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1.
J Tradit Complement Med ; 12(3): 260-268, 2022 May.
Artigo em Inglês | MEDLINE | ID: mdl-35493314

RESUMO

Background and aim: African trypanosomiasis poses serious health and economic concerns to humans and livestock in several sub-Saharan African countries. The aim of the present study was to identify the antitrypanosomal compounds from B. pilosa (whole plant) through a bioactivity-guided isolation and investigate the in vitro effects and mechanisms of action against Trypanosoma brucei (T. brucei). Experimental procedure: Crude extracts and fractions were prepared from air-dried pulverized plant material of B. pilosa using the modified Kupchan method of solvent partitioning. The antitrypanosomal activities of the fractions were determined through cell viability analysis. Effects of fractions on cell death and cell cycle of T. brucei were determined using flow cytometry, while fluorescence microscopy was used to investigate alterations in cell morphology and distribution. Results and conclusion: The solvent partitioning dichloromethane (BPFD) and methanol (BPFM) fractions of B. pilosa exhibited significant activities against T. brucei with respective half-maximal inhibitory concentrations (IC50s) of 3.29 µg/ml and 5.86 µg/ml and resulted in the formation of clumpy subpopulation of T. brucei cells. Butyl (compound 1) and propyl (compound 2) esters of tryptophan were identified as the major antitrypanosomal compounds of B. pilosa. Compounds 1 and 2 exhibited significant antitrypanosomal effects with respective IC50 values of 0.66 and 1.46 µg/ml. At the IC50 values, both compounds significantly inhibited the cell cycle of T. brucei at the G0-G1 phase while causing an increase in G2-M phase. The results suggest that tryptophan esters may possess useful chemotherapeutic properties for the control of African trypanosomiasis.

2.
Int J Biomater ; 2022: 4106558, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35154327

RESUMO

Silver nanoparticles (AgNPs) have been synthesized from the more chemically rich and diverse cocoa pod; the synthesis of silver nanoparticles from cocoa leaves, which are less rich and have low diversity in bioactive molecules, is yet to be achieved. In this work, AgNPs produced using the extracts of the cocoa leaf (CL) and cocoa pods (CP) have been investigated and their antimicrobial activity against E. coli was evaluated. UV-visible absorption spectroscopy was used to examine the reduction of silver ions in solution and the surface plasmon resonance of AgNPs. Scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), dynamic light scattering (DLS), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR) were used to further characterize the nanoparticles. The crystalline nature of AgNPs was confirmed by XRD, and the purity and presence of elemental silver were determined by EDX. CL-AgNPs were observed to have a surface plasmon resonance of 425 nm, while CP-AgNPs had a surface plasmon resonance of 440 nm. CL-AgNPs had a significantly higher purity than CP-AgNPs. With a shorter nucleation time, the intensity of the UV-Vis spectrum was always higher in the case of CL-AgNPs, indicating a larger population of bioactive molecules available for CL-AgNPs synthesis. FTIR confirmed the presence of phenolic compounds in the leaf and pod extract, implying that water-soluble polyphenolic and flavonoid chemicals are responsible for nanoparticle reduction, capping, and stability. AgNPs generated from CL and CP extracts are polydispersed, with particle sizes of 10-110 nm and 20-680 nm, respectively, according to DLS. The corresponding zeta potentials measured are -2.7 mV for CL-AgNPs and -0.93 mV for CP-AgNPs. The zeta potential values suggest that the particles have long-term stability. Furthermore, CL-AgNPs outperformed CP-AgNPs in terms of antibacterial activity against Escherichia coli. CL-AgNPs were found to have a maximal inhibitory zone of 21 mm.

3.
Nat Commun ; 13(1): 62, 2022 01 10.
Artigo em Inglês | MEDLINE | ID: mdl-35013184

RESUMO

Non-Ribosomal Peptide Synthetases (NRPSs) assemble a diverse range of natural products with important applications in both medicine and agriculture. They consist of several multienzyme subunits that must interact with each other in a highly controlled manner to facilitate efficient chain transfer, thus ensuring biosynthetic fidelity. Several mechanisms for chain transfer are known for NRPSs, promoting structural diversity. Herein, we report the first biochemically characterized example of a type II thioesterase (TEII) domain capable of catalysing aminoacyl chain transfer between thiolation (T) domains on two separate NRPS subunits responsible for installation of a dehydrobutyrine moiety. Biochemical dissection of this process reveals the central role of the TEII-catalysed chain translocation event and expands the enzymatic scope of TEII domains beyond canonical (amino)acyl chain hydrolysis. The apparent co-evolution of the TEII domain with the NRPS subunits highlights a unique feature of this enzymatic cassette, which will undoubtedly find utility in biosynthetic engineering efforts.


