Browsing by Author "Camas, M."
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Item Butrepyrazinone, a New Pyrazinone with an Unusual Methylation Pattern from a Ghanaian Verrucosispora sp. K51G(Mar. Drugs 12, 5197-5208, 2014) Kyerematen, K.; Acquah, K.S.; Camas, M.; Tabudravu, J.; Houssen, W.; Deng, H.; Jaspars, M.We report the structural characterization of a new pyrazinone analogue; butrepyrazinone, which was isolated from a new actinomycete strain Verrucosispora sp. K51G recovered from Ghanaian mangrove river sediment. Spectroscopy-guided fractionation led to the isolation of a compound from the fermentation culture and a combination of NMR spectroscopy, high-resolution mass spectrometry and computer-aided calculations revealed that butrepyrazinone (10) possesses an unusual methylation pattern on the pyrazinone ring. Butrepyrazinone (10), however, displayed no antibacterial activity against Gram-positive S. aureus ATCC 25923, the Gram-negative E. coli ATCC 25922 and a panel of clinical isolates of methicillin-resistant S. aureus (MRSA) strains, suggesting that 10 may act as a signal molecule for this strain. Although the same molecule has been synthesized previously, this is the first report to disclose the discovery of butrepyrazinone (10) from nature.Item Extracellular Synthesis and Characterization of Gold Nanoparticles Using Mycobacterium sp. BRS2A-AR2 Isolated from the Aerial Roots of the Ghanaian Mangrove Plant, Rhizophora racemosa(Springer India, 2018-06) Camas, M.; Sazak Camas, A.; Kyeremeh, K.Through the use of genomes that have undergone millions of years of evolution, marine Actinobacteria are known to have adapted to rapidly changing environmental pressures. The result is a huge chemical and biological diversity among marine Actinobacteria. It is gradually becoming a known fact that, marine Actinobacteria have the capability to produce nanoparticles which have reasonable sizes and structures with possible applications in biotechnology and pharmacology. Mycobacterium sp. BRS2A-AR2 was isolated from the aerial roots of the mangrove plant Rhizophora racemosa. The Mycobacterium was demonstrated for the first time ever to produce AuNPs with sizes that range between 5 and 55 nm. The highest level absorbance of the biosynthesized AuNPs was typical for actinobacterial strains (2.881 at 545 nm). The polydispersity index was measured as 0.207 in DLS and the zeta potential was negatively charged (− 28.3 mV). Significant vibration stretches were seen at 3314, 2358, 1635 and 667 cm−1 in FT-IR spectra. This demonstrated the possible use of small aliphatic compounds containing –COOH, –OH, –Cl and –NH2 functional groups in the stabilization of the AuNPs. The effect of the biosynthesized AuNPs on HUVEC and HeLA cell lines was measured at 48 h. IC50 values were determined at 3500 µg/ml concentration for HUVEC and HeLA cell lines at 45.25 and 53.41% respectively. © 2018, Association of Microbiologists of India.Item Microbial Sorption of Uranium Using Amycolatopsis sp. K47 Isolated from Uranium Deposits(Water, Air, and Soil Pollution, 2018-04) Celik, F.; Camas, M.; Kyeremeh, K.; Sazak Camas, A.The increasing contamination of soils, sediments, and water with heavy metals through natural and industrial processes is a worldwide problem. Mining processes produce tons of material contaminated with radionuclides such as U and different heavy metals such as Cd, Ni, and Pb. U(VI) adsorbs strongly on bacteria, exhibiting pH-dependent adsorption behavior that is caused by a range of uranyl surface complexes on bacteria cell walls. The Amycolatopsis sp. K47 was isolated from Manisa Koprubasi Kasar open-cast uranium mine and identified for the first time. Using the batch adsorption method, the biosorption potential of this microbe was investigated by studying the effects of changes in pH (1–10), biomass dose (0.1–5 g/l), initial uranium metal concentration (5–200 mg/l), contact time (5–180 min), and temperature (20–60 °C). Interpretation of FTIR data obtained for both the uranium loaded and unloaded Amycolatopsis sp. K47 biomass showed the presence of carboxylic acid, hydroxyl, and amide functional groups that could interact with uranium ions. Scanning electron microscopy images demonstrated that uranium was intensely adsorbed on the microbial biomass surface. The sorption isotherms were investigated by analysis of the Langmuir, Freundlich, and Dubinin–Radushkevich (D–R) models. The Langmuir isotherm model was found to show the best fit for the experimental data obtained. Furthermore, thermodynamic parameters, such as ΔH°, ΔS°, and ΔG°, were calculated using adsorption equilibrium constant obtained from the Langmuir isotherm. The optimal