Asperlones A and B,Dinaphthalenone Derivatives from a Mangrove Endophytic Fungus Aspergillus sp. 16-5C

Racemic dinaphthalenone derivatives, (±)-asperlone A (1) and (±)-asperlone B (2), and two new azaphilones, 6″-hydroxy-(R)-mitorubrinic acid (3) and purpurquinone D (4), along with four known compounds, (−)-mitorubrinic acid (5), (−)-mitorubrin (6), purpurquinone A (7) and orsellinic acid (8), were isolated from the cultures of Aspergillus sp. 16-5C. The structures were elucidated using comprehensive spectroscopic methods, including 1D and 2D NMR spectra and the structures of 1 further confirmed by single-crystal X-ray diffraction analysis, while the absolute configuration of 3 and 4 were determined by comparing their optical rotation and CD with those of the literature, respectively. Compounds 1, 2 and 6 exhibited potent inhibitory effects against Mycobacterium tuberculosis protein tyrosine phosphatase B (MptpB) with IC₅₀ values of 4.24 ± 0.41, 4.32 ± 0.60 and 3.99 ± 0.34 μM, respectively.     

Secondary Metabolites with α-Glucosidase Inhibitory Activity from Mangrove Endophytic Fungus Talaromyces sp. CY-3

Eight new compounds, including two sambutoxin derivatives (1–2), two highly oxygenated cyclopentenones (7–8), four highly oxygenated cyclohexenones (9–12), together with four known sambutoxin derivatives (3–6), were isolated from semimangrove endophytic fungus Talaromyces sp. CY-3, under the guidance of molecular networking. The structures of new isolates were elucidated by analysis of detailed spectroscopic data, ECD spectra, chemical hydrolysis, ¹³C NMR calculation, and DP4+ analysis. In bioassays, compounds 1–5 displayed better α-glucosidase inhibitory activity than the positive control 1-deoxynojirimycin (IC₅₀ = 80.8 ± 0.3 μM), and the IC₅₀ value was in the range of 12.6 ± 0.9 to 57.3 ± 1.3 μM.     

Isolation,Structural Characterization and Antidiabetic Activity of New Diketopiperazine Alkaloids from Mangrove Endophytic Fungus Aspergillus sp. 16-5c

Six new DIKETOPIPERAZINE alkaloids aspergiamides A–F (1–6), together with ten known alkaloids (7–16), were isolated from the mangrove endophytic fungus Aspergillus sp. 16-5c. The structures of the new compounds were elucidated based on 1D/2D NMR spectroscopic and HR-ESIMS data analyses. The absolute configurations of aspergiamides A-F were established based on the experimental and calculated ECD data. All the compounds were evaluated for the antidiabetic activity against α-glucosidase and PTP1B enzyme. The bioassay results disclosed compounds 1 and 9 exhibited significant α-glucosidase inhibitory with IC₅₀ values of 18.2 and 7.6 μM, respectively; compounds 3, 10, 11, and 15 exhibited moderate α-glucosidase inhibition with IC₅₀ values ranging from 40.7 to 83.9 μM; while no compounds showed obvious PTP1B enzyme inhibition activity.     

Eurothiocin A and B,Sulfur-Containing Benzofurans from a Soft Coral-Derived Fungus Eurotium rubrum SH-823

Two new sulfur-containing benzofuran derivatives, eurothiocin A and B (1 and 2), along with five known compounds, zinniol (3), butyrolactone I (4), aspernolide D (5), vermistatin (6), and methoxyvermistatin (7), were isolated from the cultures of Eurotium rubrum SH-823, a fungus obtained from a Sarcophyton sp. soft coral collected from the South China Sea. The new compounds (1 and 2) share a methyl thiolester moiety, which is quite rare among natural secondary metabolites. The structures of these metabolites were assigned on the basis of detailed spectroscopic analysis. The absolute configurations of 1 and 2 were determined by comparison of the experimental and calculated electronic circular dichroism (ECD) data. Compounds 1 and 2 exhibited more potent inhibitory effects against α-glucosidase activity than the clinical α-glucosidase inhibitor acarbose. Further mechanistic analysis showed that both of them exhibited competitive inhibition characteristics.     

