Chemical Stability of Petrichorins.

The structure of petrichorin C1 (4) converted from petrichorin C (3) was determined using NMR spectroscopy and X-ray crystallography. The chemical stability of petrichorins A and C (1 and 3) was investigated by NMR spectroscopy, X-ray crystallography, and calculations.

Fusarium fruiting body microbiome member Pantoea agglomerans inhibits fungal pathogenesis by targeting lipid rafts.

Plant-pathogenic fungi form intimate interactions with their associated bacterial microbiota during their entire life cycle. However, little is known about the structure, functions and interaction mechanisms of bacterial communities associated with fungal fruiting bodies (perithecia). Here we examined the bacterial microbiome of perithecia formed by Fusarium graminearum, the major pathogenic fungus causing Fusarium head blight in cereals. A total of 111 shared bacterial taxa were identified in the microbiome of 65 perithecium samples collected from 13 geographic locations. Within a representative culture collection, 113 isolates exhibited antagonistic activity against F. graminearum, with Pantoea agglomerans ZJU23 being the most efficient in reducing fungal growth and infectivity. Herbicolin A was identified as the key antifungal compound secreted by ZJU23. Genetic and chemical approaches led to the discovery of its biosynthetic gene cluster. Herbicolin A showed potent in vitro and in planta efficacy towards various fungal pathogens and fungicide-resistant isolates, and exerted a fungus-specific mode of action by directly binding and disrupting ergosterol-containing lipid rafts. Furthermore, herbicolin A exhibited substantially higher activity (between 5- and 141-fold higher) against the human opportunistic fungal pathogens Aspergillus fumigatus and Candida albicans in comparison with the clinically used fungicides amphotericin B and fluconazole. Its mode of action, which is distinct from that of other antifungal drugs, and its efficacy make herbicolin A a promising antifungal drug to combat devastating fungal pathogens, both in agricultural and clinical settings.

Discovery of unusual dimeric piperazyl cyclopeptides encoded by a Lentzea flaviverrucosa DSM 44664 biosynthetic supercluster.

Rare actinomycetes represent an underexploited source of new bioactive compounds. Here, we report the use of a targeted metabologenomic approach to identify piperazyl compounds in the rare actinomycete Lentzea flaviverrucosa DSM 44664. These efforts to identify molecules that incorporate piperazate building blocks resulted in the discovery and structural elucidation of two dimeric biaryl-cyclohexapeptides, petrichorins A and B. Petrichorin B is a symmetric homodimer similar to the known compound chloptosin, but petrichorin A is unique among known piperazyl cyclopeptides because it is an asymmetric heterodimer. Due to the structural complexity of petrichorin A, solving its structure required a combination of several standard chemical methods plus in silico modeling, strain mutagenesis, and solving the structure of its biosynthetic intermediate petrichorin C for confident assignment. Furthermore, we found that the piperazyl cyclopeptides comprising each half of the petrichorin A heterodimer are made via two distinct nonribosomal peptide synthetase (NRPS) assembly lines, and the responsible NRPS enzymes are encoded within a contiguous biosynthetic supercluster on the L. flaviverrucosa chromosome. Requiring promiscuous cytochrome p450 crosslinking events for asymmetric and symmetric biaryl production, petrichorins A and B exhibited potent in vitro activity against A2780 human ovarian cancer, HT1080 fibrosarcoma, PC3 human prostate cancer, and Jurkat human T lymphocyte cell lines with IC50 values at low nM levels. Cyclic piperazyl peptides and their crosslinked derivatives are interesting drug leads, and our findings highlight the potential for heterodimeric bicyclic peptides such as petrichorin A for inclusion in future pharmaceutical design and discovery programs.

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.

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.

Waikikiamides A-C: Complex Diketopiperazine Dimer and Diketopiperazine-Polyketide Hybrids from a Hawaiian Marine Fungal Strain Aspergillus sp. FM242.

Waikikiamides A-C (1-3), structurally complex diketopiperazine derivatives, and putative biogenic precursors, (+)-semivioxanthin (4), notoamide F (5), and (-)-notoamide A (6), were isolated from Aspergillus sp. FM242. 1 and 2, bearing a hendecacyclic ring system, represent a novel skeleton. 3 features the first unique heterodimer of two notoamide analogs with an N-O-C bridge. Compounds 1 and 3 exhibit antiproliferative activity with IC50 values in the range of 0.56 to 1.86 µM. The gene clusters mined from the sequenced genome support their putative biosynthetic pathways.

