New phenalenone derivatives from the Hawaiian volcanic soil-associated fungus Penicillium herquei FT729 and their inhibitory effects on indoleamine 2,3-dioxygenase 1 (IDO1).

Phenalenone derivatives sourced from fungi are polyketides that have attracted significant interest because of their diverse chemical structures and potential bioactivities. As part of our ongoing quest to discover novel natural products with biological properties from diverse natural resources, three unreported phenalenone derivatives (1-3), named ent-12-methoxyisoherqueinone (1), (-)-scleroamide (2), and (+)-scleroamide (3), together with four known phenalenone derivatives, ent-atrovenetinone (4), isoherqueinone (5), herqueinone (6), and ent-peniciherquinone (7) were isolated from the Hawaiian soil fungus Penicillium herquei FT729, collected on the Big Island, Hawaii. Compounds 2 and 3 were enantiomers, which were separated using a chiral-phase HPLC column, which provided optically pure compounds 2 and 3. The structures of the novel compounds were established by extensive spectroscopic analyses, including 1D and 2D NMR and high-resolution ESIMS. Their absolute configurations were determined using quantum chemical electronic circular dichroism (ECD) calculations. The inhibitory activity of the isolated compounds (1-7) against indoleamine 2,3-dioxygenase 1 (IDO1) was assessed. Compounds 1, 5-7 inhibited IDO1, with IC50 values of 32.59, 36.86, 19.05, and 24.18 µM, respectively. These findings demonstrated that the phenalenone derivatives 1 and 5-7, as IDO1 inhibitors, are promising anticancer immunotherapeutic agents.

Preliminary Studies of Antimicrobial Activity of New Synthesized Hybrids of 2-Thiohydantoin and 2-Quinolone Derivatives Activated with Blue Light.

Thiohydantoin and quinolone derivatives have attracted researchers' attention because of a broad spectrum of their medical applications. The aim of our research was to synthesize and analyze the antimicrobial properties of novel 2-thiohydantoin and 2-quinolone derivatives. For this purpose, two series of hybrid compounds were synthesized. Both series consisted of 2-thiohydantoin core and 2-quinolone derivative ring, however one of them was enriched with an acetic acid group at N3 atom in 2-thiohydantoin core. Antibacterial properties of these compounds were examined against bacteria: Staphylococcus aureus, Bacillus subtilis, Enterococcus faecalis, Escherichia coli, Pseudomonas aeruginosa, and Klebsiella pneumoniae. The antimicrobial assay was carried out using a serial dilution method to obtain the MIC. The influence of blue light irradiation on the tested compounds was investigated. The relative yield of singlet oxygen (1O2*, 1Δg) generation upon excitation with 420 nm was determined by a comparative method, employing perinaphthenone (PN) as a standard. Antimicrobial properties were also investigated after blue light irradiation of the suspensions of the hybrids and bacteria placed in microtitrate plates. Preliminary results confirmed that some of the hybrid compounds showed bacteriostatic activity to the reference Gram-positive bacterial strains and a few of them were bacteriostatic towards Gram-negative bacteria, as well. Blue light activation enhanced bacteriostatic effect of the tested compounds.

Phytochemical Profiling and Biological Testing of the Constituents of the Australian Plant Haemodorum brevisepalum.

Phytochemical profiling was undertaken on the crude extracts of the bulbs, stems, and the fruits of Haemodorum brevisepalum, to determine the nature of the chemical constituents present. This represents the first study to investigate the fruits of a species of Haemodorum. In total, 13 new and 17 previously reported compounds were isolated and identified. The new compounds were of the phenylphenalenone-type class, with a representative of a novel structural form, named tentatively "oxabenzochromenone" (1), a compound akin to an intermediate in a recently proposed phenylphenalenone metabolic network (2), seven new phenylphenalenones (4-10), four new phenylbenzoisochromenones (11-14), and a new phenylbenzoisochromenone derivative (18). The previously reported compounds identified were of the following structure classes: oxabenzochrysenone (3, 23-26), flavonol (15, 16), phenylbenzoisochromenone (17, 21, 22, 27-30), and phenylphenalenone (19, 20). Compounds 2-4, 6-9, 15-18, 21, 22, and 26 were subjected to antimicrobial evaluation with moderate activity observed against Staphylococcus aureus MRSA and slight activity against Pseudomonas aeruginosa and Candida albicans. Compounds 4, 6-9, 17, and 21 were also evaluated for anthelminthic activity against larvae of the blood-feeding parasitic nematode Haemonchus contortus.

