, 12 and 13 exhibited anti-inflammatory activity in inhibiting the production of inflammatory cytokines IL-6 in LPS-induced RAW264.7 macrophages.

Marinacarboline glucuronide, a new member of β-carboline alkaloids from sponge-derived actinomycete Actinoalloteichus cyanogriseus LHW52806.

A new member of β-carboline alkaloids, Marinacarboline glucuronide (1), along with nine known compounds (2-10), were isolated from static liquid fermentation extracts of Actinoalloteichus cyanogriseus LHW52806 isolated from the marine sponge Phakellia fusca. Their structures were elucidated by NMR, mass spectrometry and single-crystal X-ray diffraction. All compounds exhibited neither antimicrobial activity nor cytotoxicity. Compounds 1, 8 and 10 showed anti-inflammatory potential of significant decreasing the expressions of IL- 6 in vitro at 20 µM.

First report on the synthesis and structural studies of trans-Phakellistatin 18: a rotamer of marine natural product phakellistatin 18

Phakellistatin peptides from marine organisms are the sources of proline-rich cyclic peptides with reported significant antitumor activities. Phakellistatin 18 (1), reported from marine sponge Phakellia fusca, contains three proline-peptide linkages in cis form. We attempted the total synthesis of natural product 1 through solution-phase macrocyclization approach, as a result, the synthetic cyclic peptide 2 was obtained as a rotamer of natural product having all three proline residues in trans-conformation. Here, we describe the synthesis, structural, and cytotoxicity studies of trans-Phakellistatin 18 (2), and its analog [Ala1,3,6]-Phakellistatin 18 (3). Detailed NMR studies were carried out to characterize the synthesized peptides, and anti-cancer screening was performed by using MTT assay. The synthetic trans-Phakellistatin 18 (2) (IC50=67.5 ± 2.938 µM) showed comparable cytotoxicity against HepG2 cancer cell line with standard drug doxorubicin (IC50=63.88 ± 6.48 µM). Here, the first synthetic and structural studies on trans-Phakellistatin 18 (2), and its anticancer screening against HepG2 cell line was reported.

Phakefustatins A-C: Kynurenine-Bearing Cycloheptapeptides as RXRα Modulators from the Marine Sponge Phakellia fusca.

A neutral-loss scanning mass method was used to explore new kynurenine-containing cycloheptapeptides, phakefustatins A-C (1-3), from the marine sponge Phakellia fusca. Their structures were elucidated by spectroscopic analysis and the advanced Marfey's method. 1 was total synthesized via a final-stage ozonolysis strategy by the combination of solid/solution-phase synthesis. Phakefustatin A (1) was identified as a RXRα modulator to inhibit cancer cell growth, and its pharmacophores could be Kyn and guanidine groups.

Structurally diverse sesquiterpenoids and polyketides from a sponge-associated fungus Aspergillus sydowii SCSIO41301

Five new compounds, including one bisabolane-type sesquiterpenoids, namely aspergillusene D (1), two new xanthones (2 and 3), and two new catecholderivatives (4 and 5), together with fourteen known compounds (6–19), were isolated and identified from the fungus Aspergillus sydowiiSCSIO 41,301 from the sponge Phakellia fusca. Their structures and absolute configurations were determined by extensive spectroscopic analysis and electronic circular dichroism (ECD) calculations. Most of the isolated compounds (1–3, and 6–19) were evaluated for their antiviral, cytotoxic, and antibacterial activities. Among them, new compounds 2 and 3 displayed obvious selective inhibitory activities against two influenza A virus subtypes, including A/Puerto Rico/8/34 (H1N1) and A/FM-1/1/47 (H1N1), with IC50 values ranging from 2.17 ± 1.39 to 4.70 ± 1.11 μM.

Fuscasins A-D, Cycloheptapeptides from the Marine Sponge Phakellia fusca.

