Meroterpenoid and diphenyl ether derivatives from Penicillium sp. MA-37, a fungus isolated from marine mangrove rhizospheric soil

Penicillides from Penicillium and Talaromyces: Chemical Structures, Occurrence and Bioactivities

Penicillide is the founder product of a class of natural products of fungal origin. Although this compound and its analogues have been identified from taxonomically heterogeneous fungi, they are most frequently and typically reported from the species of Talaromyces and Penicillium. The producing strains have been isolated in various ecological contexts, with a notable proportion of endophytes. The occurrence of penicillides in these plant associates may be indicative of a possible role in defensive mutualism based on their bioactive properties, which are also reviewed in this paper. The interesting finding of penicillides in fruits and seeds of Phyllanthus emblica is introductory to a new ground of investigation in view of assessing whether they are produced by the plant directly or as a result of the biosynthetic capacities of some endophytic associates.

Chemistry and biology of marine-derived Trichoderma metabolites

Marine-derived fungi of the genus Trichoderma have been surveyed for pharmaceuticals and agrochemicals since 1993, with various new secondary metabolites being characterized from the strains of marine animal, plant, sediment, and water origin. Chemical structures and biological activities of these metabolites are comprehensively reviewed herein up to the end of 2022 (covering 30 years). More than 70 strains that belong to at least 18 known Trichoderma species have been chemically investigated during this period. As a result, 445 new metabolites, including terpenes, steroids, polyketides, peptides, alkaloids, and others, have been identified, with over a half possessing antimicroalgal, zooplankton-toxic, antibacterial, antifungal, cytotoxic, anti-inflammatory, and other activities. The research is highlighted by the molecular diversity and antimicroalgal potency of terpenes and steroids. In addition, metabolic relevance along with co-culture induction in the production of new compounds is also concluded. Trichoderma strains of marine origin can transform and degrade heterogeneous molecules, but these functions need further exploration.

High hydrostatic pressure harnesses the biosynthesis of secondary metabolites via the regulation of polyketide synthesis genes of hadal sediment-derived fungi

Deep-sea fungi have evolved extreme environmental adaptation and possess huge biosynthetic potential of bioactive compounds. However, not much is known about the biosynthesis and regulation of secondary metabolites of deep-sea fungi under extreme environments. Here, we presented the isolation of 15 individual fungal strains from the sediments of the Mariana Trench, which were identified by internal transcribed spacer (ITS) sequence analysis as belonging to 8 different fungal species. High hydrostatic pressure (HHP) assays were performed to identify the piezo-tolerance of the hadal fungi. Among these fungi, Aspergillus sydowii SYX6 was selected as the representative due to the excellent tolerance of HHP and biosynthetic potential of antimicrobial compounds. Vegetative growth and sporulation of A. sydowii SYX6 were affected by HHP. Natural product analysis with different pressure conditions was also performed. Based on bioactivity-guided fractionation, diorcinol was purified and characterized as the bioactive compound, showing significant antimicrobial and antitumor activity. The core functional gene associated with the biosynthetic gene cluster (BGC) of diorcinol was identified in A. sydowii SYX6, named as AspksD. The expression of AspksD was apparently regulated by the HHP treatment, correlated with the regulation of diorcinol production. Based on the effect of the HHP tested here, high pressure affected the fungal development and metabolite production, as well as the expression level of biosynthetic genes which revealed the adaptive relationship between the metabolic pathway and the high-pressure environment at the molecular level.

The Chemical Space of Marine Antibacterials: Diphenyl Ethers, Benzophenones, Xanthones, and Anthraquinones

The emergence of multiresistant bacteria and the shortage of antibacterials in the drug pipeline creates the need to search for novel agents. Evolution drives the optimization of the structure of marine natural products to act as antibacterial agents. Polyketides are a vast and structurally diverse family of compounds that have been isolated from different marine microorganisms. Within the different polyketides, benzophenones, diphenyl ethers, anthraquinones, and xanthones have shown promising antibacterial activity. In this work, a dataset of 246 marine polyketides has been identified. In order to characterize the chemical space occupied by these marine polyketides, molecular descriptors and fingerprints were calculated. Molecular descriptors were analyzed according to the scaffold, and principal component analysis was performed to identify the relationships among the different descriptors. Generally, the identified marine polyketides are unsaturated, water-insoluble compounds. Among the different polyketides, diphenyl ethers tend to be more lipophilic and non-polar than the remaining classes. Molecular fingerprints were used to group the polyketides according to their molecular similarity into clusters. A total of 76 clusters were obtained, with a loose threshold for the Butina clustering algorithm, highlighting the large structural diversity of the marine polyketides. The large structural diversity was also evidenced by the visualization trees map assembled using the tree map (TMAP) unsupervised machine-learning method. The available antibacterial activity data were examined in terms of bacterial strains, and the activity data were used to rank the compounds according to their antibacterial potential. This potential ranking was used to identify the most promising compounds (four compounds) which can inspire the development of new structural analogs with better potency and absorption, distribution, metabolism, excretion, and toxicity (ADMET) properties.

