Bioactive Indolyl Diketopiperazines from the Marine Derived Endophytic Aspergillus versicolor DY180635

Recent Discovery of Nitrogen Heterocycles from Marine-Derived Aspergillus Species

Nitrogen heterocycles have drawn considerable attention because of their structurally novel and significant biological activities. Marine-derived fungi, especially the Aspergillus species, possess unique metabolic pathways to produce secondary metabolites with novel structures and potent biological activities. This review prioritizes the structural diversity and biological activities of nitrogen heterocycles that are produced by marine-derived Aspergillus species from January 2019 to January 2024, and their relevant biological activities. A total of 306 new nitrogen heterocycles, including seven major categories-indole alkaloids, diketopiperazine alkaloids, quinazoline alkaloids, isoquinoline alkaloids pyrrolidine alkaloids, cyclopeptide alkaloids, and other heterocyclic alkaloids-are presented in this review. Among these nitrogen heterocycles, 52 compounds had novel skeleton structures. Remarkably, 103 compounds showed various biological activities, such as cytotoxic, antimicrobial, anti-inflammatory, antifungal, anti-virus, and enzyme-inhibitory activities, and 21 compounds showed potent activities. This paper will guide further investigations into the structural diversity and biological activities of nitrogen heterocycles derived from the Aspergillus species and their potential contributions to the future development of new natural drug products in the medicinal and agricultural fields.

The potential of marine-derived piperazine alkaloids: Sources, structures and bioactivities

Marine-derived piperazine alkaloids (MDPAs) constitute a significant group of natural compounds known for their diverse structures and biological activities. Over the past five decades, substantial efforts have been devoted to isolating these alkaloids from marine sources and characterizing their chemical and bioactive profiles. To date, a total of 922 marine-derived piperazine alkaloids have been reported from various marine organisms. These compounds demonstrate a wide range of pharmacological properties, including cytotoxicity, antibacterial, antifungal, antiviral, and various other activities. Notably, among these activities, cytotoxicity emerges as the most prominent characteristic of marine-derived piperazine alkaloids. This review also summarizes the structure-activity relationship (SAR) studies associated with the cytotoxicity of these compounds. In summary, our objective is to provide an overview of the research progress concerning marine-derived piperazine alkaloids, with the aim of fostering their continued development and utilization.

Four previously undescribed diketopiperazines from marine fungus Aspergillus puniceus FAHY0085 and their effects on liver X receptor α

Four previously undescribed diketopiperazine-type alkaloids including one oxepin-containing diketopiperazine-type alkaloid, oxepinamide L (1), three 4-quinazolinone alkaloids, puniceloids E-G (10-12), together with 12 known analogues, protuboxepin D (2), oxepinamides D-G, J-K and I (3-9), puniceloids B-D (13-15) and protubonine B (16), were isolated from the culture of the marine-derived fungus Aspergillus puniceus FAHY0085. The structures of the previously undescribed compounds were comprehensively elucidated by detailed interpretation of their NMR and HRESIMS data. Their absolute configurations were unambiguously determined by ROESY experiments, Marfey's method, calculated ECD experiments and single-crystal X-ray diffraction analysis. Compounds (3-4, 6-8, 14-15) were evaluated for their cytotoxic activity against HepG2, MCF-7, SW1116 and HeLa cells and compound 6 and 14 showed moderate cytotoxic activity against HeLa cells with IC50 49.61 ± 2.91 and 28.38 ± 1.57 μM, respectively. Compounds (1-8, 11-15) were screened for their transcriptional activation of liver X receptor α and compound 11 with known compounds 13-15 showed significant transcriptional activation of liver X receptor α with EC50 values in the range 2-50 μM.

The vital role of animal, marine, and microbial natural products against COVID-19

CONTEXT

Since the outbreak of SARS-CoV-2, researchers have been working on finding ways to prevent viral entry and pathogenesis. Drug development from naturally-sourced pharmacological constituents may be a fruitful approach to COVID-19 therapy.

