Alveolarides: Antifungal Peptides from Microascus alveolaris Active against Phytopathogenic Fungi.

Three novel cyclodepsipeptides, alveolarides A (1), B (2), and C (3), each possessing the rare 2,3-dihydroxy-4-methyltetradecanoic acid unit and a ß-phenylalanine amino acid residue, along with the known peptide scopularide were isolated and identified from the culture broth of Microascus alveolaris strain PF1466. The pure compounds were evaluated for biological activity, and alveolaride A (1) provided strong in vitro activity against the plant pathogens Pyricularia oryzae, Zymoseptoria tritici, and Ustilago maydis. Moderate activity of alveolaride A was observed under in planta conditions against Z. tritici, Puccinia triticina, and Phakopsora pachyrhizi. Structures of 1, 2, and 3 were determined by detailed analysis of NMR (1D and 2D) and mass spectrometry data. The partial absolute configuration of alveolaride A (1) was established.

Succinylated Apoptolidins from Amycolatopsis sp. ICBB 8242.

Two new apoptolidins, 2'-O-succinyl-apoptolidin A (11) and 3'-O-succinyl-apoptolidin A (12), were isolated from the culture broth of an Indonesian Amycolatopsis sp. ICBB 8242. These compounds inhibit the proliferation and viability of human H292 and HeLa cells. However, in contrast to apoptolidin A (1), they do not inhibit cellular respiration in H292 cells. It is proposed that apoptolidins are produced and secreted in their succinylated forms and 1 is the hydrolysis product of 11 and 12.

Neolignans and other metabolites from Ocotea cymosa from the Madagascar rain forest and their biological activities.

Ten new neolignans including the 6'-oxo-8.1'-lignans cymosalignans A (1a), B (2), and C (3), an 8.O.6'-neolignan (4a), ococymosin (5a), didymochlaenone C (6a), and the bicyclo[3.2.1]octanoids 7-10 were isolated along with the known compounds 3,4,5,3',5'-pentamethoxy-1'-allyl-8.O.4'-neolignan, 3,4,5,3'-tetramethoxy-1'-allyl-8.O.4'-neolignan, didymochlaenone B, virologin B, ocobullenone, and the unusual 2'-oxo-8.1'-lignan sibyllenone from the stems or bark of the Madagascan plant Ocotea cymosa. The new 8.O.6'-neolignan 4a, dihydrobenzofuranoid 5a, and the bicyclo[3.2.1]octanoid 7a had in vitro activity against Aedes aegypti, while the new compounds 5a, 7a, 8, and 10a and the known virolongin B (4b) and ocobullenone (10b) had antiplasmodial activity. We report herein the structure elucidation of the new compounds on the basis of spectroscopic evidence, including 1D and 2D NMR spectra, electronic circular dichroism, and mass spectrometry, and the biological activities of the new and known compounds.

Apoptolidins A and C activate AMPK in metabolically sensitive cell types and are mechanistically distinct from oligomycin A.

Apoptolidin A was first isolated as a secondary metabolite of a Nocardiopsis sp. and is the founding member of a family of potential selective cancer cell toxins. We now report the isolation, production and pharmacological characterization of apoptolidins A and C from an alternate actinomycete producer, an Amycolatopsis sp. from soil samples collected in Indonesia. We investigated the action of apoptolidins A and C in representative human glioblastoma cells, lung cancer cells and mouse embryonic fibroblasts (MEFs) to better understand the mechanism of action of the known apoptolidins. Shifts in cellular metabolism in intact cells and the status of the AMP-activated protein kinase (AMPK) stress pathway in response to apoptolidin A were entirely consistent with the actions of an ATP synthase inhibitor. We find the metabolic phenotype of the cell to be a critical determinant of apoptolidin sensitivity and the likely basis for cancer cell selectivity. The apoptolidins induce indirect activation of AMPK and trigger autophagy in sensitive cell types without significant inhibition of mTORC1. Human U87-MG glioblastoma cells and wild type MEFs showed increased phosphorylation of AMPK (Thr172), ACC (Ser79) and ULK1 (Ser555), whereas AMPKα-null MEFs and more glycolytic SF-295 glioblastoma cells lacked this response. Although both are reported to be selective inhibitors of mitochondrial ATP synthase, differences between apoptolidin- and oligomycin A-induced responses in cells indicate that the action of these macrolides is not identical.

Phoslactomycins from Streptomyces sp. MLA1839 and their biological activities.

