Discussion of absolute configuration for bioactive Griseusins by comparing computed optical rotations and electronic circular dichroism with the experimental results

A new epimer of azaphilone derivative pinophilin B from the gorgonian-derived fungus Aspergillus fumigatus 14-27

A new epimer of azaphilone derivative pinophilin B, epi-pinophilin B (1), and three known analogues (2-4) were obtained from the culture of the gorgonian-derived fungus Aspergillus fumigatus 14-27. The structures of 1-4, including their relative configurations were determined by extensive spectroscopic analysis and comparing with literature data. The absolute configuration of 1 was determined by electronic circular dichroism (ECD) and optical rotatory (OR) calculations methods. Compounds 1-4 were isolated from A. fumigatus for the first time. Their antibacterial and cytotoxic activities were also evaluated.

Anti-Vibrio Indole-Diterpenoids and C-25 Epimeric Steroids From the Marine-Derived Fungus Penicillium janthinellum

A systematic chemical exploration of the marine-derived fungus Penicillium janthinellum led to the isolation of four indole-diterpenoid derivatives (1–4), including new penijanthines C and D (1 and 2), and a pair of new steroidal epimers, penijanthoids A and B (5 and 6). The calculated ECD spectra and Snatzke's method for the new compound 1 were carried out to determine its absolute configuration. The absolute configuration of 3 was established by X-ray diffraction and calculated ECD methods for the first time. DP4plus approach was used to elucidate the absolute configurations of the C-25 epimeric steroids 5 and 6. 25-Epimeric 5 and 6 represent the first examples of steroids forming a five-membered lactone between C-23 and C-27 from marine fungi. Compounds 1, 2, 5, and 6 displayed significant anti-Vibrio activity (Minimum inhibitory concentration, MIC values ranging from 3.1 to 50.0 μM) against three pathogenic Vibrio spp.

New Verrucosidin Derivatives from the Marine-Derived Fungus Penicillium sp. XL-01

Two new verrucosidin derivatives, named nordeoxyverrucosidin (1) and norverrucosidinol acetate (2), along with three known analogues (3–5) were isolated from the marine-derived fungus Penicillium sp. XL-01 collected from the Bohai Sea. Their structures and relative configurations were elucidated by comparing with literature data and a combination of spectroscopic techniques. The absolute configuration of 1 was assigned by quantum chemical calculation of the electronic circular dichroism (ECD) spectrum. Compounds 1 and 3 displayed promising cytotoxic activity against the MGC-803 cell line, with IC50 values of 0.96 and 1.14 μM, respectively, more effective than the positive control (cisplatin).

Caudatan A, an undescribed human kidney-type glutaminase inhibitor with tetracyclic flavan from Ohwia caudata

Human kidney-type glutaminase (KGA) is an important target that is often over expressed in many cancer cells but very few effective inhibitors of this enzyme have yet reached clinical trials. Caudatan A and caudatan B, two undescribed tetracyclic flavans with an unusual ether bond between the C-4 and C-2' were isolated from the roots of Ohwia caudata (Thunb.) H.Ohashi. Caudatan A exhibited stronger inhibitory activity and caudatan B showed moderate effect from the results of inhibitory activities evaluations on KGA. The molecular docking and primary structure-activity relationship analysis revealed that the less steric hindrance at ring A was necessary to the effect. Therefore, combined its better solubility than that of bis-2-(5-phenylacetimido-1,2,4-thiadiazol-2-yl)ethyl sulfide (BPTES), caudatan A might be the potential candidate as the inhibitor of KGA for further studies.

New Oxygenated Steroid from the Marine-Derived Fungus Aspergillus flavus

One new oxygenated steroid, named aspersteroid A (1), and three known analogues (2–4) were isolated from the marine-derived fungus Aspergillus flavus collected from the Bohai Sea. Their structures were elucidated by spectroscopic analyses and by comparison with previously reported data. The absolute configuration of tetracyclic nucleus in 1 was assigned by quantum chemical calculation of the electronic circular dichroism (ECD) spectrum. All the compounds were evaluated for their cytotoxic and antibacterial activities.