Methylthio-Aspochalasins from a Marine-Derived Fungus Aspergillus sp.

Two novel aspochalasins, 20-β-methylthio-aspochalsin Q (named as aspochalasin V), (1) and aspochalasin W (2), were isolated from culture broth of Aspergillus sp., which was found in the gut of a marine isopod Ligia oceanica. The structures were determined on the basis of NMR and mass spectral data analysis. This is the first report about methylthio-substituted aspochalasin derivatives. Cytotoxicity against the prostate cancer PC3 cell line and HCT116 cell line was assayed using the MTT method. Apochalasin V showed moderate activity at IC₅₀ values of 30.4 and 39.2 μM, respectively.     

Alterporriol-Type Dimers from the Mangrove Endophytic Fungus,Alternaria sp. (SK11), and Their MptpB Inhibitions

A new alterporriol-type anthranoid dimer, alterporriol S (1), along with seven known anthraquinone derivatives, (+)-aS-alterporriol C (2), hydroxybostrycin (3), halorosellinia A (4), tetrahydrobostrycin (5), 9α-hydroxydihydrodesoxybostrycin (6), austrocortinin (7) and 6-methylquinizarin (8), were isolated from the culture broth of the mangrove fungus, Alternaria sp. (SK11), from the South China Sea. Their structures and the relative configurations were elucidated using comprehensive spectroscopic methods, including 1D and 2D NMR spectra. The absolute configurations of 1 and the axial configuration of 2 were defined by experimental and theoretical ECD spectroscopy. 1 was identified as the first member of alterporriols consisting of a unique C-10−C-2′ linkage. Atropisomer 2 exhibited strong inhibitory activity against Mycobacterium tuberculosis protein tyrosine phosphatase B (MptpB) with an IC₅₀ value 8.70 μM.     

Three New Resveratrol Derivatives from the Mangrove Endophytic Fungus Alternaria sp.

Three new resveratrol derivatives, namely, resveratrodehydes A–C (1–3), were isolated from the mangrove endophytic fungus Alternaria sp. R6. The structures of these compounds were elucidated by analysis of their MS, 1D and 2D NMR spectroscopic data. All compounds showed broad-spectrum inhibitory activities against three human cancer cell lines including human breast MDA-MB-435, human liver HepG2, and human colon HCT-116 by MTT assay (IC₅₀ < 50 μM). Among them, compounds 1 and 2 both exhibited marked cytotoxic activities against MDA-MB-435 and HCT-116 cell lines (IC₅₀ < 10 μM). Additionally, compounds 1 and 3 showed moderate antioxidant activity by DPPH radical scavenging assay.     

Bioactive Monoterpenes and Polyketides from the Ascidian-Derived Fungus Diaporthe sp. SYSU-MS4722

There has been a tremendous increase in the rate of new terpenoids from marine-derived fungi being discovered, while new monoterpenes were rarely isolated from marine-derived fungi in the past two decades. Three new monoterpenes, diaporterpenes A–C (1–3), and one new α-pyrones, diaporpyrone A (6), along with nine known polyketides 4, 5, and 7–13 were isolated from the ascidian-derived fungus Diaporthe sp. SYSU-MS4722. Their planar structures were elucidated based on extensive spectroscopic analyses (1D and 2D NMR and HR-ESIMS). The absolute configurations of 1 and 3 were identified by an X-ray crystallographic diffraction experiment using Cu-Ka radiation, and those of compound 2 were assigned by calculating NMR chemical shifts and ECD spectra. It afforded an example of natural epimers with different physical properties, especially crystallization, due to the difference in intermolecular hydrogen bonding. Compounds 9, 10, and 13 showed moderate total antioxidant capacity (0.82 of 9; 0.70 of 10; 0.48 of 13) with Trolox (total antioxidant capacity: 1.0) as a positive control, and compounds 5 and 7 showed anti-inflammatory activity with IC₅₀ values of 35.4 and 40.8 µM, respectively (positive control indomethacin: IC₅₀ = 35.8 µM).     

