异香豆素噁二唑类化合物的合成及除草活性

为了寻找具有较高除草活性的异香豆素类化合物,设计合成了16个新型异香豆素噁二唑类化合物4a～4p,其结构均经核磁共振氢谱、碳谱及高分辨质谱确证。初步除草活性测定结果表明,部分目标化合物在500 mg/L下对马唐Digitaria sanguinalis L.和反枝苋Amaranthusretroflexus L.具有一定的除草活性,其中化合物4j（4-[5-（4-氯-苯基）-[1,2,4]二唑-3-基]-3-己基-6,7-二甲氧基异香豆素）的活性最好,对马唐和反枝苋的致死率分别为64%和62%。     

红树林来源真菌Xylaria sp. HNWSW-2异香豆素类次生代谢产物及其生物活性的研究

为了研究红树林来源真菌Xylaria sp. HNWSW-2的次生代谢产物及其生物活性,综合利用多种色谱技术对该菌株发酵产物进行分离纯化,结合波谱学与理化常数分析进行化合物结构鉴定,分别采用液体浸泡法和Ellman比色法对化合物的全齿复活线虫致死活性和乙酰胆碱酯酶抑制活性进行测试。从Xylaria sp. HNWSW-2发酵产物乙酸乙酯萃取物中分离鉴定了7个异香豆素类化合物,分别为 (S)-(+)-8-O-methylmellein (1),(3S,4S)-(+)-4-hydroxy-8-O- methylmellein (2),(3S,4R)-(+)-4-hydroxy-8-O-methylmellein (3),(3S,4S)-(+)-4-hydroxymellein (4),(3S,4R)-(+)-4- hydroxymellein (5),(3R,4R)-(-)-4-hydroxy-5-methylmellein (6)和(3R,4S)-(+)-4-hydroxy-5-methylmellein (7)。其中,化合物1具有较强全齿复活线虫致死活性,化合物1~3、6和7具有一定的乙酰胆碱酯酶抑制活性。本研究首次发现化合物(S)-(+)-8-O-methylmellein具有较强的抗线虫活性,为相关杀线虫药物的研发提供理论依据。     

New Isocoumarin Analogues from the Marine-Derived Fungus Paraphoma sp. CUGBMF180003

Nine new secondary metabolites, including six isocoumarin analogues, 7-hydroxyoospolactone (1), 7-methoxyoospolactone (2), 7-methoxy-9-hydroxyoospolactone (3), 10-acetoxy-9-hydroxyoospolactone (4), 6-dehydroxysescandelin (5), parapholactone (6), and three compounds with a rare skeleton of isocoumarin coupled with phenylethylamine, namely paraphamide A (12), paraphamide B (13), and paraphamide C (14), together with five known compounds, oospolactone (7), 8-O-methyloospolactone (8), 10-hydroxyoospolactone (9), 9,10-dihydroxyoospolactone (10), and oospoglycol (11), were isolated and identified from the marine-derived fungus Paraphoma sp. CUGBMF180003. Their chemical structures were determined using spectroscopic data, including HRESIMS and 1D and 2D NMR techniques. Furthermore, the stereogenic carbons in 5 and 14 were determined by comparing the experimental and calculated electronic circular dichroism (ECD) spectra. The carbon skeleton of 12–14 was identified as the first example of isocoumarin coupled with phenylethylamine derivatives. All of these compounds were examined for antimicrobial activities against Candida albicans and Staphylococcus aureus. Both 1 and 6 showed antibacterial activity against S. aureus with MIC values of 12.5 μg/mL.     

New Alkylpyridinium Anthraquinone,Isocoumarin, C-Glucosyl Resorcinol Derivative and Prenylated Pyranoxanthones from the Culture of a Marine Sponge-Associated Fungus,Aspergillus stellatus KUFA 2017

An unreported isocoumarin, (3S,4R)-4-hydroxy-6-methoxymellein (2), an undescribed propylpyridinium anthraquinone (4), and an unreported C-glucosyl resorcinol derivative, acetyl carnemycin E (5c), were isolated, together with eight previously reported metabolites including p-hydroxybenzaldehyde (1), 1,3-dimethoxy-8-hydroxy-6-methylanthraquinone (3a), 1,3-dimethoxy-2,8-dihydroxy-6-methylanthraquinone (3b), emodin (3c), 5[(3E,5E)-nona-3,5-dien-1-yl]benzene (5a), carnemycin E (5b), tajixanthone hydrate (6a) and 15-acetyl tajixanthone hydrate (6b), from the ethyl acetate extract of the culture of a marine sponge-derived fungus, Aspergillus stellatus KUFA 2017. The structures of the undescribed compounds were elucidated by 1D and 2D NMR and high resolution mass spectral analyses. In the case of 2, the absolute configurations of the stereogenic carbons were determined by comparison of their calculated and experimental electronic circular dichroism (ECD) spectra. The absolute configurations of the stereogenic carbons in 6a and 6b were also determined, for the first time, by X-ray crystallographic analysis. Compounds 2, 3a, 3b, 4, 5a, 5b, 5c, 6a, and 6b were assayed for antibacterial activity against four reference strains, viz. two Gram-positive (Staphylococcus aureus ATCC 29213, Enterococcus faecalis ATCC 29212) and two Gram-negative (Escherichia coli ATCC 25922, Pseudomonas aeruginosa ATCC 27853), as well as three multidrug-resistant strains. However, only 5a exhibited significant antibacterial activity against both reference and multidrug-resistant strains. Compound 5a also showed antibiofilm activity against both reference strains of Gram-positive bacteria.     

Isolation of a phytotoxic isocoumarin from Diaporthe eres‐infected Hedera helix (English ivy) and synthesis of its phytotoxic analogs

BACKGROUND

The fungus Diaporthe eres was isolated from a fungal pathogen‐infected leaf of Hedera helix (English ivy) exhibiting necrosis. It is hypothesized that the causative fungus produces phytotoxins as evidenced by necrotic lesions on the leaves.

RESULTS

The fungus was isolated and grown in Czapek Dox broth culture medium and potato dextrose broth culture medium and identified as Diaporthe eres. The ethyl acetate extracts of the culture broths were phytotoxic to lettuce (Lactuca sativa) and bentgrass (Agrostis stolonifera). 3,4‐Dihydro‐8‐hydroxy‐3,5‐dimethylisocoumarin ( 1 ) and tyrosol ( 2 ) were isolated and identified as the phytotoxic constituents. Six analogs of 3,4‐dihydro‐isocoumarin were synthesized and shown to be phytotoxic. The synthesized 3,4‐dihydro‐8‐hydroxy‐3,7‐dimethylisocoumarin and 3,4‐dihydro‐8‐hydroxy‐3,3,7‐trimethylisocoumarin were two‐ to three‐fold more phytotoxic than the naturally occurring 1 in a Lemna paucicostata growth bioassay.

CONCLUSION

Synthesis and herbicidal activities of the several new analogs of 1 are reported for the first time. These promising molecules should be used as templates for synthesis and testing of more analogs. © 2017 Society of Chemical Industry