OBJECTIVE

Most of the published literature has focussed on medicinal plants, while less attention has been given to biodiverse sources such as animal, marine, and microbial products. This review focuses on highlighting natural products and their derivatives that have been evaluated for antiviral, anti-inflammatory, and immunomodulatory properties.

METHODS

We searched electronic databases such as PubMed, Scopus, Science Direct and Springer Link to gather raw data from publications up to March 2021, using terms such as 'natural products', marine, micro-organism, and animal, COVID-19. We extracted a number of documented clinical trials of products that were tested in silico, in vitro, and in vivo which paid specific attention to chemical profiles and mechanisms of action.

RESULTS

Various classes of flavonoids, 2 polyphenols, peptides and tannins were found, which exhibit inhibitory properties against viral and host proteins, including 3CLpro, PLpro, S, hACE2, and NF-κB, many of which are in different phases of clinical trials.

DISCUSSION AND CONCLUSIONS

The synergistic effects of logical combinations with different mechanisms of action emphasizes their value in COVID19 management, such as iota carrageenan nasal spray, ermectin oral drops, omega-3 supplementation, and a quadruple treatment of zinc, quercetin, bromelain, and vitamin C. Though in vivo efficacy of these compounds has yet to be established, these bioproducts are potentially useful in counteracting the effects of SARS-CoV-2.

Fungal Load of Groundwater Systems in Geographically Segregated Islands: A Step Forward in Fungal Control

The fungal distribution, diversity, and load were analyzed in the geographically segregated island groundwater systems in Korea. A total of 79 fungal isolates were secured from seven islands and identified based on the internal transcribed spacer (ITS) sequences. They belonged to three phyla (Ascomycota, Basidiomycota, and Chlorophyta), five classes, sixteen orders, twenty-two families, and thirty-one genera. The dominant phylum was Ascomycota (91.1%), with most fungi belonging to the Cladosporium (21.5%), Aspergillus (15.2%), and Stachybotrys (8.9%) genera. Cladosporium showed higher dominance and diversity, being widely distributed throughout the geographically segregated groundwater systems. Based on the diversity indices, the genera richness (4.821) and diversity (2.550) were the highest in the groundwater system of the largest scale. As turbidity (0.064-0.462) increased, the overall fungal count increased and the residual chlorine (0.089-0.308) had low relevance compared with the total count and fungal diversity. Cladosporium showed normal mycelial growth in de-chlorinated sterilized samples. Overall, if turbidity increases under higher fungal diversity, bio-deterioration in groundwater-supplying facilities and public health problems could be intensified, regardless of chlorine treatment. In addition to fungal indicators and analyzing methods, physical hydrostatic treatment is necessary for monitoring and controlling fungal contamination.

Aspergilli series Versicolores: importance of species identification in the clinical setting

The moulds of the genus Aspergillus section Nidulantes series Versicolores are ubiquitous and particularly recurrent in indoor air. They are considered present in 70% of the bioaerosols to which we are exposed most of our time spent indoors. With the taxonomic revision proposed in 2012 and the discovery of four new species, the series Versicolores currently includes 18 species. These moulds, although considered as cryptic (except Aspergillus sydowii), are opportunistic pathogens that can exhibit increased minimal inhibitory concentrations to conventional antifungal agents. In this review, we discuss the ecology and clinical implications of each species belonging to the series Versicolores. This survey also highlights the lack of consideration for taxonomic revisions in clinical practice and in scientific studies which greatly limits the acquisition of specific knowledge on species belonging to the series Versicolores.

Natural bioactive compounds from marine fungi (2017-2020)

Secondary metabolites generated by marine fungi have relatively small molecular weights and excellent activities and have become an important source for developing drug lead compounds. The review summarizes the structures of novel small-molecule compounds derived from marine fungi in recent years; introduces representative monomers in antimicrobial, antitumor, anti-viral, and anti-neuritis aspects; and discusses their biological activities and molecular mechanisms. This review will act as a guide for further discovering marine-derived drugs with novel chemical structures and specific targeting mechanisms.