Phoslactomycins H (1) and I (2), two new members of the phoslactomycin class of chemistry, were isolated from Streptomyces sp. MLA1839 on the basis of their antifungal activities. Their structures were elucidated using extensive NMR spectroscopy and mass spectrometry. Phoslactomycin H (1) featured a rare and unprecedented N,N-dimethylamine substitution at C-4 and existed as a hydroxy acid rather than the more common lactone. Herein, we report the structure of these compounds and their biological activities.

Aqabamycins A-G: novel nitro maleimides from a marine Vibrio species: II. Structure elucidation.

The structures of secondary metabolites with antibacterial and cytotoxic activities produced by a marine Vibrio strain from the Red Sea were elucidated. Aqabamycin A (1a) and seven further nitro-substituted maleimide derivates named aqabamycins B-G (1b-f and 2) were obtained together with 12 known metabolites, 3-nitro-1H-indazole (3), indazole-3-carbaldehyde (4), 3-nitro-4-hydroxycinnamic acid, 4-hydroxycinnamic acid, 3-nitro-4-hydroxybenzaldehyde, phenyl-2-bis-indolylmethane (5a), turbomycin B (5b), vibrindole A (6), phenylacetic acid, 3-hydroxybenzoic acid, benzoic acid and 1,4-dithiane (7). Some of the known metabolites (for example, 3, 4 and 7) are described in this study for the first time as natural products. Their structures were elucidated based on 1D and 2D NMR, MS spectra and by comparison with synthetic material.

Modified phenazines from an Indonesian Streptomyces sp.

Fractionation of the extract from the Indonesian Streptomyces sp. ICBB8198 as directed by the antibacterial activity delivered the known phenazine antibiotics griseoluteic acid (1a) and griseolutein A (1b), as well as two new phenazine derivatives (2 and 3). In addition, the known compounds spirodionic acid, dihydrosarkomycins, and 6-ethyl-4-hydroxy-3,5-dimethyl-2H-pyran-2-one (4a), along with the new pyrone 3,6-diethyl-4-hydroxy-5-methyl-2H-pyran-2-one (4b), were isolated. We report here the isolation, structure elucidation, and antibiotic activity of the new metabolites as well as a hypothetical pathway for the formation of the new phenazine derivatives.

Turrealabdane, turreanone and an antisalmonellal agent from Turraeanthus africanus.

Phytochemical investigation of the seeds of Turraeanthus africanus (Meliaceae), a Cameroonian plant species traditionally used in the treatment of typhoid fever, afforded eight compounds, including two labdanes, a C-arabinoside derivative, a sesquiterpene, and several triterpenes, two of which are new: 15',16'-dihydroxy-15(12'),15'(16')-diolidebislabd-8(17),8'(17'),12-trien-16-al ( 1), trivially named turrealabdane and a C-arabinoside derivative ( 2), trivially named turreanone. The other compounds are 12,15-epoxylabda-8(17),12,14-trien-16-acetate ( 3), (+)-eudesmanol- O-L-arabinoside, cyclolaudenol, stigmasterol, sitosterol glucoside and lupeol. Acetylation and oxidation of turrealabdane yielded 15',16'-diacetoxyturrealabdane and 15,12'-dioxoturrealabdane-15',16'-dial, respectively. Their structures were determined by means of spectroscopic data including 1D and 2D NMR in combination with MS. The compounds were evaluated for antibacterial activities, chloramphenicol and amoxicillin being used as standard. Compound 3 was the only active principle, possessing the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values of respectively 25 microg/mL and 100 microg/mL against Salmonella typhi, S. paratyphi a and S. paratyphi B.This compound did not show any activity against Pseudomonas aeruginosa, Escherichia coli, Klebsiella pneumoniae and Staphylococcus aureus.

Control of steroid 21-oic acid synthesis by peroxisome proliferator-activated receptor alpha and role of the hypothalamic-pituitary-adrenal axis.