Bioactive Chaetoglobosins from the Mangrove Endophytic Fungus Penicillium chrysogenum

A novel chaetoglobosin named penochalasin I (1) with a unprecedented six-cyclic 6/5/6/5/6/13 fused ring system, and another new chaetoglobosin named penochalasin J (2), along with chaetoglobosins G, F, C, A, E, armochaetoglobosin I, and cytoglobosin C (3–9) were isolated from the culture of Penicillium chrysogenum V11. Their structures were elucidated by 1D, 2D NMR spectroscopic analysis and high resolution mass spectroscopic data. The absolute configuration of compounds 1 and 2 were determined by comparing the theoretical electronic circular dichroism (ECD) calculation with the experimental CD. Compound 1 was the first example, with a six-cyclic fused ring system formed by the connection of C-5 and C-2′ of the chaetoglobosin class. Compounds 5–8 remarkably inhibited the plant pathogenic fungus R. solani (minimum inhibitory concentrations (MICs) = 11.79–23.66 μM), and compounds 2, 6, and 7 greatly inhibited C. gloeosporioides (MICs = 23.58–47.35 μM), showing an antifungal activity higher than that of carbendazim. Compound 1 exhibited marked cytotoxicity against MDA-MB-435 and SGC-7901 cells (IC₅₀ < 10 μM), and compounds 6 and 9 showed potent cytotoxicity against SGC-7901 and A549 cells (IC₅₀ < 10 μM).     

Identification and Bioactivity of Compounds from the Mangrove Endophytic Fungus Alternaria sp.

Racemic new cyclohexenone and cyclopentenone derivatives, (±)-(4R*,5S*,6S*)-3-amino-4,5,6-trihydroxy-2-methoxy-5-methyl-2-cyclohexen-1-one (1) and (±)-(4S*,5S*)-2,4,5-trihydroxy-3-methoxy-4-methoxycarbonyl-5-methyl-2-cyclopenten-1-one (2), and two new xanthone derivatives 4-chloro-1,5-dihydroxy-3-hydroxymethyl-6-methoxycarbonyl-xanthen-9-one (3) and 2,8-dimethoxy-1,6-dimethoxycarbonyl-xanthen-9-one (4), along with one known compound, fischexanthone (5), were isolated from the culture of the mangrove endophytic fungus Alternaria sp. R6. The structures of these compounds were elucidated by analysis of their MS (Mass), one and two dimensional NMR (nuclear magnetic resonance) spectroscopic data. Compounds 1 and 2 exhibited potent ABTS [2,2′-azino-bis(3-ethylbenzthiazoline-6-sulphonic acid)] scavenging activities with EC₅₀ values of 8.19 ± 0.15 and 16.09 ± 0.01 μM, respectively. In comparison to Triadimefon, compounds 2 and 3 exhibited inhibitory activities against Fusarium graminearum with minimal inhibitory concentration (MIC) values of 215.52 and 107.14 μM, respectively, and compound 3 exhibited antifungal activity against Calletotrichum musae with MIC value of 214.29 μM.     

Meroterpenes from Endophytic Fungus A1 of Mangrove Plant Scyphiphora hydrophyllacea

Four new meroterpenes, guignardones F–I (1–4), together with two known compounds guignardones A (5) and B (6) were isolated from the endophytic fungus A1 of the mangrove plant Scyphiphora hydrophyllacea. Their structures and relative configurations were elucidated by spectroscopic data and single-crystal X-ray crystallography. A possible biogenetic pathway of compounds 1–6 was also proposed. All compounds were evaluated for inhibitory activity against methicillin-resistant Staphylococcus aureus (MRSA) and Staphylococcus aureus.     

Four eremophilane sesquiterpenes from the mangrove endophytic fungus Xylaria sp. BL321

Three new eremophilane sesquiterpenes (1–3) were isolated from the mangrove endophytic fungus Xylaria sp. BL321 together with 07H239-A (4), a known analogue of the new compounds. The structures of these compounds were elucidated by analysis of their MS, 1D and 2D NMR spectroscopic data. Compound 4 showed activation activity on α-glucosidase at 0.15 μM (146%), and then, 4 gradually produced inhibitory activity on α-glucosidase with increasing concentration, and the IC₅₀ value is 6.54 μM.     

