Metabolomic Profiling and Biological Investigation of the Marine Sponge-Derived Fungus Aspergillus sp. SYPUF29 in Response to NO Condition.

Marine-derived fungi are assuming an increasingly central role in the search for natural leading compounds with unique chemical structures and diverse pharmacological properties. However, some gene clusters are not expressed under laboratory conditions. In this study, we have found that a marine-derived fungus Aspergillus sp. SYPUF29 would survive well by adding an exogenous nitric oxide donor (sodium nitroprusside, SNP) and nitric oxide synthetase inhibitor (L-NG-nitroarginine methyl ester, L-NAME) in culture conditions. Moreover, using the LC-MS/MS, we initially assessed and characterized the difference in metabolites of Aspergillus sp. SYPUF29 with or without an additional source of nitrogen. We have found that the metabolic pathway of Arginine and proline metabolism pathways was highly enriched, which was conducive to the accumulation of alkaloids and nitrogen-containing compounds after adding an additional source of nitrogen in the cultivated condition. Additionally, the in vitro anti-neuroinflammatory study showed that the extracts after SNP and L-NAME were administrated can potently inhibit LPS-induced NO-releasing of BV2 cells with lower IC50 value than without nitric oxide. Further Western blotting assays have demonstrated that the mechanism of these extracts was associated with the TLR4 signaling pathway. Additionally, the chemical investigation was conducted and led to nine compounds (SF1-SF9) from AS1; and six of them belonged to alkaloids and nitrogen-containing compounds (SF1-SF6), of which SF1, SF2, and SF8 exhibited stronger activities than the positive control, and showed potential to develop the inhibitors of neuroinflammation.

Uncovering the Potent Antiviral Activity of the Sesterterpenoids from the Sponge Ircinia felix against Human Adenoviruses: from the Natural Source to the Total Synthesis.

Human Adenovirus (HAdV) infections in immunocompromised patients can result in disseminated diseases with high morbidity and mortality rates due to the absence of available treatments for these infections. Ircinia felix sponge was selected for the significant anti-HAdV activity displayed by its organic extracts. Its chemical analysis yielded three novel sesterterpene lactams, ircinialactams J-L, along with three known sesterterpene furans which structures were established by a deep spectrometric analysis. Ircinialactam J displayed significant antiviral activity against HAdV without significant cytotoxicity, showing an effectiveness 11 times greater than that of the standard treatment, cidofovir®. Some structure-activity relationships were deduced. Mechanistic assays suggest that ircinialactam J targets an early step of the HAdV replicative cycle before HAdV genome reaches the nucleus of the host cell. The first total synthesis of ircinialactam J was also accomplished to prove the structure and to provide access to analogues. Key steps are a regio- and stereoselective construction of the trisubstituted Z-olefin at Δ7 by iron-catalyzed carbometallation of a homopropargylic alcohol, a stereoselective methylation to generate the stereogenic center at C18, and the formation of the (Z)-Δ20 by stereoselective aldol condensation to introduce the tetronic acid unit. Ircinialactam J is a promising antiviral drug against HAdV infections.

Multi-omic analysis reveals genes and proteins integral to bioactivity of Echinochrome A isolated from the waste stream of the sea urchin industry in Aotearoa New Zealand.

Evechinus chloroticus (commonly known as kina) is a sea urchin species endemic to New Zealand. Its roe is a culinary delicacy to the indigenous Maori and a globally exported food product. Echinochrome A (Ech A) is a bioactive compound isolated from the waste product of kina shells and spines; however, the molecular mechanisms of Ech A bioactivity are not well understood, partly due to Ech A never being studied using unbiased genome-wide analysis. To explore the high-value pharmaceutical potential of kina food waste, we obtained unbiased functional genomic and proteomic profiles of yeast cells treated with Echinochrome A. Abundance was measured for 4100 proteins every 30 min for four hours using fluorescent microscopy, resulting in the identification of 92 proteins with significant alterations in protein abundance caused by Ech A treatment that were over-represented with specific changes in DNA replication, repair and RNA binding after 30 min, followed by specific changes in the metabolism of metal ions (specifically iron and copper) from 60-240 min. Further analysis indicated that Ech A chelated iron, and that iron supplementation negated the growth inhibition caused by Ech A. Via a growth-based genome-wide analysis of 4800 gene deletion strains, 20 gene deletion strains were sensitive to Ech A in an iron-dependent manner. These genes were over-represented in the cellular response to oxidative stress, suggesting that Ech A suppressed growth inhibition caused by oxidative stress. Unexpectedly, genes integral to cardiolipin and inositol phosphate biosynthesis were required for Ech A bioactivity. Overall, these results identify genes, proteins, and cellular processes mediating the bioactivity of Ech A. Moreover, we demonstrate unbiased genomic and proteomic methodology that will be useful for characterizing bioactive compounds in food and food waste.