Assuntos
Ácido Graxo Sintases/química , Ácido Graxo Sintases/metabolismo , Peptídeo Sintases/metabolismo , Tioléster Hidrolases/química , Tioléster Hidrolases/metabolismo , Catálise , Escherichia coli/genética , Ácido Graxo Sintases/genética , Engenharia Metabólica , Domínios Proteicos , Tioléster Hidrolases/genética
4.
Molecules ; 26(15)2021 Jul 25.
Artigo em Inglês | MEDLINE | ID: mdl-34361641

RESUMO

The search for novel antitrypanosomals and the investigation into their mode of action remain crucial due to the toxicity and resistance of commercially available antitrypanosomal drugs. In this study, two novel antitrypanosomals, tortodofuordioxamide (compound 2) and tortodofuorpyramide (compound 3), were chemically derived from the natural N-alkylamide tortozanthoxylamide (compound 1) through structural modification. The chemical structures of these compounds were confirmed through spectrometric and spectroscopic analysis, and their in vitro efficacy and possible mechanisms of action were, subsequently, investigated in Trypanosoma brucei (T. brucei), one of the causative species of African trypanosomiasis (AT). The novel compounds 2 and 3 displayed significant antitrypanosomal potencies in terms of half-maximal effective concentrations (EC50) and selectivity indices (SI) (compound 1, EC50 = 7.3 µM, SI = 29.5; compound 2, EC50 = 3.2 µM, SI = 91.3; compound 3, EC50 = 4.5 µM, SI = 69.9). Microscopic analysis indicated that at the EC50 values, the compounds resulted in the coiling and clumping of parasite subpopulations without significantly affecting the normal ratio of nuclei to kinetoplasts. In contrast to the animal antitrypanosomal drug diminazene, compounds 1, 2 and 3 exhibited antioxidant absorbance properties comparable to the standard antioxidant Trolox (Trolox, 0.11 A; diminazene, 0.50 A; compound 1, 0.10 A; compound 2, 0.09 A; compound 3, 0.11 A). The analysis of growth kinetics suggested that the compounds exhibited a relatively gradual but consistent growth inhibition of T. brucei at different concentrations. The results suggest that further pharmacological optimization of compounds 2 and 3 may facilitate their development into novel AT chemotherapy.


Assuntos
Tripanossomicidas , Trypanosoma brucei brucei/crescimento & desenvolvimento , Tripanossomíase Africana/tratamento farmacológico , Animais , Camundongos , Células RAW 264.7 , Tripanossomicidas/síntese química , Tripanossomicidas/química , Tripanossomicidas/farmacologia , Tripanossomíase Africana/metabolismo
5.
Mar Drugs ; 19(6)2021 Jun 03.
Artigo em Inglês | MEDLINE | ID: mdl-34205180

RESUMO

Three dermacozines, dermacozines N-P (1-3), were isolated from the piezotolerant Actinomycete strain Dermacoccus abyssi MT 1.1T, which was isolated from a Mariana Trench sediment in 2006. Herein, we report the elucidation of their structures using a combination of 1D/2D NMR, LC-HRESI-MSn, UV-Visible, and IR spectroscopy. Further confirmation of the structures was achieved through the analysis of data from density functional theory (DFT)-UV-Visible spectral calculations and statistical analysis such as two tailed t-test, linear regression-, and multiple linear regression analysis applied to either solely experimental or to experimental and calculated 13C-NMR chemical shift data. Dermacozine N (1) bears a novel linear pentacyclic phenoxazine framework that has never been reported as a natural product. Dermacozine O (2) is a constitutional isomer of the known dermacozine F while dermacozine P (3) is 8-benzoyl-6-carbamoylphenazine-1-carboxylic acid. Dermacozine N (1) is unique among phenoxazines due to its near infrared (NIR) absorption maxima, which would make this compound an excellent candidate for research in biosensing chemistry, photodynamic therapy (PDT), opto-electronic applications, and metabolic mapping at the cellular level. Furthermore, dermacozine N (1) possesses weak cytotoxic activity against melanoma (A2058) and hepatocellular carcinoma cells (HepG2) with IC50 values of 51 and 38 µM, respectively.


