Butyrolactone I derivatives from Aspergillus terreus carrying an unusual sulfate moiety

C-4-Modified Isotetrones Prevent Biofilm Growth and Persister Cell Resuscitation in Mycobacterium smegmatis

Hyperphosphorylated nucleotide (p)ppGpp, synthesized by Rel protein, regulates the stringent response pathway responsible for biofilm and persister cell growth in mycobacteria. The discovery of vitamin C as an inhibitor of Rel protein activities raises the prospect of tetrone lactones to prevent such pathways. The closely related isotetrone lactone derivatives are identified herein as inhibitors of the above processes in a mycobacterium. Synthesis and biochemical evaluations show that an isotetrone possessing phenyl substituent at C-4 inhibit the biofilm formation at 400 μg mL^-1, 84 h post-exposure, followed by moderate inhibition by the isotetrone possessing the p-hydroxyphenyl substituent. The latter isotetrone inhibits the growth of persister cells at 400 μg mL^-1 f.c. when monitored for 2 weeks, under PBS starvation. Isotetrones also potentiate the inhibition of antibiotic-tolerant regrowth of cells by ciprofloxacin (0.75 μg mL^-1) and thus act as bioenhancers. Molecular dynamics studies show that isotetrone derivatives bind to the Rel_Msm protein more efficiently than vitamin C at a binding site possessing serine, threonine, lysine, and arginine.

Unearthing the fungal endophyte Aspergillus terreus for chemodiversity and medicinal prospects: a comprehensive review

Aspergillus terreus microorganism represents a promising prospective source for drug discovery since it is rich in diverse kinds of bioactive secondary metabolites. It contributed to many biotechnological applications and its metabolites are used in the synthesis of certain pharmaceuticals and food products, in addition to its useful uses in fermentation processes. There are about 346 compounds identified from marine and terrestrial-derived A. terreus from 1987 until 2022, 172 compounds of them proved a vast array of bioactivity. This review aimed to create an up-to-date comprehensive literature data of A. terreus's secondary metabolites classes supported by its different bioactivity data to be a scientific record for the next work in drug discovery.

Cdk5-p25 as a key element linking amyloid and tau pathologies in Alzheimer's disease: Mechanisms and possible therapeutic interventions

Despite the fact that the small atypical serine/threonine cyclin-dependent kinase 5 (Cdk5) is expressed in a number of tissues, its activity is restricted to the central nervous system due to the neuron-only localization of its activators p35 and p39. Although its importance for the proper development and function of the brain and its role as a switch between neuronal survival and death are unmistakable and unquestionable, Cdk5 is nevertheless increasingly emerging, as supported by a large number of publications on the subject, as a therapeutic target of choice in the fight against Alzheimer's disease. Thus, its aberrant over activation via the calpain-dependent conversion of p35 into p25 is observed during the pathogenesis of the disease where it leads to the hyperphosphorylation of the β-amyloid precursor protein and tau. The present review highlights the pivotal roles of the hyperactive Cdk5-p25 complex activity in contributing to the development of Alzheimer's disease pathogenesis, with a particular emphasis on the linking function between Aβ and tau that this kinase fulfils and on the fact that Cdk5-p25 is part of a deleterious feed forward loop giving rise to a molecular machinery runaway leading to AD pathogenesis. Additionally, we discuss the advances and challenges related to the possible strategies aimed at specifically inhibiting Cdk5-p25 activity and which could lead to promising anti-AD therapeutics.

γ-Aromatic Butenolides of Microbial Source - A Review of Their Structures, Biological Activities and Biosynthesis

γ-Aromatic butenolides (γ-AB) are an important type of structures found in many bioactive microbial secondary metabolites (SMs). γ-AB refer to a group of natural products (NPs) containing five-membered (unsaturated) lactones with 3-phenyl and 4-benzyl substituents. Their wide-range biological activities have inspired pharmaceutical chemists to explore its biosynthesis mechanisms and design strategies to construct the γ-AB skeleton. Recently, there are a great deal of interesting research progress on the structures, biological activities and biosynthesis of γ-AB. This review will focus on these aspects and summarize the important achievements of γ-AB from 1975 to 2021.

