A new cyclohexenone from the tin mine tailings-derived fungus Aspergillus flavus YIM DT 10012

A new cyclohexenone, named phomaligol D (1), together with two known compounds, kojic acid (2) and phomaligol A (3) were isolated from the tin mine tailings-derived fungus Aspergillus flavus YIM DT 10012. Their structures were elucidated by detailed analysis of spectroscopic data.     

Aspergillicins A-E: five novel depsipeptides from the marine-derived fungus Aspergillus carneus

A search for new antiparasitic agents from a strain of the fungus Aspergillus carneus isolated from an estuarine sediment collected in Tasmania, Australia, yielded the known terrestrial fungal metabolite marcfortine A (1) as an exceptionally potent antiparasitic agent. This study also yielded a series of new depsipeptides, aspergillicins A-E (2-6) and the known terrestrial fungal metabolite acyl aszonalenin (7). Marcfortine A (1) and acyl aszonalenin (7) were identified by spectroscopic analysis, with comparison to literature data. Complete stereostructures were assigned to aspergillicins A-E (2-6) on the basis of detailed spectroscopic analysis, together with ESIMS analysis of the free amino acids generated by acid hydrolysis, and HPLC analysis of Marfey derivatives prepared from the acid hydrolysate. The peptide amino acid sequence for all aspergillicins was unambiguously assigned by MS(n) ion-trap ESI mass spectrometry.     

Biselides A-E: novel polyketides from the Okinawan ascidian Didemnidae sp.

Five new polyketides, biselides A (1), B (2), C (3), D (4), and E (5), were isolated from the Okinawan ascidian Didemnidae sp. Their structures were determined by spectroscopic analysis. Biselides A (1), B (2), and C (3) showed cytotoxicity against human cancer cells NCI-H460 and MDA-MB-231.     

Insecticidal activity of a novel fatty acid amide derivative from Streptomyces species against Helicoverpa armigera

Helicoverpa armigera, an important pest causes serious damage to grain legumes. The main objective of this study was to isolate and identify the metabolite against H. armigera from a previously characterised Streptomyces sp. CAI-155. The culture filtrate of CAI-155 was extracted using Diaion HP-20 and the active fractions were fractionated on Silica and C18 column chromatography. The C18 active fraction was further fractionated on Silica gel 60 F₂₅₄ thin layer chromatography (TLC). The most active fraction (Rf 0.64) purified from TLC led to the identification of a novel metabolite N-(1-(2,2-dimethyl-5-undecyl-1,3-dioxolan-4-yl)-2-hydroxyethyl)stearamide by spectral studies. The purified metabolite showed 70–78% mortality in 2nd instar H. armigera by diet impregnation assay, detached leaf assay and greenhouse assay. The LD₅₀ and LD₉₀ values of the purified metabolite were 627 and 2276 ppm, respectively. Hence, this novel metabolite can be exploited for pest management in future.     

Aspergillazines A-E: novel heterocyclic dipeptides from an Australian strain of Aspergillus unilateralis

Biological and chemical profiling of an Australian strain of the fungus Aspergillus unilateralis(MST-F8675), isolated from a soil sample collected near Mount Isa, Queensland, revealed a complex array of metabolites displaying broad chemotherapeutic properties. Noteworthy among these metabolites were a unique series of highly modified dipeptides aspergillazines A-E, incorporating a selection of unprecedented and yet biosynthetically related heterocyclic systems. Co-occurring with the aspergillazines was the recently described marine-derived fungal metabolite trichodermamide A (cf. penicillazine), whereas re-fermentation of A. unilateralis in NaCl (1%) enriched media resulted in co-production of the only other known example of this structure class, the marine-derived fungal metabolite trichodermamide B. Further investigation of A. unilateralis returned the known terrestrial fungal metabolite viridicatumtoxin as the cytotoxic and antibacterial principle, together with E-2-decenedioic acid, ferulic acid, (7E,7'E)-5,5'-diferulic acid and (7E,7'E)-8,5'-diferulic acid. The aromatic diacids have previously been reported from the chemical and enzymatic (esterase) treatment of plant cell wall material, with their isolation from A. unilateralis being their first apparent reported occurrence as natural products. Structures for all metabolites were determined by detailed spectroscopic analysis and, where appropriate, comparison to literature data and/or authentic samples.     

Abyssomicin E, a highly functionalized polycyclic metabolite from Streptomyces species

Abyssomicin E (1), a new polycyclic metabolite with a C19 skeleton, was isolated from Streptomyces sp. (HKI0381). Its chemical structure was determined by comprehensive NMR and MS spectroscopic analyses. For the first time in this recently discovered class of compounds, the absolute stereochemistry was directly established by subsequent single-crystal X-ray diffraction study using anomalous dispersion with copper radiation.     