Marine natural products

Covering: 2020This review covers the literature published in 2020 for marine natural products (MNPs), with 757 citations (747 for the period January to December 2020) referring to compounds isolated from marine microorganisms and phytoplankton, green, brown and red algae, sponges, cnidarians, bryozoans, molluscs, tunicates, echinoderms, mangroves and other intertidal plants and microorganisms. The emphasis is on new compounds (1407 in 420 papers for 2020), together with the relevant biological activities, source organisms and country of origin. Pertinent reviews, biosynthetic studies, first syntheses, and syntheses that led to the revision of structures or stereochemistries, have been included. A meta analysis of bioactivity data relating to new MNPs reported over the last five years is also presented.

Mass spectrometry applied to diagnosis, prognosis, and therapeutic targets identification for the novel coronavirus SARS-CoV-2: A review

Mass spectrometry (MS) has found numerous applications in medicine and has been widely used in the detection and characterization of biomolecules associated with viral infections such as COVID-19. COVID-19 is a multisystem disease and, therefore, the need arises to carry out a careful and conclusive assessment of the pathophysiological parameters involved in the infection, to develop an effective therapeutic approach, assess the prognosis of the disease, and especially the early diagnosis of the infected population. Thus, the urgent need for highly accurate methods of diagnosis and prognosis of this infection presents new challenges for the development of laboratory medicine, whose methods require sensitivity, speed, and accuracy of the techniques for analyzing the biological markers involved in the infection. In this context, MS stands out as a robust analytical tool, with high sensitivity and selectivity, accuracy, low turnaround time, and versatility for the analysis of biological samples. However, it has not yet been adopted as a frontline clinical laboratory technique. Therefore, this review explores the potential and trends of current MS methods and their contribution to the development of new strategies to COVID-19 diagnosis and prognosis and how this tool can assist in the discovery of new therapeutic targets, in addition, to comment what could be the future of MS in medicine.

Cyclic Dipeptides: The Biological and Structural Landscape with Special Focus on the Anti-Cancer Proline-Based Scaffold

Cyclic dipeptides, also know as diketopiperazines (DKP), the simplest cyclic forms of peptides widespread in nature, are unsurpassed in their structural and bio-functional diversity. DKPs, especially those containing proline, due to their unique features such as, inter alia, extra-rigid conformation, high resistance to enzyme degradation, increased cell permeability, and expandable ability to bind a diverse of targets with better affinity, have emerged in the last years as biologically pre-validated platforms for the drug discovery. Recent advances have revealed their enormous potential in the development of next-generation theranostics, smart delivery systems, and biomaterials. Here, we present an updated review on the biological and structural profile of these appealing biomolecules, with a particular emphasis on those with anticancer properties, since cancers are the main cause of death all over the world. Additionally, we provide a consideration on supramolecular structuring and synthons, based on the proline-based DKP privileged scaffold, for inspiration in the design of compound libraries in search of ideal ligands, innovative self-assembled nanomaterials, and bio-functional architectures.

Structures and Biological Activities of Diketopiperazines from Marine Organisms: A Review

Diketopiperazines are potential structures with extensive biological functions, which have attracted much attention of natural product researchers for a long time. These compounds possess a stable six-membered ring, which is an important pharmacophore. The marine organisms have especially been proven to be a wide source for discovering diketopiperazine derivatives. In recent years, more and more interesting bioactive diketopiperazines had been found from various marine habitats. This review article is focused on the new 2,5-diketopiperazines derived from marine organisms (sponges and microorganisms) reported from the secondary half-year of 2014 to the first half of the year of 2021. We will comment their chemical structures, biological activities and sources. The objective is to assess the merit of these compounds for further study in the field of drug discovery.

