Griseofulvin enantiomers and bromine-containing griseofulvin derivatives with antifungal activity produced by the mangrove endophytic fungus Nigrospora sp. QQYB1.

Marine microorganisms have long been recognized as potential sources for drug discovery. Griseofulvin was one of the first antifungal natural products and has been used as an antifungal agent for decades. In this study, 12 new griseofulvin derivatives [(±)-1-2, (+)-3, (±)-4, 10-12, and 14-15] and two new griseofulvin natural products (9 and 16) together with six known analogues [(-)-3, 5-8, and 13] were isolated from the mangrove-derived fungus Nigrospora sp. QQYB1 treated with 0.3% NaCl or 2% NaBr in rice solid medium. Their 2D structures and absolute configurations were established by extensive spectroscopic analysis (1D and 2D NMR, HRESIMS), ECD spectra, computational calculation, DP4 + analysis, and X-ray single-crystal diffraction. Compounds 1-4 represent the first griseofulvin enantiomers with four absolute configurations (2S, 6'S; 2R, 6'R; 2S, 6'R; 2R, 6'S), and compounds 9-12 represent the first successful production of brominated griseofulvin derivatives from fungi via the addition of NaBr to the culture medium. In the antifungal assays, compounds 6 and 9 demonstrated significant inhibitory activities against the fungi Colletotrichum truncatum, Microsporum gypseum, and Trichophyton mentagrophyte with inhibition zones varying between 28 and 41 mm (10 µg/disc). The structure-activity relationship (SAR) was analyzed, which showed that substituents at C-6, C-7, C-6' and the positions of the carbonyl and double bond of griseofulvin derivatives significantly affected the antifungal activity. Supplementary Information: The online version contains supplementary material available at 10.1007/s42995-023-00210-0.

4-Hydroxy-2-pyridone derivatives with antitumor activity produced by mangrove endophytic fungus Talaromyces sp. CY-3.

OSMAC strategy is a useful tool for discovering series of metabolites from microorganism. Five new sambutoxin derivatives (1-2, 4, 8-9), together with seven known compounds (3, 5-7, 10-12), were isolated from Talaromyces sp. CY-3 under OSMAC strategy and guidance of molecular networking. Their planar structures and absolute configurations were determined by NMR, HRESIMS, ECD spectra and common biosynthetic pathway. In bioassay, compounds 1-12 showed cytotoxicity to tumor cell lines with IC50 values in the range of 1.76-49.13 µM. The antitumor molecular mechanism of 10 was also explored. In vitro compound 10 significantly inhibited the growth and proliferation of two lung cancer cell lines (A549 and H1703). Furthermore, colony formation, EdU analysis, flow cytometry and Western blot analysis showed that 10 could induce cell cycle arrest in G0/G1 phase by promoting the expression of p53 and p21. The molecular mechanism of its antitumor effects in vitro is that 10 arrests the cell cycle by activating the p21/CyclinD1/Rb signaling pathway and the p53 pathway. Our results identified a lead small molecule compound with efficient antitumor growth and proliferation activity.

Heterologous Biosynthesis of the Sterol O-Acyltransferase Inhibitor Helvamide Unveils an α-Ketoglutarate-Dependent Cross-Linking Oxygenase.

We have identified the biosynthetic gene cluster (hvm) for the sterol O-acyltransferase inhibitor helvamide (1) from the genome of Aspergillus rugulosus MST-FP2007. Heterologous expression of hvm in A. nidulans produced a previously unreported analog helvamide B (5). An α-ketoglutarate-dependent oxygenase Hvm1 was shown to catalyze intramolecular cyclization of 1 to yield 5. The biosynthetic branch to the related hancockiamides and helvamides was found to be controlled by the substrate selectivity of monomodular nonribosomal peptide synthetases.

The Polyketides with Antimicrobial Activities from a Mangrove Endophytic Fungus Trichoderma lentiforme ML-P8-2.

Five new polyketides, including two chromones (1-2), two phenyl derivatives (4-5), and a tandyukusin derivative (6), along with five known polyketides (3 and 7-10) were isolated from mangrove endophytic fungus Trichoderma lentiforme ML-P8-2. The planar structures of compounds were elucidated via detailed 1D, 2D NMR, and HR-ESI-MS analysis. ECD spectra, optical rotation values calculation, and alkali hydrolysis were applied in the determination of the absolute configuration of the new compounds. In bioassays, 6 and 9 exhibited promising antifungal activities against Penicillium italicum, with an MIC value of 6.25 µM for both compounds. Moreover, 3 displayed moderate AChE inhibitory activity with an IC50 value of 20.6 ± 0.3 µM.

