Boerelasins A-D, Four Unprecedented Cytochalasins from the Endophytic Fungus Boeremia Exigua.

Four undescribed cytochalasins (1-4) were isolated from the endophytic fungus Boeremia exigua. Structurally, boerelasin A (1) represents the first example of a cytochalasin with a rare 5/5 bicyclic carbon core. Boerelasin B (2) possesses an unprecedented 5/6/5/6/8 pentacyclic ring system. Boerelasin C (3), a derivative from the common biosynthetic intermediate to 1, is a macrocyclic ring-opening cytochalasin, and boerelasin D (4) contains an uncommon six-carbon alkyl acid side chain. The structures were elucidated based on spectroscopic methods, electronic circular dichroism, spin-spin coupling constants, and calculated nuclear magnetic resonance with DP4+ analysis. These compounds exhibited significant cytotoxicity against the tumor cells.

Ophiorrhines F and G, Key Biogenetic Intermediates of Ophiorrhine Alkaloids from Ophiorrhiza japonica and Their Immunosuppressant Activities.

Continued interest in bioactive alkaloids led to the isolation of two undescribed alkaloids, ophiorrhines F (1) and G (2), from the aerial parts of Ophiorrhiza japonica. Their structures were elucidated based on spectroscopic methods, electronic circular dichroism, and calculated NMR with DP4+ analysis. These two alkaloids represent key biological genetic intermediates in the formation of ring C in the ophiorrhines. Compound 1 exhibited good inhibition on LPS-induced B cell proliferation with an IC50 value of 0.38 µM and showed significant selective inhibitory activity on a B cell proliferation response with a selective index of 548.42. A preliminary study indicated that 1 may have a new mechanism of immunosuppression.

Structure and cytotoxicity of trichothecenes produced by the potato-associated fungus Trichothecium crotocinigenum.

Seven previously undescribed trichothecenes, named trichothecrotocins M-S (1-7), along with five known compounds, were isolated from rice cultures of the potato-associated fungus Trichothecium crotocinigenum. Their structures and absolute configurations were determined through spectroscopic methods, single-crystal X-ray diffraction, and quantum chemistry calculations on ECD. Compound 1 possesses a rare 6,11-epoxy moiety in the trichothecene family. Compound 6 exhibited strong cytotoxic activity against MCF-7 cancer cell lines with an IC50 value of 2.34 ± 0.45 µM. It promoted apoptosis induction in MCF-7 cells. Moreover, cell cycle analysis showed cell cycle arrest caused by compound 6 at the G2/M phase which resulted to cell proliferation inhibition and pro-apoptotic activity. Further quantitative real-time PCR (qRT-PCR) analysis confirmed that the G2/M arrest was accompanied by upregulation of p21 and down regulation of cyclins B1 in 6-treated MCF-7 cells.

Comparative transcriptome combined with metabolome analyses revealed key factors involved in nitric oxide (NO)-regulated cadmium stress adaptation in tall fescue.

BACKGROUND: It has been reported that nitric oxide (NO) could ameliorate cadmium (Cd) toxicity in tall fescue; however, the underlying mechanisms of NO mediated Cd detoxification are largely unknown. In this study, we investigated the possible molecular mechanisms of Cd detoxification process by comparative transcriptomic and metabolomic approaches. RESULTS: The application of Sodium nitroprusside (SNP) as NO donor decreased the Cd content of tall fescue by 11% under Cd stress (T1 treatment), but the Cd content was increased by 24% when treated with Carboxy-PTIO (c-PTIO) together with Nitro-L-arginine methyl ester (L-NAME) (T2 treatment). RNA-seq analysis revealed that 904 (414 up- and 490 down-regulated) and 118 (74 up- and 44 down-regulated) DEGs were identified in the T1 vs Cd (only Cd treatment) and T2 vs Cd comparisons, respectively. Moreover, metabolite profile analysis showed that 99 (65 up- and 34-down- regulated) and 131 (45 up- and 86 down-regulated) metabolites were altered in the T1 vs Cd and T2 vs Cd comparisons, respectively. The integrated analyses of transcriptomic and metabolic data showed that 81 DEGs and 15 differentially expressed metabolites were involved in 20 NO-induced pathways. The dominant pathways were antioxidant activities such as glutathione metabolism, arginine and proline metabolism, secondary metabolites such as flavone and flavonol biosynthesis and phenylpropanoid biosynthesis, ABC transporters, and nitrogen metabolism. CONCLUSIONS: In general, the results revealed that there are three major mechanisms involved in NO-mediated Cd detoxification in tall fescue, including (a) antioxidant capacity enhancement; (b) accumulation of secondary metabolites related to cadmium chelation and sequestration; and (c) regulation of cadmium ion transportation, such as ABC transporter activation. In conclusion, this study provides new insights into the NO-mediated cadmium stress response.

