Two New Compounds from the AscomyceteDaldinia concentrica

Bioactivity-guided isolation of anti-hepatitis B virus active sesquiterpenoids from the traditional Chinese medicine: Rhizomes of Cyperus rotundus

ETHNOPHARMACOLOGICAL RELEVANCE

The rhizome of Cyperus rotundus (C. rotundus) is a well-known traditional Chinese medicine to cure hepatitis in many formulae, but the active components responsible for hepatitis have not been elucidated. According to our bioassay on HepG2.2.15 cell line in vitro, the ethanol extract of C. rotundus demonstrated potent anti-HBV activity. This current study was designed to isolate and identify the anti-HBV active constituents from the rhizomes of C. rotundus.

MATERIAL AND METHODS

Bioactivity and LC-MS guided fractionation on the extract of C. rotundus using various chromatographic techniques including open-column, Sephadex LH-20 and semi-preparative high performance liquid chromatography led to the isolation and identification of thirty-seven sesquiterpenoids. Structural elucidation of the isolates was carried out by extensive spectroscopic analyses (UV, IR, HRMS, 1D- and 2D -NMR). The anti-HBV activity and cytotoxicity were evaluated on the HBV-transfected HepG2.2.15 cell line in vitro. The cytotoxicity effects of the isolates were assessed by a MTT assay. The secretions of HBsAg and HBeAg in the culture medium were detected by ELISA method, and the load of HBV DNA was quantified by real-time fluorescent PCR technique.

RESULTS

Five new patchoulane-type sesquiterpenoids, namely cyperene-3, 8-dione (1), 14-hydroxy cyperotundone (2), 14-acetoxy cyperotundone (3), 3β-hydroxycyperenoic acid (4) and sugetriol-3, 9-diacetate (5), along with 32 known sesquiterpenoids were isolated from the active fractions of C. rotundus. Compounds 2 and 3 were the first cyperotundone-type sesquiterpenoids with a hydroxyl group at C-14 position. Nine eudesmane-type sesquiterpenoids (15-21 and 23-24) significantly inhibited the HBV DNA replication with IC50 values of 42.7±5.9, 22.5±1.9, 13.2±1.2, 10.1±0.7, 14.1±1.1, 15.3±2.7, 13.8±0.9, 19.7±2.1 and 11.9±0.6 μM, respectively, of which, compounds 17, 21, 23 and 24 possessed high SI values of 250.4, 125.5,>259.6 and 127.5, respectively. Two patchoulane-type sesquiterpenoids (4 and 7) effectively suppressed the secretion of HBsAg in a dose-dependent manner with IC50 values of 46.6±14.3 (SI=31.0) and 77.2±13.0 (SI=1.7) μM, respectively. Compounds 2, 8, 12, 15, 17 and 25 possessed moderate activities against HBeAg secretion with IC50 values of 162.5±18.9 (SI=13.3), 399.2±90.0 (SI=10.6), 274.7±70.8 (SI=5.2), 313.9±87.5 (SI=7.2), 334.0±70.4 (SI=9.9) and 285.3±20.9 (SI=15.5) μM, respectively.

CONCLUSIONS

This is the first study to reveal the anti-HBV constituents of C. rotundus, demonstrating that the eudesmane-type sesquiterpenoids might contribute to the anti-HBV activity of the rhizomes of C. rotundus.

A polyphasic taxonomy of Daldinia (Xylariaceae)

