Two new tetrahydrofuran derivatives from the fungus Mucor spp. SNB-VECD11D isolated from the Chrysomelidae Acalymma bivittula

Two new tetrahydrofuran derivatives, mucorinic acids A (1) and B (2) as well as the three known secondary metabolites dehydroabietic acid (3), Δ8-dihydroabietic acid (4) and 8-pimarenic acid (5) were isolated from a solid culture of the fungus Mucor spp. isolated on insect Acalymma bivittula. The structure of these compounds was elucidated by analysis of NMR and MS spectroscopic data. Compounds were tested in antimicrobial and insecticidal assays. Dehydroabietic acid exhibited moderate larvicidal activity on Aedes aegypti larvae with 65% mortality at 10 ppm. Both new compounds 1 and 2 showed interesting antibacterial activity on Staphylococcus aureus and methicillin resistant S. aureus with MIC values in the 8–16 μg/ml.     

Prenylated indole alkaloids and chromone derivatives from the fungus Penicillium sp. SCSIO041218

Four new prenylated indole alkaloids (1–4), and four new chromone derivatives (7–10), together with six known compounds (5, 6, and 11–14), have been isolated from the mangrove sediment derived fungus Penicillium sp. SCSIO041218, cultured in the 1% NaCl PDB substrate. The structures of new compounds were determined by analysis of the NMR and MS spectroscopic data. The absolute configuration of the prenylated indole alkaloids were elucidated based on the comparison of ECDs with known analogues. The absolute configurations of the chromone derivatives were determined by time-dependent density functional theory calculations of the ECD spectra. In all of these isolated compounds, penixanthones A and B (12 and 13) exhibited antiallergic activities in vitro.     

Polyketides and nitrogenous metabolites from the endophytic fungus Phomopsis sp. D15a2a

Three new polyketides, phomopones A−C (1–3), one new cyclic tetrapeptide, 18-hydroxydihydrotentoxin (4), and a new amide, 6-hydroxyenamidin (5) together with a known derivative, enamindin (6) were obtained from the endophytic fungus Phomopsis sp. D15a2a isolated from the plant Alternanthera bettzickiana. The structures of the new compounds were elucidated by 1D, 2D NMR and HRMS data. The absolute configurations of the isolated metabolites were determined either by X-ray crystallography, Marfey’s method or by converting the compounds to Mosher esters.     

Cyclopiane-type diterpenes from the deep-sea-derived fungus Penicillium commune MCCC 3A00940

Three new cyclopiane diterpenes (1–3) and one rare spirocyclolide (5) were isolated from the deep-sea-derived fungus Penicillium commune MCCC 3A00940, along with 11 known compounds. The planar structures of the new compounds were determined by extensive analysis of their NMR and HRESIMS spectra, and the absolute configurations were established on the basis of specific rotation data in association with calculated ECD spectra. Four of the cyclopiane diterpenes (1–4), with a rigid 6/5/5/5 fused tetracyclic ring framework, are rarely found in Nature. Notably, conidiogenone J (1) is the first naturally occurring enantiomer of the cyclopiane diterpenes. Additionally, penijanthine B (6) and 3-hydroxy-5-methoxystilbene (14) exhibited moderate antiallergic effects with IC₅₀ values of 30 and 33?μM, respectively.     

Secondary metabolites of the lichen-associated fungus Apiospora montagnei

The endolichenic fungus Apiospora montagnei isolated from the lichen Cladonia sp. was cultured on solid rice medium, yielding the new diterpenoid libertellenone L (1), the new pyridine alkaloid, 23-O-acetyl-N-hydroxyapiosporamide (2) and the new xanthone derivative 8-hydroxy-3-hydroxymethyl-9-oxo-9H-xanthene-1-carboxylic acid methyl ether (3) together with 19 known compounds (4–22). The structures of the new compounds were elucidated by 1D and 2D NMR spectra as well as by HRESIMS data. The absolute configuration of the new 6,7-seco-libertellenone derivative 1 was determined by single-crystal X-ray diffraction. Four additional known compounds 23–26 were isolated when NaCl or NH₄Cl were added to solid rice medium. Compounds 7–9, 18 and 26 exhibited significant cytotoxicity against the L5178 murine lymphoma cell line with IC₅₀ values of 2.6, 0.2, 2.1, 2.7 and 1.7 μM, respectively.     