Trichothecrotocins D-L, Antifungal Agents from a Potato-Associated Trichothecium crotocinigenum.

Seven new merosesquiterpenoids, trichothecrotocins D-J (1-7), two new trichothecene sesquiterpenoids, trichothecrotocins K (12) and L (13), and six known compounds (8-11, 14, and 15), were isolated from a potato-associated fungus, Trichothecium crotocinigenum. Compounds 5 and 6 were racemates which were further separated as pure enantiomers. Structures together with absolute configurations were established by extensive spectroscopic analysis, as well as quantum chemistry calculations on ECD and optical rotations. Compounds 1-4 are rare meroterpenoids featuring a seco-phenyl group, while 1 and 2 possessed a novel 6-6/5 fused ring system. Compounds 1-4, 8, 11, and 12 showed antifungal activity against four plant pathogens with MIC values of 8-128 µg/mL. It is suggested that the meroterpenoids produced by T. crotocinigenum may play an important role in the antifungal property of the fungus, thereby protecting the host plant, i.e., potato.

Dietary Ginkgo biloba leaf extract alters immune-related gene expression and disease resistance to Aeromonas hydrophila in common carp Cyprinus carpio.

Ginkgo biloba leaf is widely used in traditional medicine in China. The present study aimed to illustrate the effects of dietary Ginkgo biloba leaf extract (GBLE) on growth performance and immune responses in common carp infected by Aeromonas hydrophila. Six different diets either not treated (control) or treated with 0.5, 1, 2, 5 and 10 g/kg of GBLE were designed to feed the fishes for 8 weeks. The results indicated that, compared to the control groups, 10 g/kg dietary GBLE significantly increased body growth and feed utilization. In GBLE dietary groups, red blood cell levels, white blood cells, hematocrit, hemoglobin, total protein, albumin and globulin were significantly increased relative to the control groups. Dietary supplementation with 5 g/kg GBLE increased the phagocytic ratio, and phagocytic indexes increased in the 2, 5 and 10 g/kg groups relative to the control groups. Moreover, 2, 5 and 10 g/kg GBLE diets increased O2- production compared to the control groups. Additionally, GBLE diets stimulated lysozyme activity (in 10 g/kg group) and inhibited bactericidal activity (in 0.5, 2, 5 and 10 g/kg group). Quantitative real-time PCR showed that IL1ß, IL8, TNF-α, IL10, TGFß, and inducible enzyme genes were prone to decrease while SAA, hepcidin and GPX1 were increased due to the GBLE diet in the intestine. In the head-kidney, the GBLE treatment decreased IL1ß, IL8, TNF-α, IL10, TGFß, INOS and arginase gene expressions, whereas SOD upregulation was found in the GBLE condition. The mRNA expressions of IL1ß, IL8, TNF-α, IL10 and INOS were decreased, but SAA, hepcidin, GPX1 and SOD mRNA levels were increased in the spleen in the GBLE diet compared to the control. Additionally, diet supplemented with GBLE improved the survival rate infected with A. hydrophila. Our observations suggest that GBLE effectively enhanced growth performance, modulated immune-related gene expression. It improved survival rate of common carp after A. hydrophila infection and the optimum concentration we recommend is 10 g/kg of GBLE.

Curtachalasins, immunosuppressive agents from the endophytic fungus Xylaria cf. curta.

Eleven new cytochalasins, curtachalasins F-P (1-11), were isolated from the rice fermentation of endophytic fungus Xylaria cf. curta. Their structures were identified by extensive spectroscopic methods, X-ray diffraction, and quantum chemistry calculations. Curtachalasin P possesses a unique 5/6/6/7 fused ring system. In the bioactivity screening for curtachalasins F-P, A-C, and E (1-15), compounds 1, 3-6, 8-13, and 15 did not show obvious cytotoxicity against primary mouse splenocytes. Furthermore, the immunosuppressive assay against concanavalin A (ConA) induced T lymphocyte cell proliferation and lipopolysaccharide (LPS) induced B lymphocyte cell proliferation showed that compound 1 results in significant selective inhibition on B-cell proliferation (IC50 value of 2.42 µM) and compound 10 has selective inhibition on T-cell proliferation (IC50 value of 12.15 µM). These interesting immunosuppressive properties of this class of compounds provide new clues to fulfill the urgent demand for new immunosuppressive drugs.