Assuntos
Actinobacteria/química , Sedimentos Geológicos/microbiologia , Fenazinas/química , Fenazinas/isolamento & purificação , Processos Fotoquímicos , Luz , Espectroscopia de Ressonância Magnética , Análise de Regressão , Espectrofotometria/métodos
6.
Synth Syst Biotechnol ; 6(1): 12-19, 2021 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-33553705

RESUMO

Non-ribosomal peptides are a group of structurally diverse natural products with various important therapeutic and agrochemical applications. Bacterial pyrrolizidine alkaloids (PAs), containing a scaffold of two fused five-membered ring system with a nitrogen atom at the bridgehead, have been found to originate from a multidomain non-ribosomal peptide synthetase to generate indolizidine intermediates, followed by multistep oxidation, catalysed by single Bayer-Villiger (BV) enzymes, to yield PA scaffolds. Although bacterial PAs are rare in natural product inventory, bioinformatics analysis suggested that the biosynthetic gene clusters (BGCs) that are likely to be responsible for the production of PA-like metabolites are widely distributed in bacterial genomes. However, most of the strains containing PA-like BGCs are not deposited in the public domain, therefore preventing further assessment of the chemical spaces of this group of bioactive metabolites. Here, we report a genomic scanning strategy to assess the potential of PA metabolites production in our culture collection without prior knowledge of genome information. Among the strains tested, we found fifteen contain the key BV enzymes that are likely to be involved in the last step of PA ring formation. Subsequently one-strain-many-compound (OSMAC) method, supported by a combination of HR-MS, NMR, SMART 2.0 technology, and GNPS analysis, allowed identification and characterization of a new [5 + 7] heterobicyclic carbamate, legoncarbamate, together with five known PAs, bohemamine derivatives, from Streptomyces sp. CT37, a Ghanaian soil isolate. The absolute stereochemistry of legoncarbamate was determined by comparison of measured and calculated ECD spectra. Legoncarbamate displays antibacterial activity against E. coli ATCC 25922 with an MIC value of 3.1 µg/mL. Finally, a biosynthetic model of legoncarbamate and other bohemamines was proposed based on the knowledge we have gained so far.

7.
PLoS Negl Trop Dis ; 14(12): e0008919, 2020 12.
Artigo em Inglês | MEDLINE | ID: mdl-33382717

RESUMO

BACKGROUND: Ghana is endemic for some neglected tropical diseases (NTDs) including schistosomiasis, onchocerciasis and lymphatic filariasis. The major intervention for these diseases is mass drug administration of a few repeatedly recycled drugs which is a cause for major concern due to reduced efficacy of the drugs and the emergence of drug resistance. Evidently, new treatments are needed urgently. Medicinal plants, on the other hand, have a reputable history as important sources of potent therapeutic agents in the treatment of various diseases among African populations, Ghana inclusively, and provide very useful starting points for the discovery of much-needed new or alternative drugs. METHODOLOGY/PRINCIPAL FINDINGS: In this study, extracts of fifteen traditional medicines used for treating various NTDs in local communities were screened in vitro for efficacy against schistosomiasis, onchocerciasis and African trypanosomiasis. Two extracts, NTD-B4-DCM and NTD-B7-DCM, prepared from traditional medicines used to treat schistosomiasis, displayed the highest activity (IC50 = 30.5 µg/mL and 30.8 µg/mL, respectively) against Schistosoma mansoni adult worms. NTD-B2-DCM, also obtained from an antischistosomal remedy, was the most active against female and male adult Onchocera ochengi worms (IC50 = 76.2 µg/mL and 76.7 µg/mL, respectively). Antitrypanosomal assay of the extracts against Trypanosoma brucei brucei gave the most promising results (IC50 = 5.63 µg/mL to 18.71 µg/mL). Incidentally, NTD-B4-DCM and NTD-B2-DCM, also exhibited the greatest antitrypanosomal activities (IC50 = 5.63 µg/mL and 7.12 µg/mL, respectively). Following the favourable outcome of the antitrypanosomal screening, this assay was selected for bioactivity-guided fractionation. NTD-B4-DCM, the most active extract, was fractionated and subsequent isolation of bioactive constituents led to an eupatoriochromene-rich oil (42.6%) which was 1.3-fold (IC50 <0.0977 µg/mL) more active than the standard antitrypanosomal drug, diminazene aceturate (IC50 = 0.13 µg/mL). CONCLUSION/SIGNIFICANCE: These findings justify the use of traditional medicines and demonstrate their prospects towards NTDs drug discovery.