Bioactive compounds from the scale insect fungus Conoideocrella tenuis BCC 44534

Eleven new compounds, including two quinone derivatives of bioxanthracene, conoideocrellones A (1) and B (2), two bioxanthracenes 3 and 4, four isocoumarins and isocoumarin glycosides 7–10, two phenolic compounds 16 and 17, and a diterpenoid compound, conoideocin A (18), were isolated from culture of the scale-insect pathogenic fungus Conoideocrella tenuis BCC 44534. Seventeen known compounds, compounds 5 and 6, ES-242-2 and its atropisomer, isocoumarins and isocoumarin glycosides 11–15, 3,4,6-trihydroxymellein, cis-4,6-dihydroxymellein, metarhizins A (19) and B (20), BR-050 (21), 5α,8α-epidioxy-24(R)-methylcholesta-6,22-dien-3β-ol, zeorin, and conoideocrellide A, were also isolated from this fungus. Structures of these compounds were elucidated by NMR and MS data analyses. Compound 4 was active against Plasmodium falciparum K1 (IC₅₀ 6.6?μg/mL), while it did not show cytotoxicity. Conoideocrellone A (1) and compounds 3 and 7 exhibited cytotoxic activity, while conoideocin A (18) showed broad range of biological activities including antimalarial, antibacterial, and cytotoxic activities.     

Induced secondary metabolites from the endophytic fungus Aspergillus versicolor through bacterial co-culture and OSMAC approaches

Two new cryptic 3,4-dihydronaphthalen-(2H)-1-one (1-tetralone) derivatives, aspvanicin A (1) and its epimer aspvanicin B (2), as well as several known cryptic metabolites (3–8), were obtained from the ethyl acetate extract of the co-culture of the endophytic fungus Aspergillus versicolor KU258497 with the bacterium Bacillus subtilis 168 trpC2 on solid rice medium. When A. versicolor was cultured axenically in liquid Wickerham medium supplemented with 3.5% DMSO, an additional three known secondary metabolites (9–11) were isolated that were lacking when the fungus was fermented on rice medium. The structures of the new compounds were elucidated using one- and two-dimensional NMR spectroscopy as well as HRESIMS. The relative and absolute configurations of 1 and 2 were determined by the combination of NMR and electronic circular dichroism (ECD) analysis aided by DFT conformational analysis and TDDFT-ECD calculations. The ECD calculations revealed that although the sign of the blue-shifted overlapping n-π¹ ECD transition follows the helicity rule of cyclic aryl ketones, the calculation of low-energy conformers and ECD spectra was necessary to determine the stereochemistry. All metabolites were assessed for their antibacterial and cytotoxic activities; one of the new diastereomers, compound 2, showed moderate cytotoxic activity against the mouse lymphoma cell line L5178Y.     

(+)- and (−)-Eurotone A: A pair of enantiomeric polyketide dimers from a marine-derived fungus Eurotium sp. SCSIO F452

(±)-Eurotone A [(±)-1], a pair of new enantiomeric polyketide dimers, as well as six known biogenetically related polyketides (2–7) were isolated from a marine-derived fungus Eurotium sp. SCSIO F452. Their structures were determined by comprehensive spectroscopic methods, X-ray diffraction and quantum chemical calculations. Compound 1 represented the first pair of spirodihydrobenzanthracene enantiomers isolated from marine fungi with their absolute configurations assigned. A plausible biosynthetic pathway involving a key acid-mediated dimerization was proposed for 1. The antioxidative activities of the new enantiomers were evaluated.     

New bioactive pyrrospirones C−I from a marine-derived fungus Penicillium sp. ZZ380

Seven rare pyrrospirones C?I (1–7) as well as 18 known compounds were isolated from a marine-derived fungus Penicillium sp. ZZ380. Structures of the new pyrrospirones were elucidated by extensive NMR spectroscopic analyses, HRESIMS data, and Mosher's method. Pyrrospirone D (2) was also confirmed by X-ray diffraction analysis. Pyrrospirone G (5) showed potent activity in inhibiting the proliferation of different glioma cells with IC₅₀ values of 1.06–8.52 μM and pyrrospirones C (1), F (4), and I (7) had antimicrobial activity against the growth of both methicillin-resistant Staphylococcus aureus and Escherichia coli with MIC values of 2.0–5.0 μg/mL.     