Novel Metabolites from the Endophytic Fungus Chaetomium subaffine L01.

One natural p-terphenyl glycoside, gliocladinin C, and two furano-polyene derivatives, chaetominins A and B, were isolated from potato endophytic fungus Chaetomium subaffine. The absolute configurations of these compounds were elucidated by HR-ESI-MS, NMR, the DP4+ probabilities and electronic circular dichroism (ECD) spectra. Furthermore, gliocladinin C and chaetominin A showed cytotoxic activity against two selected human tumor cell lines (Hep-2 and HepG-2).

Nitric oxide alleviates toxicity of hexavalent chromium on tall fescue and improves performance of photosystem II.

Tall fescue (Festuca arundinacea Schreb) was widely studied for phytoremediation of organic or heavy metal contaminated soils. However, there is still little information concerning toxicity of chromium (Cr) to tall fescue and roles of nitric oxide (NO) in plants against Cr(VI) stress. In this study, different Cr(VI) treatments (0, 1, 5 and 10 mg/L Cr(VI)) and NO treatments were applied with different combinations in hydroponics culture and their interactions to tall fescue were studied. Specifically, 100 µM sodium nitroprusside (SNP) and 100 µM NG-nitro-L-arginine-methyl ester (L-NAME) treatments were used to apply exogenous NO or inhibit synthesis of NO respectively. Our results showed that tall fescue exhibits comparable Cr(VI) tolerance as wheat (Triticum aestivum L.). Additionally, Cr(VI) accumulation in tall fescue leaves were carefully studied and discussed. Moreover, we observed the significantly increased reactive oxygen species (ROS) contents of tall fescue when subjected to Cr(VI) stress, as well as decreased photosynthetic activities induced by Cr(VI) stress by methods of chlorophyll a fluorescence transient, slow chlorophyll fluorescence kinetics and rapid light response curves. Decreased behaviors of photosynthetic activities may due to destruction of antennae pigments by Cr(VI), ROS burst induced by Cr(VI), and down regulation of photosystem II (PSII) by non-photochemical quenching to avoid over reduction of quinone A, which could be considered as an important strategy to cope with Cr(VI) stress. Meanwhile, exogenous NO treatment improves overall physiological and photosynthetic behaviors of tall fescue against Cr(VI) stress. Moreover, increased translocation factors and improved Cr(VI) tolerance of plants under exogenous NO treatment suggest that SNP treatment could be a useful application for Cr phytoremediation.

Transcriptome analysis providing novel insights for Cd-resistant tall fescue responses to Cd stress.

Cadmium (Cd) is a severely toxic heavy metal and environmental pollutant. Tall fescue is a cold season turf grass which has high resistance to Cd as well as the ability to enrich it. To investigate the molecular mechanism underlying the adaptability of tall fescue to Cd stress, RNA-Seq was used to examine Cd stress responses of tall fescue at a transcriptional level. A total of 12 cDNA libraries were constructed from the total RNA of roots or leaves of tall fescue with or without Cd treatments. A total of 2594 (1768 up- and 826 down-regulated) differentially expressed genes (DEGs) were detected in the roots of Cd-stressed tall fescue compared with control roots (R_cd vs R_ck), while only 52 (29 up- and 23 down-regulated) DEGs were found in the leaves of Cd-stressed plants versus the controls (L_cd vs L_ck). The genes encoding glutathione S-transferase (GST), transporter proteins including the ABC transporter, ZRT/IRT-like protein, potassium transporter/channel, nitrate transporter, putative iron-phytosiderophore transporter, copper-transporting ATPase or transporter and multidrug and toxic compound extrusion (MATE) proteins, and numerous transcription factors were found to be significantly induced in Cd-treated roots. In addition, pathogenesis/disease-related gene mRNAs were accumulated in Cd-treated roots of tall fescue. Furthermore, the significantly enriched KEGG pathways in roots were related to 'Glutathione metabolism', 'Ribosome', 'alpha-Linolenic acid metabolism', 'Diterpenoid biosynthesis', 'Sulfur metabolism', 'Phenylpropanoid biosynthesis', 'Protein processing in endoplasmic reticulum', 'Protein export' and 'Nitrogen metabolism'. The study provides novel insights for further understanding the molecular mechanisms of tall fescue responses to Cd stress.

Distribution and phytotoxicity of soil labile aluminum fractions and aluminum species in soil water extracts and their effects on tall fescue.

