Pyrone derivatives from the soil fungus Fusarium solani PSU-RSPG37

Fusarpyrones A (1) and B (2), two new pyrone derivatives, were isolated from the soil fungus Fusarium solani PSU-RSPG37 together with eight known compounds, anhydrofusarubin, fusarubin, 5-hydroxy-8-methoxy-2,4-dimethylnaphtho[1,2,b]furan-6,9-dione, 2,3-dihydro-5-hydroxy-8-methoxy-2,4-dimethylnaphtho[1,2,b]furan-6,9-dione, javanicin, fusalanipyrone, p-hydroxyacetophenone, and tyrosol. The cytotoxic, antimalaria, and antimycobacterial activities of isolated compounds were examined.     

Eudesmane-type sesquiterpene derivatives from Laggera alata

Ten eudesmane-type sesquiterpene derivatives (1–10), including six cuauhtemone derivatives (1–6), one di-norsesquiterpene (3-oxo-di-nor-eudesma-4-en-11-oic acid, 7), and three eudesmane glycosides (alatoside F–H, 8–10) were isolated from the whole plants of Laggera alata together with 12 known compounds. Their structures were elucidated on the basis of extensive spectroscopic analysis, acid hydrolysis, and compounds 1 and 7 were studied by single-crystal X-ray diffraction analysis. The absolute configuration of 1 was determined by the application of the modified Mosher’s method. All of the isolated eudesmane-type sesquiterpenes were evaluated for their cytotoxic activities on six human cancer cell lines, but all of the compounds were inactive on the tested cell lines in the concentration of 100 μg/mL.     

Silphiperfolane sesquiterpene acids from Artemisia chamaemelifolia Vill

The aerial parts of Artemisia chamaemelifolia Vill. afforded, in addition to five known sesquiterpene acids, a new 5-epi-cantabrenolic acid (6).     

Pyrone derivatives from the marine-derived fungus Nigrospora sp. PSU-F18

Pyrones, named nigrosporapyrones A-D (1-4), and five known compounds were isolated from the marine-derived fungus Nigrospora PSU-F18. Their structures were elucidated on the basis of spectroscopic evidence. The antibacterial activity against the standard Staphylococcus aureus ATCC 25923 and methicillin-resistant S. aureus was evaluated.     

Antimicrobial activities of sesquiterpene lactones and inositol derivatives from Hymenoxys robusta

Six compounds from the aerial parts of the Argentinean plant Hymenoxys robusta (Rusby) Parker were isolated and their structures elucidated using extensive spectroscopic analyses. These compounds comprise two inositol derivatives and four 3,4-seco-pseudoguaianolides, including vermeerin. Bioactivity assays of these compounds against bacterial and fungal pathogens showed that only vermeerin possessed antimicrobial activity specific against Staphylococcusaureus, and showed no toxicity when exposed to human-derived macrophages.     

A tetracyclic sesquiterpene,further isocedrene and guaiene derivatives from Jungia stuebelii

The aerial parts of Jungia stuebelii afforded, in addition to known compounds, two guaiene derivatives, a pseudoguaiane derivative, nine isocedrene     

New sesquiterpene lactones,geranyllinalol derivatives and other constituents from Geigeria species

The investigation of three Geigeria species and five subspecies afforded, in addition to known compounds, the following 32 new compounds: two geigeranolides with a new carbon skeleton, two xanthanolides, five guaianolides, three pseudoguaianolides, a sesquiterpene related to ivaxillarin, a nerolidol derivative, 15 geranyllinalol derivatives, two thiophene acetylenes and a dimeric coniferyl isobutyrate. The structures and the stereochemistry of the new compounds were elucidated by spectroscopic methods and a few chemical transformation. Chemotaxonomic aspect and relationship of the comnounds are discussed.     

4α,15-Dihydroencelin and related sesquiterpene acids from perymenium featherstonei

Perymenium featherstonei afforded, in addition to the known ent-kaurene derivative 4α, 15-dihydroencelin, two closely related epimeric acids.     

Alkaloids from Pycnarrhena longifolia

From the root and stem of Pycnarrhena longifolia the following alkaloids were isolated and identified: obaberine, homoaromoline, aromoline, daphnoline, limacine, krukovine, magnoflorine and pycnarrhine. Pycnarrhine is a simple isoquinoline derivative which has not previously been reported as a natural product.     

Quassinoids from Eurycoma longifolia

Three quassinoids, eurycolactone D (1), eurycolactone E (2) and eurycolactone F (3) were isolated from the roots of Eurycoma longifolia Jack. The structures of 1-3 were elucidated by spectroscopic methods, and that of 3 was further confirmed by X-ray crystallography. The known quassinoids, laurycolactone B (4) and eurycomalactone (5) were also identified.     

Quantitative analysis of sesquiterpene lactones and thymol derivatives in extracts from Telekia speciosa

A high-performance liquid chromatographic method based on a gradient elution and the application of core–shell type stationary phase was developed to estimate contents of sesquiterpene lactones and monoterpenoid thymol derivatives in the tissues of Telekia speciosa. The detection and quantification limits of the analytes were 0.05–0.29 μg ml⁻¹ and 0.15–0.89 μg ml⁻¹, respectively. Calibration curves showed good linearities (R² > 0.9996) within the test ranges. Intra-day and inter-day precisions were satisfactory with RSD < 2.6%. The recoveries of the standards tested ranged from 96 to 107%. The overall time of analysis was less than 35 min. Using the method, seven major sesquiterpene lactones and one thymol derivative were quantified in different organs of the plant and plants of different origin. Aerial parts of T. speciosa accumulated miscellaneous sesquiterpene lactones, mainly of guaiane, pseudoguaiane, xanthane and eudesmane type, whereas roots of the plant contained almost exclusively isoalantolactone – an eudesmanolide of antiproliferative and anti-inflammatory activity (up to 1.2% dry weight). Flowers of T. speciosa proved to be an excellent source of xanthanolide – 8-epi-tomentosin (0.16–0.94%). Provenience of the plant material strongly influenced its biosynthetic potential.     

