Chemical structures, biological activities, and biosynthetic analysis of secondary metabolites of the Diatrypaceae family: A comprehensive review

The family Diatrypaceae is a less well-known group within the order Xylariales (Ascomycota). Initially, the focus on its metabolites was related to the pathogenicity of one of its members, Eutypa lata. To date, a total of 254 natural products have been identified from Diatrypaceae strains. These compounds include terpenoids, sterols, polyketones, phenols, and acetylene aromatic compounds, which have shown anticancer, cytotoxic, anti-inflammatory, antimicrobial, and antiviral activities. The complex and diverse structural types, along with the diverse bioactivities, highlight the potential of Diatrypaceae as a valuable source of bioactive natural products. In this review, a deep analysis of the biosynthesis of pimarane diterpenes and scoparasin-type cytochalasins is provided, coupled with a compilation of the biosynthetic pathways of aromatic acetylene compounds in filamentous fungi. This comprehensive review not only enhances our understanding of the natural product chemistry, biological activities, and biosynthesis of secondary metabolites from the Diatrypaceae family but also promotes the exploitation and development of important bioactive compounds and potential strains.

Novel 6/7/6 ring system diterpenoids and cytochalasins from the fungus Eutypella scoparia GZU-4-19Y and their anti-inflammatory activity

Two new compounds eutyditerpenoid A (1) and seco-phenochalasin B (5), together with seven known compounds diaporthein A (2), aspergillon A (3), phenochalasin B (4), cytochalasins Z24 and Z25 (6 and 7), scoparasins A and B (8 and 9) were isolated from marine-derived Eutypella scoparia GZU-4-19Y. Among them, eutyditerpenoid A (1) with a rare 6/7/6 ring system possesing an anhydride moiety was the first example in the pimarane-type diterpenoids. Their structures were determined based on spectroscopic methods and the electronic circular dichroism (ECD) calculations. In the bioassays, all of the isolates were evaluated for their inhibitory activity against NO production induced by lipopolysaccharide in RAW 264.7 cells. Compounds 3 and 7 showed potent NO inhibition activity with IC50 values of 2.1 and 17.1 μM respectively, and the former also significantly suppressed the protein expression of iNOS and COX-2 at the concentration of 2.5 μM.

Rapid Discovery of Substances with Anticancer Potential from Marine Fungi Based on a One Strain-Many Compounds Strategy and UPLC-QTOF-MS

The secondary metabolites of marine fungi with rich chemical diversity and biological activity are an important and exciting target for natural product research. This study aimed to investigate the fungal community in Quanzhou Bay, Fujian, and identified 28 strains of marine fungi. A total of 28 strains of marine fungi were screened for small-scale fermentation by the OSMAC (One Strain-Many Compounds) strategy, and 77 EtOAc crude extracts were obtained and assayed for cancer cell inhibition rate. A total of six strains of marine fungi (P-WZ-2, P-WZ-3-2, P-WZ-4, P-WZ-5, P56, and P341) with significant changes in cancer cell inhibition induced by the OSMAC strategy were analysed by UPLC-QTOF-MS. The ACD/MS Structure ID Suite software was used to predict the possible structures with inhibitory effects on cancer cells. A total of 23 compounds were identified, of which 10 compounds have been reported to have potential anticancer activity or cytotoxicity. In this study, the OSMAC strategy was combined with an untargeted metabolomics approach based on UPLC-QTOF-MS to efficiently analyse the effect of changes in culture conditions on anticancer potentials and to rapidly find active substances that inhibit cancer cell growth.

Pimarane-Type Diterpenes with Anti-Inflammatory Activity from Arctic-Derived Fungus Eutypella sp. D-1

The Arctic-derived fungus Eutypella sp. D-1 can produce numerous secondary metabolites, and some compounds exhibit excellent biological activity. Seven pimarane-type diterpenes, including three new compounds eutypellenone F (1), libertellenone Y (2), and libertellenone Z (3), and four known compounds (4-7), were isolated from fermentation broth of Eutypella sp. D-1 by the OSMAC strategy of adding ethanol as a promoter in the culture medium. Compound 2 has a rare tetrahydrofuran-fused pimarane diterpene skeleton. The anti-inflammatory activity of all compounds was evaluated. Compounds 3-6 showed a significant inhibitory effect on cell NO release at 10 μmol/L by in vitro experiments, of which 3-5 had inhibitory rates over 60% on nitric oxide (NO) release. Subsequently, the anti-inflammatory activity of 3-5 was evaluated based on a zebrafish model, and the results showed that 3 had a significant inhibitory effect on inflammatory cells migration at 40 μmol/L, while 4 and 5 had a significant inhibitory effect at 20 μmol/L. Moreover, compounds 3-5 have the same conjugated double bond structure, which may be an important group for these compounds to exert anti-inflammatory activity.

