Yonarolide A,an unprecedented furanobutenolide-containing norcembranoid derivative formed by photoinduced intramolecular [2+2] cycloaddition

Eight polycyclic furanobutenolide-containing norcembrane diterpenoids featuring C19 frameworks (1–8) were rapidly recognized and isolated from the Hainan soft coral Sinularia sp. by the HSQC-based small molecule accurate recognition technology. Yonarolide A (1a), featuring an unprecedented 5/6/4/4/7 pentacyclic ring skeleton, was surprisingly obtained as a transformed product by leaving compound 1 under indoor natural light, and was further proved to be a [2 + 2] cycloaddition product of 1 by photochemical reaction. The absolute stereochemistry of 1a and the three known norcembrane diterpenoids 1, 4, and 7 were determined by using X-ray diffraction (XRD) analyses. Further, with the aid of XRD analysis, the structure of scabrolide B (2), which was previously reported of possessing 5/6/7 tricyclic skeleton, was firmly revised as 2a with the rare inelegane skeleton featured by the highly oxygenated 5/7/6 tricyclic carbocycle.     

Development of environmentally friendly biological algicide and biochemical analysis of inhibitory effect of diatom Skeletonema costatum

Skeletonema costatum is a diatom widely distributed in red tide microalgae blooms and as one of the main algae causing harmful algal blooms, because of their rapid reproduction and production of toxic and harmful substances, often play a negative role in aquatic ecosystems, and human health and wellbeing. Bacillomycin D is a nonribosomal cyclic antifungal lipopeptide in the iturins family. In this study,Bacillomycin D was tested for its ability to inhibit the growth of S. costatum. The EC_50...     

Synthesis and stereochemical assignment of (+)-Cladospolide D

Cladospolides A-D are 12-membered, α,β-unsaturated lactones isolated from various species of Cladosporium. Cladospolide D is unique in its γ-keto functionality and possesses antifungal activity; however, the stereochemistry of Cladoapolide D was unknown. We report the asymmetric syntheses to generate both possible diastereomers of Cladospolide D. Two regioselective cross-metatheses were applied to form the carbon skeleton, and the two olefins were differentiated by Michael addition, hydrogenation, and elimination. Later, the macrocycle was achieved through the Yamaguchi protocol. After comparing the spectroscopic data of the synthetic Cladospolide D with the reported values, the stereochemistry of Cladospolide D is confirmed as (2E,5R,11S).     

Identification and in silico molecular modelling study of newly isolated Bacillus subtilis SI-18 strain against S9 protein of Rhizoctonia solani

The numerous bioactive components from Bacillus subtilis are commonly used as antimicrobial agents for reducing plant diseases caused by fungal pathovars. In this study, we isolated and identified B. subtilis SI-18 strain from twenty isolates of rhizosphere soil through morphological and molecular approaches, and explored its inhibitory activities against Rhizoctonia solani. According to morphological features and 16S rRNA and gyrB gene sequence analysis, B. subtilis SI-18 strain was identified. Additionally, the culture filtrate of B. subtilis SI-18 resulted in the suppression of R. solani mycelium growth and material leakage from the cells. Then, we have performed homology modelling and molecular docking study of S9 protein from R. solani where three potential compounds (D1, D2, and D3) were identified among 134 antimicrobial compounds derived from B. subtilis group based on higher binding energy and interaction at the active grove of the target protein. The D1 compound creates alkyl bond at Val48 whereas D2 also binds with Val48 by creating hydrogen bond. On the other hand, two hydrogen bonds were observed at Val48 and Ile52 by D3, which might be responsible for possible blocking of the target S9 protein of R. solani. To validate the docking study and understand the change in drug-ligand conformation, molecular dynamics simulation was assessed where rigid conformation was found for D1, D2 and D3 complexes. Moreover, ADMET study confirms that no toxicity and carcinogenicity were found for screened compounds. Based on our studies, we demonstrated that compounds D1, D2, and D3 derived from B. subtilis can be a potential inhibitor of S9 protein of R. solani that might be a possible strategy for fungal disease prevention.     

Does the Metabolome of Wild-like Dendrobium officinale of Different Origins Have Regional Differences?

Dendrobium officinale, as a traditional Chinese medicine, has considerable commercial value and pharmacological activity. Environmental factors of different origins have a great influence on Dendrobium officinale metabolites, which affect its pharmacological activity. This study sought to identify the differential metabolites of wild-imitating cultivated D. officinale stems of different origins. Using the widely-targeted metabolomics approach, 442 metabolites were detected and characterized, including flavonoids, lipids, amino acids and derivatives, and alkaloids. We found that although the chemical constitution of D. officinale cultured in the three habitats was parallel, the contents were significantly different. Meanwhile, the KEGG pathway enrichment analysis revealed that the distinctive metabolites among the three groups were mainly involved in flavone and flavonol biosynthesis. To further explore the different contents of flavonoids, HPLC was performed on four main flavonoid contents, which can be used as one of the references to distinguish D. officinale from different growing origins. In conclusion, a comprehensive profile of the metabolic differences of D. officinale grown in different origins was provided, which contributed a scientific basis for further research on the quality evaluation of D. officinale.     

