Chemical screening of the ethyl acetate extract from the marine-derived Streptomyces sp. isolate Mei37 resulted in five isoquinolinequinones, four new derivatives, mansouramycin A-D (1, 3-5), and the known 3-methyl-7-(methylamino)-5,8-isoquinolinedione (2). Their structures were elucidated by NMR and MS techniques and by comparison with related compounds. Cytotoxicity profiling of the mansouramycins in a panel of up to 36 tumor cell lines indicated significant cytotoxicity of several derivatives, with pronounced selectivity for non-small cell lung cancer, breast cancer, melanoma, and prostate cancer cells.
Chemical examination of two marine Streptomycetes has resulted in the isolation of four new butenolides, namely 4,10-dihydroxy-10-methyl-dodec-2-en-1,4-olide (1), two diastereomeric 4,11-dihydroxy-10-methyldodec-2-en-1,4-olides (2/3), and 4-hydroxy-10-methyl-11-oxo-dodec-2-en-1,4-olide (4). The structures were identified by interpretation of the 2D NMR and mass spectral data.Butenolides, a family of R, -unsaturated lactones, are often encountered among fungi, 2 bacteria, 3 and gorgonians, 4 to name a few. Their saturated analogues act as signaling substances in bacteria 5 and enhance spore formation of Streptomycetes or induce metabolite production. 6 In a continuing search for bioactive constituents from marine microorganisms, we found that extracts from the Streptomycete strains B 5632 and B 3497 from marine sediments formed several new butenolides.The isolate B 5632 was fermented in a 20-L scale on YMG medium with artificial seawater for 3 days. The fermentation broth was filtered over Celite and exhaustively extracted with ethyl acetate. This extract was partitioned between methanol and cyclohexane for defatting, and the methanol layer, after concentration, was chromatographed on a flash column. Bioassay-guided fractionation led to the localization of the activity from which four known antimycins and three new butenolides (1-3) were obtained. In a similar way, strain B 3497 delivered a new keto butenolide (4) in addition to antimycin A. The antimycins were responsible for the strong antifungal activity of the extracts against Mucor miehei (Tü 284).Analytical HPLC indicated that the butenolide fraction (localized by a strong blue-violet color on spraying with anisaldehyde) contained two related compounds. Compound 1 was obtained as an oil by preparative HPLC. Under EIMS conditions, no molecular ion was visible; however, its molecular mass was fixed as 226 Da by pseudomolecular ions at m/z 244 [M + + NH 4 ] and 226 [M + + NH 4 -H 2 O] on CIMS. An APT spectrum showed that the compound contained two methyl, six methylene, three methine, and two quaternary carbons, according to a formula C 13 H 22 O 3 , in agreement with chemical shifts. The proton signals at δ 7.44 and 6.11 and a carbon signal at δ 173.2 indicated that the compound had an R, -unsaturated lactone, ester, or acid moiety. The molecular formula demands three double-bond equivalents. As two are accounted for by an ester or lactone carbonyl and a double bond, the molecule must be monocyclic. The H-H COSY spectrum showed couplings between the two olefinic protons and a multiplet at δ 5.01, indicating an oxygenated carbon next to the double bond. This methine showed further coupling to two methylene protons, which, in turn, were coupled to another methylene group. An HMQC spectrum correlated the proton signal at δ 5.01 to a methine signal at δ 83.4. This sequence resulted in fragment a.Additionally, the 1 H NMR spectrum showed a clear quartet and a triplet, indicating the presence of an isolated ethyl group in the molecule. A signal for an isolated me...
The marine strain Pseudoalteromonas maricaloris KMM 636 T was found to produce an inseparable mixture of two brominated yellow main pigments, bromoalterochromide A and AЈ, in a ratio of 3 : 1. Both pigments are Thr-Val-Asn-Asn-X pentapeptide lactones, where the amino group of Thr is acylated with 9-(3-bromo-4-hydroxyphenyl)-nona-2,4,6,8-tetraenoic acid, and X is aIle and Leu, respectively. They possess cytotoxic effects on developing eggs of the sea urchin Strongylocentrotus intermedius, but no antibiotic activity.
