Short peptide induces an "uncultivable" microorganism to grow in vitro.

Microorganisms comprise the bulk of biodiversity, but only a small fraction of this diversity grows on artificial media. This phenomenon was noticed almost a century ago, repeatedly confirmed, and termed the "great plate count anomaly." Advances in microbial cultivation improved microbial recovery but failed to explain why most microbial species do not grow in vitro. Here we show that at least some of such species can form domesticated variants capable of growth on artificial media. We also present evidence that small signaling molecules, such as short peptides, may be essential factors in initiating growth of nongrowing cells. We identified one 5-amino-acid peptide, LQPEV, that at 3.5 nM induces the otherwise "uncultivable" strain Psychrobacter sp. strain MSC33 to grow on standard media. This demonstrates that the restriction preventing microbial in vitro growth may be different from those offered to date to explain the "great plate count anomaly," such as deficiencies in nutrient composition and concentrations in standard media, medium toxicity, and inappropriate incubation time. Growth induction of MSC33 illustrates that some microorganisms do not grow in vitro because they are removed from their native communities and the signals produced therein. "Uncultivable" species represent the largest source of unexplored biodiversity, and provide remarkable opportunities for both basic and applied research. Access to cultures of some of these species should be possible through identification of the signaling compounds necessary for growth, their addition to standard medium formulations, and eventual domestication.

Novel extracellular diterpenoids with biological activity from the cyanobacterium Nostoc commune.

Five novel extracellular metabolites with an unprecedented diterpenoid skeleton, 5-[(5-carboxy-2-hydroxy)benzyl]-11-hydroxymethyl-2,5,6,8a, 11-pentamethyldodecahydrocyclopentanaphthalene (1), 5-[(5-carboxy-2-hydroxy)benzyl]-11-formyl-2,5,6,8a, 11-pentamethyl-dodecahydrocyclopentanaphthalene (2), 5-[(5-carboxy-2-hydroxy)benzyl]-11-carboxy-2,5,6,8a, 11-pentamethyl-dodecahydrocyclopentanaphthalene (3), 5-[(5-carboxy-2-hydroxy)benzyl]-11-dihydroxymethyl-2,5,6,8a, 11-pentamethyldodecahydrocyclopentanaphthalene (4), and 5-[(5-carboxy-2-hydroxy)benzyl]-11-acetyl-2,5,6, 8a-tetramethyldodecahydrocyclopentanaphthalene (5), have been isolated from the culture medium of the terrestrial cyanobacterium Nostoc commune by means of bioguided isolation. The molecules were designated as comnostins A-E. The structures were determined by spectroscopic methods, mainly NMR and mass spectrometry. The relative stereochemistry of comnostin A was confirmed by single-crystal X-ray structure analysis. All comnostins showed antibacterial activities. Additionally, cytotoxic and molluscicidal activities were found for comnostin B.

A novel extracellular diterpenoid with antibacterial activity from the cyanobacterium Nostoc commune.

A novel extracellular metabolite with an unprecedented diterpenoid skeleton, 8-[(5-carboxy-2-hydroxy)benzyl]-2-hydroxy-1,1,4a,7, 8-pentamethyl-1,2,3,4,4a,6,7,8,8a,9,10,10a-dodecahydrophenanthrene , has been isolated from the culture medium of the terrestrial cyanobacterium Nostoc commune Vaucher (EAWAG 122b) by means of bioguided isolation. The molecule was designated as noscomin. The structure was determined by spectroscopic methods, mainly NMR and mass spectrometry. Noscomin exhibited antibacterial activity against Bacillus cereus, Staphylococcus epidermidis, and Escherichia coli.

Acylated flavonol glycosides from leaves of Stenochlaena palustris.