Assuntos
Filaricidas/farmacologia , Onchocerca/efeitos dos fármacos , Schistosoma mansoni/efeitos dos fármacos , Esquistossomicidas/farmacologia , Tripanossomicidas/farmacologia , Trypanosoma brucei brucei/efeitos dos fármacos , Animais , Gana , Medicina Tradicional Africana , Doenças Negligenciadas/tratamento farmacológico , Doenças Negligenciadas/parasitologia , Extratos Vegetais/química , Extratos Vegetais/farmacologia , Plantas Medicinais/química
8.
Biomolecules ; 10(12)2020 12 13.
Artigo em Inglês | MEDLINE | ID: mdl-33322191

RESUMO

In the absence of vaccines, there is a need for alternative sources of effective chemotherapy for African trypanosomiasis (AT). The increasing rate of resistance and toxicity of commercially available antitrypanosomal drugs also necessitates an investigation into the mode of action of new antitrypanosomals for AT. In this study, furoquinoline 4, 7, 8-trimethoxyfuro (2, 3-b) quinoline (compound 1) and oxylipin 9-oxo-10, 12-octadecadienoic acid (compound 2) were isolated from the plant species Zanthoxylum zanthoxyloides (Lam) Zepern and Timler (root), and their in vitro efficacy and mechanisms of action investigated in Trypanosoma brucei (T. brucei), the species responsible for AT. Both compounds resulted in a selectively significant growth inhibition of T. brucei (compound 1, half-maximal effective concentration EC50 = 1.7 µM, selectivity indices SI = 74.9; compound 2, EC50 = 1.2 µM, SI = 107.3). With regards to effect on the cell cycle phases of T. brucei, only compound 1 significantly arrested the second growth-mitotic (G2-M) phase progression even though G2-M and DNA replication (S) phase arrest resulted in the overall reduction of T. brucei cells in G0-G1 for both compounds. Moreover, both compounds resulted in the aggregation and distortion of the elongated slender morphology of T. brucei. Analysis of antioxidant potential revealed that at their minimum and maximum concentrations, the compounds exhibited significant oxidative activities in T. brucei (compound 1, 22.7 µM Trolox equivalent (TE), 221.2 µM TE; compound 2, 15.0 µM TE, 297.7 µM TE). Analysis of growth kinetics also showed that compound 1 exhibited a relatively consistent growth inhibition of T. brucei at different concentrations as compared to compound 2. The results suggest that compounds 1 and 2 are promising antitrypanosomals with the potential for further development into novel AT chemotherapy.


Assuntos
Antiprotozoários/farmacologia , Oxilipinas/isolamento & purificação , Oxilipinas/farmacologia , Quinolinas/isolamento & purificação , Quinolinas/farmacologia , Trypanosoma brucei brucei/efeitos dos fármacos , Zanthoxylum/química , Pontos de Checagem do Ciclo Celular/efeitos dos fármacos , Cromatografia Gasosa-Espectrometria de Massas , Cinética , Oxidantes/toxicidade , Trypanosoma brucei brucei/citologia , Trypanosoma brucei brucei/crescimento & desenvolvimento
9.
Biomolecules ; 10(10)2020 10 20.
Artigo em Inglês | MEDLINE | ID: mdl-33092156