Harrisotones A-E, five novel prenylated polyketides with a rare spirocyclic skeleton from Harrisonia perforata

Five novel prenylated polyketides, harrisotones A-E (1-5) representing a rare spirocyclic skeleton, along with a new hydroperoxypolyketide harrisonol A (6), were isolated from the stems and leaves of Harrisonia perforata. The structures of harrisotones A-E (1-5) were extensively elucidated on the basis of spectroscopic analysis, especially 2D NMR and CD spectra. A plausible origin of compounds 1-5 was rationalized biogenetically, and traced back to harrisonol A (6). Harrisotones A-C (1-3) and harrisonol A (6) exhibited significant cytotoxicity against P-388 and/or A-549 tumor cell lines.     

Houttuynoids A-E, anti-herpes simplex virus active flavonoids with novel skeletons from Houttuynia cordata

Houttuynoids A-E (1-5), a new type of flavonoid with houttuynin tethered to hyperoside, and their presumed biosynthetic precursor hyperoside (6) were isolated from the whole plant of Houttuynia cordata. Their structures were elucidated by analysis of 1D and 2D NMR. A hypothetical biogenetic pathway for houttuynoids A-E was proposed. Compounds 1-5 exhibited potent anti-HSV (herpes simplex viruses) activity.     

Chartrenoline,a novel alkaloid isolated from a marine Streptomyces chartreusis NA02069

A novel alkaloid featuring a unique tetracyclic ring system was isolated from a marine actinobacterium.     

Erythrolic acids A-E, meroterpenoids from a marine-derived Erythrobacter sp

Erythrolic acids A-E (1-5) are five unusual meroterpenoids isolated from the bacterium Erythrobacter sp. derived from a marine sediment sample collected in Galveston, TX. The structures were elucidated by means of detailed spectroscopic analysis and chemical derivatization. The erythrolic acids contain a 4-hydroxybenzoic acid appended with a modified terpene side chain. The side-chain modifications include oxidation of a terminal methyl substituent and in the case of 1-4 addition of a two-carbon unit to give terpene side chains of unusual length: C22 for 1 and 2, C17 for 3, and C12 for 4. The relative and absolute configurations of the meroterpenoids were determined by coupling constant, NOE, and Mosher's analysis. In vitro cytotoxicity toward a number of nonsmall cell lung cancer (NSCLC) cell lines revealed only modest activity for erythrolic acid D (4) (2.5 μM against HCC44). The discovery of these unusual diterpenes, along with the previously reported erythrazoles, demonstrates the natural product potential of a previously unstudied group of bacteria for drug discovery. The unusual nature of the terpene side chain, we believe, involves an oxidation of a terminal methyl group to a carboxylic acid and subsequent Claisen condensation with acetyl-CoA.     

Benhamycin, novel alkaloid from terrestrial Streptomyces sp

During our screening for bioactive natural compounds from microorganisms, a novel alkaloid has been isolated from a terrestrial Streptomyces sp. isolate NR12, and named as benhamycin (1). This was along with the known metabolites, uracil, thymine, p-hydroxybenzoic acid, 2'-deoxyuridin, tryptophol, indolyl-3-carboxylic acid, and indolyl-3-carbaldehyde. Chemical structure of the novel compound was determined by detailed analysis of its spectroscopic data (extensive NMR experiments, 1 & 2D, MS spectroscopy, and MS high resolution). Structurally, Benhamycin (1) is a pentacyclic aromatic compound bearing an acridine moiety lactamized with benzene. Biological studies showed that the strain extract was moderately active against Gram-positive, Gram-negative bacteria and fungi.     

A tin hydride designed to facilitate removal of tin species from products of stannane-mediated radical reactions

The stannane 1, which is simple to prepare, behaves like the conventional reagents Bu3SnH and Ph3SnH in standard free radical reactions, but with the special characteristic that the tin-containing byproducts are easily and very largely removed by mild hydrolysis (LiOH-water-THF or TsOH-water-THF), which converts them into base-soluble (aqueous NaHCO3) materials. The performance of stannane 1 was evaluated for a range of radical reactions involving halides, selenides, Barton-McCombie deoxygenation, and enyne cyclization. In several cases the effectiveness of the workup procedure in removing tin species was monitored by 1H NMR.     