Epigenetic small-molecule screen for inhibition and reversal of acinar ductal metaplasia in mouse pancreatic organoids.

Background: Acinar ductal metaplasia (ADM) is among the earliest initiating events in pancreatic ductal adenocarcinoma (PDAC) development. Methods: We developed a novel morphology-based screen using organoids from wildtype and p48Cre/+ (Cre) mice to discover epigenetic modulators that inhibit or reverse pancreatic ADM more effectively than the broad-spectrum HDAC inhibitor trichostatin A (TSA). Results: Of the 144 compounds screened, nine hits and two additional natural product HDAC inhibitors were validated by dose-response analysis. The class I HDAC inhibitors apicidin and FK228, and the histone methyltransferase inhibitor chaetocin demonstrated pronounced ADM inhibition and reversal without inducing significant cytotoxicity at 1 µM. Thioester prodrug class I HDAC inhibitor largazole attenuated ADM while its disulfide homodimer was effective in both ADM inhibition and reversal. Prioritized compounds were validated for ADM reversal in p48Cre/+; LSL-KrasG12D/+ (KC) mouse organoids using both morphological and molecular endpoints. Molecular index analysis of ADM reversal in KC mouse organoids demonstrated improved activity compared to TSA. Improved prodrug stability translated into a stronger phenotypic and molecular response. RNA-sequencing indicated that angiotensinogen was the top inhibited pathway during ADM reversal. Conclusion: Our findings demonstrate a unique epigenetic mechanism and suggest that the phenotypic screen developed here may be applied to discover potential treatments for PDAC.

Bioluminescence of (R)-Cypridina Luciferin with Cypridina Luciferase.

Cypridina luciferin (CypL) is a marine natural product that functions as the luminous substrate for the enzyme Cypridina luciferase (CypLase). CypL has two enantiomers, (R)- and (S)-CypL, due to its one chiral center at the sec-butyl moiety. Previous studies reported that (S)-CypL or racemic CypL with CypLase produced light, but the luminescence of (R)-CypL with CypLase has not been investigated. Here, we examined the luminescence of (R)-CypL, which had undergone chiral separation from the enantiomeric mixture, with a recombinant CypLase. Our luminescence measurements demonstrated that (R)-CypL with CypLase produced light, indicating that (R)-CypL must be considered as the luminous substrate for CypLase, as in the case of (S)-CypL, rather than a competitive inhibitor for CypLase. Additionally, we found that the maximum luminescence intensity from the reaction of (R)-CypL with CypLase was approximately 10 fold lower than that of (S)-CypL with CypLase, but our kinetic analysis of CypLase showed that the Km value of CypLase for (R)-CypL was approximately 3 fold lower than that for (S)-CypL. Furthermore, the chiral high-performance liquid chromatography (HPLC) analysis of the reaction mixture of racemic CypL with CypLase showed that (R)-CypL was consumed more slowly than (S)-CypL. These results indicate that the turnover rate of CypLase for (R)-CypL was lower than that for (S)-CypL, which caused the less efficient luminescence of (R)-CypL with CypLase.

The Identification and Heterologous Expression of the Biosynthetic Gene Cluster Encoding the Antibiotic and Anticancer Agent Marinomycin.

With the rise in antimicrobial resistance, there is an urgent need for new classes of antibiotic with which to treat infectious disease. Marinomycin, a polyene antibiotic from a marine microbe, has been shown capable of killing methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Enterococcus faecium (VREF), as well as having promising activity against melanoma. An attractive solution to the photoprotection of this antibiotic has been demonstrated. Here, we report the identification and analysis of the marinomycin biosynthetic gene cluster (BGC), and the biosynthetic assembly of the macrolide. The marinomycin BGC presents a challenge in heterologous expression due to its large size and high GC content, rendering the cluster prone to rearrangement. We demonstrate the transformation of Streptomyces lividans using a construct containing the cluster, and the heterologous expression of the encoded biosynthetic machinery and production of marinomycin B.

Mebamamide C, a deoxy analogue of mebamamides in Bryopsis marine green algae and Elysia sacoglossan mollusks.

