Jinyan Dong

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.

Secondary metabolites of plants from the genus chloranthus: chemistry and biological activities.

Chloranthus, a genus of the family Chloranthaceae, which is mainly distributed in eastern and southern Asia, has been used in Chinese folk medicine due to its antitumor, antifungal, and anti‐inflammatory activities. This review compiles the research on isolation, structure elucidation, structural diversity, and bioactivities of Chloranthus secondary metabolites reported between 2007 and 2013. The metabolites listed encompass 82 sesquiterpenoids, 50 dimeric sesquiterpenoids, 15 diterpenoids, one coumarin, and five other compounds. Among them, dimeric sesquiterpenoids, the characteristic components of plants from the genus Chloranthus, have attracted considerable attention due to their complex structures and significant biological features, e.g., antitumor, antibacterial, antifungal, anti‐inflammatory, and hepatoprotective activities, and potent and selective inhibition of the delayed rectifier (IK) K+ current and tyrosinase.

Diversity and biotransformative potential of endophytic fungi associated with the medicinal plant Kadsura angustifolia

This study investigated the diversity and host component-transforming activity of endophytic fungi in medicinal plant Kadsura angustifolia. A total of 426 isolates obtained were grouped into 42 taxa belonging to Fungi Imperfecti (65.96%), Ascomycota (27.00%), Zygomycota (1.64%), Basidiomycota (0.47%) and Mycelia Sterilia (4.93%). The abundance, richness, and species composition of endophytic assemblages were significantly dependent on the tissue and the sampling site. Many phytopathogenic species associated with healthy K. angustifolia were found prevalent. Among them, Verticillium dahliae was dominant with 16.43% abundance. From 134 morphospecies selected, 39 showed remarkable biocatalytic activity and were further identified as species belonging to the genera Colletotrichum, Eupenicillium, Fusarium, Hypoxylon, Penicillium, Phomopsis, Trametes, Trichoderma, Umbelopsis, Verticillium and Xylaria on the basis of the sequence analysis of the internal transcribed spacer (ITS1-5.8S-ITS2). The results obtained in this work show that K. angustifolia is an interesting reservoir of pathogenic fungal species, and could be a community model for further ecological and evolutionary studies. Additionally, the converting potency screening of some endophytic fungi from this specific medicinal plant may provide an interesting niche on the search for novel biocatalysts.

Chemical and bioactive diversities of the genera Stachybotrys and Memnoniella secondary metabolites

During the course of search for novel and bioactive molecules of microbial origin for drug development, Stachybotrys and Memnoniella fungi generally have been found to be a rich source of novel and bioactive secondary metabolites of great importance. Results of phylogenetic analyses were in agreement that the Memnoniella is paraphyletic to Stachybotrys. Interestingly, most Memnoniella spp. were found to produce the similar chemical substances. Up until now, almost 200 secondary metabolites belonging to diverse structural types of trichothecene, triprenyl phenol, diterpenoid, isochroman, polyketide, cochlioquinone and cyclic peptide have been discovered. Most of these fungal metabolites were reported to possess several interesting biological activities, such as disruption of the complement system, inhibition of TNF-α release, endothelin receptor antagonism, anti-influenza A virus, antimalarial, inhibition of avian myeloblastosis virus protease, cholesterol esterase, tyrosine kinase, farnesyl-protein transferase, squalene synthase and human heart chymase as well as stimulation of plasminogen, fibrinolysis, thrombolysis. This review summarizes the research on the isolation, structure elucidation, structural diversity, and bioactivities of the Stachybotrys and Memnoniella fungal secondary metabolites reported up to the year of 2014, and then highlights some bioactive compounds as well as their mechanisms of action and structure–activity relationships.

The fungal-specific transcription factor Vdpf influences conidia production, melanized microsclerotia formation and pathogenicity in Verticillium dahliae

Verticillium dahliae is a soil-borne, hemibiotrophic phytopathogenic fungus that causes wilting in crop plants. Here, we constructed a random insertional mutant library using Agrobacterium tumefaciens-mediated transformation to study the pathogenicity and regulatory mechanisms of V. dahliae. The fungal-specific transcription factor-encoding gene Vdpf was shown to be associated with vegetative growth and virulence, with the highest transcript expression occurring during conidia formation in the V991 strain. The deletion mutants (ΔVdpf) and insertion mutants (IMΔVdpf) produced fewer conidia than did the wild-type (WT) fungi, which contributed to the reduced virulence. Unlike the WT, the complemented strains and IMΔVdpf, ΔVdpf formed swollen, thick-walled and hyaline mycelium rather than melanized microsclerotia. The ΔVdpf mutants were melanin deficient, with undetectable expression of melanin biosynthesis-related genes (Brn1, Brn2 and Scd1). The melanin deficiency was related to cyclic adenosine monophosphate (cAMP) and the G-protein-coupled signalling pathways in this study. Similar to the WT and complemented strains, the ΔVdpf and IMΔVdpf mutants could also successfully penetrate into cotton and tobacco roots, but displayed reduced virulence because of lower biomass in the plant roots and significantly reduced expression of pathogenicity-related genes in V. dahliae. In conclusion, these results provide insights into the role of Vdpf in melanized microsclerotia formation, conidia production and pathogenicity.