Characteristic α-Acid Derivatives from Humulus lupulus with Antineuroinflammatory Activities

Twenty compounds, including 14 new α-acid derivatives, a new chromone, and five known compounds, were identified from the pistillate inflorescence of Humulus lupulus (hops), and their structures were elucidated via physical data analysis. The absolute configurations of new α-acid derivatives 1-11b were determined by comparing their computed and experimental electronic circular dichroism spectra using TDDFT and NMR spectroscopic data. A putative biosynthetic pathway for the identified components was deduced. Their antineuroinflammatory effects were assayed systematically, and their structure-activity relationships are discussed briefly. Among the identified compounds, compound 14 displayed moderate inhibitory effects against nitric oxide production with an IC₅₀ value of 7.92 μM.

Bioactive Azaphilone Derivatives from the Fungus Talaromyces aculeatus

Six new azaphilone derivatives, talaraculones A-F (1-6), together with five known analogues (7-11), were obtained from the saline soil-derived fungus Talaromyces aculeatus. The absolute configurations of 1 and 6 were assigned by quantum chemical calculations of the electronic circular dichroism (ECD) spectra. Compounds 1 and 5 represent the first reported azaphilone derivatives with a C4 aliphatic side chain and a methylal group at C-3, respectively. Talaraculones A and B (1 and 2) exhibited stronger inhibitory activity against α-glucosidase than the positive control acarbose (IC₅₀ = 101.5 μM), with IC₅₀ values of 78.6 and 22.9 μM, respectively.

New alkenylated tetrahydropyran derivatives from the marine sediment-derived fungus Westerdykella dispersa and their bioactivities

Six new alkenylated tetrahydropyran derivatives belonged to polyketides, designated as (12R,13R)-dihydroxylanomycinol (1), (12S,13S)-dihydroxylanomycinol (2), (12R,13S)-dihydroxylanomycinol (3) and (12S,13R)-dihydroxylanomycinol (4), (12S,13R)-N-acetyl-dihydroxylanomycin (5) and (12S,13S)-N-acetyl-dihydroxylanomycin (6), together with one related known compound lanomycinol (7) were isolated from the liquid cultures of Westerdykella dispersa obtained from the marine sediments. Their structures and absolute configurations were determined on the basis of extensive analysis of NMR spectra combined with comparison of NMR data to those of known compound, and computational method via calculation of the electronic circular dichroism (ECD). The anti-agricultural pathogenic fungal and antibacterial activities of all isolated compounds were evaluated. Compounds 1-7 exhibited moderate antifungal activities selectively against tested fungal strains with minimum inhibitory concentration (MIC) values ranging from 12.5 to 50μg/mL, and weak antibacterial activities selectively against tested antibacterial strains with MIC value at 100μg/mL.

Diastereo- and enantioselective construction of biologically important pyrrolo[1,2-a]indole scaffolds via catalytic asymmetric [3 + 2] cyclodimerizations of 3-alkyl-2-vinylindoles

A catalytic asymmetric [3 + 2] cyclodimerization of 3-alkyl-2-vinylindoles has been established, which efficiently constructed a pyrrolo[1,2-a]indole scaffold in a diastereo- and enantioselective fashion.

Alismanoid A, an unprecedented 1,2-seco bisabolene from Alisma orientale, and its protective activity against H2O2-induced damage in SH-SY5Y cells

A pair of unprecedented 1,2-seco bisabolenes, (8R)-alismanoid A (1a) and (8S)-alismanoid A (1b), were isolated from A. orientale.