From the leaves of Stenochlaena palustris five new O-acylated flavonol glycosides, stenopalustrosides A-E (1-5), have been isolated along with five known compounds, kaempferol 3-O-(3' '-O-E-p-coumaroyl)-(6' '-O-E-feruloyl)-beta-D-glucopyranoside (6), kaempferol 3-O-(3' ',6' '-di-O-E-p-coumaroyl)-beta-D-glucopyranoside (7), kaempferol 3-O-(3' '-O-E-p-coumaroyl)-beta-D-glucopyranoside (8), kaempferol 3-O-(6' '-O-E-p-coumaroyl)-beta-D-glucopyranoside (9); and kaempferol 3-O-beta-D-glucopyranoside (10). The structures of the isolates were elucidated by spectroscopic methods, mainly 1D and 2D NMR. Compounds 1-4 showed significant antibacterial activities against Gram-positive strains. The structural difference between the isolated antibacterial and nonantibacterial compounds is discussed.

Gibbilimbols A-D, cytotoxic and antibacterial alkenylphenols from Piper gibbilimbum.

Fractionation of the petroleum ether extract from the leaves of Piper gibbilimbum collected in Papua New Guinea afforded four new alkenylphenols, gibbilimbols A-D (1-4). The structures of the isolates were elucidated by spectroscopic methods, mainly 1D- and 2D-NMR spectroscopy. Gibbilimbols A-D were found to be toxic to brine shrimp with an LC50 of approximately 5 microg/mL. Gibbilimbols A-D were further found to be cytotoxic toward KB nasopharyngal carcinoma cells (ED50 7.8-2.1 microg/mL). All isolates also showed antibacterial activity toward Staphylococcus epidermidis and Bacillus cereus.

Carmabins A and B, new lipopeptides from the Caribbean cyanobacterium Lyngbya majuscula.

Carmabins A and B have been isolated as linear lipotetrapeptides from the BuOH extract of the marine cyanobacterium Lyngbya majuscula. The planar structures were elucidated by extensive 2D NMR analysis, including 1H-15N HMBC and HMQC-TOCSY experiments, together with MS measurements.

Dammarane Triterpenes from the Leaves of Securinega melanthesoides

Two new dammarane triterpenoids, trans-securinegin [(20S)-24-methylidenedammarane-3alpha-yl(2E)-3-(4-hydroxyphenyl)-2-propenate (1)] and cis-securinegin [(20S)-24-methylidenedammarane-3alpha-yl(2Z)-3-(4-hydroxyphenyl)-2-propenate (2)], were isolated from the leaves of Securinega melanthesoides, along with the known compound bergenin. The structures of 1 and 2 were elucidated using spectroscopic methods, mainly 2D NMR techniques.

Phytochemical and biological investigation of Begonia heracleifolia.

From the rhizomes of Begonia heracleifolia six known cucurbitacins ( 1- 6) were isolated. Based on spectral data (1D and 2D (1)H-, (13)C-NMR, ESI- and CI-MS) the structures were established as cucurbitacin B ( 1), cucurbitacin D ( 2), 23,24-dihydrocucurbitacin D ( 3), 23,24-dihydrocucurbitacin F ( 4), 2- O-beta-glucopyranosyl-cucurbitacin B ( 5), and 2- O-beta-glucopyranosyl-cucurbitacin D ( 6). Four of them ( 3- 6) were so far not reported as constituents of Begonia spp. Varyingly strong antiproliferative activity towards tumor and immune cells was observed for three compounds ( 1 - 3), due to different structural features.

Two quinoline alkaloids from the Caribbean cyanobacterium Lyngbya majuscula.

Fractionation of the lipid extract of the marine cyanobacterium Lyngbya majuscula collected from Curaçao afforded two quinoline alkaloids in low yield. Their structures were determined as 4,8-dimethyl-6-O-(2'-4'-di-O-methyl-beta-D-xylopyranosyl)-hydroxyquinoli ne and 4,8-dimethyl-6-hydroxyquinoline on the basis of spectroscopic analysis, mainly 2D NMR spectroscopy.

Barbamide, a chlorinated metabolite with molluscicidal activity from the Caribbean cyanobacterium Lyngbya majuscula.