Pimarane Diterpenes from Fungi

Pimarane diterpenes are a kind of tricyclic diterpene, generally isolated from plant and fungi. In nature, fungi distribute widely and there are nearly two to three million species. They provide many secondary metabolites, including pimarane diterpenes, with novel skeletons and bioactivities. These natural products from fungi have the potential to be developed into clinical medicines. Herein, the structures and bioactivities of 197 pimarane diterpenes are summarized and the biosynthesis and pharmacological researches of pimarane diterpenes are introduced. This review may be useful improving the understanding of pimarane diterpenes from fungi.

The Mangrove-Derived Diterpenoid Diaporthe B Inhibits the Stemness and Increases the Efficacy of Docetaxel in Prostate Cancer PC-3 Cells

The absolute configuration of diaporthe B, a pimarane diterpene isolated from the mangrove derived endophytic fungus Eutypella sp #3E, was determined by a single-crystal x-ray diffraction study. The present study aimed to investigate the effects of diaporthe B on docetaxel-resistant prostate cancer PC-3 cells. Results of our studies showed that docetaxel-resistant PC-3 cells had higher sphere-forming efficiency and an increase in adherence to collagen-coated culture plates. The protein levels of cancer stem cell (CSC)-related markers CD44, CD133, and ALDH1A1 were higher in the docetaxel-resistant PC-3 cells than in the parental cells. Treatment with diaporthe B dose-dependently inhibited the growth and induced apoptosis in the resistant cells. Moreover, diaporthe B treatment decreased the sphere-forming efficiency and the adherence to collagen-coated plates in docetaxel-resistant PC-3 cells. Diaporthe B also decreased the protein levels of CSC-related markers CD44, CD133, and ALDH1A1 in the resistant cells. In addition, a combination of diaporthe B and docetaxel had a more potent effect on growth inhibition and apoptosis in the resistant cells than either agent alone. Our studies suggest that diaporthe B inhibits the stemness of prostate cancer cells and may have therapeutic potential for enhancing the efficacy of docetaxel in docetaxel-resistant prostate cancer cells.

Sesquiterpenes and Steroids from an Endophytic Eutypella scoparia

A chemical investigation on the EtOAc extract of the endophytic fungus Eutypella scoparia SCBG-8 led to the isolation of eight new sesquiterpenes eutyscoparins A-H (1-8), one C-28 steroid eutyscoparene A (9), one triterpenoid eutyscoparene B (10), six known terpenoids, and two known steroids. Their structures including absolute configurations were established on the basis of spectroscopic data analysis, single-crystal X-ray diffraction experiments, and electronic circular dichroism (ECD) calculations. Compound 7 displayed antibacterial activity against S. aureus and MRSA (methicillin-resistant Staphylococcus aureus) with MIC values of 6.3 μg/mL.

The first demonstration of a novel isolated fungus Eutypella sp. BJ associated with the biodegradation of polyvinyl alcohol

The aim of this work is to study the potential degradation of polyvinyl alcohol (PVA) by a novel fungus Eutypella sp. BJ isolated from soil compost. When it was cultured on a semi-synthetic medium containing PVA at 30 °C and 160 rpm for 8 days, the removal rates of PVA 1788, 1799 and 2488 reached 87.40%, 86.31% and 44.80%, respectively. Gel permeation chromatography (GPC) analysis revealed significant reductions of the number average molecular weight and the weight average molecular weight of PVA 1788 from 47 358 to 13 345 and from 71 387 to 24 238, respectively, after 8 days. Fourier transform infrared spectroscopy (FTIR) indicated that some substances containing carbonyl groups (likely aldehydes or ketones) might have been produced during the biodegradation process. These results indicate that the isolate has potential for degrading PVA. This study provides the first demonstration that Eutypella has the ability to assimilate PVA.

An isolated fungus Eutypella sp. BJ is firstly demonstrated to have the ability to degrade polyvinyl alcohol.

Seven new guanacastane-type diterpenoids from the fungus Verticillium dahliae

Seven new guanacastane-type diterpenoids, namely dahlianes E-K (1-7), and three known ones (8-10) were isolated from the cultures of the fungus Verticillium dahliae. Their structures were established by extensive spectroscopic data analysis along with Rh₂(OCOCF₃)₄- and Mo₂(OAc)₄-induced electronic circular dichroism (ECD) experiment. Dahliane G showed an 80-fold potentiation effect on the sensitization of doxorubicin at the concentration of 15 μM when screening the reversal activity on doxorubicin-resistant human breast cancer cells (MCF-7/DOX).

Bioactive Pimarane Diterpenes from the Arctic Fungus Eutypella sp. D-1

Two new pimarane diterpenes, libertellenone M (1) and libertellenone N (2), together with five known compounds were isolated from the culture extract of Eutypella sp. D-1 derived from high-latitude soil of the Arctic. The structures of these compounds were determined by spectroscopic data as well as experimental and calculated electronic circular dichroism (ECD) analysis. Antimicrobial and cytotoxic activities of the isolated compounds were evaluated. Compound 3 exhibited weak antibacterial activity against Escherichia coli, Bacillus subtilis, and Vibrio vulnificus, each with MIC values of 16 μg/mL. Compounds 2 and 3 showed moderate cytotoxic activity against K562 and MCF-7 cell lines with IC₅₀ values of 7.67 and 9.57 μm, respectively.