A previous study identified the peroxisome proliferator-activated receptor alpha (PPARalpha) activation biomarkers 21-steroid carboxylic acids 11beta-hydroxy-3,20-dioxopregn-4-en-21-oic acid (HDOPA) and 11beta,20-dihydroxy-3-oxo-pregn-4-en-21-oic acid (DHOPA). In the present study, the molecular mechanism and the metabolic pathway of their production were determined. The PPARalpha-specific time-dependent increases in HDOPA and 20alpha-DHOPA paralleled the development of adrenal cortex hyperplasia, hypercortisolism, and spleen atrophy, which was attenuated in adrenalectomized mice. Wy-14,643 activation of PPARalpha induced hepatic FGF21, which caused increased neuropeptide Y and agouti-related protein mRNAs in the hypothalamus, stimulation of the agouti-related protein/neuropeptide Y neurons, and activation of the hypothalamic-pituitary-adrenal (HPA) axis, resulting in increased adrenal cortex hyperplasia and corticosterone production, revealing a link between PPARalpha and the HPA axis in controlling energy homeostasis and immune regulation. Corticosterone was demonstrated as the precursor of 21-carboxylic acids both in vivo and in vitro. Under PPARalpha activation, the classic reductive metabolic pathway of corticosterone was suppressed, whereas an alternative oxidative pathway was uncovered that leads to the sequential oxidation on carbon 21 resulting in HDOPA. The latter was then reduced to the end product 20alpha-DHOPA. Hepatic cytochromes P450, aldehyde dehydrogenase (ALDH3A2), and 21-hydroxysteroid dehydrogenase (AKR1C18) were found to be involved in this pathway. Activation of PPARalpha resulted in the induction of Aldh3a2 and Akr1c18, both of which were confirmed as target genes through introduction of promoter luciferase reporter constructs into mouse livers in vivo. This study underscores the power of mass spectrometry-based metabolomics combined with genomic and physiologic analyses in identifying downstream metabolic biomarkers and the corresponding upstream molecular mechanisms.

Limazepines A-F, pyrrolo[1,4]benzodiazepine Antibiotics from an Indonesian Micrococcus sp.

In our screening of Indonesian microorganisms for novel bioactive natural products we have isolated seven new compounds, designated as limazepines A, B1 and B2 (isolated as an isomeric mixture), C, D, E, and F, from the culture broth of Micrococcus sp. strain ICBB 8177. In addition, the known natural products prothracarcin and 7-O-succinylmacrolactin A, as well as two previously reported synthetic compounds, 2-amino-3-hydroxy-4-methoxybenzoic acid methyl ester and 4-ethylpyrrole-2-carboxaldehyde, were obtained from the extract. Chemical structures were determined by spectroscopic methods and by comparison with the NMR data of structurally related compounds. The limazepines belong to the growing group of the pyrrolo[1,4]benzodiazepine antitumor antibiotics isolated from various soil bacteria. Limazepines B1/B2 mixture, C, and E were active against the Gram-positive bacterium Staphylococcus aureus and the Gram-negative bacterium Escherichia coli. Limazepine D was also active against S. aureus, but was not active against E. coli. Interestingly, only the limazepines B1/B2 mixture and D were active against Pseudomonas aeruginosa.

Rearranged and unrearranged angucyclinones from Indonesian Streptomyces spp.

Two Indonesian Streptomyces strains, ICBB8309 and ICBB8415, were investigated for their ability to produce antibiotic compounds. In addition to the known antibiotics actiphenol, naramycin B, and sabaramycin, six new angucyclinones were identified. The isolation, structure elucidation and biological activities for the six new compounds are presented. The angucyclinones 7-deoxo-6-deoxy-7-hydroxy-8-O-methylrabelomycin, 1-deoxo-1-hydroxy-8-O-methylrabelomycin, and the angucycline 7-deoxo-7-hydroxy-1-O-alpha-rhamnosyl-8-O-methyltetrangulol have common angular backbones, while angucyclinone C, limamycin A, and limamycin B appear to be rearranged angucyclinones.

Furan oligomers and beta-carbolines from terrestrial streptomycetes.

2,5-Bis(hydroxymethyl)furan monoacetate (3) and 2,5-bis(hydroxymethyl)furan diacetate (4) were obtained as new natural products from an ethyl acetate extract of the terrestrial Streptomyces sp. isolate GW11/1695. Another Streptomyces isolate, GW21/1313, delivered a dimer (6) and a trimer (7) of (hydroxymethyl)furfural. The latter strain also produced 4-hydroxy-2-(5-(hydroxymethyl)furan-2-ylmethylene)-5-methylfuran-3-one (5), perlolyrin (8), and two new beta-carboline derivatives, 9 and 10. 2,5-Bis(hydroxymethyl)furan diacetate (4) exhibited weak cytotoxic activity against brine shrimp larvae.

Hualyzin, a symmetrical urea derivative isolated from Penicillium herquei isolate GA4.