Novel antifungal polyene amides from the myxobacterium Cystobacter fuscus: isolation, antifungal activity and absolute structure determination

Three new unstable metabolites, (6E,10Z)-2′-O-methylmyxalamide D (1), 2′-O-methylmyxalamide D (2) and (6E)-2′-O-methylmyxalamide D (3) were isolated from the myxobacterium Cystobacter fuscus. The planar structures were elucidated by spectroscopic analyses to be geometrical isomers of a polyene amide related to a myxobacterial metabolite, myxalamide D (4). Their absolute stereochemistry was determined by synthesis of degradation products. Antifungal activities of 1-3 as well as their acetates were evaluated against the phythopathogenic fungus Phythopthora capsici.     

Identification of Coumarins and Antimicrobial Potential of Ethanolic Extracts of Dipteryx odorata and Dipteryx punctata

Dipteryx odorata and Dipteryx punctata are species native to the Amazonian, traded by extractivists to obtain coumarin. We aimed to analyze the presence of coumarin in the ethanolic extracts of leaves, branches and fruits of D. odorata and D. punctata and to evaluate the antimicrobial activity of these extracts against phytopathogenic fungi and bacteria of clinical interest. Chemical analyses were performed by thin layer chromatography (TLC) and by gas chromatography coupled to mass spectrometry (GC-MS). For the antifungal assays, the fungi used were Cercospora longissima, Colletotrichum gloeosporioides, two isolates of Fusarium spp. and Sclerotium rolfsii, and the antibacterial assay was performed using the minimum inhibitory concentration (MIC) test with Burkholderia cepacia, Escherichia coli, Pseudomonas aeruginosa and Staphylococcus aureus bacteria. In D. odorata seed extracts and in D. punctata husks, endocarps, and seeds, we identified 1,2-benzopyrone. D. odorata endocarp extracts and D. punctata seeds provided the greatest decrease in mycelial growth of the evaluated phytopathogens, showing promise as an alternative control. The husk and endocarp extracts of both species had a weak effect on E. coli. This research is the first to compare the different parts of species of the genus Dipteryx and to evaluate the use of husks and endocarps of D. punctata fruits to obtain coumarin. Chemical analyses used to quantify the compounds existing in the extracts, and tests with phytopathogens in vitro and in vivo are currently being carried out.     

Cloning and Expression of a Novel Xylanase Gene (Auxyn11D) from Aspergillus usamii E001 in Pichia pastoris

A full-length complementary DNA (cDNA) of Auxyn11D, a gene that encodes a novel endo-??-1,4-d-xylanase of Aspergillus usamii E001 (abbreviated to AuXyn11D), was obtained using 3??- and 5??-rapid amplification of cDNA ends (RACE) methods. The cDNA sequence is 855?bp in length, containing 5??- and 3??-untranslated regions and a 696-bp open reading frame (ORF) that encodes a 32-aa signal peptide and a 199-aa mature peptide (namely AuXyn11D). Multiple homology alignment of amino acid sequences verified that AuXyn11D belongs to glycoside hydrolase family 11. Moreover, a mature peptide-encoding cDNA fragment of Auxyn11D was cloned and expressed in Pichia pastoris GS115. One P. pastoris transformant expressing the highest recombinant AuXyn11D (reAuXyn11D) activity of 15.0?U/mL, labeled as P. pastoris GSAuXyn4-16, was chosen by shake flask test. SDS?CPAGE assay demonstrated that the reAuXyn11D, a glycosylated protein with an apparent molecular mass of 32.0?kDa, was secreted into the medium. The purified reAuXyn11D displayed the highest activity at pH 4.5 and 55?°C. It was stable at a pH range of 3.5?C6.5 and at a temperature of 50?°C or below. Its activity was not significantly affected by most of metal ions tested and EDTA, but increased by Ca²⁺ and inhibited by Mn²⁺. The K _m and V _max of the reAuXyn11D towards birchwood xylan were 6.32?mg/mL and 391.6?U/mg, respectively.     

