Cadinane-Type Sesquiterpenoids with Cytotoxic Activity from the Infected Stems of the Semi-mangrove Hibiscus tiliaceus.

Eight new cadinane sesquiterpenoids (1-8), along with two known compounds (9 and 10), were isolated from infected stems of the semi-mangrove plant, Hibiscus tiliaceus. The structures of compounds 1-8 were elucidated through the analysis of their 1D and 2D NMR and MS data, and their absolute configurations were determined by comparing their experimental and calculated ECD spectra and by single-crystal X-ray diffraction. The two confused known compounds (9 and 10) were resolved using single-crystal X-ray crystallography. Compounds 1-3 have novel norsesquiterpene carbon skeletons arising from a ring contraction rearrangement. All obtained isolates were evaluated against the HepG2 and Huh7 cell lines, and compounds 1b, 2b, 4, 6, and 8 showed cytotoxic activity toward both cell lines, with IC50 values ranging from 3.5 to 6.8 µM.

Cadinane-type sesquiterpenoid dimeric diastereomers hibisceusones A-C from infected stems of Hibiscus tiliaceus with cytotoxic activity against triple-negative breast cancer cells.

Three new cadinane-type sesquiterpenoid dimeric diastereomers (1-3) named hibisceusones A-C were obtained from the infected stems of Hibiscus tiliaceus. The structures were determined by NMR spectroscopy and MS techniques, and the absolute configurations were assigned by ECD and single-crystal X-ray diffraction techniques. Compounds 1-3 are diastereomers, and contain a 1,4-dioxane ring linearly fused to different cadinane-type polycyclic skeletons. This is the first time that such a structure has been identified in natural products. Compounds 1-3 exhibited cytotoxic activities, and 2 showed a significantly high anti-triple-negative breast cancer (TNBC) effect. The anti-cancer effect of compound 2 was 3-4 fold higher than that of 1 and 3. The anti-cancer effect was generated via the induction of the apoptosis of the MDA-MB-231 cells by inhibiting the PI3Kα pathway.

Phenolics, Flavonoids Content and Antioxidant Activities of Tuber indicum at Different Maturity Stages.

The Chinese black truffle Tuber indicum (Ascomycota, Pezizales) is an ectomycorrhizal fungus forming hypogeous edible ascocarps. As a famous wild edible mushroom in the world, this species also attracted an increasing interest in their chemical composition and pharmacological activity. In this study, the total phenolic content, total flavonoid content and antioxidant activities of Tuber indicum collected from July to November at different maturity stages in China were analyzed. Our results showed that T. indicum collected in July (immature stage) possessed the highest amount of flavonoids (3.89 mg/g dw) and the highest ABTS.+ scavenging activity (EC50 =3.73 mg/ml). In addition, those samples collected in August (moderate mature stage) contained the highest phenolics content (4.78 mg/g dw), the highest DPPH⋅ radical scavenging activity (EC50 =3.73 mg/ml) and ferric reducing activity power (243.63 µmol FeSO4 /g). The study reveals T. indicum in the early maturity stage yield significantly higher content of phenolics and flavonoids and possessed stronger antioxidant activity than those collected in other months. This study provided important data for understanding the relationship between maturity stages and truffle formation and evaluating the quality of Chinese black truffle at different maturity.

Diversity and spatial distribution of endophytic fungi in Cinnamomum longepaniculatum of Yibin, China.