Anti-Inflammatory, Antiallergic and COVID-19 Main Protease (Mpro) Inhibitory Activities of Butenolides from a Marine-Derived Fungus Aspergillus costaricaensis

Amid the current COVID-19 pandemic, the emergence of several variants in a relatively high mutation rate (twice per month) strengthened the importance of finding out a chemical entity that can be potential for developing an effective medicine. In this study, we explored ethyl acetate (EtOAc) extract of a marine-derived fungus Aspergillus cosatricaensis afforded three butenolide derivatives, butyrolactones I, VI and V (1-3), two naphtho-γ-pyrones, TMC-256 A1 (4) and rubrofusarin B (5) and methyl p-hydroxyphenyl acetate (6). Structure identification was unambiguously determined based on exhaustive spectral analyses including 1D/2D NMR and mass spectrometry. The isolated compounds (1-6) were assessed for their in vitro anti-inflammatory, antiallergic, elastase inhibitory activities and in silico SARS-CoV-2 main protease (Mpro). Results exhibited that only butenolides (1 and 2) revealed potent activities similar to or more than reference drugs unlike butyrolactone V (3) suggesting them as plausible chemical entities for developing lead molecules.

Discovery of GOT1 Inhibitors from a Marine-Derived Aspergillus terreus That Act against Pancreatic Ductal Adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) is a devastating digestive system carcinoma with high incidence and death rates. PDAC cells are dependent on the Gln metabolism, which can preferentially utilize glutamic oxaloacetate transaminase 1 (GOT1) to maintain the redox homeostasis of cancer cells. Therefore, small molecule inhibitors targeting GOT1 can be used as a new strategy for developing cancer therapies. In this study, 18 butyrolactone derivatives (1–18) were isolated from a marine-derived Aspergillus terreus, and asperteretone B (5), aspulvinone H (AH, 6), and (+)-3′,3′-di-(dimethylallyl)-butyrolactone II (12) were discovered to possess significant GOT1-inhibitory activities in vitro, with IC₅₀ values of (19.16 ± 0.15), (5.91 ± 0.04), and (26.38 ± 0.1) µM, respectively. Significantly, the molecular mechanism of the crystal structure of GOT1–AH was elucidated, wherein AH and the cofactor pyrido-aldehyde 5-phosphate competitively bound to the active sites of GOT1. More importantly, although the crystal structure of GOT1 has been discovered, the complex structure of GOT1 and its inhibitors has never been obtained, and the crystal structure of GOT1–AH is the first reported complex structure of GOT1/inhibitor. Further in vitro biological study indicated that AH could suppress glutamine metabolism, making PDAC cells sensitive to oxidative stress and inhibiting cell proliferation. More significantly, AH exhibited potent in vivo antitumor activity in an SW1990-cell-induced xenograft model. These findings suggest that AH could be considered as a promising lead molecule for the development of anti-PDAC agents.

Exploring natural microbial resources for the discovery of anti-malarial compounds