Polyketides with antimicrobial activities from Penicillium canescens DJJ-1

Two undescribed polyketides canecines A-B, one unreported cyclopentenone canecine C, together with 12 known compounds were isolated from an extract of the fungus Penicillium canescens DJJ-1. Their structures were elucidated by detailed analysis of spectroscopic data, NMR calculations with dJ-DP4 or DP4+, and their absolute configurations were further determined by quantum chemical calculations of ECD spectra or X-crystallography. Canecine A was a grisan polyketide featuring a dimethyltetrahydro-4H-furo[2,3-b]pyran. Canecine A exhibited significant inhibitory activity against Candida albicans with an MIC value of 1 μg/mL and showed inhibitory effect on nitric oxide production in LPS-activated RAW264.7 macrophages. These results enrich the structural diversities of polyketides from endophytic fungi.

Microwave-Assisted Cu-Catalyzed Diaryletherification for Facile Synthesis of Bioactive Prenylated Diresorcinols

Prenylated diresorcinols exhibit various bioactivities, including cytotoxic, antibacterial, and antifungal activities. Therefore, establishing facile and efficient synthetic routes for prenylated diresorcinols facilitates their development as chemical probes or drugs with a novel mode of action. In this study, microwave-assisted copper catalysis was explored as a cost-effective and environmentally friendly method for the cross-coupling of sterically hindered ortho-prenylated phenols and aryl halides to produce bioactive prenylated diresorcinols, diorcinol I and leotiomycene B. Notable advantages of microwave-assisted catalysis include not only operational simplicity and rapid heating but also shorter reaction times and higher chemical yields. In addition, highly regioselective prenylation of phenol was achieved for the preparation of ortho-prenyl phenol via directed lithiation and subsequent alkylation. This study provides valuable insights for the preparation of other bioactive prenylated diresorcinols. Furthermore, considering that prenylated benzenoids are biosynthetic precursors of various polycyclic natural products, this synthetic route could be expanded to more complex bioactive compounds possessing diaryl ethers.

The Novel Compounds with Biological Activity Derived from Soil Fungi in the Past Decade

The secondary metabolites isolated from soil fungi have received more and more attention, especially new compounds that exhibited good biological activities. In this review, a total of 546 new compounds are included in the relevant literature since 2011. The new compounds are isolated from soil fungi, We divided these compounds into seven categories, including alkaloids, terpenoids, steroids, ketones, phenylpropanoids, quinones, esters, lactones, etc. In addition, the biological activities and structure-activity relationships of these compounds have also been fully discussed. The activities of these compounds are roughly divided into eight categories, including anticancer activity, antimicrobial activity, anti-inflammatory activity, antioxidant activity, antiviral activity, antimalarial activity, immunosuppressive activity and other activities. Since natural products are an important source of new drugs, this review may have a positive guiding effect on drug screening.

Undescribed diphenyl ethers betaethrins A-I from a desert plant endophytic strain of the fungus Phoma betae A.B. Frank (Didymellaceae)

Ten diphenyl ethers (DPEs), including nine undescribed analogs named betaethrins A-I, were isolated from the desert plant endophytic fungus Phoma betae A.B. Frank (Didymellaceae). Their structures were determined mainly by NMR, HR-ESI-MS spectral and X-ray diffraction experiments. Betaethrins D-I possessed different fatty acid chains connected with the B-ring, which was the first report in all DPEs. The shielding effect of the B-ring on H-6 (A-ring) in methyl barceloneate, betaethrin A and betaethrins D-F (asterric acid analogs) was first observed and analyzed, which could differentiate the ¹H-NMR chemical shift values of H-4/H-6 without the assistance of 3-OH. An empirical rule was then suggested: the steric hindrance between the A- and B-rings in asterric acid analogs might prevent these two aromatic rings from rotating freely, which led to the ¹H-NMR chemical shift value of H-6 being in the high field zone due to the shielding effect of the B-ring on H-6. Based on the empirical rule, the chemical shift values of the A-ring in methyl barceloneate were revised. The possible biosynthesis of these isolates was postulated. Betaethrin H showed moderate cytotoxicity against MCF-7 and HepG2 cancer cell lines. Betaethrins A-F, H and I displayed strong antioxidant activities. These results further implied that endophytic fungi from unique environments, such as desert plants, with few chemical studies are an important resource of undescribed and bioactive metabolites.

Two New Nor-seco-Isodhilarane-Type Meroterpenoids from the Endophytic Fungus Penicillium purpurogenum

Two new nor-seco isodhilarane meroterpenoids (NSIMs), purpurogenolides F (1) and G (2), along with three known meroterpenoid analogs (3-5), were isolated from the cultures of an endophytic fungus, Penicillium purpurogenum. Structures and absolute configurations of the new NSIMs were determined based on extensive spectroscopic data analyses, including HR-ESI-MS, UV, IR, NMR chemical shift calculations together with DP4+ probability analysis, as well as ECD calculations. All the isolated meroterpenoids were assessed for their anti-inflammatory activities, and compound 4 exhibited moderate inhibitory activity against the nitric oxide (NO) production in lipopolysaccharide (LPS) induced RAW 264.7 cells with an IC₅₀ value of 20.85±2.31 μM.