Separation and configurational assignment of stereoisomeric phenalenones from the marine mangrove-derived fungus Penicillium herquei MA-370.

Eight phenalenone derivatives, including four new compounds, aceneoherqueinones A and B (1 and 2), (+)-aceatrovenetinone A (3a), and (+)-aceatrovenetinone B (3d), along with four known congeners, (-)-aceatrovenetinone A (3b), (-)-aceatrovenetinone B (3c), (-)-scleroderolide (4a), and (+)-scleroderolide (4b), were characterized from the marine mangrove-derived fungus Penicillium herquei MA-370. Among them, compounds 1 and 2 are rare phenalenone derivatives featuring cyclic ether unit between C-5 and C-2'. All of these compounds were subjected to chiral HPLC analysis, and the unstable stereoisomers 3a-3d, containing configurationally labile chirality centers, were characterized by online HPLC-ECD measurements supported with TDDFT-ECD calculations. The structures of these compounds were elucidated by detailed analysis of their NMR and mass spectroscopic data, and the absolute configuration of compound 1 was confirmed by X-ray diffraction analysis, while those of compounds 2 and 3a-3d were determined by TDDFT-ECD calculations of their ECD spectra. All of the isolated compounds were tested for the inhibitory activity against angiotensin-I-converting enzyme (ACE), and compounds 1 and 2 displayed activity with IC50 values 3.10 and 11.28 µM, respectively. The intermolecular interaction and potential binding sites of 1 and 2 with ACE were elaborated by molecular docking, showing that compound 1 bound well with ACE via hydrogen interactions with residues Ala261, Gln618, Trp621, and Asn624, while compound 2 interacted with residues Asp358 and Tyr360.

Herqueilenone A, a unique rearranged benzoquinone-chromanone from the Hawaiian volcanic soil-associated fungal strain Penicillium herquei FT729.

The study of a Hawaiian volcanic soil-associated fungal strain Penicillium herquei FT729 led to the isolation of one unprecedented benzoquinone-chromanone, herqueilenone A (1) and two phenalenone derivatives (2 and 3). Their structures were determined through extensive analysis of NMR spectroscopic data and gauge-including atomic orbital (GIAO) NMR chemical shifts and ECD calculations. Herqueilenone A (1) contains a chroman-4-one core flanked by a tetrahydrofuran and a benzoquinone with an acetophenone moiety. Plausible pathways for the biosynthesis of 1-3 are proposed. Compounds 2 and 3 inhibited IDO1 activity with IC50 values of 14.38 and 13.69 µM, respectively. Compounds 2 and 3 also demonstrated a protective effect against acetaldehyde-induced damage in PC-12 cells.

New phenalenone analogues with improved activity against Leishmania species.

The in vitro activity against Leishmania spp. of five novel designed compounds, phenalenone derivatives, is described in this study. Previous works have shown that some phenalenones present leishmanicidal activity, some of which could induce programmed cell death events in L. amazonensis parasites. In this research, we focused on the determination of the programmed cell death evidence by detecting the characteristic features of the apoptosis-like process, such as phosphatidylserine exposure and mitochondrial membrane potential, among others. The results showed that the new derivatives have comparable or better activity and selectivity than the commonly prescribed anti-leishmanial drug. This result was obtained by inducing stronger mitochondrial depolarization or more intense phosphatidylserine exposure than miltefosine, highlighting compound 8 with moreover 9-times better selectivity index. In addition, the new five molecules activated the apoptosis-like process in the parasite. All the signals observed were indicative of the death process that the parasites were undergoing.

Dimeric phenalenones from Talaromyces sp. (IQ-313) inhibit hPTP1B1-400: Insights into mechanistic kinetics from in vitro and in silico studies.