Microorganisms in nature are highly diverse biological resources, which can be explored for drug discovery. Some countries including Brazil, Columbia, Indonesia, China, and Mexico, which are blessed with geographical uniqueness with diverse climates and display remarkable megabiodiversity, potentially provide microorganismal resources for such exploitation. In this review, as an example of drug discovery campaigns against tropical parasitic diseases utilizing microorganisms from such a megabiodiversity country, we summarize our past and on-going activities toward discovery of new antimalarials. The program was held in a bilateral collaboration between multiple Indonesian and Japanese research groups. In order to develop a new platform of drug discovery utilizing Indonesian bioresources under an international collaborative scheme, we aimed at: 1) establishment of an Indonesian microbial depository, 2) development of robust enzyme-based and cell-based screening systems, and 3) technology transfer necessary for screening, purification, and identification of antimalarial compounds from microbial culture broths. We collected, characterized, and deposited Indonesian microbes. We morphologically and genetically characterized fungi and actinomycetes strains isolated from 5 different locations representing 3 Indonesian geographical areas, and validated genetic diversity of microbes. Enzyme-based screening was developed against two validated mitochondrial enzymes from Plasmodium falciparum, dihydroorotate dehydrogenase and malate:quinone oxidoreductase, while cell-based proliferation assay was developed using the erythrocytic stage parasite of 3D7 strain. More than 17 thousands microbial culture extracts were subjected to the enzyme- and cell-based screening. Representative anti-malarial compounds discovered in this campaign are discussed, including a few isolated compounds that have been identified for the first time as anti-malarial compounds. Our antimalarial discovery campaign validated the Indonesian microbial library as a powerful resource for drug discovery. We also discuss critical needs for selection criteria for hits at each stage of screening and hit deconvolution such as preliminary extraction test for the initial profiling of the active compounds and dereplication techniques to minimize repetitive discovery of known compounds.

Anti-Inflammatory, Antiallergic, and COVID-19 Main Protease (Mpro) Inhibitory Activities of Butenolides from a Marine-Derived Fungus Aspergillus terreus

In December 2020, the U.K. authorities reported to the World Health Organization (WHO) that a new COVID-19 variant, considered to be a variant under investigation from December 2020 (VUI-202012/01), was identified through viral genomic sequencing. Although several other mutants were previously reported, VUI-202012/01 proved to be about 70% more transmissible. Hence, the usefulness and effectiveness of the newly U.S. Food and Drug Administration (FDA)-approved COVID-19 vaccines against these new variants are doubtfully questioned. As a result of these unexpected mutants from COVID-19 and due to lack of time, much research interest is directed toward assessing secondary metabolites as potential candidates for developing lead pharmaceuticals. In this study, a marine-derived fungus Aspergillus terreus was investigated, affording two butenolide derivatives, butyrolactones I (1) and III (2), a meroterpenoid, terretonin (3), and 4-hydroxy-3-(3-methylbut-2-enyl)benzaldehyde (4). Chemical structures were unambiguously determined based on mass spectrometry and extensive 1D/2D NMR analyses experiments. Compounds (1-4) were assessed for their in vitro anti-inflammatory, antiallergic, and in silico COVID-19 main protease (Mpro) and elastase inhibitory activities. Among the tested compounds, only 1 revealed significant activities comparable to or even more potent than respective standard drugs, which makes butyrolactone I (1) a potential lead entity for developing a new remedy to treat and/or control the currently devastating and deadly effects of COVID-19 pandemic and elastase-related inflammatory complications.

Production of Terretonin N and Butyrolactone I by Thermophilic Aspergillus terreus TM8 Promoted Apoptosis and Cell Death in Human Prostate and Ovarian Cancer Cells

The anticancer activity of terretonin N (1) and butyrolactone I (2), obtained from the thermophilic fungus Aspergillus terreus TM8, was intensively studied against prostate adenocarcinoma (PC-3) and ovary adenocarcinoma (SKOV3) human cell lines. According to this study, both compounds showed potent cytotoxicity towards ovarian adenocarcinoma cells (SKOV3) with IC₅₀ 1.2 and 0.6 μg/mL, respectively. With respect to metastatic prostate cells (PC-3), the two compounds 1 and 2 showed a significantly promising cytotoxicity effect with IC₅₀ of 7.4 and 4.5 μg/mL, respectively. The tested fungal metabolites showed higher rates of early and late apoptosis with little or no necrotic apoptotic pathway in all treated prostate adenocarcinoma (PC-3) and ovary adenocarcinoma (SKOV3) human cell lines, respectively. The results reported in this study confirmed the promising biological properties of terretonin N (1) and butyrolactone I (2) as anticancer agents via the induction of cellular apoptosis. However, further studies are needed to elucidate the molecular mechanism by which cellular apoptosis is induced in cancer cells.