Natural products from mangrove sediments-derived microbes: Structural diversity, bioactivities, biosynthesis, and total synthesis

The mangrove forests are a complex ecosystem, and the microbial communities in mangrove sediments play a critical role in the biogeochemical cycles of mangrove ecosystems. Mangrove sediments-derived microbes (MSM), as a rich reservoir of natural product diversity, could be utilized in the exploration of new antibiotics or drugs. To understand the structural diversity and bioactivities of the metabolites of MSM, this review for the first time provides a comprehensive overview of 519 natural products isolated from MSM with their bioactivities, up to 2021. Most of the structural types of these compounds are alkaloids, lactones, xanthones, quinones, terpenoids, and steroids. Among them, 210 compounds are obtained from bacteria, most of which are from Streptomyces, while 309 compounds are from fungus, especially genus Aspergillus and Penicillium. The pharmacological mechanisms of some representative lead compounds are well studied, revealing that they have important medicinal potentials, such as piericidins with anti-renal cell cancer effects, azalomycins with anti-MRSA activities, and ophiobolins as antineoplastic agents. The biosynthetic pathways of representative natural products from MSM have also been summarized, especially ikarugamycin, piericidins, divergolides, and azalomycins. In addition, the total synthetic strategies of representative secondary metabolites from MSM are also reviewed, such as piericidin A and borrelidin. This review provides an important reference for the research status of natural products isolated from MSM and the lead compounds worthy of further development, and reveals that MSM have important medicinal values and are worthy of further development.

Seco and Nor-seco Isodhilarane-Type Meroterpenoids from Penicillium purpurogenum and the Configuration Revisions of Related Compounds

Seco and nor-seco isodhilarane-type meroterpenoids (SIMs and NSIMs) are mainly found in Penicillium fungi and have been characterized by highly congested polycyclic skeletons and a broad range of bioactivities. However, the literature reports inconsistent configuration assignments for some SIMs and NSIMs, due to their complex polycyclic systems and multichiral centers. Herein, we described eight SIMs and NSIMs isolated from the EtOAc extract of Penicillium purpurogenum, which led to the configuration revisions of purpurogenolide C (1a), berkeleyacetal B (2a), chrysogenolide F (3a), and berkeleyacetal C (4a) as compounds 1-4, respectively. Furthermore, extensive re-evaluation of the experimental and computational ¹³C NMR chemical shifts of the reported 39 SIMs and NSIMs provided an empirical approach for determining the C-9 relative configuration, according to the ¹³C NMR chemical shifts of C-9, which contributed to the configuration revisions of another three SIMs (5a and 6a) and NSIMs (7a), denoted as compounds 5-7, respectively. Biological assays indicated that compound 3 exhibited cytotoxic activity against HepG2 and A549 cell lines with IC₅₀ values of 5.58 and 6.80 μM, respectively. Compounds 2-4, 8, 9, and 32 showed moderate hepatoprotective activity at 10 μM in the APAP-induced HepG2 cell injury model.

Secondary metabolites from mangrove-associated fungi: source, chemistry and bioactivities

Covering 1989 to 2020The mangrove forests are a complex ecosystem occurring at tropical and subtropical intertidal estuarine zones and nourish a diverse group of microorganisms including fungi, actinomycetes, bacteria, cyanobacteria, algae, and protozoa. Among the mangrove microbial community, mangrove associated fungi, as the second-largest ecological group of the marine fungi, not only play an essential role in creating and maintaining this biosphere but also represent a rich source of structurally unique and diverse bioactive secondary metabolites, attracting significant attention of organic chemists and pharmacologists. This review summarizes the discovery relating to the source and characteristics of metabolic products isolated from mangrove-associated fungi over the past thirty years (1989-2020). Its emphasis included 1387 new metabolites from 451 papers, focusing on bioactivity and the unique chemical diversity of these natural products.

Multifunctional Therapeutic Potential of Phytocomplexes and Natural Extracts for Antimicrobial Properties

Natural products have been known for their antimicrobial factors since time immemorial. Infectious diseases are a worldwide burden that have been deteriorating because of the improvement of species impervious to various anti-infection agents. Hence, the distinguishing proof of antimicrobial specialists with high-power dynamic against MDR microorganisms is central to conquer this issue. Successful treatment of infection involves the improvement of new drugs or some common source of novel medications. Numerous naturally occurring antimicrobial agents can be of plant origin, animal origin, microbial origin, etc. Many plant and animal products have antimicrobial activities due to various active principles, secondary metabolites, or phytochemicals like alkaloids, tannins, terpenoids, essential oils, flavonoids, lectins, phagocytic cells, and many other organic constituents. Phytocomplexes' antimicrobial movement frequently results from a few particles acting in cooperative energy, and the clinical impacts might be because of the direct effects against microorganisms. The restorative plants that may furnish novel medication lead the antimicrobial movement. The purpose of this study is to investigate the antimicrobial properties of the phytocomplexes and natural extracts of the plants that are ordinarily being utilized as conventional medications and then recommended the chance of utilizing them in drugs for the treatment of multiple drug-resistant disease.

