Four New Chromones from the Endophytic Fungus Phomopsis asparagi DHS-48 Isolated from the Chinese Mangrove Plant Rhizophora mangle

Four new chromones, phomochromenones D–G (1–4), along with four known analogues, diaporchromone A (5), diaporchromanone C (6), diaporchromanone D (7), and phomochromenone C (8), were isolated from the culture of Phomopsis asparagi DHS-48 from Chinese mangrove Rhizophora mangle. Their structures were elucidated on the basis of comprehensive spectroscopic analysis. The absolute configurations of 1 and 4 were assigned on the basis of experimental and calculated electronic circular dichroism (ECD) data, and those of enantiomers 2 and 3 were determined by a modified Mosher’s method and basic hydrolysis. To the best of our knowledge, phomochromenones D–F (1–4) possessing a 3-substituted-chroman-4-one skeleton are rarely found in natural sources. Diaporchromone A (5) showed moderate to weak immunosuppressive activity against T and/or B lymphocyte cells with IC50 of 34 μM and 117 μM.

Sacraoxides A–G, Bioactive Cembranoids from Gum Resin of Boswellia sacra

Seven undescribed cembranoids, sacraoxides A–G (1, 3–8) were isolated from the gum resin of Boswellia sacra. Their structures were elucidated by extensive physicochemical and spectroscopic analysis, as well as ECD calculation, modified Mosher’s method and X-ray diffraction crystallography. Compounds 6 and 7 exhibited inhibitory activities on nitric oxide (NO) production induced by lipopolysaccharide in RAW264.7 cells with IC50 values of 24.9 ± 1.7 and 36.4 ± 2.9 μM.

Three New Polyketides from the Insect-Associated Fungus Letendraea sp. 5XNZ4-2

Chemical investigation of the EtOAc extract of an insect-associated fungus Letendraea sp. 5XNZ4-2 cultured in Potato Dextrose Broth (1/2 PDB) medium lead to the isolation of three new polyketides, named letendronol D (1), phomopsiketones H-I (2-3). The structures of new compounds were elucidated by the analysis of HRESIMS and NMR spectroscopic data, and the absolute configurations were determined by modified Mosher’s method, ECD calculation and single-crystal X-ray diffraction. Cytotoxicity and antibacterial activities of 1 were assayed and regrettably 1 didn’t display any cytotoxicity and antibacterial activity. 3 was the first phomopsiketone derivative obtaining the lactone.

New Acetophenones and Chromenes from the Leaves of Melicope barbigera A. Gray

The dichloromethane extract from leaves of Melicope barbigera (Rutaceae), endemic to the Hawaiian island of Kaua’i, yielded four new and three previously known acetophenones and 2H-chromenes, all found for the first time in M. barbigera. The structures of the new compounds obtained from the dichloromethane extract after purification by chromatographic methods were unambiguously elucidated by spectroscopic analyses including 1D/2D NMR spectroscopy and HRESIMS. The absolute configuration was determined by modified Mosher’s method. Compounds 2, 4 and the mixture of 6 and 7 exhibited moderate cytotoxic activities against the human ovarian cancer cell line A2780 with IC50 values of 30.0 and 75.7 µM for 2 and 4, respectively, in a nuclear shrinkage cytotoxicity assay.

Chemical constituents of Chaenomeles sinensis twigs and their biological activity

A new megastigmane-type norsesquiterpenoid glycoside, chaemeloside (1), was isolated from the twigs of Chaenomeles sinensis together with 11 known phytochemicals through chromatographic methods. The chemical structure of the new isolate 1 was determined by conventional 1D and 2D NMR data analysis, ECD experiment, hydrolysis followed by a modified Mosher’s method, and LC–MS analysis. The characterized compounds’ biological effects including cytotoxicity against cancer cell lines, antineuroinflammatory activity, and potential neurotrophic effect were evaluated.