The lipid extract from a Curaçao collection of the marine cyanobacterium Lyngbya majuscula was toxic to the mollusc Biomphalaria glabrata. Subsequent bioassay-guided fractionation of this extract yielded a novel lipopeptide, barbamide, as the active compound (LC100 = 10 micrograms/mL). The structure of barbamide was determined by spectroscopic methods and was found to contain several unique structural features, including a trichloromethyl group and the methyl enol ether of a beta-keto amide.

Malyngamide H, an ichthyotoxic amide possessing a new carbon skeleton from the Caribbean cyanobacterium Lyngbya majuscula.

Guided by ichthyotoxic activity against goldfish, a new lipopeptide, malyngamide H [1], and its corresponding free acid, 7-methoxytetradec-4(E)-enoic acid [2], have been isolated from the tropical marine cyanobacterium Lyngbya majuscula. The structure of the new carbon skeleton borne by malyngamide H was elucidated on the basis of spectroscopic analysis, mainly 2D nmr. The absolute stereochemistry of the cyclohexenone moiety of malyngamide H [1] was deduced by a combination of 2D NOESY and exciton chirality circular dichroism spectroscopy.

Cytotoxic and antibacterial dihydrochalcones from Piper aduncum.

Bioactivity-guided fractionation of a CH2Cl2 extract from the leaves of Piper aduncum afforded three new dihydrochalcones, piperaduncins A [3], B [4], and C [5], as well as two known dihydrochalcones, 2',6'-dihydroxy-4'-methoxydihydrochalcone [1] and 2',6',4-trihydroxy-4'-methoxydihydrochalcone [2] (asebogenin), together with sakuranetin, anodendroic acid methyl ester, and the carotenoid lutein. The structures of the isolates were elucidated by spectroscopic methods, mainly 1D- and 2D nmr spectroscopy. The proposed stereochemistry for compound 4 was deduced by NOESY spectroscopy and the corresponding energy minimum was established by molecular modelling calculations and translated into a 3D structure.

Five new prenylated p-hydroxybenzoic acid derivatives with antimicrobial and molluscicidal activity from Piper aduncum leaves.

Five new prenylated benzoic acid derivatives, methyl 3-(3,7-dimethyl-2,6-octadienyl)-4-methoxybenzoate (1), 1-(1-methylethyl)-4-methyl-3-cyclohexenyl 3,5-bis(3-methyl-2-butenyl)-4-hydroxybenzoate (2), 1-(1-methylethyl)-4-methyl-3-cyclohexenyl 3,5-bis(3-methyl-2-butenyl)-4-methoxybenzoate (3), methyl 3,5-bis(3-methyl-2-butenyl)-4-methoxybenzoate (4), and 4-hydroxy-3-(3-methyl-2-butenyl)-5-(3-methyl-2-butenyl)-benzoic acid (5) were isolated from the dried leaves of Piper aduncum L. (Piperaceae). Together with the new metabolites, four known prenylated benzoic acid derivatives, 3,5-bis(3-methyl-2-butenyl)-4-methoxybenzoic acid (6), 4-hydroxy-3,5-bis(3-methyl-2-butenyl)-benzoic acid (nervogenic acid, 7), methyl 4-hydroxy-3,5-bis(3-methyl-2-butenyl)-benzoate (8), and methyl 4-hydroxy-3-(3-methyl-2-butenyl)-benzoate (9) as well as, dillapiol (10), myristicin, and the three sesquiterpenes humulene, caryophyllene epoxide, and humulene epoxide were isolated. Compounds 7, 8, and 9 are reported as natural products for the first time. The structures of the isolates were elucidated by spectroscopic methods, mainly 1D-and 2D-NMR spectroscopy. Isolates 4-7, 9, and 10 were molluscicidal while 2, 5-7, and 9 displayed significant antibacterial activities.

New indole alkaloid glycosides from Nauclea orientalis.

Two new indole alkaloid glycosides, 10-hydroxystrictosamide and 6'-O-acetylstrictosamide, as well as the known alkaloids strictosamide and vincosamide were isolated from the leaves of Nauclea orientalis L. The structures of the isolated compounds were determined using spectroscopic methods, mainly 1D- and 2D-NMR spectroscopy.