New diphenyl ethers from a fungus Epicoccum sorghinum L28 and their antifungal activity against phytopathogens

The strategy "IEMAHC" (Induction of Endophyte Metabolism by Adding Host Components) was applied to the fermentation of the endophytic fungus Epicoccum sorghinum L28 from Myoporum bontioides by introducing guaiol, an ingredient of M. bontioides, into the cultivation medium, which resulted in the purification of nine new diphenyl ethers, epicoccethers A-I (1-9). Their structures were determined by overall spectroscopic analysis. HPLC-MS analysis revealed that compounds 5-7 were products generated by induction of guaiol. Compounds 6 and 7 are the first members containing an ester moiety formed by the natural long-chain fatty acid and the hydroxyl group in the phenylmethanol unit of the diphenyl ether class. The antifungal activities of compounds 1, 2, and 4-7 against Fusarium oxysporum were 1, 1, 2, 1, 2 and 4 times as high as those of the positive control triadimefon, respectively. Compounds 4 and 5 showed 1.6 times the antifungal activities of triadimefon towards Colletotrichum musae.

Ochraceopetalin, a Mixed-Biogenetic Salt of Polyketide and Amino Acid Origins from a Marine-Derived Aspergillus ochraceopetaliformis Fungus

Ochraceopetalin (1), a mixed-biogenetic salt compound and its component 2 were isolated from the culture broths of a marine-derived fungus, Aspergillus ochraceopetaliformis. Based on combined spectroscopic and chemical analyses, the structure of 1 was determined to be a sulfonated diphenylether-aminol-amino acid ester guanidinium salt of an unprecedented structural class, while 2 was determined to be the corresponding sulfonated diphenylether. Ochraceopetaguanidine (3), the other guanidine-bearing aminol amino acid ester component, was also prepared and structurally elucidated. Compound 1 exhibited significant cytotoxicity against K562 and A549 cells.

The chemistry and biology of fungal meroterpenoids (2009-2019)

Fungal meroterpenoids are secondary metabolites from mixed terpene-biosynthetic origins. Their intriguing chemical structural diversification and complexity, potential bioactivities, and pharmacological significance make them attractive targets in natural product chemistry, organic synthesis, and biosynthesis. This review provides a systematic overview of the isolation, chemical structural features, biological activities, and fungal biodiversity of 1585 novel meroterpenoids from 79 genera terrestrial and marine-derived fungi including macrofungi, Basidiomycetes, in 441 research papers in 2009-2019. Based on the nonterpenoid starting moiety in their biosynthesis pathway, meroterpenoids were classified into four categories (polyketide-terpenoid, indole-, shikimate-, and miscellaneous-) with polyketide-terpenoids (mainly tetraketide-) and shikimate-terpenoids as the primary source. Basidiomycota produced 37.5% of meroterpenoids, mostly shikimate-terpenoids. The genera of Ganoderma, Penicillium, Aspergillus, and Stachybotrys are the four dominant producers. Moreover, about 56% of meroterpenoids display various pronounced bioactivities, including cytotoxicity, enzyme inhibition, antibacterial, anti-inflammatory, antiviral, antifungal activities. It's exciting that several meroterpenoids including antroquinonol and 4-acetyl antroquinonol B were developed into phase II clinically used drugs. We assume that the chemical diversity and therapeutic potential of these fungal meroterpenoids will provide biologists and medicinal chemists with a large promising sustainable treasure-trove for drug discovery.

Structure and absolute configuration assignments of ochracines F-L, chamigrane and cadinane sesquiterpenes from the basidiomycete Steccherinum ochraceum HFG119

Ochracines F-L (1-7), seven previously undescribed chamigrane and cadinane sesquiterpenoids, together with four known chamigranes were isolated from cultures of the wood-decaying fungus Steccherinum ochraceum HFG119. Ochracines F-L were structurally characterized by extensive analysis of HRMS and NMR spectroscopic data. The relative configurations were assigned through a combination of NOE correlations and J-based configuration analysis (JBCA), while the absolute configurations were determined by X-ray single-crystal diffraction, and calculated methods (ECD, [α], 13C NMR). All the new isolates were evaluated for their cytotoxicity against five human cancer cell lines HL-60, SMMC-7721, A549, MCF-7, and SW-480, and inhibitory activity on NO production in RAW 264.7 macrophages.

Meroterpenoids produced by fungi: Occurrence, structural diversity, biological activities, and their molecular targets

Meroterpenoids are partially derived from the terpenoids, distributing widely in the plants, animals and fungi. The complex structures and diverse bioactivities of meroterpenoids have attracted more attention for chemists and pharmacologists. Since the first review summarized by Geris in 2009, there are absent of systematic reviews reported about meroterpenoids from the higher and lower fungi up to now. In the past decades, myriads of meroterpenoids were discovered, and it is necessary to summarize these meroterpenoids about their unique structures and promising bioactivities. In this review, we use a new classification method based on the non-terpene precursors, and also highlight the structural features, bioactivity of natural meroterpenoids from the higher and lower fungi covering the period of September 2008 to February 2020. A total of 709 compounds were discussed and cited the 182 references. Meanwhile, we also primarily summarize their occurrence, structural diversity, biological activities, and molecular targets.