Diketopiperazine Gels: New Horizons from the Self-Assembly of Cyclic Dipeptides

Cyclodipeptides (CDPs) or 2,5-diketopiperazines (DKPs) can exert a variety of biological activities and display pronounced resistance against enzymatic hydrolysis as well as a propensity towards self-assembly into gels, relative to the linear-dipeptide counterparts. They have attracted great interest in a variety of fields spanning from functional materials to drug discovery. This concise review will analyze the latest advancements in their synthesis, self-assembly into gels, and their more innovative applications.

Indole diketopiperazine alkaloids from the deep-sea-derived fungus Aspergillus sp. FS445

Twelve indole diketopiperazine alkaloids (1‒12) including four new ones aspechinulins A‒D (1, 3, 5 and 12) were isolated from the deep-sea-derived fungus Aspergillus sp. FS445. Their structures were elucidated through spectroscopic analysis and the absolute configurations were determined by analyzing the experimental ECD data as well as the quantum chemical calculations. Compounds 1, 3 and 5 represented the first examples of indole diketopiperazine derivatives constructing a C₅ unit at 11-NH through an imide linkage. The NO production inhibitory activity of the isolated compounds was evaluated and compounds 2‒5, 7 and 9 exhibited potential inhibitory activities against NO production with the IC₅₀ values in the range of 20 ∼ 90 µM.

Antibacterial Secondary Metabolites from Marine-Derived Fungus Aspergillus sp. IMCASMF180035

Four new secondary metabolites, including one spiro[anthracenone-xanthene] derivative aspergiloxathene A (1), one penicillide analogue, Δ^2′-1′-dehydropenicillide (2), and two new phthalide derivatives, 5-methyl-3-methoxyepicoccone (3) and 7-carboxy-4-hydroxy-6-methoxy-5-methylphthalide (4), together with four known compounds, yicathin C (5), dehydropenicillide (6), 3-methoxyepicoccone (7), 4-hydroxy-6-methoxy-5-methylphthalide (8), were identified from the marine-derived fungus Aspergillus sp. IMCASMF180035. Their structures were determined by spectroscopic data, including high-resolution electrospray ionization mass spectrometry (HRESIMS), 1D and 2D nuclear magnetic resonance (NMR) techniques. Compound 1 was identified as the first jointed molecule by xanthene and anthracenone moieties possessing an unprecedented carbon skeleton with spiro-ring system. All compounds were evaluated activities against Staphylococcus aureus, methicillin resistant S. aureus (MRSA), Escherichia coli, Escherichia faecium, Pseudomonas aeruginosa, and Helicobacter pylori. Compound 1 showed significant inhibitory effects against S. aureus and MRSA, with minimum inhibitory concentration (MIC) values of 5.60 and 22.40 µM. Compounds 2 and 6 exhibited potent antibacterial activities against H. pylori, with MIC values of 21.73 and 21.61 µM, respectively.

Bioactive Indole Diketopiperazine Alkaloids from the Marine Endophytic Fungus Aspergillus sp. YJ191021

Six new prenylated indole diketopiperazine alkaloids, asperthrins A–F (1–6), along with eight known analogues (7–14), were isolated from the marine-derived endophytic fungus Aspergillus sp. YJ191021. Their planar structures and absolute configurations were elucidated by HR-ESI-MS, 1D/2D NMR data, and time-dependent density functional theory (TDDFT)/ECD calculation. The isolated compounds were assayed for their inhibition against three agricultural pathogenic fungi, four fish pathogenic bacteria, and two agricultural pathogenic bacteria. Compound 1 exhibited moderate antifungal and antibacterial activities against Vibrioanguillarum, Xanthomonas oryzae pv. Oryzicola, and Rhizoctoniasolani with minimal inhibitory concentration (MIC) values of 8, 12.5, and 25 μg/mL, respectively. Furthermore, 1 displayed notable anti-inflammatory activity with IC₅₀ value of 1.46 ± 0.21 μM in Propionibacteriumacnes induced human monocyte cell line (THP-1).