Soil acidification can alter the biogeochemistry of ecosystems and adversely affect biota; however, there are still many debates about the toxicity of aluminum (Al) fractions and Al species in soil:water extracts to plants. In this study, five crude soils with different pH values (4.92-8.51) were collected, seeded with tall fescue and grown in rhizosphere boxes for 120 days. Then, soil properties, labile Al fractions and Al species in soil:water extracts were determined, and their toxicities to plants were analyzed. Our study showed that a stable exchangeable Al fraction (ExAl) pool exists and is supplied by other labile Al fractions. Dissolution of Al from adsorbed hydroxyl-Al fraction (HyAl) and organic-Al fraction (OrAl) may play important roles in soil Al toxicity, as HyAl and OrAl account for major parts of soil labile Al. Additionally, Al3+ and mononuclear hydroxyl-Al species in soil:water extracts have few effects to plants. Nevertheless, high negative correlations were found between Al-F- complexes and tall fescue biomass, indicating their toxicity in the natural soil environment. Thus, in many cases, Al3+ toxicity should not be emphasized because of its lower activity in soil water extracts. Moreover, toxicities of AlF3(aq) and AlF4- to plants should be emphasized, because they have been confirmed in soil water extracts in this study.

Two new phenolic compounds and antitumor activities of asparinin A from Asparagus officinalis.

Two new phenolic acid compounds, asparoffin C (1) and asparoffin D (2), together with four known compounds, asparenyol (3), gobicusin B (4), 1-methoxy-2-hydroxy-4-[5-(4-hydroxyphenoxy)-3-penten-1-ynyl] phenol (5), and asparinin A (6), have been isolated from the stems of Asparagus officinalis. The structures were established by extensive spectroscopic methods (MS and 1D and 2D NMR). Compound 6 has obvious antitumor activities both in vitro and in vivo.

Two new acetylenic compounds from Asparagus officinalis.

Two new acetylenic compounds, asparoffins A (1) and B (2), together with two known compounds, nyasol (3) and 3″-methoxynyasol (4), were isolated from stems of Asparagus officinalis. The structures of two new compounds were elucidated on the basis of detailed spectroscopic analyses (UV, IR, MS, 1D, and 2D NMR). All compounds were evaluated for their cytotoxicities against three human cancer cell lines.

Three new sativene sesquiterpenoids from cultures of endophytic fungus Bipolaris eleusines.

Three new sativene sesquiterpenoids, bipolenins A-C (1-3), together with two known analogs (4 and 5), were obtained from cultures of endophytic fungus Bipolaris eleusines. The structures of new compounds were elucidated on the basis of extensive spectroscopic analyses. Compound 2 showed weak inhibitory activities against lung cancer A-549 and breast cancer MCF-7 with IC50 values of 33.2 and 19.1 µmol, respectively.

Harzianic acids and oxazolidinone from the endophytic fungus Ilyonectria sp. and their cytotoxicity activity.

Four undescribed compounds including three harzianic acids (1, 3 and 4) and one oxazolidinone (2), along with three known ones (5-7) were isolated from the solid fermented product of endophytic fungus Ilyonectria sp., their structures were elucidated as 1-amino-harzianic acid (1), ilyonectria-oxazolidinone (2),10'-nor- isoharzianic acid (3), isohomoharzianic acid (4), harzianic acid (5), isoharzianic acid (6), homoharzianic acid (7) by means of detailed chemical evidences and spectroscopic data analysis. All the compounds were evaluated for cytotoxicity against SMMC-7721 human cancer cell lines by MTS assay. Among the seven tested compounds, 1-amino-harzianic acid (1) demonstrated well cytotoxic activity against SMMC-7721 with IC50 value of 26.84 µM. The results of molecular docking indicated that compound exhibited moderate anti-tumor activity may through binding to apoptosis related proteins.

A facile strategy for the construction of a phage display cyclic peptide library for the selection of functional macrocycles.

Cyclic peptides represent invaluable scaffolds in biological affinity, providing diverse collections for discovering functional molecules targeting challenging biological entities and protein-protein interactions. The field increasingly focuses on developing cyclization strategies and chemically modified combinatorial libraries in conjunction with M13 phage display, to identify macrocyclic peptide inhibitors for traditionally challenging targets. Here, we introduce a cyclization strategy utilizing ortho-phthalaldehyde (OPA) for the discovery of active macrocycles characterized by asymmetric scaffolds with side-chain cyclization. Through this approach, aldehyde groups attached to free molecules sequentially attack the ε-amine of lysine and the thiol of cysteine, facilitating the rapid cyclization of genetically encoded linear precursor libraries displayed on phage particles. The construction of a 109-member library and subsequent screening successfully identified cyclic peptide binders targeting three therapeutically relevant proteins: PTP1B, NEK7, and hKeap1. The results confirm the efficacy in rapidly obtaining active ligands with micromolar potency. This work provides a fast and efficient operable high-throughput platform for screening functional peptide macrocycles, which hold promise for broad application in therapeutics, chemically biological probes, and disease diagnosis.