A critical biological event that contributes to the appearance and progress of cancer and diabetes is the reversible phosphorylation of proteins, a process controlled by protein tyrosine-kinases (PTKs) and protein tyrosine-phosphatases (PTPs). Within the PTPs, PTP1B has gained significant interest since it is a validated target in drug discovery. Indeed, several PTP1B inhibitors have been developed, from both, synthesis and natural products. However, none have been approved by the FDA, due to their poor selectivity and/or pharmacokinetic properties. One of the most significant challenges to the discovery of PTP1B inhibitors (in vitro or in silico) is the use of truncated structures (PTP1B1-300), missing valuable information about the mechanisms of inhibition, and selectivity of ligands. The present study describes the biochemical characterization of a full-length PTP1B (hPTP1B1-400), as well as the description of phenalenones 1-4 and ursolic acid (5) as allosteric modulators. Compounds 1-5 showed inhibitory potential on hPTP1B1-400, with IC50 values ranging from 12.7 to 82.1 µM. Kinetic studies showed that 1 and 5 behave as mixed and non-competitive inhibitors, respectively. Circular dichroism experiments confirmed that 1 and 5 induced conformational changes to hPTP1B1-400. Further insights into the structure of hPTP1B1-400 were obtained from a homology model, which pointed out that the C-terminus (residues 301-400) is highly disordered. Molecular docking with the homologated model suggested that compounds 1 and 3-5 bind to the C-terminal domain, likely inducing conformational changes on the protein. Docking positions of compounds 1, 4, and 5 were refined with molecular dynamics simulations. Importantly, these simulations confirmed the high flexibility of the C-terminus of hPTP1B1-400, as well as the changes to its rigidity when bound to 1, 4, and 5.

Structure-based design, synthesis, and evaluation of Bcl-2/Mcl-1 dual inhibitors.

Based on our previously reported Bcl-2/Mcl-1 dual inhibitor 4-thiomorpholinyl-2-cyano-3-amidinophenalenone (A1) that simultaneously occupies the p2 and p4 hydrophobic pockets of Bcl-2 and Mcl-1, we optimized molecules with different bond angles of the groups extending to the p4 pocket and bulky hydrophobic groups to explore p2. Research on structure-activity relationship resulted in a new derivative B4 that is capable of occupying both the p2 and p4 more deeply and completely than A1, with Ki values determined by fluorescence polarization assay (FPAs) improving to 0.31 µM for Bcl-2 and 0.16 µM for Mcl-1. Furthermore, B4 exhibited selective lethality on cancer cells over normal cells. It showed stronger apoptosis induction than (-)-gossypol on a Bcl-2/Mcl-1-dependent cancer cell line and killed an Mcl-1-dependent cell line which is resistant to ABT-199 treatment.

Trypethelone and phenalenone derivatives isolated from the mycobiont culture of Trypethelium eluteriae Spreng. and their anti-mycobacterial properties.

The metabolites of the mycobiont culture of the lichen Trypethelium eluteriae were isolated by column chromatography and preparative TLC. Nine compounds (1-9) including two new trypethelones, 8-methoxytrypethelone (6) and 5'-hydroxy-8-ethoxytrypethelone (9), together with four known trypethelones (3-4, 7-8), and two known phenalenones (1-2) were characterized. It is the first report of 8-methoxytrypethelone methyl ether (5) purification as a racemic mixture in T. eluteriae. Earlier, 7-hydroxyl-8-methoxyltrypethelone (10) was reported as new compound with erroneous spectroscopic data. This compound was identified later as 8-hydroxytrypethelone methyl ether (4). X-ray crystallographic structures of compounds 5-7 were elucidated for the first time. Phenalenones (1-2) and trypethelones (5-6 and 9) were the additional compounds discovered in the cultured mycobiont of T. eluteriae. Six compounds (1-2, 5-8) were screened against Mycobacterium tuberculosis H37Rv and two compounds (7-8) against non-tuberculosis mycobacteria and other human pathogenic bacteria. Compound (7) inhibited M. tuberculosis H37Rv strain with an MIC of 12.5 µg/mL.

An Activatable Photosensitizer Targeting Human NAD(P)H: Quinone Oxidoreductase†1.