Screening of potent phytochemical inhibitors against SARS-CoV-2 protease and its two Asian mutants

Background

COVID-19, declared a pandemic in March 2020 by the World Health Organization is caused by Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2). The virus has already killed more than 2.3 million people worldwide.

Object

The principal intent of this work was to investigate lead compounds by screening natural product library (NPASS) for possible treatment of COVID-19.

Methods

Pharmacophore features were used to screen a large database to get a small dataset for structure-based virtual screening of natural product compounds. In the structure-based screening, molecular docking was performed to find a potent inhibitor molecule against the main protease (M^pro) of SARS-CoV-2 (PDB ID: 6Y7M). The predicted lead compound was further subjected to Molecular Dynamics (MD) simulation to check the stability of the leads compound with the evolution of time.

Results

In pharmacophore-based virtual screening, 2,361 compounds were retained out of 30,927. In the structure-based screening, the lead compounds were filtered based on their docking scores. Among the 2,360 compounds, 12 lead compounds were selected based on their docking score. Kazinol T with NPASS ID: NPC474104 showed the highest docking score of −14.355 and passed criteria of Lipinski's drug-like parameters. Monitoring ADMET properties, Kazinol T showed its safety for consumption. Docking of Kazinol T with two Asian mutants (R60C and I152V) showed variations in binding and energy parameters. Normal mode analysis for ligand-bound and unbound form of protease along with its mutants, revealed displacement and correlation parameters for C-alpha atoms. MD simulation results showed that all ligand-protein complexes remained intact and stable in a dynamic environment with negative Gibbs free energy.

Conclusions

The natural product Kazinol T was a predicted lead compound against the main protease of SARS-CoV-2 and will be the possible treatment for COVID-19.

Cyclin-Dependent Kinase 5 Inhibitor Butyrolactone I Elicits a Partial Agonist Activity of Peroxisome Proliferator-Activated Receptor γ

Adiponectin is an adipocyte-derived cytokine having an insulin-sensitizing activity. During the phenotypic screening of secondary metabolites derived from the marine fungus Aspergillus terreus, a poly cyclin-dependent kinase (CDK) inhibitor butyrolactone I affecting CDK1 and CDK5 was discovered as a potent adiponectin production-enhancing compound in the adipogenesis model of human bone marrow-derived mesenchymal stem cells (hBM-MSCs). CDK5 inhibitors exhibit insulin-sensitizing activities by suppressing the phosphorylation of peroxisome proliferator-activated receptor γ (PPARγ). However, the adiponectin production-enhancing activities of butyrolactone I have not been correlated with the potency of CDK5 inhibitor activities. In a target identification study, butyrolactone I was found to directly bind to PPARγ. In the crystal structure of the human PPARγ, the ligand-binding domain (LBD) in complex with butyrolactone I interacted with the amino acid residues located in the hydrophobic binding pockets of the PPARγ LBD, which is a typical binding mode of the PPARγ partial agonists. Therefore, the adiponectin production-enhancing effect of butyrolactone I was mediated by its polypharmacological dual modulator activities as both a CDK5 inhibitor and a PPARγ partial agonist.

Anti-prion Butenolides and Diphenylpropanones from the Australian Ascidian Polycarpa procera

A library of 500 Australian marine invertebrate extracts was screened for anti-prion activity using a yeast-based assay, and this resulted in an extract from the ascidian Polycarpa procera showing potent activity. Purification of this extract led to the isolation of six new butenolide metabolites, the procerolides 1-4 and two related diphenylpropanones, the procerones 5 and 6, as the bioactive components. The structures of 1-6 were elucidated from the analysis of 1D/2D NMR and MS data, and their absolute configurations determined from comparison of experimental and computed ECD data. Compounds 1-6 were tested for anti-prion activity in a yeast-based assay, and 1 and 5 displayed potent bioactivity (EC₅₀ of 23 and 29 μM, respectively) comparable to the potently active anti-prion compound guanabenz. The procerolides and procerones are the first anti-prion compounds to be reported from ascidians, indicating that ascidians may be an untapped source of new lead anti-prion compounds.