An Unusual Benzoisoquinoline-9-one Derivative and Other Related Compounds with Antiproliferative Activity from Hawaiian Endophytic Fungus Peyronellaea sp. FT431.

A new polyketide containing the benzoisoquinoline-9-one moiety, peyronetide A (1), and three other new derivatives peyronetides B⁻D (2⁻4), as well as one known compound (5) were purified from the cultured broth of the endophytic fungus Peyronellaea sp. FT431, which was isolated from the Hawaiian indigenous plant, Verbena sp. The structures of the new compounds were determined through the analysis of HRMS and NMR spectroscopic data. Compounds 1, 2, and 5 showed cytotoxic activities against TK-10 (human kidney adenocarcinoma cells), cisplatin sensitive A2780S (human ovarian carcinoma cells), and cisplatin resistant A2780CisR cell lines, with IC50 values between 6.7 to 29.2 µM.

Verbenanone, an octahydro-5H-chromen-5-one from a Hawaiian-Plant Associated Fungus FT431.

A new secondary metabolite verbenanone (1) with a unique (4aS,8aS)-octahydro-5H-chromen-5-one moiety has been obtained from the endophytic fungus FT431, which was isolated from the native Hawaiian plant Verbena sp. The structure of compound 1 was characterized based on NMR and MS spectroscopic analysis. The absolute configuration (AC) of compound 1 was determined by Mosher acids. Compound 1 was tested against A2780 and A2780cisR, but it was inactive.

NF-κB inhibitors, unique γ-pyranol-γ-lactams with sulfide and sulfoxide moieties from Hawaiian plant Lycopodiella cernua derived fungus Paraphaeosphaeria neglecta FT462.

LC-UV/MS-based metabolomic analysis of the Hawaiian endophytic fungus Paraphaeosphaeria neglecta FT462 led to the identification of four unique mercaptolactated γ-pyranol-γ-lactams, paraphaeosphaerides E-H (1-4) together with one γ-lactone (5) and the methyl ester of compound 2 (11). The structures of the new compounds (1-5 and 11) were elucidated through the analysis of HRMS and NMR spectroscopic data. The absolute configuration was determined by chemical reactions with sodium borohydride, hydrogen peroxide, α-methoxy-α-(trifluoromethyl)phenylacetyl chlorides (Mosher reagents), and DP4 + NMR calculations. All the compounds were tested against STAT3, A2780 and A2780cisR cancer cell lines, E. coli JW2496, and NF-κB. Compounds 1 and 3 strongly inhibited NF-κB with IC50 values of 7.1 and 1.5 µM, respectively.

A New N-methoxypyridone from the Co-Cultivation of Hawaiian Endophytic Fungi Camporesia sambuci FT1061 and Epicoccum sorghinum FT1062.

A new N-methoxypyridone analog (1), together with four known compounds, was isolated from the co-culture of Hawaiian endophytic fungi Camporesia sambuci FT1061 and Epicoccum sorghinum FT1062. The structure of the new compound was elucidated as 11S-hydroxy-1-methoxyfusaricide (1) by extensive spectroscopic analysis and comparison with the literature. The absolute configuration of 1 was determined by comparison with the experimental and calculated ECD spectra. The absolute configuration of compound 3 was investigated and renamed as (+)-epipyridone by comparison of the optical rotation and CD spectrum with those of 1. The other known compounds were identified as epicoccarine B (2), D8646-2-6 (4), and iso-D8646-2-6 (5). Compounds 4 and 5 showed modest inhibitory activity towards pathogenic fungi. Epicoccarine B (2) inhibited A2780 and TK-10 with an IC50 value of 22 µM.

Anti-proliferative ambuic acid derivatives from Hawaiian endophytic fungus Pestalotiopsis sp. FT172.