Pyrone glycosides from Acosmium panamense (Benth.) Yacovlev

Besides caffeic acid three pyrones have been isolated from aquous bark extracts from Acosmium panamense and their structures were determined using spectroscopical methods. Besides the already described desmethylyangonine its O4'-mono as well as the di(1-6)glucoside are found the first time.     

Two new sesquiterpene derivatives from soil actinomycete Streptomyces albospinus 15-4-2

Two new sesquiterpene derivatives, 4α,10β-dimethyl-decahydronaphthalene-1β,3β,5α,8α-tetraol (1) and 5β H-eudesmane-1β,6α,11-triol (2) were isolated from the soil actinomycete Streptomyces albospinus 15-4-2. Their structures were elucidated on the basis of spectroscopic analysis. Compound 1 exhibited antibacterial activity against methicillin-resistant Staphylococcus aureus (MRSA) strain in vitro.     

A new rare asteriscane sesquiterpene and other related derivatives from the Hainan aeolid nudibranch Phyllodesmium magnum

Chemical analysis of the secondary metabolite pattern of the aeolid nudibranch Phyllodesmium magnum collected from the South China sea resulted in the isolation of eight sesquiterpenes, exhibiting very different structural features, which included one asteriscane (1), two africanane (2, 3), one elemane (4), two selinane (5, 6), and two furano- (7, 8) sesquiterpenes. Among them, compound 1, a new molecule, represents the fourth example of a rare asteriscane skeleton from a natural source, and the seven known sesquiterpenes (2-8) are new for P. magnum. The occurrence of the metabolites possessed by Phyllodesmium guamensis supports recent chemecological studies that it preys on the soft coral Sinularia sp., and uses these dietary chemicals as its defensive weapon.     

Synthesis of selenocysteine and selenomethionine derivatives from sulfur-containing amino acids

Selenium-containing amino acids have attracted increasing interest from view points of the importance as active centers of several selenoenzymes, the biological synthesis, the metabolism, and the use for structure determination of proteins. In this article, our recent progresses in the transformation from sulfur-containing amino acids to selenocysteine (SeCys) and selenomethionine (SeMet) derivatives are reviewed along with the surveys of general organic methodologies for the synthesis of SeCys and SeMet derivatives in the literature. The S-->Se modification (i.e., the chemical atomic mutation) would be a useful approach to peptide synthesis involving selenoamino acid residues.     

Synthesis and antimycobacterial activity of isoniazid derivatives from renewable fatty acids

This work describes the synthesis of a series of fatty acid hydrazide derivatives of isoniazid (INH). The compounds were tested against Mycobacterium tuberculosis H37Rv (ATCC 27294) as well as INH-resistant (ATCC 35822 and 1896 HF) and rifampicin-resistant (ATCC 35338) M. tuberculosis strains. The fatty acid derivatives of INH showed high antimycobacterial potency against the studied strains, which is desirable for a pharmaceutical compound, suggesting that the increased lipophilicity of isoniazid plays an important role in its antimycobacterial activity.     

Guaiane sesquiterpene from Lactarius sanguifluus

The isolation of pigments from the fungus Lactarius sanguifluus and the determination of their structures is reported. The structure of a new compound with a guaiane skeleton has been elucidated by 2D NMR spectroscopy.     

Bioconjugate of lysozyme and the antibacterial marine sesquiterpene quinone avarone and its derivatives

A conjugate of lysozyme with avarone, a bioactive sesquiterpene quinone of marine origin, and its three derivatives were synthesized. MALDI TOF mass spectral analysis and tryptic digestion showed that the only residue in lysozyme that was modified by all derivatives was lysine 97. The identity of the residue was in full correlation with the prediction obtained by molecular modeling. All bioconjugates preserved most of the enzymatic activity of lysozyme. The melting point of the conjugates was slightly increased in comparison to lysozyme, indicating a slight stabilization of structure. The antibacterial activity of all the conjugates to both Gram positive and Gram negative bacteria was stronger than the activity of either lysozyme or the quinones, the MIC values being in low micromolar range for some conjugates.     

Cytotoxic and antimalarial constituents from the roots of Eurycoma longifolia

Sixty-five compounds were isolated from the roots of Eurycoma longifolia and characterized by comprehensive analyses of their 1D and 2D NMR, and mass spectral data. Among these isolates, four quassinoid diterpenoids were reported from natural sources for the first time, namely eurycomalide A (1), eurycomalide B (2), 13beta, 21-dihydroxyeurycomanol (3), and 5alpha, 14beta, 15beta-trihydroxyklaineanone (4). Screening of cytotoxicity, anti-HIV and antimalarial activity of these isolated compounds was also furnished by in vitro assays. Compounds 12, 13, 17, 18, 36, 38, 59, and 62 demonstrated strong cytotoxicity toward human lung cancer (A-549) cell lines, however, 12, 13, 17, 38, 57, 58, and 59 exhibited strong cytoxicity toward human breast cancer (MCF-7) cell lines. Compounds 57 and 58 displayed potent antimalarial activity against the resistant Plasmodium falciparum. The thorough studies on the stereochemistry of the different quassinoid diterpenoids provide a clear reference to the scientists who are interested on this field.