Butyrolactone-I, an efficient α-glucosidase inhibitor, improves type 2 diabetes with potent TNF-α-lowering properties through modulating gut microbiota in db/db mice

The aim of this study was to evaluate the effects of butyrolactone-I (A6) on type 2 diabetes (T2D) in db/db mice because A6 was found to inhibit α-glucosidase activities and TNF-α release, which were associated with improving T2D. Male db/db mice were divided into 6 groups and given an equivalent volume of olive oil, acarbose, or different doses of A6 for 4 wk (n = 8/group). In this study, 11 butenolide derivatives were screened for their α-glucosidase and TNF-α suppressive activity in vitro. A6, an efficient α-glucosidase inhibitor, exerts hypoglycemic and multiple activities in reducing weight, improving glucose tolerance and insulin resistance, increasing short-chain fatty acid (SCFA) levels, activating SCFA-induced increases in glucagon-like peptide 1 and peroxisome proliferator-activated receptor-γ expression, enhancing intestinal mucosal barrier function and mitigating endoxemia in db/db mice. These effects may result from mediation of gut microbiota by A6. Meanwhile, A6, with potent TNF-α-lowering properties, was demonstrated to have multiple salutary effects with excellent structural stability and long-term safety in vivo. A6, an effective α-glucosidase inhibitor with high security and stability, exerted potent antidiabetic effects in vivo. Furthermore, the modulation of gut microbiota of A6 was demonstrated to be one of the mechanisms contributing to anti-inflammation properties and improving endoxemia. Our work confirms that the compound A6 is a prospective drug candidate for T2D.-Wu, W., Liu, L., Zhu, H., Sun, Y., Wu, Y., Liao, H., Gui, Y., Li, L., Liu, L., Sun, F., Lin, H. Butyrolactone-I, an efficient α-glucosidase inhibitor, improves type 2 diabetes with potent TNF-α-lowering properties through modulating gut microbiota in db/db mice.

Recent Advances on Metal-Free, Visible-Light- Induced Catalysis for Assembling Nitrogen- and Oxygen-Based Heterocyclic Scaffolds

Heterocycles are important class of structures, which occupy a major space in the domain of natural and bioactive compounds. For this reason, development of new synthetic strategies for their controllable synthesis became of special interests. The development of novel photoredox systems with wide-range application in organic synthesis is particularly interesting. Organic dyes have been widely applied as photoredox catalysts in organic synthesis. Their low costs compared to the typical photocatalysts based on transition metals make them an excellent alternative. This review describes proceedings since 2015 in the area of application of metal-free, visible-light-mediated catalysis for assembling various heterocyclic scaffolds containing five- and six-membered rings bearing nitrogen and oxygen heteroatoms.

Water enables an asymmetric cross reaction of α-keto acids with α-keto esters for the synthesis of quaternary isotetronic acids

A water promoted asymmetric aldol/lactonization/enolization cascade reaction of α-keto acids and α-keto esters affords chiral quaternary isotetronic acids with excellent enantioselectivity.

Butyrolactone-I from Coral-Derived Fungus Aspergillus terreus Attenuates Neuro-Inflammatory Response via Suppression of NF-κB Pathway in BV-2 Cells