Four new cycloheptapeptides, fuscasins A-D (1-4), were isolated from the marine sponge Phakellia fusca collected from the South China Sea. Their planar structures were fully characterized by spectroscopic methods, and the absolute configurations of amino acid residues were determined using the advanced Marfey's method. Structurally, 1 is a unique cycloheptapeptide with a backbone bearing a pyrrolidine-2,5-dione unit. Among the isolated compounds, 1 exhibited potent growth-inhibitory activity against HepG2 cells with an IC50 value of 4.6 μM, whereas it did not show apparent inhibitory effects against the other five human cancer cell lines, MCF-7, HeLa, NCI-H460, PC9, and SW480. Encouragingly, 1 exhibited no cytotoxicity against nonmalignant cells even with a concentration up to 100 μM. These findings suggest that 1 may display a selective inhibitory effect on the growth of HepG2 cells.

New butenolide derivatives from the marine sponge-derived fungus Aspergillus terreus

Two new butenolide derivatives (±)-asperteretal D ((±)-1) and asperteretal E (2) containing rare 2-benzyl-3-phenyl substituted lactone core, together with nine known analogues (3–11) were obtained from a fungus Aspergillus terreus derived from the marine sponge Phakellia fusca. All the structures were elucidated on the basis of extensive NMR spectroscopic data. The chiral chromatography analyses allowed the separation of the (±)-asperteretal D, of which the absolute configurations were determined by comparing the experimental to calculated electronic circular dichroic (ECD) spectra. Compounds (±)-1, 2–5, and 7 exhibited potent inhibitory activities against α-glucosidase with IC50 values ranging from 8.65 to 20.3 µM (positive control acarbose with an IC50 value of 320 µM). In addition, derivatives 5–8 also showed moderate antioxidant activities.

New Metabolites and Bioactive Chlorinated Benzophenone Derivatives Produced by a Marine-Derived Fungus Pestalotiopsis heterocornis.

Four new compounds, including two isocoumarins, pestaloisocoumarins A and B (1, 2), one sesquiterpenoid degradation, isopolisin B (4), and one furan derivative, pestalotiol A (5), together with one known isocoumarin, gamahorin (3), and three chlorinated benzophenone derivatives, pestalachloride B (6), pestalachloride E (7) and a mixture of pestalalactone atropisomers (8a/8b), were isolated from a culture of the fungus Pestalotiopsis heterocornis associated with sponge Phakellia fusca. These new chemical structures were established using NMR and MS spectroscopic data, as well as single-crystal X-ray crystallographic analysis and CD Cotton effects. All of the isolated compounds were evaluated for their antimicrobial and cytotoxic activities. Isocoumarins 1–3, showed antibacterial activities against Gram-positive bacteria Staphylococcus aureus and Bacillus subtilis with MIC values ranging from 25 to 100 μg/mL and weak antifungal activities. Chlorinated benzophenone derivatives 6–8 exhibited antibacterial activities against S. aureus and B. subtilis with MIC values ranging from 3.0 to 50 μg/mL and cytotoxicities against four human cancer cell lines with IC50 values of 6.8–87.8 μM.

Asymmetric Total Syntheses of Two Possible Diastereomers of Gliomasolide E and Its Structural Elucidation.

The first total syntheses of two possible diastereomers of gliomasolide E, a 14-membered macrolides isolated from the marine sponge Phakellia fusca Thiele, which was collected from the South China Sea, is reported. Highlights of the synthesis include macrolactonization through intramolecular Horner-Wadsworth-Emmons olefination, Yamaguchi-Hirao alkynylation, and base-induced elimination reactions for propargyl alcohol synthesis as the key reactions. Detailed comparison of their 1H and 13C NMR (1D and 2D NMR data) and specific rotation with those of the natural product revealed that the absolute stereochemistry of gliomasolide E should be (2E,5R,7R,9R,13R).

