Westerdijkin A,a new hydroxyphenylacetic acid derivative from deep sea fungus Aspergillus westerdijkiae SCSIO 05233

A new methyl 2-(4-((2-hydroxy-3-methylbut-3-en-1-yl)oxy)phenyl) acetate 1, together with five known compounds 2–6, was isolated from the culture of the deep sea-derived fungus Aspergillus westerdijkiae SCSIO 05233. The new structure was determined by NMR (¹H and ¹³C NMR, HSQC, HMBC and MS) and optical rotation analysis. Compound 5 displayed weak inhibitory activities towards K562 and promyelocytic HL-60 with IC₅₀ values of 25.8 and 44.9 μM, and compound 6 showed strong antifouling activity with EC₅₀ value 8.81 μg/mL.     

Biotransformation of agallochaexcoerin A by Aspergillus flavus

Agallochaexcoerin A (1), a seco-manoyl oxide diterpenoid was metabolised by pathogenic fungus, Aspergillus flavus, in growth media to yield a new metabolite, termed agallochaexcoerin G (2). It was confirmed by using IR, UV, ¹H NMR and HR-ESI-MS techniques. This microbial bioconversion was achieved by unusual dehydration at C-4 position.     

Structural characterization of 1β, 11α-dihydroxycanrenone biotrans- formed from canrenone by Aspergillus ochraceus SIT34205

Canrenone(1) was biotransformed into 11α-hydroxycanrenone(2) and a main byproduct(3) by Aspergillus ochraceus SIT34205.Compound 3 was separated and purified using silica gel column chromatography,and its structure was characterized via MS and NMR methods.These results indicated that 3 was 1β,11α-dihydroxycanrenone and the product of further hydroxylation of 2.Thus,investigating the structure and synthesis of 3 may be a promising method to improve the efficiency and purity of 2.     

Novel pyridino-α-pyrone sesquiterpene type pileotin produced by a sea urchin-derived Aspergillus sp.

A new metabolite, pileotin A, was isolated from a strain of Aspergillus fumigatus originally obtained from the sea urchin Toxopneustes pileolus together with the known compound oxalicine B. The relative stereostructure of pileotin A was elucidated based on spectroscopic analyses, including 1D and 2D NMR techniques. This unique pyridino-α-pyrone sesquiterpene type metabolite has spiro-δ-lactone at C-4.     

Fluoreszenzfarbstoffe in der Natur

Cumarines as fluorescent substances are widely spread in living nature and can be found in different genera of plants and fungi. Due to their intensive fluorescence they can be easily observed. This gives the opportunity to make experiments with low costs, low complexity and without using toxic materials.     

Biosynthesis of aspergiolide A, a novel antitumor compound by a marine-derived fungus Aspergillus glaucus via the polyketide pathway

Aspergiolide A, a novel antitumor compound, was produced by a marine-derived filamentous fungus Aspergillus glaucus. The biosynthesis of it was unambiguously determined by feeding experiments using [l-¹³C]sodium acetate, [2-¹³C]sodium acetate, and [1,2-¹³C₂]sodium acetate precursors followed by ¹³C NMR spectroscopic investigation of the isolated products. Analysis of the patterns of ¹³C-enrichment revealed that all 25 carbon atoms in skeleton of aspergiolide A were derived from labeled acetate. And among them, 12 carbon atoms were labeled from the carboxylic group of acetate, while the other 13 carbon atoms were labeled from the methylic group of acetate. Besides, the labeling pattern of [1,2-¹³C₂]sodium acetate feeding experiment demonstrated that 12 intact acetate units were incorporated in aspergiolide A by polyketide pathway.     

A new pregnane steroid from cultures of Aspergillus versicolor

A new pregnane steroid, named aspergillon A (1), together with two known compounds, (22E,24R)-ergosta-5,7,22-trien-3β-ol (2) and (22E, 24R)-ergosta-4,6,8(14),22-tetraen-3-one (3) were isolated from cultures of the tin mine tailings-associated fungus Aspergillus versicolor. The new structure and absolute configuration were determined with the help of extensive spectroscopic analyses and quantum chemical calculations of the electronic circular dichroism (ECD) spectra.     

Biotransformation of (+)-isofraxinellone by Aspergillus niger and insect antifeedant activity

The biotransformation of (+)-isofraxinellone (1) by Aspergillus niger was investigated. Compound 1 was transformed to only one new compound 2. The structure of 2 was identified as (-)-(4S)-4-hydroxyisofraxinellone which was regio- and stereo-selective hydroxylated at the C-4 position by IR, EI-MS 1D and 2D NMR. Absolute configuration of hydroxyl group at the C-4 position was detected by modified Mosher’s method. Antifeedant activity of compounds 1 and 2 against larvae of Spodoptera litura was assayed. These compounds showed potent antifeedant activity and ED₅₀ (50% of effective dose) values were 3.91 and 4.43 μg/cm², respectively.     

Bioactive Polyketide and Diketopiperazine Derivatives from the Mangrove-Sediment-Derived Fungus Aspergillus sp. SCSIO41407

Ten polyketide derivatives (1–10), including a new natural product named (E)-2,4-dihydroxy-3-methyl-6-(2-oxopent-3-en-1-yl) benzaldehyde (1), and five known diketopiperazines (11–15), were isolated from the mangrove-sediment-derived fungus Aspergillus sp. SCSIO41407. The structures of 1–15 were determined via NMR and MS spectroscopic analysis. In a variety of bioactivity screening, 3 showed weak cytotoxicity against the A549 cell line, and 2 exhibited weak antibacterial activity against methicillin-resistant Staphylococcus aureus (MRSA). Compounds 3, 5, and 6 showed inhibition against acetylcholinesterase (AChE) with IC₅₀ values of 23.9, 39.9, and 18.6 μM. Compounds 11, 12, and 14 exhibited obvious inhibitory activities of lipopolysaccharide (LPS)-induced nuclear factor-κB (NF-κB) with IC₅₀ values of 19.2, 20.9, and 8.7 μM, and they also suppressed RANKL-induced osteoclast differentiation in bone marrow macrophages cells (BMMCs), with the concentration of 5 μM. In silico molecular docking with AChE and NF-κB p65 protein were also performed to understand the inhibitory activities, and 1, 11–14 showed obvious protein/ligand-binding effects to the NF-κB p65 protein.     

柠檬醛抑制黄曲霉生长相关机理的研究

对经柠檬醛损伤的黄曲霉,采用Irwin等入方法测定质膜通透性,Miller方法测定试验菌对还原糖和蛋白质吸收利用率,Hodge等入方法纯化质膜[Na^ ,K^ ]-ATPase,并用Liberg方法测定其活性,以琥珀酸,丙酮酸和α－酮戊二酸为底物测定Mt呼吸速率,并结合扫描电镜观察和彗星图像分析,发现该醛能破坏细胞壁,质膜,Mt和膜选择通透性,并损伤核DNA,而引起细胞的死亡,揭示这种单体芳香醛抗霉是多途径的复合作用,为其走向粮油,食品贮藏领域提供了理论依据。