New anthracycline antibiotics 3'-O-demethyl mutactimycin (3) and 4-O, 3'-Odidemethyl mutactimycin (4) were isolated from two actinomycetes strains, Nocardia transvalensis and Streptomyces sp. GW 60/1571. The chemical structures were elucidated by mass spectrometry and NMR spectroscopy. Antibiotic 3 displayed moderate antimicrobial activity against Gram-positive bacteria and cytotoxicity against P388, L1210 Human nocardioses are caused by members of the Nocardia asteroides complex (N. asteroides sensu stricto, N. farcinica and N. nova), N. brasiliensis, N. otitidiscaof the productivity of pathogenic Nocardia strains suggested that bioactive metabolite formation is limited to N. brasiliensis. Recently we investigated a series of Nocardia strains belonging to species other than N. brasiliensis. One of these strains from the National Institute of Health, Nonthaburi (Thailand) identified as N. transvalensis3) was found to produce several antibacterial coloured
Aims: This study aims at evaluating the impact of the nutrient medium components on the in vitro production of the cytotoxic alterochromides. Methods and Results: The employment matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) facilitated the identification of a range of brominated cyclic depsipeptides with molecular masses of 843/845, 857/859 and 922/924/926 Da, and 936/938/940 Da produced by the marine bacterium Pseudoalteromonas maricaloris KMM 636T . The fractions of cytotoxic yellow pigments yielded after methanol extraction of P. maricaloris KMM 636T cells grown on five nutrient media were solely composed of brominated cyclic depsipeptides. Bromo-alterochromides A and B were obtained after cultivation on low nutrient media, while dibrominated derivatives were the principal components of the biosynthesis during cultivation on nutrient rich media. Conclusions: The quantity of bromo-alterochromides and their dibromo-derivates varied depending on the media composition. Significance and Impact of the Study: MALDI-TOF mass spectrometry enables to generate accurate mass analysis for the identification of peptide and its derivates which is important in controlling the production of biologically active compounds in vitro.
Cinmethylin is a well-known benzyl-ether derivative of the natural terpene 1,4-cineole that is used industrially as a pre-emergence herbicide in grass weed control for crop protection. Cinmethylin detoxification in plants has not been reported, but in animals, it prominently involves hydroxylation at the benzylic C15 methyl group. Here, we show enzymatic β-glycosylation of synthetic 15-hydroxy-cinmethylin to prepare a putative phase II detoxification metabolite of the cinmethylin in plants. We examined eight Leloir glycosyltransferases for reactivity with 15-hydroxy cinmethylin and revealed the selective formation of 15-hydroxy cinmethylin β- d -glucoside from uridine 5′-diphosphate (UDP)-glucose by the UGT71E5 from safflower ( Carthamus tinctorius ). The UGT71E5 showed a specific activity of 431 mU/mg, about 300-fold higher than that of apple ( Malus domestica ) UGT71A15 that also performed the desired 15-hydroxy cinmethylin mono-glycosylation. Bacterial glycosyltransferases (OleD from Streptomyces antibioticus , 2.9 mU/mg; GT1 from Bacillus cereus , 60 mU/mg) produced mixtures of 15-hydroxy cinmethylin mono- and disaccharide glycosides. Using UDP-glucose recycling with sucrose synthase, 15-hydroxy cinmethylin conversion with UGT71E5 efficiently provided the β-mono-glucoside (≥95% yield; ∼9 mM) suitable for biological studies.
In the course of our chemical screening of actinomycetes and other bacteria from terrestrial and marine sources, several extracts showed colourless middle polar bands with strong UV absorption at 254 nm and brown to grey colouration with anisaldehyde/sulphuric acid. Working-up of such strains led to the isolation of a number of isoflavonoids. Daidzein (1a) and genistein (1b) are very wide-spread, however, compounds like kakkatin (2b, Streptomyces sp. GW39/1530) were known only from plant sources. Additionally, three new isoflavonoids were obtained, namely 4',7-bis-(β -cymaropyranosyl)-genistein (1e) and 4'-hydroxy-6,7-methoxyisoflavone (2c) from the actinomycete isolate HKI 129-L, and genistein-4'-(6"-methyl)-salicylate (1d) from Streptomyces sp. isolate GW27/2506. 1d is the first natural 4'-ester of an isoflavonoid and an aromatic acid. For the first time, also two flavonoids were isolated from bacteria, apigenin (5a) and luteolin-3'-methyl ether (5b).
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