RESUMO

Continued mining of natural products from the strain Streptomyces sp. MA37 in our laboratory led to the discovery of a minor specialized metabolite (SM) called accramycin A. Owing to its low yield (0.2 mg/L) in the wild type strain, we investigated the roles of regulatory genes in the corresponding biosynthetic gene cluster (acc BGC) through gene inactivation with the aim of improving the titer of this compound. One of the resulting mutants (∆accJ) dramatically upregulated the production of accramycin A 1 by 330-fold (66 mg/L). Furthermore, ten new metabolites, accramycins B-K 2-11, were discovered, together with two known compounds, naphthacemycin B112 and fasamycin C 13 from the mutant extract. This suggested that accJ, annotated as multiple antibiotic resistance regulator (MarR), is a negative regulator gene in the accramycin biosynthesis. Compounds 1-13 inhibited the Gram-positive pathogens (Staphylococcus aureus, Enterococcus faecalis) and clinical isolates Enterococcus faecium (K59-68 and K60-39) and Staphylococcus haemolyticus with minimal inhibitory concentration (MIC) values in the range of 1.5-12.5 µg/mL. Remarkably, compounds 1-13 displayed superior activity against K60-39 (MIC = 3.1-6.3 µg/mL) compared to ampicillin (MIC = 25 µg/mL), and offered promising potential for the development of accramycin-based antibiotics that target multidrug-resistant Enterococcus clinical isolates. Our results highlight the importance of identifying the roles of regulatory genes in natural product discovery.


Assuntos
Antibacterianos/farmacologia , Produtos Biológicos/farmacologia , Microbiologia do Solo , Streptomyces/química , Antibacterianos/química , Antibacterianos/metabolismo , Produtos Biológicos/química , Produtos Biológicos/metabolismo , Enterococcus/efeitos dos fármacos , Enterococcus/patogenicidade , Enterococcus faecalis/efeitos dos fármacos , Enterococcus faecalis/patogenicidade , Humanos , Testes de Sensibilidade Microbiana , Staphylococcus aureus/efeitos dos fármacos , Staphylococcus aureus/patogenicidade
10.
Appl Microbiol Biotechnol ; 104(9): 3885-3896, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-32140842

RESUMO

ß-Hydroxy-α-amino acids (ßH-AAs) are key components of many bioactive molecules as well as exist as specialised metabolites. Among these ßH-AAs, 4-fluorothreonine (4-FT) is the only naturally occurring fluorinated AA discovered thus far. Here we report overexpression and biochemical characterisation of 4-fluorothreonine transaldolase from Streptomyces sp. MA37 (FTaseMA), a homologue of FTase previously identified in the biosynthesis of 4-FT in S. cattleya. FTaseMA displays considerable substrate plasticity to generate 4-FT as well as other ß-hydroxy-α-amino acids with various functionalities at C4 position, giving the prospect of new chemo-enzymatic applications. The enzyme has a hybrid of two catalytic domains, serine hydroxymethyltransferase (S) and aldolase (A). Site-directed mutagenesis allowed the identification of the key residues of FTases, suggesting that the active site of A domain has a historical reminiscent feature in metal-dependent aldolases. Elemental analysis demonstrated that FTaseMA is indeed a Zn2+-dependent enzyme, the first example of pyridoxal phosphate (PLP) enzyme family fused with a metal-binding domain carrying out a distinct catalytic role. Finally, FTaseMA showed divergent evolutionary origin with other PLP dependent enzymes.


Assuntos
Aminoácidos Aromáticos/metabolismo , Streptomyces/enzimologia , Streptomyces/genética , Treonina/análogos & derivados , Transaldolase/metabolismo , Zinco/metabolismo , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Catálise , Domínio Catalítico , Cristalografia por Raios X , Cinética , Mutagênese Sítio-Dirigida , Treonina/metabolismo , Transaldolase/genética
11.
Molecules ; 25(5)2020 Mar 02.
Artigo em Inglês | MEDLINE | ID: mdl-32131464

RESUMO

Four compounds (1-4) were isolated from the extracts of Streptomyces sp. CT37 using bioassay in conjunction with mass spectrometric molecular networking (MN) driven isolation. Their complete structures were established by high-resolution electrospray ionization mass spectrometry (HR-ESIMS), and 1D and 2D nuclear magnetic resonance (NMR) data. Legonimide 1 was identified as a new alkaloid containing a rare linear imide motif in its structure, while compounds 2-4 were already known and their structures were elucidated as 1H-indole-3-carbaldehyde, actinopolymorphol B, (2R,3R)-1-phenylbutane-2,3-diol, respectively. The biosynthetic pathways of 1-4 were proposed based on the reported biogenesis of indole alkaloids in literature. Bioactivity tests for 1 and 2 revealed moderate growth inhibition activity against Candida albicans ATCC 10231 with MIC95 values of 21.54 µg/mL and 11.47 µg/mL, respectively.