Five previously undescribed ambuic acid derivatives, pestallic acids A-E and three known analogs were isolated from the cultured broth of Pestalotiopsis sp. FT172. The structures of the pestallic acids A-E were determined through the analysis of HRMS and NMR spectroscopic data. The absolute configurations (ACs) of pestallic acids B-E were assigned by comparison of the experimental electric circular dichroism (ECD) spectra or the optical rotations with those in the literature. All compounds were tested against A2780 and cisplatin resistant A2780 (A2780CisR) cell lines. Pestallic acid E and (+)-ambuic acid showed potent activities with IC50 values from 3.3 to 17.0 µM.

Anti-inflammatory activity of Barleria lupulina: Identification of active compounds that activate the Nrf2 cell defense pathway, organize cortical actin, reduce stress fibers, and improve cell junctions in microvascular endothelial cells.

ETHNOPHARMACOLOGICAL RELEVANCE: Hot aqueous extracts of the plant Barleria lupulina (BL) are used for treating inflammatory conditions and diabetic vascular complications. AIM OF THE STUDY: The goal was to identify active compounds in hot aqueous extracts of BL (HAE-BL) that are consistent with a role in reducing inflammation and reducing the vascular pathology associated with diabetes. In particular, we examined activation of the Nrf2 cell defense pathway because our initial findings indicated that HAE-BL activates Nrf2, and because Nrf2 is known to suppress inflammation. Activation of Nrf2 by HAE-BL has not been described previously. MATERIALS AND METHODS: Human endothelial cells, real-time PCR, western blotting, cytoskeletal analyses, and assay-guided fractionation with HPLC were used to identify specific compounds in HAE-BL that activate the Nrf2 cell defense pathway and reduce markers of inflammation in vitro. RESULTS: HAE-BL potently activated the Nrf2 cell defense pathway in endothelial cells consistent with its traditional use and reported success in reducing inflammation. Assay guided fractionation with HPLC identified three alkyl catechols: 4-ethylcatechol, 4-vinylcatechol, and 4-methylcatechol, that are each potent Nrf2 activators. In addition to activating Nrf2, HAE-BL and akyl catechols each profoundly improved organization of the endothelial cell actin cytoskeleton, reduced actin stress fibers, organized cell-cell junctions, and induced expression of mRNA encoding claudin-5 that is important for formation of endothelial tight junctions and reducing vascular leak. CONCLUSIONS: HAE-BL contains important alkyl catechols that potently activate the Nrf2 cell defense pathway, improve organization of the endothelial cell cytoskeleton, and organize tight cell junctions. All of these properties are consistent with a role in reducing inflammation and reducing vascular leak. Because activation of the Nrf2 cell defense pathway also prevents cancers, neuro-degeneration, age-related macular degeneration, and also reduces the severity of chronic obstructive pulmonary disorder and multiple sclerosis, HAE-BL warrants additional consideration for these other serious disorders.

Meroterpenoids with Antiproliferative Activity from a Hawaiian-Plant Associated Fungus Peyronellaea coffeae-arabicae FT238.

Three unusual polyketide-sesquiterpene metabolites peyronellins A-C (1-3), along with the new epoxyphomalin analog 11-dehydroxy epoxyphomalin A (4), have been isolated from the endophytic fungus Peyronellaea coffeae-arabicae FT238, which was isolated from the native Hawaiian plant Pritchardia lowreyana. The structures of compounds 1-4 were characterized based on NMR and MS spectroscopic analysis. The absolute configuration (AC) of the compounds was determined by electronic circular dichroism (ECD). Compound 4 showed antiproliferative activity with an IC50 of 0.5 µM against OVCAR3, and it also strongly inhibited Stat3 at 5 µM.

Hawaii natural compounds are promising to reduce ovarian cancer deaths.

The low survival rate of patients with ovarian cancer largely results from the advanced ovarian tumors as well as tumor resistance to chemotherapy, leading to metastasis and recurrence. However, it is missing as to an effective therapeutic approach that focuses on these aspects to prolong progression-free survival and to decrease mortality in ovarian cancer patients. Here, based on our cancer drug discovery studies, we provide prospective insights into the development of a future line of drugs to effectively reduce ovarian cancer deaths. Pathways that increase the probability of cancer, such as the defective Fanconi anemia (FA) pathway, may render cancer cells more sensitive to new drug targeting.

Eremophilane sesquiterpenes from Hawaiian endophytic fungus Chaetoconis sp. FT087.

