Community Structure and Diversity of Endophytic Fungi in Cultivated Polygala crotalarioides at Two Different Growth Stages Based on Culture-Independent and Culture-Based Methods.

Polygala crotalarioides, a perennial herbaceous plant found in southwest China, has the potential to be used in the treatment of Alzheimer's disease. Endophytic fungi that reside within medicinal herbs play an important ecological role in their host plants and can serve as a valuable source for identifying active components. However, little is known about the diversity, and structure of endophytic fungi in P. crotalarioides. In this study, we investigated the community structure and diversity of endophytic fungi in the leaves, stems, and roots of P. crotalarioides at both 1- and 2-year-growth stages using a modern culture-independent method using both culture-independent (high-throughput sequencing, HTS) and culture-based methods. Using HTS, our results revealed that the richness and diversity of endophytic fungi in P. crotalarioides varied depending on the organs and growth stages. Specifically, stems and leaves exhibited significantly higher diversity compared to roots. Additionally, the highest diversity of endophytic fungi was observed in the stems of the 2-year-old plants. At the genus level, Fusarium, Colletotrichum, and Phoma were the most abundant endophytic fungi in 1-year-old samples, while Cercospora, Apiotrichum, and Fusarium were prevalent in 2-year-old samples. A total of 55 endophytic fungal strains belonging to two phyla and 24 genera were isolated from 150 plant tissue segments using culture-based methods. The anti-acetylcholinesterase activity of these isolates was evaluated in vitro and five of them, Phialophora mustea PCAM010, Diaporthe nobilis PCBM027, Fusarium oxysporum LP41, F. oxysporum SR60, and Phoma herbarum SM81, showed strong activity (>50% inhibition rate). These findings will serve as a theoretical basis and practical guide for comprehending the structural composition, biological diversity and bioactivity of endophytic fungi in P. crotalarioides.

Glutathione-functionalized long-period fiber gratings sensor based on surface plasmon resonance for detection of As3+ ions.

Development of simple and accurate methods for the detection of As3+is highly desirable and technically important. In this work, a highly sensitive and selective long-period fiber gratings sensor based on surface plasmon resonance was developed for As3+detection by designing glutathione-functionalized Au nanoparticles as a signal amplification tag. Based on the chemical interaction between As3+and glutathione, the self-assembling glutathione on the surface of the gold film combines selectively with As3+, and then anchors the glutathione-functionalized Au nanoparticles, which changes the refractive index of the surrounding environment, resulting in a shift of the transmission spectrum. Results show that the sensor could detect As3+with concentrations ranging from 0.02 to 2 ppb. The sensor exhibited excellent specificity for As3+against other metal ions, such as Na+, Fe3+, Mg2+, Cu2+, Pb2+, Ni2+, Ba2+, and Co3+. The fiber sensor was successfully employed to detect As3+in pond water samples, demonstrating that it has the potential for As3+detection with the advantages of low cost, high sensitivity, and a simple structure.

Microbiological transformation of the triterpene nigranoic acid by the freshwater fungus Dictyosporium heptasporum.

The microbiological transformation of the triterpene nigranoic acid (3,4-secocycloarta-4(28),24(Z)-diene-3,26-dioic acid) (1) to 3,4-secocycloarta-4(28),17(20),24(Z)-triene-7ß-hydroxy-16ß,26-lactone-3-oic acid (2) and 3,4-secocycloarta-4(28),17(20)(Z),24(Z)-triene-7ß-hydroxy-16ß-methoxy-3,26-dioic acid (3) by the freshwater fungus Dictyosporium heptasporum YMF1.01213 has been demonstrated. The structures of the biotransformation products were determined by spectroscopic and MS analyses. Compound 2, characterized by the presence of a formed C-16/C-26 ester bridge, provided a novel nine-membered lactone ring structural skeleton for 3,4-secocycloartane triterpenoid derivatives. In addition, Compounds 1-3 exhibited weak anti-HIV activity in vitro. Compounds 2 and 3 were reported for the first time as natural product derivatives.

Novel dibenzo[b,e]oxepinones from the freshwater-derived fungus Chaetomium sp. YMF 1.02105.