Roussoelins A and B: two phenols with antioxidant capacity from ascidian-derived fungus Roussoella siamensis SYSU-MS4723

Ascidian-derived microorganisms are a significant source of pharmacologically active metabolites with interesting structural properties. When discovering bioactive molecules from ascidian-derived fungi, two new phenols, roussoelins A (1) and B (2), and ten known polyketides (3–12) were isolated from the ascidian-derived fungus Roussoella siamensis SYSU-MS4723. The planar structure of compounds 1 and 2 was established by analysis of HR-ESIMS and NMR data. The conformational analysis of the new compounds was assigned according to coupling constants and selective gradient NOESY experiments, and absolute configurations were completed by the modified Mosher’s method. Among the isolated compounds, 1, 2, and 9 showed moderate antioxidant capacity. Graphical abstract

Muyocopronones A and B: azaphilones from the endophytic fungus Muyocopron laterale

Two new azaphilones, namely muyocopronones A (1) and B (2), were isolated from the cultures of an endophytic fungus Muyocopron laterale ECN279. Their structures were elucidated by extensive spectroscopic analysis. Their absolute configurations were determined using the modified Mosher’s method and through comparisons of experimental and calculated electronic circular dichroism data. In addition, muyocopronone B (2) was found to exhibit a weak antibacterial activity against some Gram-positive bacteria.

Secondary Metabolites with Nitric Oxide Inhibition from Marine-Derived Fungus Alternaria sp. 5102

Two new benzofurans, alternabenzofurans A and B (1 and 2) and two new sesquiterpenoids, alternaterpenoids A and B (3 and 4), along with 18 known polyketides (5−22), were isolated from the marine-derived fungus Alternaria sp. 5102. Their structures were elucidated on the basis of extensive spectroscopic analyses (1D and 2D NMR, HR-ESIMS, and ECD) and X-ray crystallography, as well as the modified Mosher’s method. Compounds 2, 3, 5, 7, 9–18, and 20–22 exhibited potent anti-inflammatory activity by inhibiting the production of NO in RAW264.7 cells activated by lipopolysaccharide with IC50 values in the range from 1.3 to 41.1 μM. Structure-activity relationships of the secondary metabolites were discussed.

Chermebilaenes A and B, New Bioactive Meroterpenoids from Co-Cultures of Marine-Derived Isolates of Penicillium bilaiae MA-267 and Penicillium chermesinum EN-480

The co-cultivation of two or more different microbial strains in one culture vessel was supposed to be a viable experimental approach for enhancing the diversity of the compounds produced. Two new meroterpenoid derivatives, chermebilaenes A (1) and B (2), together with three known sesquiterpenoids, sesquicaranoic acid B (3), cyclonerodiol (4) and bisabol-l-on-13-säuremethylester (5), were characterized from a co-culture of the marine-derived fungal isolates of Penicillium bilaiae MA-267 and Penicillium chermesinum EN-480. Neither fungus produced these compounds when cultured alone under the same conditions. Compound 1 represents an unprecedented acorane-type sesquiterpene hybridized with an octadecadienoic acid skeleton. The structures were elucidated on the basis of spectroscopic analysis, and the absolute configurations were assumed on the basis of acidic hydrolysis combined with modified Mosher’s method and electronic circular dichroism (ECD) calculations. Compound 1 showed potent inhibitory activities against Ceratobasidium cornigerum and Edwardsiella tarda.

Three New Sesquiterpenoids from the Algal-Derived Fungus Penicillium chermesinum EN-480

Secondary metabolites obtained from marine-derived fungi are rich sources of drug candidates. Three new sesquiterpenoids, chermesiterpenoids A–C (1–3), along with four known alkaloids (4–7), were isolated and identified from the marine red algal-derived fungus Penicillium chermesinum EN-480. The structures of these new sesquiterpenoids were elucidated using detailed analysis of the NMR data and their relative configurations were elucidated using nuclear overhauser effect spectroscopy (NOESY) spectra as well as gauge-independent atomic orbital (GIAO) NMR shift calculations and DP4+ probability analysis. Their absolute configurations were determined using electronic circular dichroism (ECD) calculations and modified Mosher’s method. Compounds 2 and 3 exhibited potent activities against human and aquatic pathogenic bacteria and plant pathogenic fungi.