Quinone/hydroquinone meroterpenoids with antitubercular and cytotoxic activities produced by the sponge-derived fungus Gliomastix sp. ZSDS1-F7

Fifteen compounds, including six quinone/hydroquinone meroterpenoids, purpurogemutantin (1), macrophorin A (2), 4′-oxomacrophorin (3), 7-deacetoxyyanuthone A (4), 2,3-hydro-deacetoxyyanuthone A (5), 22-deacetylyanuthone A (6), anicequol (7), three roquefortine derivatives, roquefortine C (8), (16S)-hydroxyroquefortine C (9), (16R)-hydroxyroquefortine C (10), dihydroresorcylide (11), nectriapyrone (12), together with three fatty acid derivatives, methyl linoleate (13), phospholipase A2 (14), methyl elaidate (15), were isolated from the sponge-derived fungus Gliomastix sp. ZSDS1-F7 isolated from the sponge Phakellia fusca Thiele collected in the Yongxing island of Xisha. Their structures were elucidated mainly by extensive NMR spectroscopic and mass spectrometric analyses. Among these compounds, compounds 1–3 and 5–7 showed significant in vitro cytotoxicities against the K562, MCF-7, Hela, DU145, U937, H1975, SGC-7901, A549, MOLT-4 and HL60 cell lines, with IC50 values ranging from 0.19 to 35.4 μM. And compounds 2–4 exhibited antitubercular activity with IC50 values of 22.1, 2.44 and 17.5 μM, respectively. Furthermore, compound 7 had anti-enterovirus 71 activity with MIC value of 17.8 μM. To the best of our knowledge, this is the first report to product two quinone/hydroquinone meroterpenoids skeletons (linear skeleton and drimane skeleton) from the same fungal strain.

Modification of artificial sea water for the mass production of (+)-terrein by Aspergillus terreus strain PF26 derived from marine sponge Phakellia fusca.

(+)-Terrein shows multiple bioactivities, however, its mass production is a big challenge. Aspergillus terreus strain PF26 derived from South China Sea sponge Phakellia fusca has been cultured to produce (+)-terrein successfully, but artificial sea water (ASW) of high salinity used in the fermentation medium may cause the corrosion risk of metal bioreactor, which limits the fermentation on a large scale. In this study, we modified the components of ASW by removing NaCl and CaCl2 from the original formula, which reduced about 80% salinity of ASW. As a result, 7·56 g l(-1) (+)-terrein production was achieved in shake flask, which was 78·72% higher than using the original ASW, and the cultivation time was decreased from 24 to 15 days. Then, the modified ASW was used for the fermentation of A. terreus strain PF26 in a 500 l stirred bioreactor, consequently 2·5 g l(-1) of (+)-terrein production was achieved. The fermentation of marine micro-organisms always needs to use sea water or artificial sea water (ASW), which limits the fermentation on a large scale, as the high-salinity medium may cause the corrosion risk of bioreactor. In this study, the ASW formula is simplified to reduce the sea water salinity and improve the yield of (+)-terrein, finally, the modified ASW was successfully used for the mass production of (+)-terrein by A. terreus strain PF26 in a 500 l bioreactor.

New Furan and Cyclopentenone Derivatives from the Sponge-Associated Fungus Hypocrea Koningii PF04.

Two new furan derivatives, hypofurans A and B (1 and 2), and three new cyclopentenone derivatives, hypocrenones A–C (3–5), along with seven known compounds (6–12), were isolated from a marine fungus Hypocrea koningii PF04 associated with the sponge Phakellia fusca. Among them, compounds 10 and 11 were obtained for the first time as natural products. The planar structures of compounds 1–5 were elucidated by analysis of their spectroscopic data. Meanwhile, the absolute configuration of 1 was determined as 2R,3R by the comparison of the experimental and calculated electronic circular dichroism (ECD) spectra. All the isolates were evaluated for their antibacterial and antioxidant activity. Compounds 1, 10, and 12 all showed modest antibacterial activity against Staphylococcus aureus ATCC25923 (MIC, 32 μg/mL). In addition, compounds 1, 10 and 11 exhibited moderate DPPH radical scavenging capacity with IC50 values of 27.4, 16.8, and 61.7 µg/mL, respectively.

Cytotoxic cytochalasins from marine-derived fungus Arthrinium arundinis.