Cyclohexenoneterpenes A-J: Cytotoxic meroterpenoids from mangrove-associated fungus Penicillium sp. N-5.

Ten previously undescribed meroterpenoids, cyclohexenoneterpenes A-J (1-7, 18-20), together with 10 known analogues (8-17) were isolated from the mangrove-associated fungus Penicillium sp. N-5. Their structures were elucidated on the basis of extensive spectroscopic and mass spectrometric data. The absolute configurations of the undescribed compounds were assigned by electronic circular dichroism calculations, the modified Mosher's method, NMR calculations and DP4+ analysis. In the bioassay, compounds 10, 11, 15, and 20 exhibited cytotoxicities against SNB-19, MDA-MB-231, MDA-MB-435 and HCT-116 cell lines with IC50 values ranging from 1.4 to 19.1 µM.

Cytosporones W and X: Two Mutually Converting Epimers from a Mangrove Endophytic Fungus Diaporthe sp. ZJHJYZ-1.

Two new octaketides, cytosporones W (1) and X (2), along with eight known cytosporone derivatives [(±)-3-9], were isolated from mangrove endophytic fungus Diaporthe sp. ZJHJYZ-1. Compounds 1 and 2 were a pair of epimers, whose configuration of C-1 could mutually convert, causing racemization of the lactone ring. The planar structures of compounds were elucidated through detailed 1D, 2D NMR, and HR-ESI-MS analysis. ECD spectra comparison and modified Mosher ester method were applied to determine the absolute configuration of 1 and 2. In bioassays, (±)-3 exhibited promising inhibitory activities against Bacillus subtilis, Pseudomonas aeruginosa, and Penicillium italicum with MIC, respectively, for 12.5, 12.5, and 3.13 µM.

Quinolinones Alkaloids with AChE Inhibitory Activity from Mangrove Endophytic Fungus Penicillium citrinum YX-002.

Acetylcholinesterase (AChE) inhibitory activity-guided studies on the mangrove-derived endophytic fungus Penicillium citrinum YX-002 led to the isolation of nine secondary metabolites, including one new quinolinone derivative, quinolactone A (1), a pair of epimers quinolactacin C1 (2) and 3-epi-quinolactacin C1 (3), together with six known analogs (4-9). Their structures were elucidated based on extensive mass spectrometry (MS) and 1D/2D nuclear magnetic resonance (NMR) spectroscopic analyses, and compared with data in the literature. The absolute configurations of compounds 1-3 was determined by combination of electronic circular dichroism (ECD) calculations and X-Ray single crystal diffraction technique using CuKα radiation. In bioassays, compounds 1, 4 and 7 showed moderate AChE inhibitory activities with IC50 values of 27.6, 19.4 and 11.2 µmol/L, respectively. The structure-activity relationships (SARs) analysis suggested that the existence of carbonyl group on C-3 and the oxygen atom on the five-membered ring were beneficial to the activity. Molecular docking results showed that compound 7 had a lower affinity interaction energy (-9.3 kcal/mol) with stronger interactions with different sites in AChE activities, which explained its higher activities.

Plasmodium-Resistant Indole Diterpenoid Biosynthesis Gene Cluster Derived from Aspergillus oryzae Was Activated by Exogenous P450 Gene Ast B.

Synthetic biology is an effective way to activate silent biosynthetic gene clusters. Five new indole diterpenoids (1, 2, 5, 9, and 10), together with 10 known derivatives (3, 4, 6-8, and 11-15) were activated from Aspergillus oryzae transformants by an exogenous P450 gene Ast B and obtained under the guidance of molecular networking. Their planar structures were determined by NMR and HR-ESI-MS. The absolute configuration of compound 1 was determined by single crystal X-ray diffraction, and those of compounds 2, 5 , 9, and 10 were confirmed by comparing the observed ECD with the calculated ECD. HPLC analysis suggested that the BGCs of indole diterpenoids in A. oryzae were activated by exogenous P450 gene Ast B. Compounds 1-4, 7, 8, and 11 displayed strong activity against chloroquine-sensitive plasmodium strain P.f.3D7 with IC50 values ranging from 0.84 to 2.9 µM. It is the first report that indole diterpenoids have potential antimalarial activity. The structure-activity relationship study showed that the linear indole diterpenoids contribute significantly to the antiparasite activity. Molecular docking studies showed that 1 and positive control chloroquine were at the center of the active pocket of PfHsp90, while 11 was far from the active site.

