Chaetoxylariones A-G: undescribed chromone-derived polyketides from co-culture of Chaetomium virescens and Xylaria grammica enabled via the molecular networking strategy.

By co-culturing two endophytic fungi (Chaetomium virescens and Xylaria grammica) collected from the medicinal and edible plant Smilax glabra Roxb. and analyzing them with MolNetEnhancer module on GNPS platform, seven undescribed chromone-derived polyketides (chaetoxylariones A-G), including three pairs of enantiomer ones (2a/2b, 4a/4b and 6a/6b) and four optical pure ones (1, 3, 5 and 7), as well as five known structural analogues (8-12), were obtained. The structures of these new compounds were characterized by NMR spectroscopy, single-crystal X-ray diffraction, 13C NMR calculation and DP4+ probability analyses, as well as the comparison of the experimental electronic circular dichroism (ECD) data. Structurally, compound 1 featured an unprecedented chromone-derived sulfonamide tailored by two isoleucine-derived δ-hydroxy-3-methylpentenoic acids via the acylamide and NO bonds, respectively; compound 2 represented the first example of enantiomeric chromone derivative bearing a unique spiro-[3.3]alkane ring system; compound 3 featured a decane alkyl side chain that formed an undescribed five-membered lactone ring between C-7' and C-10'; compound 4 contained an unexpected highly oxidized five-membered carbocyclic system featuring rare adjacent keto groups; compound 7 featured a rare methylsulfonyl moiety. In addition, compound 10 showed a significant inhibition towards SW620/AD300 cells with an IC50 value of PTX significantly decreased from 4.09 µM to 120 nM, and a further study uncovered that compound 10 could obviously reverse the MDR of SW620/AD300 cells.

Antiproliferative ent-abietane diterpenoids from Euphorbia fischeriana.

Euphorfinoids M and N (1 and 2), two previously undescribed ent-abietane diterpenoids, together with seven known analogues (3-9), were isolated from the roots of wild Euphorbia fischeriana. Their structures were elucidated by spectroscopic analysis, including extensive NMR, HR-ESIMS, ECD, and comparison with structurally related known analogues. Bioassays against proliferative effects of HeLa cell line showed that compound 1 was the most active with IC50 3.62 ± 0.31 µM.

Euphorfinoids A and B, a pair of ent-atisane diterpenoid epimers from the roots of Euphorbia fischeriana, and their bioactivities.

Euphorfinoids A and B (1 and 2), a pair of ent-atisane diterpenoid epimers with a vicinal 2,3-diol moiety, together with four known analogues (3-6), were isolated from the roots of wild Euphorbia fischeriana. Their structures were elucidated by spectroscopic analysis, including extensive NMR, HR-ESIMS, NMR calculations, X-ray diffraction, and comparison with structurally related known analogues. Our bioassays have established that compound 1 displayed moderate anti-proliferative effects on Hcc1806 cell line with IC50 15.53 ± 0.21 µM, and compound 5 showed remarkable inhibitory effects against AChE with IC50 32.56 ± 2.74 µM by an in vitro screened experiment.

Euphorfiatnoids A-I: Diterpenoids from the roots of Euphorbia fischeriana with cytotoxic effects.

Nine previously undescribed diterpenoids, euphorfiatnoids A-I, together with seven known diterpenoids, were isolated from the roots of wild Euphorbia fischeriana. Their structures were elucidated by the interpretation of HRESIMS, UV, and NMR data. Their configurations were determined by electronic circular dichroism (ECD) spectroscopy analysis and the structure of euphorfiatnoid A was confirmed by X-ray crystallography. To further understand the antitumor effects of E. fischeriana, we tested the cytotoxicity of these compounds against H460, HepG2, and MCF-7 cell lines in vitro using MTT assays. Euphorfiatnoid B exhibited the most promising inhibitory effect against H460 cells with an IC50 value of 9.97 µM. Euphorfiatnoid A and C also exhibited moderate cytotoxicity against HepG2 cells with IC50 values of 11.64 and 13.10 µM, respectively.

Euphorfistrines A-G, cytotoxic and AChE inhibiting triterpenoids from the roots of Euphorbia fischeriana.

Seven new triterpenoids including two cycloartanes (1-2), a lanostane (3), a tirucallane (4), a dammarane (5), an ursane (6), and an oleanane (7), along with nineteen known triterpenoids (8-26), have been obtained from the roots of Euphorbia fischeriana. Their structures were established by NMR, HRESIMS, single-crystal X-ray diffraction analysis, Mosher's method, NMR calculations, ECD analysis, and comparison with structurally related known analogues. Among them, compounds 1 and 8 were a pair of cycloartane-type triterpenoids epimers. Our bioassays have established that compounds 1-5 and 10 displayed moderate cytotoxic effects, and the structure-activity relationships of cycloartane-type triterpenoids (CTTs) were further examined. Notably, some triterpenoids displayed moderate inhibitory effects against AChE by an in vitro screened experiment. Triterpenoid 7 (Euphorfistrine G, ETG) displayed the potent inhibitory effect with IC50 = 2.45 and Ki = 2.30 µM (inhibition kinetic). And, in silico docking analyses have been performed to investigate the inhibitory mechanism of compound 7.

Euphorfinoids E-L: Diterpenoids from the roots of Euphorbia fischeriana with acetylcholinesterase inhibitory activity.