Cinnamomum longepaniculatum (Gamble) N. Chao is an important woody incense plant that contains volatile terpenoids and has been extensively cultivated in Yibin, China. However, the relationship between endophytic fungal diversity and C. longepaniculatum species remains unclear. Here, fungal taxa in different tissue samples were analyzed using Illumina-based sequencing of ITS1 region of fungal rDNA genes. Results showed that 476 OTUs were identified in all tissues of C. longepaniculatum, with 78 OTUs common among all tissues. Similarity cluster analysis indicated that these OTUs belong to 5 phyla and at least 18 genera, with a large number of OTUs remaining unidentified at family and genus levels. The fungal community in seeds exhibited the greatest richness and diversity, followed by those in branches, leaves, and roots, respectively. Unclassified Chaetosphaeriales (91.66%), Passalora (57.17%), and unclassified Ascomycota (58.79%) OTUs dominated in root, branch, and leaf communities, respectively, and other common groups in the branch community included unclassified Ascomycota (12.13%), Houjia (10.38%), and Pseudoveronaea (5.43%), whereas other common groups in leaf community included Passalora (11.43%) and Uwebraunia (8.58%). Meanwhile, the seed community was dominated by unclassified Ascomycota (16.98%), unclassified Pleosporaceae (15.46%), and Talaromyces (12.50%) and also included high proportions of unclassified Nectriaceae (7.68%), Aspergillus (6.95%), Pestalotiopsis (6.02%), and Paraconiothyrium (5.11%) and several seed-specific taxa, including Peniophora, Cryptodiscus, and Penicillium. These findings suggest that Yibin-native C. longepaniculatum harbors rich and diverse endophytic communities that may represent an underexplored reservoir of biological resources.

Chemical Composition and Antioxidant Activity of Tuber indicum from Different Geographical Regions of China.

Tuber indicum, an endemic truffle species in eastern Asian, is an edible mushroom that is both an important export and widely distributed across China. Many existing studies on truffles focus on analyzing their taxonomy, population genetics, volatile organic compounds and artificial cultivation of the truffles, while little information is available about their nutrient composition and pharmacological activity, especially the relationship between chemical composition in ascocarps and their geographic distributions. This study presents a comprehensive investigation of the chemical composition of T. indicum, including free sugars, fatty acids, organic acids, phenolic acids, flavonoids, and polysaccharides, and tracks the antioxidant activity of T. indicum ascocarps collected from five geographical regions of four provinces in P. R. China: Hebei, Tibet, Yunnan, and Liaoning province. Our results showed that T. indicum collected from Qujing, Yunnan province, possessed the highest amount of free sugars (23.67 mg/g dw), total flavonoids (2.31 mg/g dw), total phenolics (4.46 mg/g dw) and the highest DPPH and ABTS radical-scavenging activities. The amount of water-soluble polysaccharides was the highest (115.24 mg/g dw) in ascocarps from Tibet, the total organic acids was the highest (22.073 mg/g dw) in ascocarps from Gongshan, and polyunsaturated fatty acids were most abundant in those from Hebei province. This study reveals that the quantity of chemical compounds in T. indicum varies by geographical origin. Detecting differences in chemical composition may provide important data for understanding the relationship between environmental factors and truffle formation, as well as quality evaluation of the commercial species T. indicum throughout China.

Two new tetracyclic triterpenoids from the endophytic fungus Hypoxylon sp. 6269.

Two new tetracyclic triterpenoids, integracide E (1) and isointegracide E (2), as well as three known secondary metabolites (i.e. integracide A (3), 2-deoxyintegracide A (4) and 2-deoxyintegracide B (5)), were isolated from mycelium of the endophytic fungus Hypoxylon sp. 6269. Structures were determined by a combination of 1D and 2D NMR techniques and mass spectrometry. All of the compounds were tested for their anti-HIV-1 integrase activities.

Phenolic constituents with antibacterial activity from Eleutherine bulbosa.

Eleutherine bulbosa (Mill.) Urb. is a medicinal and edible plant with various benefits for humans and animals. In this work, four new phenolic constituents (1-4), along with six known phenolic compounds (5-10) were obtained from the red bulbs of E. bulbosa. Their structures with absolute configurations were characterized by extensive spectroscopic analysis, combined with HR-ESI-MS and quantum mechanical electronic circular dichroism (ECD). Compounds 1 and 2 are novel homologous and heterodimers, respectively, featuring an unusual spiro ring system. All isolated phenolic constituents were tested for their antibacterial effects. The results revealed four phenolic compounds 1-3 and 7 showed moderate antibacterial activity against Bacillus subtilis, Staphylococcus aureus and Escherichia coli with minimum inhibitory concentration (MIC) values ranging from 15.6 to 250.0 µg/mL.