Butyrolactone-I (ZB5-1) from the coral-derived fungus Aspergillus terreus was investigated in this study to estimate its anti-neuroinflammatory effects on lipopolysaccharide (LPS)-induced BV-2 microglia cells. MTT assay indicated that ZB5-1 in tested concentrations had no cytotoxicity on BV-2 cells, and significantly reduced the production of nitric oxide (NO), measured using Griess reagent, and interleukin-1 beta (IL-1β), detected by enzyme-linked immunosorbent assay (ELISA). ZB5-1 also down-regulated the expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) in a dose-dependent manner by Western blot analysis. Moreover, the effect of ZB5-1 on the nuclear factor-κB (NF-κB) signaling pathway was studied via the expression of phosphorylation of NF-κB p65 and inhibitor of NF-κB (IκB), and the nuclear translocation of NF-κB p65 respectively. The results showed that ZB5-1 could inhibit the phosphorylation of p65 and IκB. Furthermore, molecular docking study suggested that ZB5-1 bound at the active sites of NF-κB to prevent its translocation to the nucleus. Therefore, we suggest ZB5-1 has a potential to reduce the anti-inflammatory response in LPS-induced BV-2 cells.

Dereplication and targeted isolation of bioactive sulphur compound from bacteria isolated from a hydrothermal field

Marine micro-organisms in the deep-sea hydrothermal vent systems are considered as potential sources of bioactive natural products. Sixteen bacterial strains were isolated from a deep-sea hydrothermal field and screened for bioactive metabolism studies. After the strains were subjected to bioactive testing at different culture media, chemical dereplication by HPLC coupled to high-resolution mass spectrometer was performed to analyse or determine the main secondary metabolisms in those strains. Strain 06204 was large-scale fermented with relative optimal media, for isolating the desired sulphur compound. Butyrolactone I 3-sulphate was isolated and structurally identified from the extract, guided by dereplication and showed moderate antivirus activities against H3N2 and EV71 viruses. Our study suggests that deep-sea hydrothermal bacteria are good sources of sulphur natural products. Meanwhile, the described approach, mainly bioactive screening, dereplication and targeted isolation, is effective and efficient to discover interesting bioactive compounds in hydrothermal bacteria.

Phenylisotertronic acids from the TCM endophytic fungus Phyllosticta sp

Four new phenylisotertronic acids (1a/1b, 2a, and 3a) were isolated from a TCM endophytic fungal strain Phyllosticta sp. J13-2-12Y obtained from the leaves of Acorus tatarinowii, along with two known ones (2b and 3b). Compounds 1-3 all existed as mixtures of enantiomers, and their corresponding optically pure enantiomers were successfully isolated by chiral HPLC. The structures of isolated compounds were determined by comprehensive spectroscopic analyses and X-ray diffraction. Their absolute configurations were determined by ECD experiments and quantum chemical calculations. In addition, the antimicrobial activities and the cytotoxicities of these three pairs of optically pure enantiomers (1a/1b, 2a/2b, and 3a/3b) had been evaluated.

γ-Butyrolactones from Aspergillus Species: Structures, Biosynthesis, and Biological Activities

Recently, numerous metabolites possessing uncommon structures and potent bioactivity have been isolated from strains of fungi collected from diverse environments. The genus Aspergillus is known as a rich source of γ-butyrolactones. These are a group of fungal secondary metabolites, consisting of a five-membered lactone bearing two aromatic rings, which shows a great variety of biological activities. This review summarizes the research on the biosynthesis, source, and biological activities of the naturally occurring γ-butyrolactones that have been isolated from Aspergillus species published over the last decades. More than 75 compounds are described and 65 references are cited.

Bioactive compounds of Aspergillus terreus-F7, an endophytic fungus from Hyptis suaveolens (L.) Poit