Effectiveness of the Influence of Selected Essential Oils on the Growth of Parasitic Fusarium Isolated from Wheat Kernels from Central Europe

The aim of the study was to determine the effectiveness of selected seven commercial essential oils (EsO) (grapefruit, lemongrass, tea tree (TTO), thyme, verbena, cajeput, and Litsea cubeba) on isolates of common Central European parasitic fungal species of Fusarium obtained from infected wheat kernels, and to evaluate the oils as potential natural fungicides. The study was conducted in 2 stages. At each stage, the fungicidal activity of EsO (with concentrations of 0.025; 0.05; 0.125; 0.25; 0.50; 1.0, and 2.0%) against Fusarium spp. was evaluated using the disc plate method and zones of growth inhibition were measured. At the first stage, the fungistatic activity of EsO was evaluated against four species of Fusarium from the Polish population (F. avenaceum FAPL, F. culmorum FCPL, F. graminearum FGPL and F. oxysporum FOPL). The correlation coefficient between the mycelial growth rate index (T) and the fungistatic activity (FA) was calculated. At the second stage, on the basis of the mycelium growth rate index, the effectiveness of the EsO in limiting the development of Fusarium isolates from the German population (F. culmorum FC1D, F. culmorum FC2D, F. graminearum FG1D, F. graminearum FG2D and F. poae FP0D) was assessed. The first and second stage results presented as a growth rate index were then used to indicate essential oils (as potential natural fungicides) effectively limiting the development of various common Central European parasitic species Fusarium spp. Finally, the sensitivity of four Fusarium isolates from the Polish population and five Fusarium isolates from the German population was compared. The data were compiled in STATISTICA 13.0 (StatSoft, Inc, CA, USA) at the significance level of 0.05. Fusarium isolates from the German population were generally more sensitive than those from the Polish population. The sensitivity of individual Fusarium species varied. Their vulnerability, regardless of the isolate origin, in order from the most to the least sensitive, is as follows: F. culmorum, F. graminearum, F. poae, F. avenaceum and F. oxysporum. The strongest fungicidal activity, similar to Funaben T, showed thyme oil (regardless of the concentration). Performance of citral oils (lemongrass and Litsea cubeba) was similar but at a concentration above 0.025%.     

Synthesis of BINOL-containing oxacalix[4]arenes

Unprecedented chiral oxacalixarenes were obtained from the reaction of (±)-1,1′-binaphthyl-2,2′-diol (BINOL) with 1,5-difluoro-2,4-dinitrobenzene. Structural elucidation of C_2h-symmetric meso (R,S)-oxacalix[4]arene and D₂-symmetric racemic (as well as enantiopure) (R,R)- and (S,S)-oxacalix[4]arene was carried out by means of 1D and 2D NMR spectroscopy, ESI-MS, X-ray diffractometry, and circular dichroism spectroscopy.     

Anisotropic thermal expansion and hydrogen bonding behavior of portlandite: A high-temperature neutron diffraction study

The structure of deuterated portlandite, Ca(OD)₂, was investigated using time-of-flight neutron diffraction in the temperature range 308-643 K. Rietveld analysis reveals that with increasing temperature, the c dimension expands at a rate ∼4.5 times larger than that for a. This anisotropy of thermal expansion is due to rapid increase in the interlayer thickness along c with increasing temperature. Fitting of the measured cell volumes yields a coefficient of thermal expansion, α=α₀+α₁T, where α₀=5.966×10⁻⁵ K⁻¹ and α₁=3.333×10⁻⁸ K⁻². On heating, hydrogen-mediated interatomic interactions within the interlayer become weakened, as reflected by increases in the interlayer D?O and D?D distances with increasing temperature. Correspondingly, the three equivalent sites over which D is disordered become further apart, suggesting a more delocalized configuration of D at high temperatures.     

An unusual diterpene glycoside from the nuts of almond (Prunus amygdalus Batsch)

A new unusual kauranoid diterpene glycoside, named amygdaloside, was isolated from the nuts of almond (Prunus amygdalus). It's structure was established as 17-O-β-D-glucopyranoside ent-6,7-epoxy-6-hydroxyl-6,7-secokaur-19-oic acid, 6,19-lactone 16β17-diol on the basis of high-resolution 1D and 2D NMR spectral studies.     