PTP1B Inhibitory and Anti-Inflammatory Effects of Secondary Metabolites Isolated from the Marine-Derived Fungus Penicillium sp. JF-55

Protein tyrosine phosphatase 1B (PTP1B) plays a major role in the negative regulation of insulin signaling, and is thus considered as an attractive therapeutic target for the treatment of diabetes. Bioassay-guided investigation of the methylethylketone extract of marine-derived fungus Penicillium sp. JF-55 cultures afforded a new PTP1B inhibitory styrylpyrone-type metabolite named penstyrylpyrone (1), and two known metabolites, anhydrofulvic acid (2) and citromycetin (3). Compounds 1 and 2 inhibited PTP1B activity in a dose-dependent manner, and kinetic analyses of PTP1B inhibition suggested that these compounds inhibited PTP1B activity in a competitive manner. In an effort to gain more biological potential of the isolated compounds, the anti-inflammatory effects of compounds 1–3 were also evaluated. Among the tested compounds, only compound 1 inhibited the production of NO and PGE₂, due to the inhibition of the expression of iNOS and COX-2. Penstyrylpyrone (1) also reduced TNF-α and IL-1β production, and these anti-inflammatory effects were shown to be correlated with the suppression of the phosphorylation and degradation of IκB-α, NF-κB nuclear translocation, and NF-κB DNA binding activity. In addition, using inhibitor tin protoporphyrin (SnPP), an inhibitor of HO-1, it was verified that the inhibitory effects of penstyrylpyrone (1) on the pro-inflammatory mediators and NF-κB DNA binding activity were associated with the HO-1 expression. Therefore, these results suggest that penstyrylpyrone (1) suppresses PTP1B activity, as well as the production of pro-inflammatory mediators via NF-κB pathway, through expression of anti-inflammatory HO-1.     

Gliotoxin Isolated from Marine Fungus Aspergillus sp. Induces Apoptosis of Human Cervical Cancer and Chondrosarcoma Cells

Gliotoxin, a secondary metabolite produced by marine fungus Aspergillus sp., possesses various biological activities including anticancer activity. However, the mechanism underlying gliotoxin-induced cytotoxicity on human cervical cancer (Hela) and human chondrosarcoma (SW1353) cells remains unclear. In this study, we focused on the effect of gliotoxin induction on apoptosis, the activating expressions of caspase family enzymes in the cells. Apoptotic cell levels were measured through DAPI and Annexin V/Propidium Iodide (PI) double staining analysis. The apoptotic protein expression of Bcl-2 and caspase family was detected by Western blot in Hela and SW1353 cells. Our results showed that gliotoxin treatment inhibited cell proliferation and induced significant morphological changes. Gliotoxin induced apoptosis was further confirmed by DNA fragmentation, chromatin condensation and disrupted mitochondrial membrane potential. Gliotoxin-induced activation of caspase-3, caspase-8 and caspase-9, down-regulation of Bcl-2, up-regulation of Bax and cytochromec (cyt c) release showed evidence for the gliotoxin activity on apoptosis. These findings suggest that gliotoxin isolated from marine fungus Aspergillus sp. induced apoptosis in Hela and SW1353 cells via the mitochondrial pathway followed by downstream events leading to apoptotic mode of cell death.     

Capgermacrenes A and B,Bioactive Secondary Metabolites from a Bornean Soft Coral,Capnella sp.

Two new bicyclogermacrenes, capgermacrenes A (1) and B (2), were isolated with two known compounds, palustrol (3) and litseagermacrane (4), from a population of Bornean soft coral Capnella sp. The structures of these metabolites were elucidated based on spectroscopic data. Compound 1 was found to inhibit the accumulation of the LPS-induced pro-inflammatory IL-1β and NO production by down-regulating the expression of iNOS protein in RAW 264.7 macrophages.     

Spirobisnaphthalenes from the Mangrove-Derived Fungus Rhytidhysteron sp. AS21B

Three new spirobisnaphthalenes (1–3) were isolated from the mangrove-derived fungus Rhytidhysteron sp., together with five known derivatives (4–8). The structures of the compounds were established on the basis of extensive spectroscopic data, and the relative configurations of their stereogenic carbons were determined by a single-crystal X-ray crystallographic analysis. Compounds 3–5 displayed cytotoxicity against both cancer cell lines, MCF-7 and CaSki, while 2 was active only on CaSKi cells.     