Eight undescribed diterpenoids, euphorfinoids E-L, together with twelve known analogues, were isolated from the roots of wild Euphorbia fischeriana. Their structures and absolute configurations were elucidated by a combination of NMR, MS, ECD, and X-ray diffraction analyses. The plausible biosynthetic pathway of 1 was also proposed. The isolated compounds displayed moderate inhibitory activity against acetylcholinesterase (AChE) with 50% inhibiting concentration (IC50) values of 6.23-192.38 µM.

Coregulation of dimorphism and symbiosis by cyclic AMP signaling in the lichenized fungus Umbilicaria muhlenbergii.

Umbilicaria muhlenbergii is the only known dimorphic lichenized fungus that grows in the hyphal form in lichen thalli but as yeast cells in axenic cultures. However, the regulation of yeast-to-hypha transition and its relationship to the establishment of symbiosis are not clear. In this study, we show that nutrient limitation and hyperosmotic stress trigger the dimorphic change in U. muhlenbergii Contact with algal cells of its photobiont Trebouxia jamesii induced pseudohyphal growth. Treatments with the cAMP diphosphoesterase inhibitor IBMX (3-isobutyl-1-methylxanthine) induced pseudohyphal/hyphal growth and resulted in the differentiation of heavily melanized, lichen cortex-like structures in culture, indicating the role of cAMP signaling in regulating dimorphism. To confirm this observation, we identified and characterized two Gα subunits UmGPA2 and UmGPA3 Whereas deletion of UmGPA2 had only a minor effect on pseudohyphal growth, the ΔUmgpa3 mutant was defective in yeast-to-pseudohypha transition induced by hyperosmotic stress or T. jamesii cells. IBMX treatment suppressed the defect of ΔUmgpa3 in pseudohyphal growth. Transformants expressing the UmGPA3G45V or UmGPA3Q208L dominant active allele were enhanced in the yeast-to-pseudohypha transition and developed pseudohyphae under conditions noninducible to the wild type. Interestingly, T. jamesii cells in close contact with pseudohyphae of UmGPA3G45V and UmGPA3Q208L transformants often collapsed and died after coincubation for over 72 h, indicating that improperly regulated pseudohyphal growth due to dominant active mutations may disrupt the initial establishment of symbiotic interaction between the photobiont and mycobiont. Taken together, these results show that the cAMP-PKA pathway plays a critical role in regulating dimorphism and symbiosis in U. muhlenbergii.

Comparative Analysis of Chemical Composition, Anti-Inflammatory Activity and Antitumor Activity in Essential Oils from Siegesbeckiaorientalis, S. glabrescens and S. pubescens with an ITS Sequence Analysis.

Herba Siegesbeckiae (HS), derived from the aerial parts of three plants, Siegesbeckia orientalis (SO), S. glabrescens (SG), and S. pubescens (SP), has been used for the treatment of inflammatory diseases in China for centuries. In the present study, hydrodistillation was applied to extract essential oils from dried SO, SG, and SP aerial parts, and chemical composition analysis by gas chromatography⁻mass spectrometry (GC-MS) led to the identification of a total of 148 compounds (56 in SO, 62 in SG, and 59 in SP). The main components in the essential oils of SO, SG, and SP differed significantly. In vitro anti-inflammatory activity assays showed that SP essential oils (IC50, 0.97 µg/mL) significantly reduced the ability of lipopolysaccharide (LPS)-stimulated RAW264.7 macrophages to release NO, and the SO essential oil (IC50, 14.99 µg/mL) was better than the others at inhibiting the LPS-induced release of cytokine IL-6. Furthermore, the essential oils exhibited antitumor activities (IC50, 37.72⁻123.16 µg/mL) against Hep3B (liver) and Hela (cervical) cells. Linear regression analysis showed that, caryophyllene oxide peak area percentages showed remarkably high negative correlation coefficients with IC50 values of Hep3B and Hela cytotoxicity, which suggested the contribution of this compound on the cancer cell cytotoxicity of three essential oils. Finally, the ITS1-5.8S-ITS2 region was amplified and sequenced in order to generate genomic reference sequences for each plant. These can be used to identify the origins of the plants, and will assist other research studies related to these three plants.

Involvements of S-nitrosylation and denitrosylation in the production of polyphenols by Inonotus obliquus.

Nitric oxide (NO) has been evidenced to mediate biosynthesis of polyphenols in Inonotus obliquus. However, it remains unknown how NO regulates their biosynthesis. Here we show that higher cellular NO levels coincided with higher accumulation of S-nitrosothiols (SNO; the products of NO combined with a specific residue in glutathione or proteins) and polyphenols, and higher activity of denitrosylated S-nitrosoglutathione reductase (GSNOR) and thioredoxin reductase (TrxR). This homeostasis was breached by GSNOR or TrxR inhibitors. Inhibiting GSNOR boosted TrxR activity, but reduced SNO formation, coinciding with an enhanced production of polyphenols. Likewise, inhibiting TrxR increased GSNOR activity and SNO production, but downregulated accumulation of polyphenols. Inhibiting GSNOR or TrxR also modified the polyphenolic profiles of I. obliquus. Suppressing GSNOR-enhanced biosynthesis of phelligridins C and H, inoscavin C and methyl inoscavin B, but reduced that of phelligridin D, methyl inoscavin A, davallialactone and methyl davallialactone, the typical polyphenols in I. obliquus. Similarly, downregulating TrxR increased production of phelligridin D, methyl inoscavin A, davallialactone, and methyl davallialactone, but shrinking that of phelligridins C and H, methyl inoscavin B and inoscavin C. Thus, in I. obliquus, the state of S-nitrosylation and denitrosylation affects not only the accumulation of polyphenols, but also their metabolic profiles.