Six new dibenzo[b,e]oxepinone metabolites, chaetones A-F (1-6), as well as three known compounds, 1-hydroxy-6-methyl-8-hydroxymethylxanthone (7), citreorosein (8), and emodin (9), were obtained from a freshwater-derived fungal strain Chaetomium sp. YMF 1.02105. Their structures were established on the basis of extensive spectroscopic data analysis and comparison with spectroscopic data reported. Compounds 1-6 are further additions to the small group of dibenzo[b,e]oxepinones represented by arugosins A-H. Compounds 1-7 were tested for their cytotoxic activities against A549, Raji, HepG2, MCF-7, and HL-60 cell lines. The results showed that compound 3 had significant cytotoxicity with IC50 values of 1.2, 1.8, 1.9, 2.3, and 1.6 µg/mL, respectively, against the five cancer cell lines. All compounds showed modest antimicrobial activity against Staphylococcus aureus (ATCC 6538) in standard disk assays.

Compounds from Kadsura angustifolia with anti-HIV activity.

Four new cycloartane triterpenoids, angustific acid A (1), angustific acid B (2), angustifodilactone A (3) and angustifodilactone B (4) were isolated from the branches of Kadsura angustifolia together with six known compounds, micranoic acid B (5), nigranoic acid (6), schisandrin (7), schisantherin D (8), interiotherin B (9), schisantherin B (10). Their structures were established on the basis of extensive spectroscopic data analyses and comparison with spectroscopic data reported. Compound 1, characterized by the presence of a C-16/C-17, C-20/C-21 conjugated diene and a C-1/C-7 ester bridge formed in rings A and B, provided a novel structural skeleton for 3,4-secocycloartane triterpenoid derivatives. In addition, the anti-HIV activities of these compounds were determined in infected C8166 cells, and it was found that angustific acid A (1) exhibited the most potent anti-HIV activity with an EC(50) value of 6.1 µg/mL and a therapeutic index of more than 32.8.

Ophiocerol, a novel macrocylic neolignan from the aquatic fungus Ophioceras dolichostomum YMF1.00988.

From cultural filtrates of the freshwater fungus Ophioceras dolichostomum YMF1.00988 a novel neolignan with an unprecedented dibenzo-1,6-dioxacyclodecane carbon skeleton, ophiocerol (1), was isolated, and the known compounds isoamericanoic acid A (2) and caffeic acid (3) were identified. The structure of the novel compound was determined by interpretation of its spectroscopic data, including 1D and 2D, (1)H and (13)C NMR (COSY, HMQC, HMBC, NOESY), and MS. Compounds 1-3 were assayed for their nematicidal activity against Bursaphelenchus xylophilus as well as their antifungal activity against several plant pathogen fungi.

Colomitides A and B: novel ketals with an unusual 2,7-dioxabicyclo[3.2.1]octane ring system from the aquatic fungus YMF 1.01029.

Two novel diastereoisomeric bicyclic ketals, colomitides A and B (1 and 2, resp.), together with the known (4RS)-3,4-dihydro-4,8-dihydroxynaphthalen-1(2H)-one (3) and preussomerin E (4), were isolated from liquid cultures of an unidentified freshwater fungus YMF 1.01029. Colomitides possess an unusual 2,7-dioxabicyclo[3.2.1]octane skeleton. The chemical structures and relative configurations of compounds 1 and 2 were elucidated by spectroscopic means, including 2D-NMR (HMBC, HMQC, TOCSY, ROESY, and (1)H,(1)H-COSY). Compounds 1, 2, and 4 showed noticeable antifungal and antibacterial activities.

Two unusual naphthalene-containing compounds from a freshwater fungus YMF 1.01029.

Two novel naphthalene-containing compounds, colelomycerones A and B (1 and 2, resp.), and three known metabolites, including preussomerin D (3), (2RS,2'SR,3'E,3SR,4E,8E)-1-O-(beta-D-glucopyranosyl)-3-hydroxy-2-[(2-hydroxyoctadec-3-enoyl)amino]-9-methyloctadeca-4,8-diene (4), and 3beta-hydroxy-5alpha,8alpha-epidioxyergosta-6,22-diene (5), were isolated from the culture broth of an unidentified freshwater water fungus YMF 1.01029. This fungus was collected from a decaying branch of an unidentified tree near Lake Fuxian in Yunnan Province, China. The structures of these five compounds were determined on the basis of their spectroscopic and mass-spectrometric data. Colelomycerones A and B (1 and 2, resp.) represent unprecendented examples of naphthalene-1,2-diones with novel cyclic acetals. Compounds 1-3 showed noticeable antifungal and antibacterial activities.