Chromones from the endophytic fungus Bipolaris eleusines.

Eight previously undescribed chromones eleusineketones A-H (1-8), as well as eight known compounds (9-16), were isolated from the endophytic fungus Bipolaris eleusines. These planar structures were created using an in-depth analysis of their spectral data, which included 1D, 2D, and HRESIMS data. Furthermore, the absolute configurations of compounds 1, 2, and 6 were determined by spectroscopic analysis and quantum chemical computational approaches, and compound 5 was determined by single-crystal X-ray diffraction analysis. The cytotoxic activity assay revealed that compounds 1 and 5 both inhibited MDA-MB-231 cells with IC50 values of 14.48 µM and 17.99 µM, respectively.

The reproductive strategy of a pollinator-limited Himalayan plant, Incarvillea mairei (Bignoniaceae).

BACKGROUND: Plants may adapt to alpine habitats by specialization in the reproductive strategy and functional aspects of their flowers and pollination systems. Alpine habitats reduce the opportunities for cross-pollination in a relatively high proportion of alpine plant species, and self-pollination may be favored in these adverse conditions. Here, we investigated the mating system and pollination of Incarvillea mairei, a perennial Himalayan herb typically found at altitudes between 3000 and 4500 m. RESULTS: Analyses of floral morphology, observation of plant-pollinator interactions, and hand pollination experiments were conducted in three natural populations. Outcrossing rates and effective numbers of pollen donors were assessed in 45 open-pollinated families by using progeny analysis based on seven microsatellite markers. Incarvillea mairei displayed a set of apparently specialized floral traits, the stigma is sensitive to touch and close immediately and its reopening allows a second opportunity for the receipt of pollen. The species is fully self-compatible but employs a predominantly outcrossing mating system according to parentage analysis (tm > 0.9). Fruit set was low (26.3%), whereas seed set was high (67.2%), indicating that this species suffers pollinator limitation. Its main effective pollinator was Halictus sp., and visitation frequency was low. CONCLUSIONS: Floral features such as having a sensitive stigma and anther-prongs, in conjunction with pollinator behavior, function together contributing to a set of unique reproductive adaptations that enhance outcrossing success. The increased floral longevity and high pollination efficiency operated as compensatory mechanisms to counteract low pollinator visitation frequency.

Six Unprecedented Cytochalasin Derivatives from the Potato Endophytic Fungus Xylaria curta E10 and Their Cytotoxicity.

Six previously undescribed cytochalasins, Curtachalasins X1-X6 (1-6), together with six known compounds (7-12) were isolated from the endophytic fungus Xylaria curta E10 harbored in the plant Solanum tuberosum. The structures were elucidated by the interpretation of HRESIMS, UV, and NMR data. The absolute configurations of Curtachalasins X1-X6 were determined by comparison of their experimental and calculated electronic circular dichroism (ECD) spectra. In bioassays, Curtachalasin X1 (1) and X5 (5) showed cytotoxic activity against the MCF-7 cell line with IC50 values of 2.03 µM and 0.85 µM, respectively.

The antifungal properties of terpenoids from the endophytic fungus Bipolaris eleusines.

A series of terpenoids (1-17), comprising six new compounds designated bipolariterpenes A-F (1-6) and eleven recognized compounds (7-17), were isolated from the wheat culture of the potato endophytic fungus Bipolaris eleusines. Their structures and stereochemistry were clarified by HRESIMS, NMR, DP4 + probability analyses, and computations for electronic circular dichroism (ECD). All compounds are made up of six meroterpenoids, four sesterterpenes and seven sesquiterpenes. Among them, four sesterterpenes (4, 5, 10, 11) were investigated for their antifungal, antibacterial and cytotoxic properties, and six meroterpenoids (1-3, 7-9) were evaluated for their antifungal properties. The compounds 7, 9, and 10 had substantial antifungal activity against Epidermophyton floccosum at a concentration of 100 µM. No antibacterial and cytotoxic activities were observed.