Human NAD(P)H: Quinone Oxidoreductase 1 (hNQO1) is an attractive enzyme for cancer therapeutics due to its significant overexpression in tumors compared to healthy tissues. Its unique catalytic mechanism involving the two-electron reduction of quinone-based compounds has made it a useful target to exploit in the design of hNQO1 fluorescent chemosensors and hNQO1-activatable-prodrugs. In this work, hNQO1 is exploited for an optical therapeutic. The probe uses the photosensitizer, phenalenone, which is initially quenched via photo-induced electron transfer by the attached quinone. Native phenalenone is liberated in the presence of hNQO1 resulting in the production of cytotoxic singlet oxygen upon irradiation. hNQO1-mediated activation in A549 lung cancer cells containing high levels of hNQO1 induces a dose-dependent photo-cytotoxic response after irradiation. In contrast, no photo-cytotoxicity was observed in the normal lung cell line, MRC9. By targeting hNQO1, this scaffold can be used to enhance the cancer selectivity of photodynamic therapy.

In vitro activity of 1H-phenalen-1-one derivatives against Leishmania spp. and evidence of programmed cell death.

BACKGROUND: The in vitro activity against Leishmania spp. of a novel group of compounds, phenalenone derivatives, is described in this study. Previous studies have shown that some phenalenones present leishmanicidal activity, and induce a decrease in the mitochondrial membrane potential in L. amazonensis parasites, so in order to elucidate the evidence of programmed cell death occurring inside the promastigote stage, different assays were performed in two different species of Leishmania. METHODS: We focused on the determination of the programmed cell death evidence by detecting the characteristic features of the apoptosis-like process, such as phosphatidylserine exposure, mitochondrial membrane potential, and chromatin condensation among others. RESULTS: The results showed that four molecules activated the apoptosis-like process in the parasite. All the signals observed were indicative of the death process that the parasites were undergoing. CONCLUSIONS: The present results highlight the potential use of phenalenone derivatives against Leishmania species and further studies should be undertaken to establish them as novel leishmanicidal therapeutic agents.

Pyridone-containing phenalenone-based photosensitizer working both under light and in the dark for photodynamic therapy.

Photosensitizer attracts great attentions and has potential applications in cancer treatment. We developed here a novel pyridone-containing phenalenone-based (PPN-PYR) photosensitizer with excellent singlet oxygen generating ability. Upon light irradiation, PPN-PYR can produce singlet oxygen and transform to its endoperoxide form which in turn release singlet oxygen via thermal cycloreversion at dark. The ability of PPN-PYR to generate reactive oxygen species (ROS) in cell culture and induce corresponding apoptosis both at dark and under light was demonstrated. The efficient PDT performance of PPN-PYR was further verified on cancer cell in vitro. Our study indicate that PPN-PYR can alleviate tumor hypoxia problem and enhance the availability of intermittent photodynamic therapy.

Phenalenones from a Marine-Derived Fungus Penicillium Sp.

Six new phenalenone derivatives (1⁻6), along with five known compounds (7⁻11) of the herqueinone class, were isolated from a marine-derived fungus Penicillium sp. The absolute configurations of these compounds were assigned based on chemical modifications and their specific rotations. 4-Hydroxysclerodin (6) and an acetone adduct of a triketone (7) exhibited moderate anti-angiogenetic and anti-inflammatory activities, respectively, while ent-peniciherqueinone (1) and isoherqueinone (9) exhibited moderate abilities to induce adipogenesis without cytotoxicity.

Distribution, biosynthesis, and biological activity of phenylphenalenone-type compounds derived from the family of plants, Haemodoraceae.