experimental conditions were determined to be pH = 4, C0 = 40 ppm, t = 150 min, temp. = 40 °C, and abs. dose = 1 g/l, and the corresponding U(VI) removal efficiency was about 97 ± 2%.Item Paenidigyamycin A, Potent Antiparasitic Imidazole Alkaloid from the Ghanaian Paenibacillus sp. DE2SH(Marine Drugs, 2018-12) Osei, E.; Kwain, S.; Mawuli, G.T.; Anang, A.K.; Owusu, K.B.A.; Camas, M.; Camas, A.S.; Ohashi, M.; Alexandru-Crivac, C.N.; Deng, H.; Jaspars, M.; Kyeremeh, K.A new alkaloid paenidigyamycin A (1) was obtained from the novel Ghanaian Paenibacillus sp. isolated from the mangrove rhizosphere soils of the Pterocarpus santalinoides tree growing in the wetlands of the Digya National Park, Ghana. Compound 1 was isolated on HPLC at tR = 37.0 min and its structure determined by MS, 1D, and 2D-NMR data. When tested against L. major, 1 (IC50 0.75 µM) was just as effective as amphotericin B (IC50 0.31 µM). Against L. donovani, 1 (IC50 7.02 µM) was twenty-two times less active than amphotericin B (IC50 0.32 µM), reinforcing the unique effectiveness of 1 against L. major. For T. brucei brucei, 1 (IC50 0.78 µM) was ten times more active than the laboratory standard Coptis japonica (IC50 8.20 µM). The IC50 of 9.08 µM for 1 against P. falciparum 3d7 compared to artesunate (IC50 36 nM) was not strong, but this result suggests the possibility of using the paenidigyamycin scaffold for the development of potent antimalarial drugs. Against cercariae, 1 showed high anticercaricidal activity compared to artesunate. The minimal lethal concentration (MLC) and minimal effective concentration (MEC) of the compound were 25 and 6.25 µM, respectively, while artesunate was needed in higher quantities to produce such results. However, 1 (IC50 > 100 µM) was not active against T. mobilensis.Item Paenidigyamycin G: 1-Acetyl-2,4-dimethyl-3-phenethyl-1H-imidazol-3-ium(molbank, 2019-11-21) Tetevi, G.M.; Kwain, S.; Mensah, T.; Camas, A.S.; Camas, M.; Dofuor, A.K.; Azerigyik, F.A.; Oluwabusola, E.; Deng, H.; Jaspars, M.; Kyeremeh, K.The Ghanaian Paenibacillus sp. DE2SH (GenBank Accession Number: MH091697) is a prolific producer of potent antiparasitic alkaloids. Further detailed study of the culture broth of this strain produced the compound Paenidigyamycin G (1), which is a derivative of the known antiparasitic compound PaenidigyamycinA(2). Compound (1) was isolated on HPLC at tR 37.5 min and its structure determined by IR, UV, MS, 1D, and 2D-NMR data. Compound 1 produced weak to moderate antileishmanial and antitrypanosomal activity when tested against Leishmania donovani (Laveran and Mesnil) Ross (D10) and Trypanosoma brucei subsp. brucei strain GUTat 3.1 with IC50 = 115.41 and 28.75 M, respectively. This result is interesting since the parent compound 2 is known to possess consistent and potent antiparasitic activity. However, 1 displayed a promising selectivity profile towards T. brucei subsp. brucei due to its relatively low toxicity against normal mouse macrophages RAW 264.7 cells (SI = 8.70). Given that compound 1 is also the main metabolite found in the hexane fraction of all extracts produced by Paenibacillus sp. DE2SH when it is co-cultured with other bacteria strains, it must possess some unique biological functions which should make it an excellent candidate for further biological activity screening in other bioassays.Item α-d-Glucopyranosyl-(1→2)-[6-O-(l-tryptophanyl)-β-d-fructofuranoside](Molbank, 2019-06-14) Kyeremeh, K.; Kwain, S.; Tetevi, G.M.; Camas, A.S.; Camas, M.; Dofuor, A.K.; Deng, H.; Jaspars, M.The Mycobacterium sp. BRS2A-AR2 is an endophyte of the mangrove plant Rhizophora racemosa G. Mey., which grows along the banks of the River Butre, in the Western Region of Ghana. Chemical profiling using 1H-NMR and HRESI-LC-MS of fermentation extracts produced by the strain led to the isolation of the new compound, α-d-Glucopyranosyl-(1→2)-[6-O-(l-tryptophanyl)-β-d–fructofuranoside] or simply tortomycoglycoside (1). Compound 1 is an aminoglycoside consisting of a tryptophan moiety esterified to a disaccharide made up of β-d-fructofuranose and α-d-glucopyranose sugars. The full structure of 1 was determined using UV, IR, 1D, 2D-NMR and HRESI-LC-MS data. When tested against Trypanosoma brucei subsp. brucei, the parasite responsible for Human African Trypanosomiasis in sub-Saharan Africa, 1 (IC50 11.25 µM) was just as effective as Coptis japonica (Thunb.) Makino. (IC50 8.20 µM). The extract of Coptis japonica (Thunb.) Makino. is routinely used as laboratory standard due to its powerful antitrypanosomal activity. It is possible that, compound 1 interferes with the normal uptake and metabolism of tryptophan in the T. brucei subsp. brucei parasite.