Seven sesquiterpene derivatives, including chaetopenoids A-F and dendryphiellin A1, and 6-methyl-(2E, 4E, 6S) octadienoic acid were isolated from the culture broth of Chaetoconis sp. FT087. Their structures were determined through the analysis of HRMS and NMR spectroscopic data. The absolute configurations of chaetopenoids A-D were elucidated by comparison of their CD and optical rotation data with those in the literature. Chaetopenoids A-C and E belong to the eremophilane type of sesquiterpenoids, while chaetopenoids D and F and dendryphiellin A1 have a trinor-eremophilane skeleton. All compounds were tested against A2780 and cisplatin resistant A2780CisR cell lines, and dendryphiellin A1 was moderately active with IC50 values of 6.6 and 9.1 µg/mL, respectively.

Characterization of a Newly Isolated Marine Fungus Aspergillus dimorphicus for Optimized Production of the Anti-Tumor Agent Wentilactones.

The potential anti-tumor agent wentilactones were produced by a newly isolated marine fungus Aspergillus dimorphicus. This fungus was derived from deep-sea sediment and identified by polyphasic approach, combining phenotypic, molecular, and extrolite profiles. However, wentilactone production was detected only under static cultures with very low yields. In order to improve wentilactone production, culture conditions were optimized using the response surface methodology. Under the optimal static fermentation conditions, the experimental values were closely consistent with the prediction model. The yields of wentilactone A and B were increased about 11-fold to 13.4 and 6.5 mg/L, respectively. The result was further verified by fermentation scale-up for wentilactone production. Moreover, some small-molecule elicitors were found to have capacity of stimulating wentilactone production. To our knowledge, this is first report of optimized production of tetranorlabdane diterpenoids by a deep-sea derived marine fungus. The present study might be valuable for efficient production of wentilactones and fundamental investigation of the anti-tumor mechanism of norditerpenoids.

A New Metabolite with a Unique 4-Pyranone-γ-Lactam-1,4-Thiazine Moiety from a Hawaiian-Plant Associated Fungus.

An endophytic fungus Paraphaeosphaeria neglecta FT462 isolated from the Hawaiian-plant Lycopodiella cernua (L.) Pic. Serm produced one unusual compound (1, paraphaeosphaeride A) with the 4-pyranone-γ-lactam-1,4-thiazine moiety, along with two new compounds (2 and 3, paraphaeosphaerides B and C, respectively) and the known compound (4). Compounds 1-3 were characterized by NMR and MS spectroscopic analysis. The absolute configuration of the 3-position of compound 1 was determined as S by electronic circular dichroism (ECD) calculations. Compound 3 also showed STAT3 inhibition at 10 µM.

Cyclodepsipeptides and other O-containing heterocyclic metabolites from Beauveria felina EN-135, a marine-derived entomopathogenic fungus.

Bioassay-guided fractionation of a culture extract of Beauveria felina EN-135, an entomopathogenic fungus isolated from a marine bryozoan, led to the isolation of a new cyclodepsipeptide, iso-isariin D (1); two new O-containing heterocyclic compounds that we have named felinones A and B (2 and 3); and four known cyclodepsipeptides (4-7). The structures were elucidated via spectroscopic analysis, and the absolute configurations of 1 and 2 were determined using single-crystal X-ray diffraction and CD, respectively. All isolated compounds were evaluated for antimicrobial activity and brine-shrimp (Artemia salina) lethality.

Laurane-, cyclolaurane-, and cuparane-type sesquiterpenes from the marine red alga Laurencia okamurai.

Chemical investigation of the secondary metabolites extracted from the marine red alga Laurencia okamurai has resulted in the isolation of one new (lauramurin, 1) and six known (2-7) sesquiterpenes. On the basis of the data obtained by our detailed spectroscopic analysis as well as by comparison with those reported, the structures of these compounds were elucidated as four laurane sesquiterpenes including lauramurin (1), laur-11-en-10-ol (2), aplysinol (3), and debromoaplysinol (4), two cyclolaurane sesquiterpenes laurequinone (5) and laurentristich-4-ol (6), and one cuparane ether sesquiterpene (7). The antibacterial activity against Staphylococcus aureus and brine shrimp (Artemia salina) lethality for the isolated compounds were evaluated. Compounds 2 and 5-7 displayed moderate lethality against brine shrimp.

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

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