Covering: up to 2018 The Haemodoraceae family is a monocotyledonous family in the order Commelinales consisting of 14 genera. Many species from the family are endemic to Australia and their use by the Aboriginal People of Australia as both pigments or remedies has been ethnobotanically documented. Phenylphenalenones are phenolic specialised metabolites consisting of a tricyclic phenalene nucleus with a ketone moiety and a lateral phenyl ring. Depending on their structural variance, four classes can be distinguished including the phenylphenalenones, oxabenzochrysenones, phenylbenzoisochromenones and phenylbenzoisoquinolinediones. The phenylphenalenone class has become the order's chemotaxonomic marker with a documented range of biological activities. This biological activity arises from the phototoxic properties of their ring system, a phenomenon most comprehensively observed amongst a widely cultivated family of the Commelinales order, Musaceae (banana). Within the family Haemodoraceae, the formation of the phenylphenalenone-class phytoanticipins is an intrinsic function of their growth, whereas within the family Musaceae these compounds are formed as phytoalexins in response to pathogenic attack or stress. The compounds produced within these two families differ in their substitution, with Musaceae-derived phytoalexins tending to be the more phototoxic 4-phenylphenalenones and the Haemodoraceae-derived phytoanticipins being of the more inert 9-phenylphenalenone type structure. Various other substitution patterns have been documented across the class, yet their biosynthetic mechanism is consistent, proceeding from simple phenylpropanoids through a diarylheptanoid intermediate, which cyclises to form the phenylphenalenone nucleus. Phenylphenalenone-related compounds have also been observed within the fungal kingdom, yet their biosynthetic route is based upon an alternative polymalonate pathway. This review focuses on Haemodoraceae-derived phenylphenalenone-type compounds, their distribution amongst species, throughout the plant organism, their biological activity and their biosynthesis.

Paradigm Shift in Drug Re-purposing From Phenalenone to Phenaleno-Furanone to Combat Multi-Drug Resistant Salmonella enterica Serovar Typhi.

Over recent years, typhoid fever has gained increasing attention with several cases reporting treatment failure due to multidrug resistant (MDR) strains of Salmonella enterica serovar Typhi. While new drug development strategies are being devised to combat the threat posed by these MDR pathogens, drug repurposing or repositioning has become a good alternative. The latter is considered mainly due to its capacity for saving sufficient time and effort for pre-clinical and optimization studies. Owing to the possibility of an unsuccessful repositioning, due to the mismatch in the optimization of the drug ligand for the changed biochemical properties of "old" and "new" targets, we have chosen a "targeted" approach of adopting a combined chemical moiety-based drug repurposing. Using small molecules selected from a combination of earlier approved drugs having phenalenone and furanone moieties, we have computationally delineated a step-wise approach to drug design against MDR Salmonella. We utilized our network analysis-based pre-identified, essential chaperone protein, SicA, which regulates the folding and quality of several secretory proteins including the Hsp70 chaperone, SigE. To this end, another crucial chaperone protein, Hsp70 DnaK, was also considered due to its importance for pathogen survival under the stress conditions typically encountered during antibiotic therapies. These were docked with the 19 marketed anti-typhoid drugs along with two phenalenone-furanone derivatives, 15 non-related drugs which showed 70% similarity to phenalenone and furanone derivatives and other analogous small molecules. Furthermore, molecular dynamics simulation studies were performed to check the stability of the protein-drug complexes. Our results showed the best binding interaction and stability, under the parameters of a virtual human body environment, with XR770, a phenaleno-furanone moiety based derivative. We therefore propose XR770, for repurposing for therapeutic intervention against emerging and significant drug resistance conferred by pathogenic Salmonella strains.

Phenalenone-photodynamic therapy induces apoptosis on human tumor cells mediated by caspase-8 and p38-MAPK activation.

Photodynamic therapy (PDT) is a rising and hopeful treatment for solid tumors and others malignancies. PDT uses harmless visible light to activate a tumor-associated photosensitizer (PS). The excited PS generates cytotoxic reactive oxygen species (ROS) that induce damage and death of tumor cells. It is known that certain phytoalexins and phytoanticipins derived from plants often display a PS-like activity due to a phenalenone (PN) moiety-an efficient singlet oxygen photosensitizer-in its skeleton. The aim of this study is to explore the phototoxic properties of PN on the human cell line tumor-derived HL60 (acute promyelocytic leukemia) and to identify the cell-specific targets of ROS involved in the tumor cell death. Our results reveal that PN acts as an excellent PS, showing a potent antitumor cell activity in presence of light. PN-PDT generates intracellular ROS, via oxidation reaction mechanisms type I and II, resulting in an induction of apoptosis. Moreover, both extrinsic (through direct activation of caspase-3) and intrinsic (through mitochondrial depolarization) pathways of apoptosis are induced by PN-PDT. Using pharmacologic inhibitors, we also find that PN-PDT activates caspase-8/tBid and p38-MAPK, triggering the activation of the apoptotic pathways. Although, survival pathways are also promoted through PI3 K/Akt and JNK activation, the net result of PN-PDT is the tumor cell death. The present work identifies to PN, for the first time, as a potent photosensitizer in human tumor cell lines and proposes a mechanism by which ROS induces apoptosis of tumor cell.