Penicillium herquei isolate GA4 was isolated from the infected Conchocelis of Porphyra yezoensis. A large-scale fermentation using yeast extract sucrose medium and repeated chromatography afforded a new symmetrical urea derivative, hualyzin (1). The structure was determined by detailed NMR spectroscopic investigations and MS fragmentation analysis.

Angucyclinones from an Indonesian Streptomyces sp.

Six new angucyclinone polyketides named panglimycins A-F were isolated together with the three known metabolites (+)-fujianmycin A, (+)-ochromycinone, and emycin C from the bioassay-guided fractionation of the extract of the Indonesian Streptomyces strain ICBB8230. The new compounds are highly oxygenated angucyclinones that appear to be biosynthetically derived from ochromycinone or fujianmycin. Their structures were determined by X-ray crystal analysis, interpretation of 1D- and 2D-NMR spectra, and comparison of the data with those of structurally related known natural products. Despite structural similarities to angucyclinones with antibiotic activities, the panglimycins did not exhibit any growth inhibition when tested against several bacteria and fungi.

Electrospray ionization mass spectra of piperazimycins A and B and gamma-butyrolactones from a marine-derived Streptomyces sp.

Chemical investigation of the marine-derived Streptomyces sp. Act8015 led to the isolation of two cyclic peptide antibiotics, piperazimycins A and B (1a, 1b). Their structures were confirmed on the basis of a detailed HRESI-MS/MS analysis. Additionally, a new butanolide, 4,10-dihydroxy-10-methyl-dodecan-4-olide (2), and the respective acid, 4,10-dihydroxy-10-methyl-dodecanoic acid (3a) were identified. Further isolated compounds were staurosporin, adenine, indole-3-carboxylic acid, ferulic acid, tryptophol, and three gamma-butyrolactones: virginiae butanolide E (4e) and Graefe's Factors I (4f) and III (4g). The structures of 2 and 3a were confirmed by detailed 1D and 2D NMR studies and MS spectra and by comparison with related structures. A full signal assignment of virginiae butanolide E (4e) is reported here for the first time.

Amorphane sesquiterpenes from a marine Streptomyces sp.

The chemical investigation of the crude extract of the marine-derived Streptomyces sp. M491 yielded three new sesquiterpenes, namely, 10alpha,11-dihydroxyamorph-4-ene (4), 10alpha,15-dihydroxyamorph-4-en-3-one (6), and 5alpha,10alpha,11-trihydroxyamorphan-3-one (7). In addition, the known compounds 10alpha-hydroxyamorph-4-en-3-one (2), o-hydroxyacetanilide, genistein, prunetin, and indole-3-carbaldehyde and the macrolide antibiotic chalcomycin A were identified. The structures were determined on the basis of spectroscopic analysis, especially 1D and 2D NMR data. This is the first report of these sesquiterpenes from bacteria.

N-carboxamido-staurosporine and selina-4(14),7(11)-diene-8,9-diol, new metabolites from a marine Streptomyces sp.

In our screening of micro-organisms for novel bioactive natural products, a new staurosporinone, N-carboxamido-staurosporine (1c), and a new sesquiterpene, (5S,8S,9R, 10S)-selina-4(14),7(11)-diene-8,9-diol (2a), were isolated from the culture broth of the marine-derived Streptomyces sp. QD518. Their structures were determined by spectroscopic methods and by comparison of the NMR data with those of structurally related known natural products, which were isolated from the same strain.

Kettapeptin: isolation, structure elucidation and activity of a new hexadepsipeptide antibiotic from a terrestrial Streptomyces sp.

The ethyl acetate extract of the Streptomyces sp. isolate GW99/1572 exhibited significant biological activity against Gram-positive bacteria and delivered kettapeptin (1), a new hexadepsipeptide antibiotic of the azinothricin type. The structure was elucidated by various 1D and 2D NMR techniques, mass spectrometry and by comparison of the NMR data with those of closely related antibiotics. The absolute configuration of the compound was derived by crystal structure analysis and by comparison with the optical rotation data of related compounds.

Alkaloids from Oriciopsis glaberrima Engl. (Rutaceae).

Two alkaloid derivatives, oriciacridone A and B, were isolated from the stem bark of Oriciopsis glaberrima (Rutaceae). The structures were elucidated by a detailed spectroscopic analysis. The extract exhibited in vitro significant antimicrobial activity against a range of micro-organisms.