Assuntos
Antifúngicos , Candida albicans/crescimento & desenvolvimento , Alcaloides Indólicos , Streptomyces/química , Antifúngicos/química , Antifúngicos/isolamento & purificação , Antifúngicos/farmacologia , Alcaloides Indólicos/química , Alcaloides Indólicos/isolamento & purificação , Alcaloides Indólicos/farmacologia , Ressonância Magnética Nuclear Biomolecular , Espectrometria de Massas por Ionização por Electrospray
12.
Org Biomol Chem ; 18(12): 2219-2222, 2020 03 25.
Artigo em Inglês | MEDLINE | ID: mdl-32159577

RESUMO

More than 500 siderophores are known to date, but only three were identified to be aryl-containing hydroxamate siderophores, legonoxamines A and B from Streptomyces sp. MA37, and aryl ferrioxamine 2 from Micrococcus luteus KLE1011. Siderophores are produced by microorganisms to scavenge iron from the environment, thereby making this essential metal nutrient available to the microbe. We demonstrate here that LgoC from MA37 is responsible for the key aryl-hydroxamate forming step in legonoxamine biosynthesis. Biochemical characterization established that LgoC displays considerable promiscuity for the acylation between N-hydroxy-cadaverine and SNAC (N-acetylcysteamines) thioester derivatives.


Assuntos
Coenzima A-Transferases/metabolismo , Sideróforos/metabolismo , Acilação , Proteínas de Bactérias/metabolismo , Ácidos Hidroxâmicos/química , Ferro/metabolismo , Micrococcus luteus/química , Sideróforos/biossíntese , Sideróforos/isolamento & purificação , Streptomyces/química , Streptomyces/enzimologia
13.
Molecules ; 25(2)2020 Jan 08.
Artigo em Inglês | MEDLINE | ID: mdl-31936318

RESUMO

Whole-genome sequence data of the genus Streptomyces have shown a far greater chemical diversity of metabolites than what have been discovered under typical laboratory fermentation conditions. In our previous natural product discovery efforts on Streptomyces sp. MA37, a bacterium isolated from the rhizosphere soil sample in Legon, Ghana, we discovered a handful of specialised metabolites from this talented strain. However, analysis of the draft genome of MA37 suggested that most of the encoded biosynthetic gene clusters (BGCs) remained cryptic or silent, and only a small fraction of BGCs for the production of specialised metabolites were expressed when cultured in our laboratory conditions. In order to induce the expression of the seemingly silent BGCs, we have carried out a co-culture experiment by growing the MA37 strain with the Gram-negative bacterium Pseudomonas sp. in a co-culture chamber that allows co-fermentation of two microorganisms with no direct contact but allows exchange of nutrients, metabolites, and other chemical cues. This co-culture approach led to the upregulation of several metabolites that were not previously observed in the monocultures of each strain. Moreover, the co-culture induced the expression of the cryptic indole alkaloid BGC in MA37 and led to the characterization of the known indolocarbazole alkaloid, BE-13793C 1. Neither bacterium produced compound 1 when cultured alone. The structure of 1 was elucidated by Nuclear Magnetic Resonance (NMR), mass spectrometry analyses and comparison of experimental with literature data. A putative biosynthetic pathway of 1 was proposed. Furthermore, BE-13793C 1 showed strong anti-proliferative activity against HT-29 (ATCC HTB-38) cells but no toxic effect to normal lung (ATCC CCL-171) cells. To the best of our knowledge, this is the first report for the activity of 1 against HT-29. No significant antimicrobial and anti-trypanosomal activities for 1 were observed. This research provides a solid foundation for the fact that a co-culture approach paves the way for increasing the chemical diversity of strain MA37. Further characterization of other upregulated metabolites in this strain is currently ongoing in our laboratory.


Assuntos
Vias Biossintéticas , Técnicas de Cocultura/métodos , Alcaloides Indólicos/metabolismo , Metaboloma , Antibacterianos/farmacologia , Biofilmes/efeitos dos fármacos , Bioensaio , Vias Biossintéticas/efeitos dos fármacos , Vias Biossintéticas/genética , Morte Celular/efeitos dos fármacos , Proliferação de Células/efeitos dos fármacos , Cromatografia Líquida de Alta Pressão , Células HT29 , Humanos , Alcaloides Indólicos/farmacologia , Testes de Sensibilidade Microbiana , Família Multigênica , Espectroscopia de Prótons por Ressonância Magnética , Pseudomonas/efeitos dos fármacos , Pseudomonas/metabolismo , Trypanosoma/efeitos dos fármacos
14.
Molecules ; 25(3)2020 Jan 22.
Artigo em Inglês | MEDLINE | ID: mdl-31979050