Antioxidative Indenone and Benzophenone Derivatives from the Mangrove-Derived Fungus Cytospora heveae NSHSJ-2.

Seven new polyketides, including four indenone derivatives, cytoindenones A-C (1, 3-4), 3'-methoxycytoindenone A (2), a benzophenone derivative, cytorhizophin J (6), and a pair of tetralone enantiomers, (±)-4,6-dihydroxy-5-methoxy-α-tetralone (7), together with a known compound (5) were obtained from the endophytic fungus Cytospora heveae NSHSJ-2 isolated from the fresh stem of the mangrove plant Sonneratia caseolaris. Compound 3 represented the first natural indenone monomer substituted by two benzene moieties at C-2 and C-3. Their structures were determined by the analysis of 1D and 2D NMR, as well as mass spectroscopic data, and the absolute configurations of (±)-7 were determined on the basis of the observed specific rotation value compared with those of the tetralone derivatives previously reported. In bioactivity assays, compounds 1, 4-6 showed potent DPPH· scavenging activities, with EC50 values ranging from 9.5 to 16.6 µM, better than the positive control ascorbic acid (21.9 µM); compounds 2-3 also exhibited DPPH· scavenging activities comparable to ascorbic acid.

A novel flavonoid and other constituents from Rubus rosifolius S.Vidal (Rosaceae).

Various reports revealed that chemical constituents from many species of Rubus exhibit diverse biological activities. In this study, a novel flavonoid with a 2-(phenanthren-9-yl)-4H-chromen-4-one structure (1), a 5-phenylthiophene-2-carbaldehyde derivative (5) first isolated from a natural source, together with five known compounds including three polyketides (2-4) and two sesquiterpenoids (6-7) were isolated from a traditional Chinese medicine Rubus rosifolius S.Vidal (Rosaceae). The structures of new compounds were elucidated by detailed spectroscopic analysis including NMR and X-ray single-crystal diffraction. The bioassays results indicated that, compound 1 displayed significant cytotoxicity against human colon cancer cell line HCT116 with IC50 value of 8.6 ± 1.9 µM, and compound 5 exhibited moderate cytotoxicity against human breast cancer cell line MDA-MB-435 with IC50 value of 24.1 ± 0.8 µM.

Antiplasmodial Asperterpenoids from Two Aspergillus oryzae Transformants with Heterologous Expression of Sesterterpene Genes.

The synthetic biology approach enables efficient and directional mining of target compounds during drug discovery. Ten new asperterpenoids (6-15) and five known analogues (1-5), possessing a rare 5/7/3/6/5 skeleton, were obtained from two Aspergillus oryzae transformants with heterologous expression of a terpene cyclase gene AstC with one or two P450 genes AstB/A under the guidance of molecular networking. Their planar structures were determined by 1D and 2D NMR and HR-ESI-MS. The absolute configurations of compounds 6 and 9-13 were determined by single crystal X-ray diffraction, and those of compounds 7-8 and 14-15 were compared with the ECD of known compounds. Seven of all the compounds are the first asperterpenoid oxidation products at C-17 or at C-25. In bioassay, compounds 1-2, 4-5, and 6-8 displayed moderate to strong eliminating activities against chloroquine-sensitive strain (P.f.3D7) with EC50 values ranging from 2.1 to 19.3 µM. The structure-activity relationship (SAR) was discussed, which showed that substituents at C-3, C-11, C-17, C-18, and C-23 of asperterpenoids significantly affected anti-plasma parasite activity.

A Pair of Chromone Epimers and an Acetophenone Glucoside from the Mangrove Endophytic Fungus Mycosphaerella sp. L3A1.

Three new compounds, including a pair of chromone derivatives (1-2), and an acetophenone glucoside (3), together with three known compounds (4-6), were isolated from the mangrove endophytic fungus Mycosphaerella sp. L3A1. Their structures were elucidated by HR-ESI-MS analysis and extensive spectroscopic data. The absolute configurations of new compounds were determined using single-crystal X-ray diffraction analysis, electronic circular dichroism (ECD) calculations and chemical hydrolysis. In bioassays, compound 4 showed moderate cytotoxic activity against MDA-MB-435, HCT116, and SNB19 with IC50 values in the range of 18.5-26.29 µM.