Chlorinated chromone and diphenyl ether derivatives from the mangrove-derived fungus Pestalotiopsis sp. PSU-MA69

Four new diphenyl ethers, pestalotethers A–D (1–4), three new chromones, pestalochromones A–C (5–7), one new xanthone, pestaloxanthone (8), and one new butenolide, pestalolide (9), together with 11 known compounds were isolated from the mangrove-derived fungus Pestalotiopsis sp. PSU-MA69. Their structures were established by spectroscopic techniques. Compounds 1–3 and 5–7 are the rare chlorinated fungal metabolites of diphenyl ethers and chromones, respectively. Pestalolide (9) displayed weak antifungal activity against Candida albicans and Cryptococcus neoformans.     

Phloroglucinol derivatives and a chromone glucoside from the leaves of Myrtus communis

Seven new phloroglucinol derivatives, myrtucommunins A–D (1–4), 6-methylisomyrtucommulone B (5), 4-methylmyrtucommulone B (6), and 2-isobutyryl-4-methylphloroglucinol 1-O-β-d-glucopyranoside (7), and one new chromone derivative, undulatoside A 6′-O-gallate (8), were isolated from the leaves of Myrtus communis (Myrtaceae). Myrtucommunins A–D (1–4) were conjugates of polymethylated acylphloroglucinol and flavonol rhamnoside. The absolute configurations of the rhamnosyl moieties for 1–4 were confirmed to be l in each case by HPLC analyses, while those of the aglycones were assigned by comparisons of the experimental and TDDFT calculated ECD spectra. 6-Methylisomyrtucommulone B (5) and 4-methylmyrtucommulone B (6) were assigned as 6/6/6 tricyclic acylphloroglucinol derivatives with a racemic nature. Antimicrobial activities of 1–8 and related known compounds were evaluated.     

Streptopyrazinones A−D,rare metabolites from marine-derived Streptomyces sp. ZZ446

Secondary metabolites from marine-associated actinomycetes are important source for the discovery of novel bioactive compounds. In this study, an actinomycete Streptomyces sp. ZZ446 was isolated from coastal soils and different media were used to culture this isolated marine actinomycete. It has been found that this actinomycete in the liquid medium of 2216?E with sea salt produced five new compounds of streptopyrazinones A?D (1–4) and N-acetyl-l-isoleucine-l-leucinamide (5) as well as six known diketopiperazines (6–11) and one alkaloid (12). Structures of the new compounds were determined by extensive NMR analyses, HRESIMS data, electronic circular dichroism (ECD) calculation, chemical degradation, Marfey's method, and X-ray diffraction analysis. This type of streptopyrazinones A?D (1–4) is rarely found in the natural resources. New compounds 1–5 showed activity in inhibiting the growth of Candida albicans and methicillin-resistant Staphylococcus aureus.     

Meroterpenoids with diverse ring systems and dioxolanone-type secondary metabolites from Phyllosticta capitalensis and their phytotoxic activity

Twenty meroterpenoids with diverse ring systems including five new ones (1, 2, 5, 6, and 15), together with two new (23 and 24) and two known dioxolanone-type secondary metabolites were isolated from Phyllosticta capitalensis, an endophytic fungus from Cephalotaxus fortunei Hook. Compound 1 was the first example with a 9,14-seco ring A and a five-membered ring B in guignardone derivatives. Compound 2 represented a novel guignardone derivative possessing a 5/7/6/5 ring system with CH₂-7 attached to C-4 rather than C-6 in ring D. The structures of all new compounds were elucidated using spectroscopic data analyses and electronic circular dichroism comparison. The phytotoxic effects of compounds 1–24 on Lactuca sativa and Lolium perenne were evaluated. Compound 22 showed inhibition activity on the shoots growth of L. sativa and L. perenne, as well as the roots growth of L. perenne.     