Chemical Diversity and Biological Activities of Meroterpenoids from Marine Derived-Fungi: A Comprehensive Update

Meroterpenoids are a class of hybrid natural products, partially derived from a mixed terpenoid pathway. They possess remarkable structural features and relevant biological and pharmacological activities. Marine-derived fungi are a rich source of meroterpenoids featuring structural diversity varying from simple to complex molecular architectures. A combination of a structural variability and their myriad of bioactivities makes meroterpenoids an interesting class of naturally occurring compounds for chemical and pharmacological investigation. In this review, a comprehensive literature survey covering the period of 2009–2019, with 86 references, is presented focusing on chemistry and biological activities of various classes of meroterpenoids isolated from fungi obtained from different marine hosts and environments.

Secondary metabolites from the Aspergillus sp. in the rhizosphere soil of Phoenix dactylifera (Palm tree)

The soil-derived fungus Aspergillus sp. isolated from the rhizospheric soil of Phoenix dactylifera (Date palm tree) and cultured on the large scale solid rice medium yielded a novel compound 1-(4-hydroxy-2,6-dimethoxy-3,5-dimethylphenyl)-2-methyl-1-butanone (1) and four known compounds; citricin (2), dihydrocitrinone (3), 2, 3, 4-trimethyl-5, 7-dihydroxy-2, 3-dihydrobenzofuran (4) and oricinol (5). The structures of the isolated compounds were elucidated by MS, 1H, 13C and 2D NMR spectra. Compound (1) exhibited potent antimicrobial activities against Staphylococcus aureus with MIC values of 2.3 μg mL⁻¹ and significant growth inhibitions of 82.3 ± 3.3 against Candida albicans and of 79.2 ± 2.6 against Candida parapsilosis. This is the first report to isolate metabolites from the fungus Aspergillus found in temperate region date plant rhizospheres.

Prenylated Diphenyl Ethers from the Marine Algal-Derived Endophytic Fungus Aspergillus tennesseensis

Considerable attention has been paid to marine derived endophytic fungi, owing to their capacity to produce novel secondary metabolites with potent bioactivities. In this study, two new compounds with a prenylated diphenyl ether structure—diorcinol L (1) and (R)-diorcinol B (2)—were isolated from the marine algal-derived endophytic fungus Aspergillus tennesseensis, along with seven known compounds: (S)-diorcinol B (3), 9-acetyldiorcinol B (4), diorcinol C (5), diorcinol D (6), diorcinol E (7), diorcinol J (8), and a dihydrobenzofuran derivative 9. Their structures were elucidated by extensive NMR spectroscopy studies. Compound 2 represents the first example of an R-configuration in the prenylated moiety. All these isolated compounds were examined for antimicrobial and cytotoxic activities. Compounds 1–9 exhibited antimicrobial activities against some human- and plant-pathogenic microbes with MIC values ranging from 2 to 64 μg/mL. Moreover, compound 9 displayed considerable inhibitory activity against the THP-1 cell line in vitro, with an IC₅₀ value of 7.0 μg/mL.

Brasilianoids A-F, New Meroterpenoids From the Sponge-Associated Fungus Penicillium brasilianum

3,5-Dimethylorsellinic acid (DMOA) derived meroterpenoids comprise an unique class of natural products with diverse scaffolds and with a broad spectrum of bioactivities. Bioinformatics analysis of the gene clusters in association with the qRT-PCR detection of the amplification of two key genes led to speculate that the sponge associated fungus Penicillium brasilianum WZXY-m122-9 is a potential producer of meroterpenoids. Chromatographic separation of the EtOAc extract of this fungal strain on a large-scale fermentation resulted in the isolation of six new DMOA-related meroterpenoids with trivial names of brasilianoids A–F (1-6), together with preaustinoid D and preaustinoid A2. The structures were determined by extensive analyses of spectroscopic data, including the X-ray diffraction and the ECD data for configurational assignment. Brasilianoids A and F showed an unprecedented skeleton with a γ-lactone in ring A, while brasilianoids B–C featured a 7/6/6/5/5 pentacyclic ring system finding in nature for the first time. The biosynthetic relationship among the isolated compounds was postulated. Compound 1 significantly stimulated the expression of filaggrin and caspase-14 in HaCaT cells in dose-dependent manner, while compounds 2 and 3 showed moderate inhibition against NO production in LPS-induced RAW 264.7 macrophages.