Four new cytochalasins, arthriniumnins A-D (1-4), a new natural product, ketocytochalasin (5), as well as five known cytochalasin analogues (6-10) were isolated and identified from the fungus Arthrinium arundinis ZSDS1-F3 from the sponge Phakellia fusca. Their structures were elucidated by NMR spectroscopic and mass spectrometric analyses, as well as single crystal X-ray diffraction. Compounds 6 and 9 showed cytotoxicity against K562, A549, Huh-7, H1975, MCF-7, U937, BGC823, HL60, Hela, and MOLT-4 cell lines, with IC50 values ranging from 1.13 to 47.4 µM.

Tetramic acid derivatives and polyphenols from sponge-derived fungus and their biological evaluation

Fifteen compounds, including two tetramic acid derivatives, penicillenol A1 (1) and penicillenol A2 (2), six polyphenols containing both phenolic bisabolane sesquiterpenoid and diphenyl ether units, expansols A–F (3–8), together with six phenolic bisabolane sesquiterpenoids (9–14) and diorcinol (15), were isolated from the fermentation broth of the marine-derived fungus ZSDS1-F11 isolated from the sponge Phakellia fusca Thiele collected in the Yongxing island of Xisha. Their structures were elucidated mainly by using extensive NMR spectroscopic and mass spectrometric analyses. Compounds 3–5, 7 and 8 showed potent COX-1 inhibitory activity with IC50 values of 5.3, 16.2, 30.2, 41.0 and 56.8 μM, respectively. Meanwhile, compounds 3–8 showed potent COX-2 inhibitory activity with IC50 values of 3.1, 5.6, 3.0, 5.1, 3.2 and 3.7 μM, respectively. In addition, compound 1 exhibited antituberculosis activity with 96.1% inhibition at concentration of 10 μM.

Enhanced production of (+)-terrein by Aspergillus terreus strain PF26 with epigenetic modifier suberoylanilide hydroxamic acid

New strategies for improving the fermentation yield of (+)-terrein which is a fungal metabolite with multiple bioactivities are very urgent. In this study, the effect of suberoylanilide hydroxamic acid, one kind of epigenetic modifier, on the biosynthesis of (+)-terrein by Aspergillus terreus strain PF26 isolated from the marine sponge Phakellia fusca was investigated. It was found that suberoylanilide hydroxamic acid exhibited a positive impact on (+)-terrein production, resulting from promoting the biosynthesis of 6-hydroxymellein, the precursor of (+)-terrein. Through optimization of feeding concentration and time of suberoylanilide hydroxamic acid, 5.58g/L (+)-terrein could be obtained in shake flask cultivation, 29.5% higher than the control. Correspondingly, the fermentation of A. terreus strain PF26 in 7.5-L stirred bioreactor with feeding suberoylanilide hydroxamic acid (900μM, day 4) yielded 9.07g/L (+)-terrein, 77.1% higher than the control. These results showed that the epigenetic modifier-suberoylanilide hydroxamic acid could be utilized to enhance the production of (+)-terrein, which laid the foundation of massive production of (+)-terrein by fermentation.

Enhanced production of (+)-terrein in fed-batch cultivation of Aspergillus terreus strain PF26 with sodium citrate

(+)-Terrein is a fungal metabolite with multiple biological activities, especially with great value in medicine. However, the mass production of single configuration terrein is still a big challenge. In this study, the effects of acetic acid, sodium acetate, citric acid and sodium citrate on the (+)-terrein production by Aspergillus terreus strain PF26 derived from marine sponge Phakellia fusca were investigated. Sodium citrate was selected for fed-batch cultivation because it showed the best effect on (+)-terrein production among the four regulators tested. As a result, 5.38 g/L (+)-terrein production was achieved by feeding 10 mM sodium citrate on the 3rd day in shake flask, which was 33.8 % higher than the control and represented the highest yield of (+)-terrein. In a 7.5-L stirred bioreactor, 2.58 g/L of (+)-terrein production was achieved by the feeding of 10 mM sodium citrate on the 8th day. The results from this study lay a basis for the high-yield production of (+)-terrein by fermentation.