Hizikia fusiforme functional oil (HFFO) prevents neuroinflammation and memory deficits evoked by lipopolysaccharide/aluminum trichloride in zebrafish.

Background: Oxidative stress, cholinergic deficiency, and neuroinflammation are hallmarks of most neurodegenerative disorders (NDs). Lipids play an important role in brain development and proper functioning. Marine-derived lipids have shown good memory-improving potentials, especially those from fish and microalgae. The cultivated macroalga Hizikia fusiforme is healthy food and shows benefits to memory, but the study is rare on the brain healthy value of its oil. Previously, we had reported that the Hizikia fusiforme functional oil (HFFO) contains arachidonic acid, 11,14,17-eicosatrienoic acid, phytol, and other molecules displaying in vitro acetylcholinesterase inhibitory and nitroxide scavenging activity; however, the in vivo effect remains unclear. In this study, we further investigated its potential effects against lipopolysaccharides (LPS)- or aluminum trichloride (AlCl3)-induced memory deficiency in zebrafish and its drug-related properties in silica. Methods: We established memory deficit models in zebrafish by intraperitoneal (i.p.) injection of lipopolysaccharides (LPS) (75 ng) or aluminum trichloride (AlCl3) (21 µg), and assessed their behaviors in the T-maze test. The interleukin-1ß (IL-1ß), tumor necrosis factor-α (TNF-α), acetylcholine (ACh), and malondialdehyde (MDA) levels were measured 24 h after the LPS/AlCl3 injection as markers of inflammation, cholinergic activity, and oxidative stress. Furthermore, the interaction of two main components, 11,14,17-eicosatrienoic acid and phytol, was investigated by molecular docking, with the important anti-inflammatory targets nuclear factor kappa B (NF-κB) and cyclooxygenase 2 (COX-2). Specifically, the absorption, distribution, metabolism, excretion, and toxicity (ADMET) and drug-likeness properties of HFFO were studied by ADMETlab. Results: The results showed that HFFO reduced cognitive deficits in zebrafish T-maze induced by LPS/AlCl3. While the LPS/AlCl3 treatment increased MDA content, lowered ACh levels in the zebrafish brain, and elevated levels of central and peripheral proinflammatory cytokines, these effects were reversed by 100 mg/kg HFFO except for MDA. Moreover, 11,14,17-eicosatrienoic acid and phytol showed a good affinity with NF-κB, COX-2, and HFFO exhibited acceptable drug-likeness and ADMET profiles in general. Conclusion: Collectively, this study's findings suggest HFFO as a potent neuroprotectant, potentially valuable for the prevention of memory impairment caused by cholinergic deficiency and neuroinflammation.

Hemiacetalmeroterpenoids A-C and Astellolide Q with Antimicrobial Activity from the Marine-Derived Fungus Penicillium sp. N-5.

Four new compounds including three andrastin-type meroterpenoids hemiacetalmeroterpenoids A-C (1-3), and a drimane sesquiterpenoid astellolide Q (15), together with eleven known compounds (4-14) were isolated from the cultures of the marine-derived fungus Penicillium sp. N-5, while compound 14 was first isolated from a natural source. The structures of the new compounds were determined by analysis of detailed spectroscopic data, and the absolute configurations were further decided by a comparison of the experimental and calculated ECD spectra. Hemiacetalmeroterpenoid A (1) possesses a unique and highly congested 6,6,6,6,5,5-hexa-cyclic skeleton. Moreover, the absolute configuration of compound 14 was also reported for the first time. Compounds 1, 5 and 10 exhibited significant antimicrobial activities against Penicillium italicum and Colletrichum gloeosporioides with MIC values ranging from 1.56 to 6.25 µg/mL.

Pyrone Derivatives from a Mangrove Endophytic Fungus Phomopsis†asparagi LSLYZ-87.

Chemical investigation of the endophytic fungus Phomopsis asparagi LSLYZ-87 cultured on PDB medium led to the isolation of two new pyrone derivatives, phomasparapyrone A (1), and phomasparapyrone B (2), together with the known kojic acid (3). Their planar structures were connected through 1D and 2D NMR spectroscopic data. And the stereo structures of 1 and 2 were defined by comparison of the experimental ECD spectra to calculated one. All isolates were evaluated for their anti-neuroinflammatory activities. Among them, compound 2 showed moderate inhibition on NO accumulation induced by LPS on BV-2 cells in a dose dependent manner at 30, 40 and 50 µM, and without cytotoxicity in a concentration of 50.0 µM.