Kahalalides, originally isolated from the sacoglossan mollusk Elysia rufescens, have been found in various Elysia and Bryopsis species, with over 20 variants identified to date. These compounds are biosynthesized by Candidatus Endobryopsis kahalalidefaciens within Bryopsis species. In this study, we report the isolation and structural determination of a new cyclic depsipeptide, mebamamide C (1), from Bryopsis sp. The planar structure was determined by spectroscopic data analyses, and the absolute configurations were determined using Marfey's method and modified Mosher's method. Additionally, our study explores the chemical relationship between Bryopsis algae and Elysia mollusks. The individual chemical profiles of these marine organisms highlight a fascinating aspect of marine chemical ecology. The distinct, species-specific chemical profiles observed in Elysia species imply the possibility of a symbiotic relationship with the kahalalide-producing bacteria.

Tartrolon E, a secondary metabolite of a marine symbiotic bacterium, is a potent inhibitor of asexual and sexual Plasmodium falciparum.

Due to the spread of resistance to front-line artemisinin derivatives worldwide, there is a need for new antimalarials. Tartrolon E (TrtE), a secondary metabolite of a symbiotic bacterium of marine bivalve mollusks, is a promising antimalarial because it inhibits the growth of sexual and asexual blood stages of Plasmodium falciparum at sub-nanomolar levels. The potency of TrtE warrants further investigation into its mechanism of action, cytotoxicity, and ease with which parasites may evolve resistance to it.

Research progress of nitrobenzoyl sesquiterpenoids as marine characteristic natural products / 药学学报

Sesquiterpenoids are widely found in nature, while nitrobenzoyl sesquiterpenoids are relatively rare. Twelve natural nitrobenzoyl sesquiterpenoids were all derived from marine Aspergillus fungi, which are typical natural products with marine characteristics. These natural products exhibit good antitumor, antiviral, and inhibition of osteoclast differentiation activity, especially in the treatment of osteoclast-related diseases, showing good medicinal development value. This article reviews the natural product sources, chemical structure, chemical synthesis, biosynthesis, bioactivity, and pharmacological mechanisms of nitrobenzoyl sesquiterpenoids and predicts and discusses their absorption, distribution, metabolism, excretion, toxicity (ADME/T), and drug-likeness, providing a comprehensive understanding of the natural products of nitrobenzoyl sesquiterpenoids from marine sources and their potential for pharmaceutical development.

Marine-Fungi-Derived Gliotoxin Promotes Autophagy to Suppress Mycobacteria tuberculosis Infection in Macrophage.

The Mycobacterium tuberculosis (MTB) infection causes tuberculosis (TB) and has been a long-standing public-health threat. It is urgent that we discover novel antitubercular agents to manage the increased incidence of multidrug-resistant (MDR) or extensively drug-resistant (XDR) strains of MTB and tackle the adverse effects of the first- and second-line antitubercular drugs. We previously found that gliotoxin (1), 12, 13-dihydroxy-fumitremorgin C (2), and helvolic acid (3) from the cultures of a deep-sea-derived fungus, Aspergillus sp. SCSIO Ind09F01, showed direct anti-TB effects. As macrophages represent the first line of the host defense system against a mycobacteria infection, here we showed that the gliotoxin exerted potent anti-tuberculosis effects in human THP-1-derived macrophages and mouse-macrophage-leukemia cell line RAW 264.7, using CFU assay and laser confocal scanning microscope analysis. Mechanistically, gliotoxin apparently increased the ratio of LC3-II/LC3-I and Atg5 expression, but did not influence macrophage polarization, IL-1ß, TNF-a, IL-10 production upon MTB infection, or ROS generation. Further study revealed that 3-MA could suppress gliotoxin-promoted autophagy and restore gliotoxin-inhibited MTB infection, indicating that gliotoxin-inhibited MTB infection can be treated through autophagy in macrophages. Therefore, we propose that marine fungi-derived gliotoxin holds the promise for the development of novel drugs for TB therapy.

Four New Diterpenoids from the South China Sea Soft Coral Sinularia nanolobata and DFT-Based Structure Elucidation.

Three new cembranoids (1-3) and a new casbanoid (4), along with three known analogues (5-7), have been isolated from the soft coral Sinularia nanolobata collected off Ximao Island. The structures, including the absolute configurations of new compounds, were established using extensive spectroscopic data analysis, time-dependent density functional theory/electronic circular dichroism (TDDFT-ECD) calculations, and the comparison with spectroscopic data of known compounds. In the in vitro bioassay, compounds 1 and 5 exhibited moderate cytotoxic activities against human erythroleukemia (HEL) cell lines, with IC50 values of 37.1 and 42.4 µM, respectively.

Penicopeptide A (PPA) from the deep-sea-derived fungus promotes osteoblast-mediated bone formation and alleviates ovariectomy-induced bone loss by activating the AKT/GSK-3ß/ß-catenin signaling pathway.