Chiral Separation of Cytotoxic Flavan Derivatives from Daphne giraldii

Twelve new flavan derivatives including four pairs of enantiomers, daphnegiralins A1-A4 (1) and daphnegiralins B1-B4 (2), and two pairs of epimers, daphnegiralins C1/C2 (3) and daphnegiralins D1/D2 (4), were isolated from the stem bark and roots of Daphne giraldii. Their structures were elucidated using spectroscopic analyses, computational approaches, and chemical methods. Separation of the enantiomeric mixtures (1a, 1b, 2a, and 2b) was achieved using chiral HPLC. The compounds were evaluated against a small panel of human cancer cell lines, and 1b-2, 2a, and 2b were cytotoxic against Hep3B human hepatoma cells.

Antifungal Monoterpene Derivatives from the Plant Endophytic Fungus Pestalotiopsis foedan

A new monoterpene lactone, (1R,4R,5R,8S)-8-hydroxy-4,8-dimethyl-2-oxabicyclo[3.3.1]nonan-3-one (1), along with one related known compound, (2R)-2-[(1R)-4-methylcyclohex-3-en-1-yl]propanoic acid (2), were isolated from the liquid culture of the plant endophytic fungus Pestalotiopsis foedan obtained from the branch of Bruguiera sexangula. The structure and absolute configuration of 1 were determined on the basis of extensive analysis of NMR spectra combined with computational methods via calculation of the optical rotation (OR) and ¹³ C-NMR. Both compounds exhibited strong antifungal activities against Botrytis cinerea and Phytophthora nicotianae with MIC values of 3.1 and 6.3 μg/ml, respectively, which are comparable to those of the known antifungal drug ketoconazole. Compound 2 also showed modest antifungal activity against Candida albicans with a MIC value of 50 μg/ml.

Penicimenolides A-F, Resorcylic Acid Lactones from Penicillium sp., isolated from the Rhizosphere Soil of Panax notoginseng

Five new 12-membered resorcylic acid lactone derivatives, penicimenolides A-E (1-5), one new ring-opened resorcylic acid lactone derivative penicimenolide F (6), and six known biogenetically related derivatives (7-12) were isolated from the culture broth of a strain of Penicillium sp. (NO. SYP-F-7919), a fungus obtained from the rhizosphere soil of Panax notoginseng collected from the Yunnan province of China. Their structures were elucidated by extensive NMR analyses, a modified Mosher's method, chemical derivatization and single crystal X-ray diffraction analysis. Compounds 2-4 exhibited potent cytotoxicity against the U937 and MCF-7 tumour cell lines and showed moderate cytotoxic activity against the SH-SY5Y and SW480 tumour cell lines. The substitution of an acetyloxy or 2-hydroxypropionyloxy group at C-7 significantly increased the cytotoxic activity of the resorcylic acid lactone derivatives. Subsequently, the possible mechanism of compound 2 against MCF-7 cells was preliminarily investigated by in silico analysis and experimental validation, indicating compound 2 may act as a potential MEK/ERK inhibitor. Moreover, proteomics analysis was performed to explore compound 2-regulated concrete mechanism underlying MEK/ERK pathway, which is still need further study in the future. In addition, compounds 2-4 and 7 exhibited a significant inhibitory effect on NO production induced by LPS.

Nigrodiquinone A, a Hydroanthraquinone Dimer Containing a Rare C-9-C-7' Linkage from a Zoanthid-Derived Nigrospora sp. Fungus

One new hydroanthraquinone dimer with a rare C-9–C-7′ linkage, nigrodiquinone A (1), and four known anthraquinone monomers 2–5, were isolated from a fungus Nigrospora sp. obtained from the zoanthid Palythoa haddoni collected in the South China Sea. The structure of 1 was established through extensive NMR spectroscopy, and the absolute configuration was elucidated by comparing computed electronic circular dichroism (ECD) and optical rotations (OR) with experimental results. All the compounds were evaluated for antiviral activity, and 1 was also evaluated for antibacterial activity. Compound 4 displayed mild antiviral activity against coxsackie virus (Cox-B3) with the IC₅₀ value of 93.7 μM, and 5 showed an IC₅₀ value of 74.0 μM against respiratory syncytial virus (RSV).