Eutypellazines A–M, thiodiketopiperazine-type alkaloids from deep sea derived fungus Eutypella sp. MCCC 3A00281

Bioassay and NMR/MS guided fractionation resulted in the isolation of 13 new alkaloids from marine fungus Eutypella sp.

A new compound from an endophytic fungus Bambusicola massarinia

One new chromone, rel-(1S,2S,3S)-2,8-dihydroxy-6-methoxy-1,3-dimethyl-3,4-dihydro-1H-xanthen-9(2H)-one (1), together with one known compound wentiquinone A (2), were isolated from solid culture of endophytic fungus strain Bambusicola massarinia. The structures of all compounds were determined mainly by analysis of their NMR spectroscopic data. The relative configuration of compound 1 was determined by the single-crystal X-ray diffraction analyses.

Fungal vincristine from Eutypella spp - CrP14 isolated from Catharanthus roseus induces apoptosis in human squamous carcinoma cell line -A431

BACKGROUND

Catharanthus roseus, a medicinal plant, is known to produce secondary metabolites, vincristine and vinblastine, which are terpenoid indole alkaloids. Previously we have reported that Eutypella spp - CrP14 isolated from stem cutting of this plant had shown significant antiproliferative activity when tested in vitro against HeLa cell line. The present study was conducted to identify the anticancer compound responsible for the anti-proliferative activity of the fungal extract and to evaluate its in vitro anticancer and apoptotic effects.

METHODS

The anti-proliferative activity of the fungal anticancer compound, vincristine was analyzed by MTT assay against different cancer cell lines. We examined its efficacy of apoptotic induction on A431 cells. The parameters examined included cell cycle distribution, loss of mitochondrial membrane potential (MMP), DNA fragmentation and reactive oxygen species (ROS) generation.

RESULTS

The presence of vincristine in fungal culture filtrate was confirmed through chromatographic and spectroscopic analyses, and the amount was estimated to be 53 ± 5.0 μg/l. The partially purified fungal vincristine had strong cytotoxic activity towards human squamous carcinoma cells - A431 in the MTT assay. Furthermore, we showed that the fungal vincristine was capable of inducing apoptosis in A431 cells through generation of reactive oxygen species and activation of the intrinsic pathway leading to loss of MMP.

CONCLUSIONS

We have demonstrated for the first time that the vincristine from Eutypella spp - CrP14 is an efficient inducer of apoptosis in A431 cells, meriting its further evaluation in vivo.

Eutypenoids A-C: Novel Pimarane Diterpenoids from the Arctic Fungus Eutypella sp. D-1

Eutypenoids A-C (1-3), pimarane diterpenoid alkaloid and two ring A rearranged pimarane diterpenoids, were isolated from the culture of Eutypella sp. D-1 obtained from high-latitude soil of the Arctic. Their structures, including absolute configurations, were authenticated on the basis of the mass spectroscopy (MS), nuclear magnetic resonance (NMR), X-ray crystallography, and electronic circular dichroism (ECD) analysis. The immunosuppressive effects of eutypenoids A-C (1-3) were studied using a ConA-induced splenocyte proliferation model, which suggested that 2 exhibited potent immunosuppressive activities.

Pimarane diterpenes from the Arctic fungus Eutypella sp. D-1

Two new diterpenes, libertellenone G(1) and libertellenone H(2) were isolated from the fungus Eutypella sp. D-1 isolated from the soil of high latitude of Arctic, together with two known pimarane diterpenes (3-4). The structures of 1 and 2 were elucidated from spectroscopic data (nuclear magnetic resonance, mass spectrometry and infrared). These compounds were evaluated for cytotoxic activity against seven human tumor cell lines. Compound 2 showed a range of cytotoxicity between 3.31 and 44.1 μM. Compound 1 exhibited antibacterial activity against Escherichia coli, Bacillus subtilis and Staphylococcus aureus.

Scopararanes C-G: new oxygenated pimarane diterpenes from the marine sediment-derived fungus Eutypella scoparia FS26

Five new oxygenated pimarane diterpenes, named scopararanes C–G (1–5) were isolated from the culture of a marine sediment-derived fungus Eutypella scoparia FS26 obtained from the South China Sea. The structures of these compounds were established on the basis of extensive spectroscopic analysis. The absolute configurations of compounds 1–5, were determined by CD spectroscopic analysis and comparison with literature data. All isolated compounds (1–5) were evaluated for their cytotoxic activities against MCF-7, NCI-H460, and SF-268 tumor cell lines by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) method.