Activation of an unconventional meroterpenoid gene cluster in Neosartorya glabra leads to the production of new berkeleyacetals

Fungal genomes carry many gene clusters seemingly capable of natural products biosynthesis, yet most clusters remain cryptic or down-regulated. Genome mining revealed an unconventional paraherquonin-like meroterpenoid biosynthetic gene cluster in the chromosome of Neosartorya glabra. The cryptic or down-regulated pathway was activated by constitutive expression of pathway-specific regulator gene berA encoded within ber biosynthetic gene cluster. Chemical analysis of mutant Ng-OE: berA extracts enabled the isolation of four berkeleyacetal congeners, in which two of them are new. On the basis of careful bioinformatic analysis of the coding enzymes in the ber gene cluster, the biosynthetic pathway of berkeleyacetals was proposed. These results indicate that this approach would be valuable for discovery of novel natural products and will accelerate the exploitation of prodigious natural products in filamentous fungi.

Anti-inflammatory meroterpenoids from the mangrove endophytic fungus Talaromyces amestolkiae YX1

Four previously undescribed meroterpenoids, amestolkolides A-D, along with three known compounds were isolated from the mangrove endophytic fungus Talaromyces amestolkiae YX1 cultured on wheat solid-substrate medium culture. Their structures were elucidated by a combination of spectroscopic analyses. The absolute configurations of amestolkolides B and C, and purpurogenolide E were determined by single-crystal X-ray diffraction using Cu Kα radiation, and those of amestolkolides A and D were elucidated on the basis of experimental and calculated electronic circular dichroism spectra. The absolute configuration of amestolkolides A-D, and purpurogenolide E (9R) at C-9 was different from that of analogues (9S) in references, so that their plausible and distinct biosynthetic pathways were proposed. Amestolkolide B showed strong anti-inflammatory activity in vitro by inhibiting nitric oxide (NO) production in lipopolysaccharide activated in RAW264.7 cells with IC₅₀ value of 1.6 ± 0.1 μM.

3,5-Dimethylorsellinic Acid Derived Meroterpenoids from Penicillium chrysogenum MT-12, an Endophytic Fungus Isolated from Huperzia serrata

Eight new chrysogenolides (A-H (1-8)) and seven known (9-15) 3,5-dimethylorsellinic acid derived meroterpenoids were isolated from the solid substrate fermentation cultures of a Huperzia serrata endophytic fungus, Penicillium chrysogenum MT-12. The structures of the new compounds were elucidated by interpretation of spectroscopic and spectrometric data (1D and 2D NMR, IR, and HRESIMS). The absolute configurations of 1-4 were determined by single-crystal X-ray crystallographic analysis, and those of 5-8 were assigned on the basis of experimental and calculated electronic circular dichroism spectra. Compounds 3, 4, 6, 11, and 12 showed inhibition of nitric oxide production in lipopolysaccharide-activated RAW 264.7 macrophage cells with IC₅₀ values in the range of 4.3-78.2 μM (positive control, indomethacin, IC₅₀ = 33.6 ± 1.4 μM).

Chamigrane Sesquiterpenes from a Basidiomycetous Endophytic Fungus XG8D Associated with Thai Mangrove Xylocarpus granatum

Six new chamigrane sesquiterpenes, merulinols A‒F (1‒6), and four known metabolites (7‒10) were isolated from the culture of the basidiomycetous fungus XG8D, a mangrove-derived endophyte. Their structures were elucidated mainly by 1D and 2D NMR, while the structures of 1 and 2 were further confirmed by single-crystal X-ray diffraction analysis. The in vitro cytotoxicity of all compounds was evaluated against three human cancer cell lines, MCF-7, Hep-G2, and KATO-3. Compounds 3 and 4 selectively displayed cytotoxicity against KATO-3 cells with IC₅₀ values of 35.0 and 25.3 μM, respectively.

Nitric Oxide Inhibitory Meroterpenoids from the Fungus Penicillium purpurogenum MHZ 111

Five new meroterpenoids, purpurogenolides A-E (1-5), and four known metabolites (6-9) were isolated from the solid substrate fermentation cultures of the fungus Penicillium purpurogenum MHz 111. The structures of the new meroterpenoids were elucidated by analysis of spectroscopic and spectrometric data (1D and 2D NMR, IR, and HRESIMS). The absolute configurations of 1 and 5 were determined by single-crystal X-ray crystallographic analysis, and those of 2-4 were elucidated on the basis of experimental and calculated electronic circular dichroism spectra. Compounds 2-4 and 6 showed inhibition of nitric oxide production in lipopolysaccharide-activated BV-2 microglial cells with IC50 values of 0.8-30.0 μM.

Biosynthesis of fungal meroterpenoids

Covering: up to September 2015. Meroterpenoids are hybrid natural products that partially originate from the terpenoid pathway. The meroterpenoids derived from fungi display quite diverse structures, with a wide range of biological properties. This review summarizes the molecular bases for their biosyntheses, which were recently elucidated with modern techniques, and also discusses the plausible biosynthetic pathways of other related natural products lacking genetic information. (Complementary to the coverage of literature by Geris and Simpson in Nat. Prod. Rep., 2009, 26, 1063-1094.).