Two Antimicrobial Heterodimeric Tetrahydroxanthones with a 7,7'-Linkage from Mangrove Endophytic Fungus Aspergillus flavus QQYZ.

Mangrove endophytic fungi represent significant and sustainable sources of novel metabolites with unique structures and excellent biological activities, attracting extensive chemical investigations. In this research, two novel heterodimeric tetrahydroxanthones, aflaxanthones A (1) and B (2), dimerized via an unprecedented 7,7'-linkage, a sp3-sp3 dimeric manner, were isolated from the mangrove endophytic fungus Aspergillus flavus QQYZ. Their structures were elucidated through high resolution electrospray ionization mass spectroscopy (HRESIMS) and nuclear magnetic resonance (NMR) spectroscopy, the absolute configurations of them were determined by a single-crystal X-ray diffraction combined with calculated electronic circular dichroism (ECD) spectra and a 1D potential energy scan. These compounds were evaluated for antifungal activities in vitro and exhibited broad-spectrum and potential antifungal activities against several pathogenic fungi with minimum inhibitory concentration (MIC) values in the range of 3.13-50 µM. They also performed moderate antibacterial activities against several bacteria with MIC values in the range of 12.5-25 µM. This research enriched the resources of lead compounds and templates for marine-derived antimicrobial drugs.

Cytotoxic Bromine- and Iodine-Containing Cytochalasins Produced by the Mangrove Endophytic Fungus Phomopsis sp. QYM-13 Using the OSMAC Approach.

Twelve new cytochalasins, phomopchalasins D-O (1-3, 5-12, and 14), including one brominated (2) and two iodinated cytochalasins (3 and 6), together with six known analogues (4, 13, and 15-18) were isolated from the mangrove-derived fungus Phomopsis sp. QYM-13 treated with 3% NaBr or 3% KI in potato liquid medium. Their structures and absolute configurations were established by extensive spectroscopic analysis (1D and 2D NMR, HRESIMS), electronic circular dichroism calculations, and a single-crystal X-ray diffraction experiment. Compounds 3 and 6 represent the first iodinated cytochalasins. Compounds 2, 15, 17, and 18 exhibited significant cytotoxicity against human cancer cell line MDA-MB-435 with IC50 values ranging from 0.2 to 8.2 µM.

Azaphilone derivatives with anti-inflammatory activity from the mangrove endophytic fungus Penicillium sclerotiorum ZJHJJ-18.

Nine undescribed azaphilone derivatives, sclerazaphilones A-H (1-9), and three known analogues (10-12), were obtained and identified from the fermented rice cultures of a mangrove endophytic fungus Penicillium sclerotiorum ZJHJJ-18. 1D and 2D NMR, HRESIMS and spectral data indicated the chemical structures of 1-9, and their absolute configurations were assigned by experimental and computational analyses of electronic circular dichroism (ECD) spectra, and application of the chemical transformations. Compounds 1-4 were the first reported N-containing azaphilone derivatives with 5/6 dicyclic core. The bioassay results showed that compounds 3-5 exhibited effective inhibitory effects on the nitric oxide (NO) production in lipopolysaccharide (LPS)-induced RAW264.7 macrophage cells with IC50 values in the range of 6.30-9.45 µM. Moreover, a molecular docking study was conducted to investigate the probable binding interaction of 3-5 with inducible nitric oxide synthase (iNOS).

Metabolites With Cytotoxic Activities From the Mangrove Endophytic Fungus Fusarium sp. 2ST2.

Two new 3-decalinoyltetramic acid derivatives with peroxide bridge fusarisetins E (1) and F (2), one new chromone fusarimone A (5), two new benzofurans fusarifurans A (9) and B (10), three new isocoumarins fusarimarins A-C (11-13), as well as five known analogues 3, 4, 6-8 and 14 were isolated from mangrove endophytic fungus Fusarium sp. 2ST2. Their structures and absolute configurations were established by spectroscopic analysis, density functional theory-gauge invariant atomic orbital NMR calculation with DP4+ statistical analysis, and electronic circular dichroism calculation. Compounds 1 and 2 showed significant cytotoxicity against human A549 cell lines with IC50 values of 8.7 and 4.3 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.