The potential of marine natural products as effective drugs for osteoporosis treatment is an understudied area. In this study, we investigated the ability of lead compounds from deep-sea-derived Penicillium solitum MCCC 3A00215 to promote bone formation in vitro and in vivo. We found that penicopeptide A (PPA) promoted osteoblast mineralization among bone marrow mesenchymal stem cells (BMSCs) in a concentration-dependent manner, and thus, we selected this natural peptide for further testing. Our further experiments showed that PPA significantly promoted the osteogenic differentiation of BMSCs while inhibiting their adipogenic differentiation and not affecting their chondrogenic differentiation. Mechanistic studies showed that PPA binds directly to the AKT and GSK-3ß and activates phosphorylation of AKT and GSK-3ß, resulting in the accumulation of ß-catenin. We also evaluated the therapeutic potential of PPA in a female mouse model of ovariectomy-induced systemic bone loss. In this model, PPA treatment prevented decreases in bone volume and trabecular thickness. In conclusion, our in vitro and in vivo results demonstrated that PPA could promote osteoblast-related bone formation via the AKT, GSK-3ß, and ß-catenin signaling pathways, indicating the clinical potential of PPA as a candidate compound for osteoporosis prevention.

Marine Natural Compound (Neviotin A) Displays Anticancer Efficacy by Triggering Transcriptomic Alterations and Cell Death in MCF-7 Cells.

We investigated the anticancer mechanism of a chloroform extract of marine sponge (Haliclona fascigera) (sample C) in human breast adenocarcinoma (MCF-7) cells. Viability analysis using MTT and neutral red uptake (NRU) assays showed that sample C exposure decreased the proliferation of cells. Flow cytometric data exhibited reactive oxygen species (ROS), nitric oxide (NO), dysfunction of mitochondrial potential, and apoptosis in sample C-treated MCF-7 cells. A qPCR array of sample C-treated MCF-7 cells showed crosstalk between different pathways of apoptosis, especially BIRC5, BCL2L2, and TNFRSF1A genes. Immunofluorescence analysis affirmed the localization of p53, bax, bcl2, MAPKPK2, PARP-1, and caspase-3 proteins in exposed cells. Bioassay-guided fractionation of sample C revealed Neviotin A as the most active compound triggering maximum cell death in MCF-7, indicating its pharmacological potency for the development of a drug for the treatment of human breast cancer.

Marine pyridoacridine, pyridoacridone and pyrroloacridine alkaloids.

The families of pyridoacridine, pyridoacridone, and pyrroloacridine alkaloids are fascinating classes of natural products that have attracted the attention of chemists for over 80 years. Since the first purification of a brightly colored molecule isolated from the sea anemone Calliactis parasitica in 1940, over 110 examples of these alkaloids have been reported from marine organisms. While the paucity of numbers of protons relative to carbons and nitrogens in these molecules presents challenges in structure solution, the chemist is rewarded by their bright pigmented colors and typically diverse biological activities. In the past, several authors have proposed biosynthetic relationships within the pyridoacridine family of alkaloids, formulating a family tree derived from the reaction of dopaminequinone and kynuramine to tie together over 75 alkaloids. Inclusion of two additional quinones, and one homologous diamine, building blocks, for which there is biomimetic synthesis support, is suggestive of a more expansive connected biogenesis that encompasses not only pyridoacridines, but also pyridoacridone, and pyrroloacridine alkaloids. This review covers the isolation, structure elucidation, and proposed biosynthesis and biogenesis of pyridoacridine, pyridoacridone and pyrroloacridine marine alkaloids published to the end of 2022. Biomimetic or bio-inspired syntheses of the compound classes are described and new biological activities reported since 2004 are updated.

Design, Synthesis, and Biological Evaluation of Novel Derivatives of the Marine Natural Product Laurene.

Plant pathogenic fungi and viruses are seriously threatening agricultural production. There is an urgent need to develop novel fungicides and antiviral agents with low toxicity and high efficiency. In this study, we designed and synthesized 32 thiazole-, hydrazone-, and amide-containing derivatives of laurene and systematically evaluated their antiviral activities and fungicidal activities. Structure-simplified compounds 5a-5c, 5i, 5k, 5l, 11a, 11j, and 12c displayed higher antiviral activities than that of ningnanmycin. Compound 11a with a simple chemical structure, convenient synthetic route, and excellent antiviral activity emerged as a secondary lead compound. The docking results show that compounds 5i, 5k, and 11a have strong interactions with the tobacco mosaic virus coat protein (TMV CP). These compounds also exhibited significant fungicidal activities. Compounds 5g, 5k, 11j, and 11l displayed 9.15-17.45 µg/mL EC50 values against Pyricularia grisea, and compounds 5h (EC50: 8.01 µg/mL) and 11i (EC50: 15.23 µg/mL) exhibited a similar level of EC50 values with chlorothalonil (EC50: 7.33 µg/mL) against Physalospora piricola. Preliminary fungicidal mechanism research indicated that compound 5h has a certain destructive effect on the hyphae of P. piricola. This work lays a foundation for the application of laurene derivatives in plant protection.