Polyketide Derivatives,Guhypoxylonols A–D from a Mangrove Endophytic Fungus Aspergillus sp. GXNU-Y45 That Inhibit Nitric Oxide Production

Four undescribed compounds, guhypoxylonols A (1), B (2), C (3), and D (4), were isolated from the mangrove endophytic fungus Aspergillus sp. GXNU-Y45, together with seven previously reported metabolites. The structures of 1–4 were elucidated based on analysis of HRESIMS and NMR spectroscopic data. The absolute configurations of the stereogenic carbons in 1–3 were established through a combination of spectroscopic data and electronic circular dichroism (ECD). Compounds 1–11 were evaluated for their anti-inflammatory activity. Compounds 1, 3, 4, and 6 showed an inhibitory activity against the production of nitric oxide (NO), with the IC₅₀ values of 14.42 ± 0.11, 18.03 ± 0.14, 16.66 ± 0.21, and 21.05 ± 0.13 μM, respectively.     

Three New Asperentin Derivatives from the Algicolous Fungus Aspergillus sp. F00785

Three new asperentin-type compounds, 6-O-α-d-ribosylasperentin (1) and 6-O-α-d-ribosyl-8-O-methylasperentin (2) and 5-hydroxyl-6-O-methylasperentin (3), along with asperentin (4) and its known analogues (5–9), were isolated from a halotolerant Aspergillus sp. strain {"type":"entrez-nucleotide","attrs":{"text":"F00785","term_id":"707638","term_text":"F00785"}}F00785, an endotrophic fungus from marine alga. Their structures were determined using extensive NMR and HRESIMS spectroscopic analysis, including the X-ray crystallographic data for the assignment of the absolute configurations of compound 9. Compound 4 exhibited highly potent inhibitory activity against crop pathogens, Colletotrichum gleosporioides Penz. and Colletotrichum gleosporioides (Penz.) Sacc.     

Asperopiperazines A and B: Antimicrobial and Cytotoxic Dipeptides from a Tunicate-Derived Fungus Aspergillus sp. DY001

Investigation of the cytotoxic fractions of the ethyl acetate extract of the fermentation broth of the tunicate-derived Aspergillus sp. DY001 afforded two new dipeptides, asperopiperazines A and B (1 and 2), along with the previously reported compounds (+)-citreoisocoumarin (3) and (−)-6,8-di-O-methylcitreoisocoumarin (4). Analyses of the 1D and 2D NMR spectroscopic data of the compounds supported their structural assignments. Asperopiperazine A (1) is a cyclic dipeptide of leucine and phenylalanine moieties, which are substituted with an N-methyl and an N-acetyl group, respectively. On the other hand, asperopiperazine B (2) is a cyclic dipeptide of proline and phenylalanine moieties with a hydroxyl group at C-2 of the proline part. The absolute configuration of the amino acid moieties in 1 and 2 were determined by Marfey’s analyses and DFT NMR chemical shift calculations, leading to their assignment as cyclo(l-NMe-Leu-l-NAc-Phe) and cyclo(d-6-OH-Pro-l-Phe), respectively. Asperopiperazines A and B displayed higher antimicrobial effects against Escherichia coli and Staphylococcus aureus than Candida albicans. Furthermore, compounds 1–4 displayed variable growth inhibitory effects towards HCT 116 and MDA-MB-231 cells, with asperopiperazine A as the most active one towards HCT 116.     

Polyketides from a Marine-Derived Fungus Xylariaceae sp.

Eighteen polyketides (1–18) including six citrinin derivatives, two phenol derivatives, one cyclopentenone, two naphthol derivatives, and seven tetralone derivatives were isolated from the culture broth of a marine-derived fungal strain Xylariaceae sp. SCSGAF0086. Five of these compounds (1, 2, 8, 9, and 10) were new, and their structures were determined by spectroscopic methods. Compounds 4, 6, 7, and 17 showed enzyme-inhibitory activities towards several tested enzymes, and 6 and 7 showed strong antifouling activity against Bugula neritina larvae settlement. This is the first time that the antifouling and enzyme-inhibitory activities of these compounds has been reported.