Shancigusins E-I, five new glucosides from the tubers of Pleione yunnanensis.

Five new glucosides, shancigusins E-I (1-5) were isolated from the tubers of Pleione yunnanensis (Rolfe) together with 18 known compounds. The structures of these compounds were determined by extensive analyses of their spectroscopic data.

Antimicrobial activities of endophytic fungi isolated from Ophiopogon japonicus (Liliaceae).

BACKGROUND: Drug resistance in bacteria has become a global concern and the search for new antibacterial agents is urgent and ongoing. Endophytes provide an abundant reservoir of bioactive metabolites for medicinal exploitation, and an increasing number of novel compounds are being isolated from endophytic fungi. Ophiopogon japonicus, containing compounds with antibacterial activity, is a traditional Chinese medicinal plant used for eliminating phlegm, relieving coughs, latent heat in the lungs, and alleviating diabetes mellitus. We investigated the antimicrobial activities of 30 strains of O. japonicus. METHODS: Fungal endophytes were isolated from roots and stems of O. japonicus collected from Chongqing City, southwestern China. Mycelial extracts (MC) and fermentation broth (FB) were tested for antimicrobial activity using peptide deformylase (PDF) inhibition fluorescence assays and MTT cell proliferation assays. RESULTS: A total of 30 endophytic strains were isolated from O. japonicus; 22 from roots and eight from stems. 53.33% of the mycelial extracts (MC) and 33.33% of the fermentation broths (FB) displayed potent inhibition of PDF. 80% of MC and 33.33% of FB significantly inhibited Staphylococcus aureus. 70% of MC and 36.67% of FB showed strong activities against Cryptococcus neoformans. None showed influence on Escherichia coli. CONCLUSION: The secondary metabolites of endophytic fungi from O. japonicus are potential antimicrobial agents.

Eleucanainones A and B: Two Dimeric Structures from the Bulbs of Eleutherine americana with Anti-MRSA Activity.

Two naphthoquinone-derived heterodimers with unprecedented carbon skeletons, eleucanainones A (1) and B (2), were isolated from the bulbs of Eleutherine americana. Their structures were elucidated by comprehensive spectroscopic methods. The structures of 1 and 2 were determined to be the first examples of dibenzofuran- and naphthalenone-containing naphthoquinone dimers. Compound 1 exhibited significant anti-MRSA activity in vitro with minimum inhibitory concentration (MIC) values of 0.78 µg/mL by downregulation of basal expression of agrA, cidA, icaA and sarA in methicillin-resistant S. aureus (MRSA).

Neuroprotective effects of chloroform and aqueous fractions of noni juice against t-Butyl hydroperoxide-induced oxidative damage in SH-SY5Y cells.

Oxidative stress is more likely to cause damage to neuronal cells and mediates some neurodegenerative disorders. It is well known that natural antioxidants can prevent oxidative stress damage and become a potential therapeutic strategy. Noni juice obtained from the fruit of the tree Morinda citrifolia, as a folk medicine, has been used for over two thousand years. In the current study, the neuroprotective effect and mechanism of noni juice extracts against tert-Butyl hydroperoxide (TBHP)-induced SH-SY5Y cell damage were investigated. The results demonstrated that chloroform fraction (CF) and aqueous fraction (AF) of noni juice protected SH-SY5Y cells against TBHP-induced oxidative stress and the associated apoptosis effectively. CF and AF treatment significantly weakened the TBHP-induced cytotoxicity, reactive oxygen species generation, mitochondrial membrane depolarization, and apoptotic features. CF and AF restored cellular antioxidant enzyme activity; upregulated expression of heme oxygenase-1, catalase, and superoxide dismutase-1; and increased the nuclear accumulation of nuclear factor-erythroid 2 related factor 2 (Nrf2). The antioxidant and neuroprotection potential of CF may account for its high total phenolic and flavonoid content, while AF may be rich in polysaccharides. These results suggest that CF and AF exhibit antioxidant defense through the upregulation of Nrf2 along with endogenous antioxidants and reduce apoptosis via inhibiting the mitochondrial pathway to protect SH-SY5Y cells damaged by TBHP. CF and AF might be developed as agents for neurodegeneration prevention or therapy.