Two new glycosidal metabolites of endophytic fungus Penicillium sp. (NO.4) from Tapiscia sinensis

Two new glycosides, 8-O-β- d-glucopyranosyl-6-methyl-1-carboxylate methyl ester xanthone (1) and 4′-O-β- d-galactopyranosyl djalonensone (2), together with four known compounds, 8-hydroxy-6-methyl-9-oxo-9H-xanthene-1-carboxylate methyl ester (3), cassionllin (4), djalonensone (5) and alternariol (6), were isolated from the endophytic fungus Penicillium sp. (NO.4) of Tapiscia sinensis Oliv. The structures of compounds 1–6 were elucidated by the analysis of 1D and 2D NMR and HRMS. The cytotoxic activities of these compounds were evaluated against four cancer cell lines, as well as antimicrobial activities against two plant-pathogenic microbes. Compounds 1–6 showed moderate cytotoxicity against the A549 cancer cell line with IC50 values ranging from 6.8 to 35.8 μg mL−1 and were found to be inactive against three other cancer cell lines MCF-7, Caski and Hep G-2.

New bioactive metabolites from Penicillium purpurogenum MM

Three new bioactive compounds, namely (S)-tenellic acid B dimethyl acetal (1a), (3R,3′R/S)-isotalarone (2), and (3R,5R)-cis-5-methyl-3-(2-oxobutyl)-dihydrofuran-2-one (3), were isolated from the terrestrial fungus Penicillium purpurogenum MM, together with 15 known metabolites: talaroflavone, pestalasin A, altenuene, penicillide, 3′-O-methyl-dehydroisopenicillide, rubralactone, tenellic acid B, diaporthin, butyrolactone 1, butyrolactone-V, 4-hydroxy-2-methoxyacetanilide, ergosterol, ergosterol peroxide, linoleic acid, and glycerol monolinoleate. The chemical structures of the three new compounds were confirmed by extensive one- and two-dimensional NMR and electron spray ionization high-resolution mass spectra measurements and by comparison with literature data. The absolute configurations of the new compounds, and of talaroflavone (4a) and tenellic acid B (2b), were determined by ab initio calculations of ECD, ORD, and NMR data. The antimicrobial and cytotoxic activities of the crude extract and of the isolated compounds were studied using a set of microorganisms and brine shrimp assay, respectively. The isolation and taxonomic characterization of P. purpurogenum MM is reported.

Penicillanthone and penicillidic acids A–C from the soil-derived fungus Penicillium aculeatum PSU-RSPG105

A new xanthone (penicillanthone, 1) and three new diphenyl ether derivatives (penicillidic acids A–C, 2–4) together with 14 known compounds (5–18) were isolated from the soil-derived fungus Penicillium aculeatum PSU-RSPG105.

Marine natural products sourced from marine-derived Penicillium fungi

Marine micro-organisms have been proven to be a major source of marine natural products (MNPs) in recent years, in which filamentous fungi are a vital source of bioactive natural products for their large metagenomes and more complex genetic backgrounds. This review highlights the 390 new MNPs from marine-derived Penicillium fungi during 1991 to 2014. These new MNPs are categorized based on the environment sources of the fungal hosts and their bioactivities are summarized.

Antibacterial and antifungal compounds from marine fungi

This paper reviews 116 new compounds with antifungal or antibacterial activities as well as 169 other known antimicrobial compounds, with a specific focus on January 2010 through March 2015. Furthermore, the phylogeny of the fungi producing these antibacterial or antifungal compounds was analyzed. The new methods used to isolate marine fungi that possess antibacterial or antifungal activities as well as the relationship between structure and activity are shown in this review.

Recent advances and applications of experimental technologies in marine natural product research

Marine natural products are a rich source of novel and biologically active compounds. The number of identified marine natural compounds has grown 20% over the last five years from 2009 to 2013. Several challenges, including sample collection and structure elucidation, have limited the development of this research field. Nonetheless, new approaches, such as sampling strategies for organisms from extreme ocean environments, nanoscale NMR and computational chemistry for structural determination, are now available to overcome the barriers. In this review, we highlight the experimental technology innovations in the field of marine natural products, which in our view will lead to the development of many new drugs in the future.

Bioactive terpenes from marine-derived fungi

Marine-derived fungi continue to be a prolific source of secondary metabolites showing diverse bioactivities. Terpenoids from marine-derived fungi exhibit wide structural diversity including numerous compounds with pronounced biological activities. In this review, we survey the last five years’ reports on terpenoidal metabolites from marine-derived fungi with particular attention on those showing marked biological activities.