Solvent effect of ionic liquids on the distribution constant of 2-thenoyltrifluoroacetone and its nickel(II) and copper(II) chelates and the evaluation of the solvent properties based on the regular solution theory

Distribution constants of 2-thenoyltrifluoroacetone (Htta) and its Ni(II)and Cu(II) chelates between 1-alkyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide (C_nmimTf₂N; n = 4, 6, and 8) as ionic liquid (IL) and an aqueous phase were determined. The enol fraction of Htta in ILs was spectrophotometrically measured to calculate the distribution constant of the enol form (K_D,HE) of Htta. The K_D,HE values in ILs were evaluated by comparing those in various molecular solvents such as alkanes, aromatic hydrocarbons, chlorohydrocarbons, ethers, ketones, and esters previously reported on the basis of the regular solution theory (RST). It was elucidated that the IL solutions of Htta (enol) can be taken as apparently regular solutions as expected in the organic solvents. On the other hand, the effect of ILs on the distribution constant of metal(II) chelates (K_D,M) was fairly complicated. The Cu(tta)₂-IL solutions behaved like the alkane and aromatic hydrocarbon solutions but the Ni(tta)₂-IL (C₄mimTf₂N) like ether and ketone solutions. In the Ni(II) case, some specific interactions between the Ni(II) chelate and IL was suggested. Finally, the solubility parameters of ILs were calculated using K_D,HE by RST and were in good agreement with the literature values obtained by the enthalpy of vaporization.     

Soldier defense secretions of the south american termites Cortaritermes Silvestri, Nasutitermes SP N.D and Nasutitermes Kemneri

The defense secretions of the soldiers of the South American termites Cortaritermes silvestri, Nasutitermes sp. n.D. and Nasutitermes kemneri have been investigated. The secretion of C. silvestri was shown to contain α-pinene, β-pinene, limonene and cis-pin-3-en-yl acetate. Three of the four diterpenes in this secretion were identified as the triacetate, diacetate propionate and acetate dipropionate of 3α, 9β, 12α-trihydroxy-11(12), 15(17-trinervitadiene. The soldier secreation of Nasutitermes sp. n.D. and Nasutitermes kemneri were found to contain a mixture of monoterpene hydrocarbons and diterpenes. The major monoterpene in these two species was shown to be β-phellandrene and terpinolene, respectively. The major diterpene in Nasutitermes sp. n.D. was identified as 9β-hydroxy-1(15), 8(19)-trinervitadiene and, for Nasutitermes kemneri, 2α, 3β-dihydroxy-1(15), 8(9)- and 1(15), 8(19)-trinervitadiene were the major components.     

A novel 10-membered macrocyclic lactone from the mangrove-derived endophytic fungus Annulohypoxylon sp.

A novel 10-membered macrolactone, hypoxylide (1), was isolated from the endophytic fungus Annulohypoxylon sp. that was obtained from the Mangrove plant Rhizophora racemosa. The structure and absolute configuration of 1 were unambiguously elucidated by comprehensive 1D and 2D NMR, as well as by HRESIMS and ECD spectroscopic analyses. Hypoxylide (1) features an unprecedented polyketide skeleton comprised of a trihydroxynaphthalene-dione moiety fused to a decalactone ring. A plausible biosynthetic pathway of this novel metabolite is proposed.     

A new isoflavane from processed Astragalus membranaceus

A new isoflavane named astraganoside,together with five known compounds had been isolated from the processed Astragralus membranaceus.The structure of the novel compound was elucidated as(3R,4R)-3-(2-hydroxy-3,4-dimethoxyphenyl)chroman- 4,7-diol-7-O-β-D-glucopyranoside(1)based on spectroscopic methods including UV,IR,ESI-MS,1D NMR and 2D NMR techniques.     

A new chiral oxathiane: synthesis,resolution and absolute configuration determination by vibrational circular dichroism

A new oxathiane, derived from 5-hydroxy-1-tetralone has been synthesized in eight steps, fully characterized as cis-fused rings by 1D and 2D NMR and resolved by preparative chiral chromatography (CHIRALCEL OD-R). The second eluting (+, MeOH)-isomer was assigned (S,S)-configuration by VCD-ab initio simulation.     

Resolution of Racemic Ofloxacin Based on Co-Technology of Bubble Fractionation and Extraction

A method of bubble fractionation, with the help of solvent extraction, was developed for the resolution of racemic ofloxacin (rac OFLX). In this method, dibenzoyl-L-tartaric (L-DBTA), di-(2-ethylhexyl) phosphoric acid (D2EHPA) and sodium lauryl sulfate (SDS) were used as chiral collector, co-extractant and foamer, respectively. Several important parameters influencing the resolution performances, such as pH in aqueous phase, concentration of OFLX, concentration of L-DBTA, concentration of SDS and volume ratio of D2EHPA to n-octanol in solution, were investigated. The optimal resolution conditions were obtained with the aqueous phase pH 7, volume ratio of D2EHPA to n-octanol 6/14 in organic phase, concentration of SDS 0.42 mg mL^?1, concentration of OFLX 1.67 mg mL^?1, and concentration of L-DBTA 0.11 g mL^?1. Under the optimal extraction conditions, the enantiomeric excess value (e.e.%) was 60.08% and the enantioselectivity (??) was 5.58. It was found that the capacity of enantioselective separation can be greatly improved by the co-technology.