Diversity and taxonomy of endophytic xylariaceous fungi from medicinal plants of Dendrobium (Orchidaceae).

Dendrobium spp. are traditional Chinese medicinal plants, and the main effective ingredients (polysaccharides and alkaloids) have pharmacologic effects on gastritis infection, cancer, and anti-aging. Previously, we confirmed endophytic xylariaceous fungi as the dominant fungi in several Dendrobium species of tropical regions from China. In the present study, the diversity, taxonomy, and distribution of culturable endophytic xylariaceous fungi associated with seven medicinal species of Dendrobium (Orchidaceae) were investigated. Among the 961 endophytes newly isolated, 217 xylariaceous fungi (morphotaxa) were identified using morphological and molecular methods. The phylogenetic tree constructed using nuclear ribosomal internal transcribed spacer (ITS), large subunit of ribosomal DNA (LSU), and beta-tubulin sequences divided these anamorphic xylariaceous isolates into at least 18 operational taxonomic units (OTUs). The diversity of the endophytic xylariaceous fungi in these seven Dendrobium species was estimated using Shannon and evenness indices, with the results indicating that the dominant Xylariaceae taxa in each Dendrobium species were greatly different, though common xylariaceous fungi were found in several Dendrobium species. These findings implied that different host plants in the same habitats exhibit a preference and selectivity for their fungal partners. Using culture-dependent approaches, these xylariaceous isolates may be important sources for the future screening of new natural products and drug discovery.

Sclerotial formation of Polyporus umbellatus by low temperature treatment under artificial conditions.

BACKGROUND: Polyporus umbellatus sclerotia have been used as a diuretic agent in China for over two thousand years. A shortage of the natural P. umbellatus has prompted researchers to induce sclerotial formation in the laboratory. METHODOLOGY/PRINCIPAL FINDING: P. umbellatus cultivation in a sawdust-based substrate was investigated to evaluate the effect of low temperature conditions on sclerotial formation. A phenol-sulfuric acid method was employed to determine the polysaccharide content of wild P. umbellatus sclerotia and mycelia and sclerotia grown in low-temperature treatments. In addition, reactive oxygen species (ROS) content, expressed as the fluorescence intensity of mycelia during sclerotial differentiation was determined. Analysis of ROS generation and sclerotial formation in mycelia after treatment with the antioxidants such as diphenyleneiodonium chloride (DPI), apocynin (Apo), or vitamin C were studied. Furthermore, macroscopic and microscopic characteristics of sclerotial differentiation were observed. Sclerotia were not induced by continuous cultivation at 25°C. The polysaccharide content of the artificial sclerotia is 78% of that of wild sclerotia. In the low-temperature treatment group, the fluorescent intensity of ROS was higher than that of the room temperature (25°C) group which did not induce sclerotial formation all through the cultivation. The antioxidants DPI and Apo reduced ROS levels and did not induce sclerotial formation. Although the concentration-dependent effects of vitamin C (5-15 mg mL(-1)) also reduced ROS generation and inhibited sclerotial formation, using a low concentration of vitamin C (1 mg mL(-1)) successfully induced sclerotial differentiation and increased ROS production. CONCLUSIONS/SIGNIFICANCE: Exposure to low temperatures induced P. umbellatus sclerotial morphogenesis during cultivation. Low temperature treatment enhanced ROS in mycelia, which may be important in triggering sclerotial differentiation in P. umbellatus. Moreover, the application of antioxidants impaired ROS generation and inhibited sclerotial formation. Our findings may help to provide new insights into the biological mechanisms underlying sclerotial morphogenesis in P. umbellatus.