Halichoblelides B and C,potent cytotoxic macrolides from a Streptomyces species separated from a marine fish

Halichoblelide B (1) and C (2), novel macrolides with potent cytotoxicity against tumor cells in culture, have been isolated from a strain of Streptomyces hygroscopicus originally derived from the marine fish Halichoeres bleekeri, and their absolute stereostructures have been elucidated on the basis of spectroscopic analyses using 1D and 2D NMR techniques and chemical transformations. These compounds exhibited significant cytotoxicity against human cancer cell lines.     

Total synthesis and structural confirmation of malayamycin A: a novel bicyclic C-nucleoside from Streptomyces malaysiensis

[reaction: see text] The stereocontrolled synthesis of malayamycin A, a novel naturally occurring bicyclic C-nucleoside of the perhydrofuropyran type, is described.     

Roseosporol A,the first isolation of a novel sesquiterpenoid from Streptomyces roseosporus

A novel sesquiterpenoid, roseosporol A (1), together with 12 known compounds (2–13) were isolated from the ethyl acetate extract of Lsr2-deletion mutant strain of Streptomyces roseosporus. Their structures were determined by spectroscopic methods, including NMR, HRMS, UV, IR and ECD.     

Turpinionosides A-E: megastigmane glucosides from leaves of Turpinia ternata Nakai

From leaves of Turpenia ternata (Staphylaceae), one megastigmane and seven of its glucosides (1-8) were isolated. Megastigmane and two of the glucosides were found to be known compounds, namely, 3S,5R,6R,9S-tetrahydroxymegastigmane (1), corchoionoside C (2), and icariside B4 (3). The structures of compounds 4-8 (turpinionosides A-E, respectively) were elucidated by means of spectroscopic analyses, and then their absolute structures were determined by the modified Mosher's method to be (3S,5R,6S,9S)-3,6,9-trihydroxymegastigman-7-ene 3-O- and 9-O-beta-D-glucopyranosides (4, 5, respectively), (1S,3S,5R,6S,9R)-3,9,12-trihydroxymegastigmane 3-O-beta-D-glucopyranoside (6), (3S,4R,9R)-3,4,6-trihydroxymegastigman-5-ene 3-O-beta-D-glucopyranoside (7), and (2S,9R)-2,9-dihydroxymegastigman-5-en-4-one 2-O-beta-D-glucopyranoside (8).     

Fargosides A-E, triterpenoid saponins from Holboellia fargesii

Five new triterpenoid saponins, fargosides A, B, C, D, and E, were isolated from the roots of Holboellia fargesii. The structures of fargosides A-E were elucidated on the basis of chemical and physicochemical evidence and found to be 3beta,20alpha-dihydroxy-29-norolean-12-en-28-oic acid 3-O-beta-D-xylopyranosyl-(1-->2)-beta-D-glucopyranoside (1), 3beta,20alpha,24-trihydroxy-29-norolean-12-en-28-oic acid 23-O-beta-D-fucopyranosyl-(1-->2)-[alpha-L-arabinopyranosyl-(1-->3)]-beta-D-glucopyranoside (2), 3beta,23-dihydroxy-30-norolean-2,20(29)-dien-28-oic acid 3-O-alpha-L-arabinopyranosyl-(1-->2)-[beta-D-glucopyranosyluronic acid-(1-->3)]-alpha-L-arabinopyranoside (3), 3beta,23-dihydroxy-30-norolean-12,20(29)-dien-28-oic acid 3-O-methyl beta-D-glucopyranosyluronate-(1-->3)-alpha-L-arabinopyranoside (4), and 3beta,23-dihydroxy-olean-12-en-28-oic acid 3-O-methyl beta-D-glucopyranosyluronate-(1-->3)-alpha-L-arabinopyranoside (5), respectively.     

Synthesis of a novel mesoporous tin phosphate,SnPO4

Novel mesoporus tin phosphates have been synthesized using alkyltrimethylammonium bromide (alkyl = C8-C18) as surfactant; the structure of the materials is stable at 500 degrees C. UV-VIS spectra show tetrahedral coordination of tin.     

Gelegamines A-E: five new oxindole alkaloids from Gelsemium elegans

Five new oxindole alkaloids, gelegamines A-E (1-5), were isolated from the roots of Gelsemium elegans. Their structures were extensively elucidated on the basis of spectroscopic analysis. Among them, the epoxy ring (C-19/C-20) of gelegamine A (1) was assigned as α-orientation by ROESY experiment and DFT method at B3LYP/6-31g(d) level, and gelegamine B (2) is the first humantenine-type alkaloid with 19-(E) ethylidene configuration. The absolute configurations of gelegamines A-E (1-5) were established on biosynthetic consideration coupled with CD experiments.