Operating conditions optimization for (+)-terrein production in a stirred bioreactor by Aspergillus terreus strain PF-26 from marine sponge Phakellia fusca

Terrein is a fungal metabolite with application values in the fields of medicine, cosmetology, and agriculture. However, mass production of single configuration terrein is still a big challenge. In this study, operating factors such as inoculation, agitation speed, aeration rate, pH control, and nutrient feeding were preliminarily optimized to improve the (+)-terrein production in the 5-L stirred bioreactor from the marine sponge-derived fungus Aspergillus terreus PF-26. Spore inoculation, low agitation speed, and aeration rate were proved to be suitable for A. terreus PF-26 to produce (+)-terrein in the stirred bioreactor. At 50 rpm agitation speed and 0.33 vvm aeration rate, 2.68 g/L (+)-terrein was achieved by feeding twofold concentrated maltose and glucose medium on the sixth day and controlling pH at 4.5 from the fourth day. This study lays foundation for the mass production of (+)-terrein by the marine filamentous A. terreus strain PF-26 in the stirred bioreactor.

Medium optimization for the high yield production of single (+)-terrein by Aspergillus terreus strain PF26 derived from marine sponge Phakellia fusca

Terrein has potential application in the fields of medicine, cosmetology and agriculture, however, the chemical synthesis of terrein with single configuration is a difficult task, and the biosynthesis of terrein always results in low production (ca. 0.33–400mg/L). In this study, we reported an Aspergillus terreus strain PF26 which could produce (+)-terrein on a high level. After the selection of a suitable basic medium, the component concentrations were optimized using Plackett–Burman design and response surface methodology. Consequently, an optimal medium containing 28.41g glucose, 23.18g maltose, 20.00g mannitol, 8.52g malt extract, 10.00g monosodium glutamate 10.00g NH4Cl in 1L ASW was obtained, and a high (+)-terrein production of 3.71g/L fermentation broth was achieved, which represents the highest fermentation production of (+)-terrein to date. The result highlighted the industry's potential of A. terreus strain PF26 in the production of bioactive (+)-terrein on a large-scale.

Bacterial and Archaeal Symbionts in the South China Sea Sponge Phakellia fusca: Community Structure, Relative Abundance, and Ammonia-Oxidizing Populations

Many biologically active natural products have been isolated from Phakellia fusca, an indigenous sponge in the South China Sea; however, the microbial symbionts of Phakellia fusca remain unknown. The present investigations on sponge microbial community are mainly based on qualitative analysis, while quantitative analysis, e.g., relative abundance, is rarely carried out, and little is known about the roles of microbial symbionts. In this study, the community structure and relative abundance of bacteria, actinobacteria, and archaea associated with Phakellia fusca were revealed by 16S rRNA gene library-based sequencing and quantitative real time PCR (qRT-PCR). The ammonia-oxidizing populations were investigated based on amoA gene and anammox-specific 16S rRNA gene libraries. As a result, it was found that bacterial symbionts of sponge Phakellia fusca consist of Proteobacteria including Gamma-, Alpha-, and Delta-proteobacteria, Cyanobacteria with Gamma-proteobacteria as the predominant components. In particular, the diversity of actinobacterial symbionts in Phakellia fusca is high, which is composed of Corynebacterineae, Acidimicrobidae, Frankineae, Micrococcineae, and Streptosporangineae. All the observed archaea in sponge Phakellia fusca belong to Crenarchaeota, and the detected ammonia-oxidizing populations are ammonia-oxidizing archaea, suggesting the nitrification function of sponge archaeal symbionts. According to qRT-PCR analysis, bacterial symbionts dominated the microbial community, while archaea represented the second predominant symbionts, followed by actinobacteria. The revealed diverse prokaryotic symbionts of Phakellia fusca are valuable for the understanding and in-depth utilization of Phakellia fusca microbial symbionts. This study extends our knowledge of the community, especially the relative abundance of microbial symbionts in sponges.