Petrosamine Revisited. Experimental and Computational Investigation of Solvatochromism, Tautomerism and Free Energy Landscapes of a Pyridoacridinium Quaternary Salt.

Petrosamine (1)-a colored pyridoacridine alkaloid from the Belizean sponge, Petrosia sp., that is also a potent inhibitor of acetylcholine esterase (AChE)-was investigated by spectroscopic and computational methods. Analysis of the petrosamine-free energy landscapes, pKa and tautomerism, revealed an accurate electronic depiction of the molecular structure of 1 as the di-keto form, with a net charge of q = +1, rather than a dication (q = +2) under ambient conditions of isolation-purification. The pronounced solvatochromism (UV-vis) reported for 1, and related analogs were investigated in detail and is best explained by charge delocalization and stabilization of the ground state (HOMO) of 1 rather than an equilibrium of competing tautomers. Refinement of the molecular structure 1 by QM methods complements published computational docking studies to define the contact points in the enzyme active site that may improve the design of new AChE inhibitors based on the pyridoacridine alkaloid molecular skeleton.

Two new compounds from the Hainan Soft Corals Sinularia tumulosa and Sinularia depressa with their anti-inflammatory or cytotoxic activities.

The detailed chemical investigations of the South China Sea soft corals Sinularia tumulosa and Sinularia depressa, yielded two new compounds, namely tumulosterol A (1) and 11'-hydroxy-α-tocopherylquinone (3), along with four related known ones (2, 5-7). Their structures were determined by extensive spectroscopic analysis and comparison with the spectral data previously reported in the literature. In bioassays, compound 1 displayed significant cytotoxic effects against H1975 and MDA-MB-231 cells with IC50 values of 6.0 and 6.3 µM, respectively. In addition, compound 3 exhibited interesting inhibitory effect on lipopolysaccharide (LPS)-induced inflammatory responses in RAW264.7 cells with IC50 value of 9.5 µM.

Marine Natural Products from the Beibu Gulf: Sources, Chemistry, and Bioactivities.

Marine natural products (MNPs) play an important role in the discovery and development of new drugs. The Beibu Gulf of South China Sea harbors four representative marine ecosystems, including coral reefs, mangroves, seaweed beds, and coastal wetlands, which are rich in underexplored marine biological resources that produce a plethora of diversified MNPs. In our ongoing efforts to discover novel and biologically active MNPs from the Beibu Gulf, we provide a systematic overview of the sources, chemical structures, and bioactive properties of a total of 477 new MNPs derived from the Beibu Gulf, citing 133 references and covering the literature from the first report in November 2003 up to September 2022. These reviewed MNPs were structurally classified into polyketides (43%), terpenoids (40%), nitrogen-containing compounds (12%), and glucosides (5%), which mainly originated from microorganisms (52%) and macroorganisms (48%). Notably, they were predominantly found with cytotoxic, antibacterial, and anti-inflammatory activities. This review will shed light on these untapped Beibu Gulf-derived MNPs as promising lead compounds for the development of new drugs.

Targeted isolation of antitubercular cycloheptapeptides and an unusual pyrroloindoline-containing new analog, asperpyrroindotide A, using LC-MS/MS-based molecular networking.

Further insights on the secondary metabolites of a soft coral-derived fungus Aspergillus versicolor under the guidance of MS/MS-based molecular networking led to the isolation of seven known cycloheptapeptides, namely, asperversiamides A-C (1-3) and asperheptatides A-D (4-7) and an unusual pyrroloindoline-containing new cycloheptapeptide, asperpyrroindotide A (8). The structure of 8 was elucidated by comprehensive spectroscopic data analysis, and its absolute configuration was determined by advanced Marfey's method. The semisynthetic transformation of 1 into 8 was successfully achieved and the reaction conditions were optimized. Additionally, a series of new derivatives (10-19) of asperversiamide A (1) was semi-synthesized and their anti-tubercular activities were evaluated against Mycobacterium tuberculosis H37Ra. The preliminary structure-activity relationships revealed that the serine hydroxy groups and the tryptophan residue are important to the activity. Supplementary Information: The online version contains supplementary material available at 10.1007/s42995-022-00157-8.