Peniciphenalenins A-F from the culture of a marine-associated fungus Penicillium sp. ZZ901.

Marine-derived fungi of the genus Penicillium represent a huge potential for synthesizing the secondary metabolites with structural and bioactive uniqueness and diversity. In this study, six previously undescribed compounds peniciphenalenins A-F and four known compounds (+)-sclerodin, (+)-scleroderolide, (+)-sclerodione, and physcion were isolated from the culture of a marine-derived fungus Penicillium sp. ZZ901. Structures of the isolated compounds were elucidated by a combination of extensive NMR spectroscopic analysis, HRESIMS data, optical rotation value, ECD calculation, and single crystal X-ray diffraction. Peniciphenalenins A-C are the second examples of the type of neoherqueinones. The possible biosynthetic route of nine phenalenone derivatives has been suggested. The known (+)-scleroderolide showed both antiproliferative activity against glioma cells with IC50 values of 23.24-37.26 µM and antibacterial activity in suppressing the growth of methicillin-resistant Staphylococcus aureus and Escherichia coli with MIC values of 7.0 and 9.0 µg/mL, respectively.

LRH-1 agonism favours an immune-islet dialogue which protects against diabetes mellitus.

Type 1 diabetes mellitus (T1DM) is due to the selective destruction of islet beta cells by immune cells. Current therapies focused on repressing the immune attack or stimulating beta cell regeneration still have limited clinical efficacy. Therefore, it is timely to identify innovative targets to dampen the immune process, while promoting beta cell survival and function. Liver receptor homologue-1 (LRH-1) is a nuclear receptor that represses inflammation in digestive organs, and protects pancreatic islets against apoptosis. Here, we show that BL001, a small LRH-1 agonist, impedes hyperglycemia progression and the immune-dependent inflammation of pancreas in murine models of T1DM, and beta cell apoptosis in islets of type 2 diabetic patients, while increasing beta cell mass and insulin secretion. Thus, we suggest that LRH-1 agonism favors a dialogue between immune and islet cells, which could be druggable to protect against diabetes mellitus.

Design, synthesis and evaluation of amino-substituted 1H-phenalen-1-ones as anti-leishmanial agents.

Screening of a designed collection of mono-substituted amino-1H-phenalen-1-ones against promastigote forms of L. donovani and L. amazonensis, identified seven compounds with anti-leishmanial activities comparable or better than the commonly prescribed anti-leishmanial drug, miltefosine. Structure-activity analysis revealed that appendages containing a basic tertiary nitrogen were favored, and that the position of the appendage also affected their potency. Like miltefosine, several of these active compounds significantly reduced the mitochondrial membrane potential in promastigotes. Further studies in amastigotes of L. amazonensis revealed that compounds 14, 15 and 33 were more active and more selective than miltefosine, with sub-micromolar potencies and selectivity indices >100.

Light-activated phenalen-1-one bactericides: efficacy, toxicity and mechanism compared with benzalkonium chloride.

AIM: Five photoactive compounds with variable elongated alkyl-substituents in a phenalen-1-one structure were examined in view of structural similarity to the antimicrobial agent benzalkonium chloride (BAC). METHODS: All phenalen-1-ones and BAC were evaluated for their antimicrobial properties against Staphylococcus aureus, methicillin-resistant S. aureus, Escherichia coli, Pseudomonas aeruginosa and for their eukaryotic toxicity against normal human epidermal keratinocyte (NHEK) cells to narrow down the BAC-like effect and the photodynamic effect depending on the chemical structure. All compounds were investigated for effective concentration ranges, where a bacterial reduction of 5 log10 is achieved, while an NHEK survival of 80% is ensured. RESULTS: Effective concentration ranges were found for four out of five photoactive compounds, but not for BAC and the compound with BAC-like alkyl chain length. CONCLUSION: Chain length size and polar area of the respective head-groups of phenalen-1-one compounds or BAC showed an influence on the incorporation inside lipid membranes and thus, head-groups may have an impact on the toxicity of antimicrobials.