For a monograph based on a polythetic concept, several thousands of herbarium specimens, and several hundreds of freshly collected and cultured specimens of Daldinia and allied Xylariaceae, originating from around the world, were studied for morphological traits, including by SEM, and chemically by HPLC profiles using UV-visible and mass spectrometric detection. Emphasis was given to tropical material, and importantly, ancient specimens, including as many types as possible, were tracked and studied to review earlier taxonomic concepts. An epitype of D. eschscholtzii was selected as representative of the morphochemotype that is most widely distributed in the tropics. Six new species of Daldinia from the tropics and the southern Hemisphere are described. Daldinia asphalatum is resurrected, and D. cudonia is regarded as its synonym. In addition, the following binomials are epi-, iso-, neo- and/or lectotypified: Daldinia asphalatum, D. caldariorum, D. clavata, D. cuprea, D. durissima, D. eschscholtzii, D. grandis, D. loculata, and D. vernicosa. Annellosporium and Versiomyces are regarded as synonyms of Daldinia. Many new synonymies in Daldinia are proposed, and some previously published names are rejected. In total, 47 taxa in Daldinia are recognised and a key is provided. Their biogeography, chorology, and ecology, as well as the importance of their secondary metabolites, are also discussed. The previous definition of the genus is emended. The species concept is based mainly on morphological and other phenotype-derived characters because, despite diligent search, no molecular data or cultures of several of the accepted species could be obtained. Daldinia is segregated into five major groups, based on phenotypic characteristics. Some unnamed but aberrant specimens were not found in good condition and are therefore not formally described as new species. However, they are illustrated in detail in a hope that this will facilitate the discovery of fresh material in future. A preliminary molecular phylogeny based on 5.8S/ITS nrDNA including numerous representatives of all hitherto described taxa for which cultures are extant, was found basically in agreement with the above mentioned segregation of the genus, based on morphological and chemotaxonomic evidence. In the rDNA based phylogenetic tree, Daldinia appears clearly distinct from members of the genera Annulohypoxylon and Hypoxylon; nevertheless, representatives of small genera of predominantly tropical origin (Entonaema, Phylacia, Ruwenzoria, Rhopalostroma, Thamnomyces) appear to have evolved from daldinioid ancestors and are nested inside the Daldinia clade. Interestingly, these findings correlate with chemotaxonomic characters to a great extent, especially regarding the distribution of marker metabolites in their mycelial cultures. Hence, the current study revealed for the first time that fungal secondary metabolite profiles can have taxonomic value beyond the species rank and even coincide with phylogenetic data.

TAXONOMIC NOVELTIES

Daldinia andina sp. nov., D. australis sp. nov., D. hausknechtii sp. nov., D. rehmii sp. nov., D. starbaeckii sp. nov., D. theissenii sp. nov., D. cahuchosa comb. nov., D. nemorosa comb. nov.

Secondary metabolites from higher fungi: discovery, bioactivity, and bioproduction

Medicinal higher fungi such as Cordyceps sinensis and Ganoderma lucidum have been used as an alternative medicine remedy to promote health and longevity for people in China and other regions of the world since ancient times. Nowadays there is an increasing public interest in the secondary metabolites of those higher fungi for discovering new drugs or lead compounds. Current research in drug discovery from medicinal higher fungi involves a multifaceted approach combining mycological, biochemical, pharmacological, metabolic, biosynthetic and molecular techniques. In recent years, many new secondary metabolites from higher fungi have been isolated and are more likely to provide lead compounds for new drug discovery, which may include chemopreventive agents possessing the bioactivity of immunomodulatory, anticancer, etc. However, numerous challenges of secondary metabolites from higher fungi are encountered including bioseparation, identification, biosynthetic metabolism, and screening model issues, etc. Commercial production of secondary metabolites from medicinal mushrooms is still limited mainly due to less information about secondary metabolism and its regulation. Strategies for enhancing secondary metabolite production by medicinal mushroom fermentation include two-stage cultivation combining liquid fermentation and static culture, two-stage dissolved oxygen control, etc. Purification of bioactive secondary metabolites, such as ganoderic acids from G. lucidum, is also very important to pharmacological study and future pharmaceutical application. This review outlines typical examples of the discovery, bioactivity, and bioproduction of secondary metabolites of higher fungi origin.

Induced daldinin A, B, C with a new skeleton from cultures of the ascomycete Daldinia concentrica

Daldinin A, B, C with a new skeleton, together with four known compounds, were induced and isolated from cultures of the ascomycete Daldinia concentrica. Their structures were elucidated by spectroscopic analysis, and that of daldinin A was confirmed by single-crystal X-ray diffraction.