Acetylcholinesterase inhibitors from a marine fungus Talaromyces sp. strain LF458

Two new oxaphenalenone dimers, talaromycesone A (1) and talaromycesone B (2), and a new isopentenyl xanthenone, talaroxanthenone (3), together with six known diphenyl ether derivatives, e.g., Δ(1',3'),-1'-dehydroxypenicillide (4), 1',2'-dehydropenicillide (5), vermixocin A (6), vermixocin B (7), 3'-methoxy-1'2'-dehydropenicillide (8), and AS-186c (9), were isolated from the culture broth and mycelia of a marine fungus Talaromyces sp. strain LF458. Compound 2 represents the first example of 1-nor oxaphenalenone dimer carbon skeleton. All isolated compounds were subjected to bioactivity assays. Compounds 1, 2, and 9 exhibited potent antibacterial activities with IC50 3.70, 17.36, and 1.34 μM, respectively, against human pathogenic Staphylococcus strains. Compounds 1, 3, and 9 displayed potent acetylcholinesterase inhibitory activities with IC50 7.49, 1.61, and 2.60 μM, respectively. Interestingly, phosphodiesterase PDE-4B2 was inhibited by compounds 3 (IC50 7.25 μM) and 9 (IC50 2.63 μM).

Bioactive natural products derived from mangrove-associated microbes

This review summarizes new findings concerning the sources and characteristics of various natural products that can be extracted from mangrove-associated microbes over the past three years (January 2011–December 2013).

Structure, absolute configuration, and conformational study of resorcylic acid derivatives and related congeners from the fungus Penicillium brocae

A new resorcylic acid derivative (4) and five new loop-opened resorcylic acid-related congeners (5–9), were identified from the marine mangrove-derived endophyte Penicillium brocae MA-192. All compounds were evaluated for the antioxidant activity against DPPH and ABTS radicals.

Diphenyl ethers from Aspergillus sp. and their anti-Aβ₄₂ aggregation activities

Two new compounds with the character of diphenyl ether structure, oxisterigmatocystin D (1) and 9-acetyldiorcinol B (6), were isolated from the endolichenic fungal strain Aspergillus sp. (No. 16-20-8-1), along with six known compounds, oxisterigmatocystin A (2), oxisterigmatocystin C (3), sterigmatocystin (4), diorcinol B (5), violaceol-I (7), and violaceol-II (8). The structures of the new compounds were determined by extensive NMR spectroscopic data, and the absolute configuration of 1 was established by single-crystal X-ray diffraction analysis. Moreover, the Aβ42 aggregation inhibitory activities of 5-8 were evaluated by the standard thioflavin T (ThT) fluorescence assay using epigallocatechin gallate (EGCG) as the positive control. Compounds 7 and 8 displayed significant anti-Aβ42 aggregation activity with IC50 values of 5.1 and 2.3μM, respectively. Preliminary structure-activity relationship of these diphenyl ethers as anti-Aβ42 aggregation inhibitors was proposed.

First total syntheses and antimicrobial evaluation of penicimonoterpene, a marine-derived monoterpenoid, and its various derivatives

The first total synthesis of marine-derived penicimonoterpene (±)-1 has been achieved in four steps from 6-methylhept-5-en-2-one using a Reformatsky reaction as the key step to construct the basic carbon skeleton. A total of 24 new derivatives of 1 have also been designed and synthesized. Their structures were characterized by analysis of their 1H NMR, 13C NMR and HRESIMS data. Some of them showed significant antibacterial activity against Aeromonas hydrophila, Escherichia coli, Micrococcus luteus, Staphylococcus aureus, Vibrio anguillarum, V. harveyi and/or V. parahaemolyticus, and some showed activity against plant-pathogenic fungi (Alternaria brassicae, Colletotrichum gloeosporioides and/or Fusarium graminearum). Some of the derivatives exhibited antimicrobial MIC values ranging from 0.25 to 4 μg/mL, which were stronger than those of the positive control. Notably, Compounds 3b and 10 showed extremely high selectively against plant-pathogenic fungus F. graminearum (MIC 0.25 μg/mL) and pathogenic bacteria E. coli (MIC 1 μg/mL), implying their potential as antimicrobial agents. SAR analysis of 1 and its derivatives indicated that modification of the carbon-carbon double bond at C-6/7, of groups on the allylic methylene unit and of the carbonyl group at C-1, effectively enhanced the antimicrobial activity.

Cyclohexadepsipeptides of the isaridin class from the marine-derived fungus Beauveria felina EN-135

Three new cyclohexadepsipeptides of the isaridin class including isaridin G (1), desmethylisaridin G (2), and desmethylisaridin C1 (3), along with three related known metabolites (4-6), were isolated and identified from the marine bryozoan-derived fungus Beauveria felina EN-135. The structures of these compounds were elucidated on the basis of extensive spectroscopic analysis, and the structures and absolute configurations of compounds 1-3 were confirmed by single-crystal X-ray diffraction analysis. The crystal structures showed the presence of β-turns for the Tyr(3)/N-Me-Val(4) and Phe(3)/N-Me-Val(4) amide bonds in compounds 2 and 3, respectively, in the cis conformations, which were opposite other reported isaridins. The conformations of the HMPA(1)-Pro(2) amide bond in compound 2 are different in the solution and in the crystal structures, which showed trans and cis geometries, respectively, while compounds 1 and 3 do not exhibit this phenomenon. Each of the isolated compounds was evaluated for antimicrobial activity and brine shrimp lethality. Compound 3 exhibited antibacterial activity against E. coli with an MIC value of 8 μg/mL.