Azaphilone and isocoumarin derivatives from the sponge-derived fungus Eupenicillium sp. 6A-9

Three new azaphilones, eupenicilazaphilones A–C (1–3), and one new isocoumarin, eupenicillin A (4), as well as five known azaphilones were isolated from the sponge-derived fungus Eupenicillium sp. 6A-9. Their structures were elucidated by detailed spectroscopic analysis, comparison with literature data, and ¹³C NMR chemical shifts and TDDFT/ECD calculations. The antibacterial activity against Staphylococcus aureus ATCC25923, methicillin-resistant Staphylococcus aureus ATCC4330, and Acinetobacter baumanii ATCC19606 as well as the cytotoxic activity towards human cancer lines MCF-7 and A549 were examined.     

Anti-inflammatory diterpenoids from an endophytic fungus Phomopsis sp. S12

Three new pimarane-type diterpenoids, along with two known compounds, were isolated from an endophytic fungus Phomopsis sp. S12. Their structures were determined by comprehensive analyses of HRESIMS, NMR, CD, as well as single-crystal X-ray diffractions. Compound 3 exhibited anti-inflammatory activity against the production of IL-1β and IL-6 induced by lipopolysaccharide (LPS) in macrophages. A putative biosynthetic pathway for compounds 1–5 were also proposed.     

Indole-benzodiazepine-2,5-dione derivatives from a soil fungus Aspergillus sp. PSU-RSPG185

Six new indole-benzodiazepine-2,5-dione derivatives, asperdiazapinones A–F (1–6), together with three known prenylated indole alkaloids were isolated from the mycelial extract of the soil fungus Aspergillus sp. PSU-RSPG185. Their structures were established by spectroscopic evidence. For compounds 2 and 5, the structures were confirmed by single-crystal X-ray diffraction crystallography. Asperdiazapine B (2) displayed weak antimalarial and noncytotoxic activities.     

Cytotoxic tropolones from the fungus Nemania sp. BCC 30850

Twelve new compounds, including nine tropolones, nemanolones A?I (1–9), three 7-isochromenones, nemanecins A?C (10–12), and a new naturally isolated 4-isochromanone (13), along with two known compounds, 7,8-dihydroxy-3-methyl isochroman-4-one (XJP), and chaetoquadrin F, were isolated from culture broth of the fungus Nemania sp. BCC 30850. Structures of these compounds were elucidated by NMR and MS spectroscopic analyses. Nemanolones exhibited cytotoxic activities and two of them, compounds 1 and 2, also showed antibacterial activity against Bacillus cereus and antifungal activity against Candida albicans.     

Aromatic polyketides from a caterpillar associated Alternaria sp.

Five new aromatic polyketides, alternaphenols A–E (1–5), and two known compounds (6–7) were isolated from a liquid culture of Alternaria sp. (strain no. NF2198), a caterpillar associated fungus. Their structures were determined by extensive spectroscopic analysis and single crystal X-ray crystallography. Compounds 1–7 were evaluated for their cytotoxic activities against a human skin melanoma A-375 cell line. Only compounds 4 and 5 showed weak cytotoxic activities.     

Spiroketals,isocoumarin, and indoleformic acid derivatives from saline soil derived fungus Penicillium raistrickii

Six new compounds, named peneciraistins A–F (1–6), were isolated from saline soil derived fungus Penicillium raistrickii. Among them, compounds 1 and 2 are rare benzannulate 6,6-spitoketals, and compounds 5 and 6 are the first naturally occurring 3-indoleformic acid derivatives. Their structures were elucidated by means of their detailed NMR and MS spectroscopic data. Their absolute configurations were assigned by the modified Mosher method, CD excitation chirality method or optical rotation by comparison with those of known compounds. Their cytotoxicities were also reported against A549 and MCF-7 cell lines along with radical scavenging activities against DPPH (1,1-diphenyl-2-picrylhydrazyl).     

Sinuhirtins A and B,two uncommon norhumulene-type terpenoids from the South China Sea soft coral Sinularia hirta

Two new uncommon norhumulene-type norsesquiterpenoids, namely sinuhirtins A (1) and B (2), along with two known norcaryophyllene-type norsesquiterpenoids (3 and 4), were isolated from the South China Sea soft coral Sinularia hirta. The structures and absolute configurations of the new compounds were determined by extensive spectroscopic data analyses, and computer-assisted methods including GIAO ¹³C NMR and TDDFT-ECD calculations. A plausible biogenetic relationship of 1–4 was proposed.