The compounds terrein (1), butyrolactone I (2), and butyrolactone V (3) were isolated from the ethyl acetate extract (EtOAc) of the endophytic fungus Aspergillus terreus-F7 obtained from Hyptis suaveolens (L.) Poit. The extract and the compounds presented schistosomicidal activity against Schistosoma mansoni; at 100 µg/mL for EtOAc extract, 1297.3 µM for compound 1, 235.6 µM for compound 2, and 454.1 µM for compound 3, they killed 100% of the parasites after 72 h of treatment. Compounds 1, 2, and 3 exerted moderate leishmanicidal activity against Leishmania amazonensis (IC₅₀ ranged from 23.7 to 78.6 µM). At 235.6 and 227.0 µM, compounds 2 and 3, respectively, scavenged 95.92 and 95.12% of the DPPH radical (2,2-diphenyl-1-picryl-hydrazyl), respectively. Regarding the cytotoxicity against the breast tumor cell lines MDA-MB-231 and MCF-7, compound 2 gave IC₅₀ of 34.4 and 17.4 µM, respectively, while compound 3 afforded IC₅₀ of 22.2 and 31.9 µM, respectively. At 117.6 µM, compound 2 inhibited the growth of and killed the pathogen Escherichia coli (ATCC 25922). Compounds 1, 2, and 3 displayed low toxicity against the normal line of human lung fibroblasts (GM07492A cells), with IC₅₀ of 15.3 × 10³, 3.4 × 10³, and 5.8 × 10³ µM, respectively. This is the first report on (i) the in vitro schistosomicidal and leishmanicidal activities of the EtOAc extract of A. terreus-F7 and compounds 1, 2, and 3; and (ii) the antitumor activity of compounds 2 and 3 against MDA-MB-231 and MCF-7 cells.

Butenolide derivatives from the plant endophytic fungus Aspergillus terreus

Three new butenolides containing 5-hydroxyfuran-2(5H)-one core, asperteretal A (1), asperteretal B (2), and asperteretal C (3), together with seven known butenolides (4-10), were obtained from an endophytic fungus Aspergillus terreus PR-P-2 isolated from the plant Camellia sinensis var. assamica. The structures of compounds 1-3 were elucidated on the basis of detailed spectroscopic analysis including UV, IR, HRESIMS, 1D and 2D NMR, and ECD spectra. Compounds 1, 3, 5 and 6-8 showed potent inhibitory effects on NO production in RAW 264.7 lipopolysaccharide-induced macrophages, and compounds 5 and 8 also exhibited moderate cytotoxicity against HL-60 cell line.

γ-Butyrolactone, cytochalasin, cyclic carbonate, eutypinic acid, and phenalenone derivatives from the soil fungus Aspergillus sp. PSU-RSPG185

Purification of an extract from the broth of the soil fungus Aspergillus sp. PSU-RSPG185 resulted in the isolation of two new cyclic carbonate derivatives, aspergillusols A (1) and B (2), and one new eutypinic acid derivative, aspergillusic acid (3), along with six known secondary metabolites. Compounds 1 and 2 contain an unusual cyclic-carbonate functionality. In addition, the mycelial extract afforded two new phenalenones, aspergillussanones A (4) and B (5), one new cytochalasin, aspergilluchalasin (6), and one new γ-butyrolactone, aspergillulactone (7). Their structures were established by interpretation of spectroscopic evidence. Compound 4 exhibited weak activity toward KB and Vero cells with IC50 values of 48.4 and 34.2 μM, respectively.

Computational & experimental evaluation of the structure/activity relationship of β-carbolines as DYRK1A inhibitors

DYRK1A has been associated with Down's syndrome and neurodegenerative diseases, therefore it is an important target for novel pharmacological interventions. We combined a ligand-based pharmacophore design with a structure-based protein/ligand docking using the software MOE in order to evaluate the underlying structure/activity relationship. Based on this knowledge we synthesized several novel β-carboline derivatives to validate the theoretical model. Furthermore we identified a modified lead structure as a potent DYRK1A inhibitor (IC50=130 nM) with significant selectivity against MAO-A, DYRK2, DYRK3, DYRK4 & CLK2.

New phenyl derivatives from endophytic fungus Aspergillus flavipes AIL8 derived of mangrove plant Acanthus ilicifolius

Two new aromatic butyrolactones, flavipesins A (1) and B (2), two new natural products (3 and 4), and a known phenyl dioxolanone (5) were isolated from marine-derived endophytic fungus Aspergillus flavipes. The structures of compounds 1-5 were elucidated by 1D- and 2D-NMR and MS analysis, the absolute configurations were assigned by optical rotation and CD data, and the stereochemistry of 1 was determined by X-ray crystallography analysis. 1 demonstrated lower MIC values against Staphylococcus aureus (8.0 μg/mL) and Bacillus subtillis (0.25 μg/mL). 1 also showed the unique antibiofilm activity of penetration through the biofilm matrix and kills live bacteria inside mature S. aureus biofilm.