Characterization of cadmium-resistant endophytic fungi from Salix variegata Franch. in Three Gorges Reservoir Region, China

The community and Cd-resistance of endophytic fungi from roots of Salix variegata Franch. collected from the water-level-fluctuation zone of Three Gorges Reservoir Region, China, were investigated. A total of 53 strains were isolated and identified to 13 morphotaxa, in which Chromosporium, Fusarium and Gonatobotrys were dominant genera. Among them, 27 isolates were selected to measure their resistance to 0.02 mg ml(-1) Cd(2+) and 11 were growth stimulated (Tolerance index>100%). Of these active isolates, four dark septate endophyte (DSE) isolates (Paraphaeosphaeria sp. SR46, Pyrenochaeta sp. SR35, Rhizopycnis vagum SR37 and R. vagum SR44) were further tested for minimum inhibitory concentrations (MICs) against Cd and SR46 was found to be the most tolerant isolate with MIC of 0.39 mg ml(-1). Additionally, the maximum uptake values of these DSEs ranged from 3.01 to 7.89 mg g(-1), but there was no significant correlation between metal uptake with fungal biomass and metal tolerance. Subsequently, a pot experiment was conducted for investigating the impact of SR46 on corn seedlings in Cd-enriched soil. The results obtained suggested that SR46 reduced the Cd bioaccumulation of plant under low (100 mg kg(-1)) Cd stress and enhanced the Cd translocation from root zone to aerial parts under high (200 mg kg(-1)) Cd stress. Besides, it promoted plant growth without Cd stress. These findings indicated S. variegata harbors an endophytic fungal flora showing a high genetic diversity as well as a high level of metal resistance to Cd that has potential values in cadmium cycling and restoration of plant, soil and water system.

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-7β-hydroxy-16β,26-lactone-3-oic acid (2) and 3,4-secocycloarta-4(28),17(20)(Z),24(Z)-triene-7β-hydroxy-16β-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.

Nematicidal metabolites from Gliocladium roseum YMF1.00133

A strain of the fungus Gliocladium roseum YMF1.00133 was found to secrete nematicidal metabolites against nematodes Panagrellus redivivus, Caenothabditis elegans and Bursaphelenchus xylophilus in experiments searching for nematicidal fungi. Through bioassay-guided fractionations, a unique trioxopiperazine alkaloid, gliocladin C (compound 1), and an alkylane resorcinol, 5-n-heneicosylresorcinol (compound 2) were obtained from the methanol extract of the fungus and determined by single-crystal X-ray analysis and spectroscopic data. In vitro immersion experiments showed that the ED50 values of compounds 1 and 2 after 24 h incubation were 15 and 30 μg/mL against C. elegans, 50 and 80 μg/mL against P. redivivus, and 200 and 180 μg/mL against B. xylophilus, respectively. The X-ray diffraction data of compound 1 and the nematicidal activity of compounds 1 and 2 were reported for the first time.

Metabolites from the co-culture of nigranoic acid and Umbelopsis dimorpha SWUKD3.1410, an endophytic fungus from Kadsura angustifolia

Abstract The ability of the endophytic fungus Umbelopsis dimorpha SWUKD3.1410 to transform the triterpene nigranoic acid (3, 4-secocycloarta-4(28), 24-(Z)-diene-3, 26-dioic acid; 1) was investigated. Co-culture of nigranoic acid with U. dimorpha SWUKD3.1410 yielded six major products, including a new triterpene (2) and 5 known compounds (3–7). Their structures were identified by the extensive 1D, 2D NMR and HR-ESI-MS Data analysis, and by comparison with those reported data. Among them, 2–4 were transformed from nigranoic acid (1), while 5–7 were derived from the culture medium stimulated by the substrate. On the basis of the structures of 2–4, it was proposed that the transformative process probably involved isomerase and hydroxylase, in which the former was rare in fungi. Additionally, all the compounds (1–7) were evaluated for their cytotoxic activity. As a result, compounds 1, 3–5 exhibited weak cytotoxicity against the tested cell lines, while others showed no cytotoxicity.

Two new polyhydroxysterols produced by Fusarium solani, an endophytic fungus from Chloranthus multistachys

Abstract A highly antagonistic endophytic fungus, designated strain CL39, was originated from the leaves of Chloranthus multistachys collected in Wulong of Chongqing municipality of China in November 2015. The strain was identified as Fusarium solani based on morphological characteristics, 5.8S gene and internal transcribed spacer sequence analysis. Two new compounds, 2β, 9α-dihydroxy-5α-methoxyergosta-7, 22-diene (1), 2β, 6β-dihydroxy-5α-methoxyergosta-7, 22-diene (2) have been isolated from the culture broth of the strain. Structures of the new compounds were elucidated by detailed analysis of their spectroscopic data aided by the comparison with reported data of related derivatives, and found to belong to the polyhydroxylated steroids with a hydroxyl at C-2 instead of C-3, a rare structure among the steroids. The extract of this strain and all isolated compounds were evaluated for their antagonistic activities.