Potential neuroprotective flavonoid-based inhibitors of CDK5/p25 from Rhus parviflora

Rhus parviflora (Anacardiaceae) is an indigenous medicinal shrub found in South Asia with flavonoid rich edible fruit. This study examined flavonoid derivatives of R. parviflora fruit with CDK5/p25 inhibition activity. Evaluation by in vitro assay and docking simulations for CDK5/p25 revealed that the aurones, sulfuretin (1) and aureusidin (2), the aurone glycoside, aureusidin-6-O-β-D-glucopyranoside (3) and hovetrichoside C (4), the flavonoid glycoside, quercetin-3-O-β-D-galactopyranoside (5), and the biflavonoid, cupressuflavone (6), had the potential to inhibit CDK5/p25, which could be useful in the treatment of neurodegenerative disorders such as Alzheimer's disease. Compound2 showed the significant in vitro inhibition capacity (IC50 value of 4.81 μM) as well as binding affinity with docking energy of -8.73 (kcal/mol) for active sites CYS83 and GLN130 of CDK5/p25 enzyme in comparison to reference compound R-roscovitine.

Titration-based screening for evaluation of natural product extracts: identification of an aspulvinone family of luciferase inhibitors

The chemical diversity of nature has tremendous potential for the discovery of molecular probes and medicinal agents. However, sensitivity of HTS assays to interfering components of crude extracts derived from plants, and macro- and microorganisms has curtailed their use in lead discovery. Here, we describe a process for leveraging the concentration-response curves obtained from quantitative HTS to improve the initial selection of "actives" from a library of partially fractionated natural product extracts derived from marine actinomycetes and fungi. By using pharmacological activity, the first-pass CRC paradigm improves the probability that labor-intensive subsequent steps of reculturing, extraction, and bioassay-guided isolation of active component(s) target the most promising strains and growth conditions. We illustrate how this process identified a family of fungal metabolites as potent inhibitors of firefly luciferase, subsequently resolved in molecular detail by X-ray crystallography.

Isoflavones with unusually modified B-rings and their evaluation as antiproliferative agents

Six novel isoflavone derivatives along with four known isoflavones were isolated from a culture of a highly nickel-resistant strain of Streptomyces mirabilis from a former uranium mining area. The structures of 7-hydroxy-3',5'-dihydroxyisoflavone (5), 5,7-dihydroxy-3',5'-dihydroxyisoflavone (6), 2'-hydroxy-3'-methoxygenistein (7), as well as hydroisoflavones A-C (8-10) were elucidated by MS and NMR analyses. Compounds 8-10 feature yet unprecedented types of non-aromatic, hydroxylated B rings, which result from plant isoflavone biotransformation. All new compounds display weak cytotoxic but potent antiproliferative activities. The anti-oestrogenic properties of 8 against MCF-7 human breast cancer cell line (GI(50): 6 microM) is even higher than the reference compound genistein.

Aspernolides A and B, butenolides from a marine-derived fungus Aspergillus terreus

Two aromatic butenolides, aspernolides A and B along with the known metabolites, butyrolactone I, terrein and physcion were isolated from the fermentation broth of a soft coral derived fungus Aspergillus terreus. The structures of these metabolites were assigned on the basis of detailed spectroscopic analysis. The absolute stereochemistry of aspernolides A (1) and B (2) was established by their preparation from the known butyrolactone I. Biogenetically aspernolides A and B must be derived from butyrolactone I, a well known specific inhibitor of cyclin dependent kinase (cdk) from A. terreus. When tested, aspernolide A exhibited mild cytotoxicity against cancer cell lines.