RESUMO

Streptomyces remains one of the prolific sources of structural diversity, and a reservoir to mine for novel natural products. Continued screening for new Streptomyces strains in our laboratory led to the isolation of Streptomyces sp. RK44 from the underexplored areas of Kintampo waterfalls, Ghana, Africa. Preliminary screening of the metabolites from this strain resulted in the characterization of a new 2-alkyl-4-hydroxymethylfuran carboxamide (AHFA) 1 together with five known compounds, cyclo-(L-Pro-Gly) 2, cyclo-(L-Pro-L-Phe) 3, cyclo-(L-Pro-L-Val) 4, cyclo-(L-Leu-Hyp) 5, and deferoxamine E 6. AHFA 1, a methylenomycin (MMF) homolog, exhibited anti-proliferative activity (EC50 = 89.6 µM) against melanoma A2058 cell lines. This activity, albeit weak is the first report amongst MMFs. Furthermore, the putative biosynthetic gene cluster (ahfa) was identified for the biosynthesis of AHFA 1. DFO-E 6 displayed potent anti-plasmodial activity (IC50 = 1.08µM) against P. falciparum 3D7. High-resolution electrospray ionization mass spectrometry (HR ESIMS) and molecular network assisted the targeted-isolation process, and tentatively identified six AHFA analogues, 7-12 and six siderophores 13-18.


Assuntos
Streptomyces/metabolismo , Antimaláricos/efeitos adversos , Antineoplásicos/efeitos adversos , Linhagem Celular Tumoral , Humanos , Família Multigênica/genética , Peptídeos/efeitos adversos , Peptídeos/metabolismo , Transdução de Sinais/efeitos dos fármacos , Espectrometria de Massas por Ionização por Electrospray
15.
Biomolecules ; 10(7)2020 07 10.
Artigo em Inglês | MEDLINE | ID: mdl-32664266

RESUMO

A fluorometabolite, 5-fluoro-5-deoxy-D-ribulose (5-FDRul), from the culture broth of the soil bacterium Streptomyces sp. MA37, was identified through a combination of genetic manipulation, chemo-enzymatic synthesis and NMR comparison. Although 5-FDRul has been chemically synthesized before, it was not an intermediate or a shunt product in previous studies of fluorometalism in S. cattleya. Our study of MA37 demonstrates that 5-FDRul is a naturally occurring fluorometabolite, rendering it a new addition to this rare collection of natural products. The genetic inactivation of key biosynthetic genes involved in the fluorometabolisms in MA37 resulted in the increased accumulation of unidentified fluorometabolites as observed from 19F-NMR spectral comparison among the wild type (WT) of MA37 and the mutated variants, providing evidence of the presence of other new biosynthetic enzymes involved in the fluorometabolite pathway in MA37.


Assuntos
Vias Biossintéticas , Meios de Cultura/química , Mutação , Pentoses/análise , Streptomyces/crescimento & desenvolvimento , Proteínas de Bactérias/genética , Imagem por Ressonância Magnética de Flúor-19 , Halogenação , Família Multigênica , Pentoses/genética , Análise de Sequência de DNA , Microbiologia do Solo , Streptomyces/química , Streptomyces/genética
16.
J Org Chem ; 84(24): 16323-16328, 2019 12 20.
Artigo em Inglês | MEDLINE | ID: mdl-31729221

RESUMO

Tricyclic carbazole is an important scaffold in many naturally occurring metabolites, as well as valuable building blocks. Here we report the reconstitution of the ring A formation of the bacterial neocarazostatin A carbazole metabolite. We provide evidence of the involvement of two unusual aromatic polyketide proteins. This finding suggests how new enzymatic activities can be recruited to specific pathways to expand biosynthetic capacities. Finally, we leveraged our bioinformatics survey to identify the untapped capacity of carbazole biosynthesis.


Assuntos
Carbazóis/metabolismo , Sistema Enzimático do Citocromo P-450/metabolismo , Streptomyces/química , Transferases/metabolismo , Carbazóis/química , Carbazóis/isolamento & purificação , Biologia Computacional , Estrutura Molecular
17.
Molecules ; 24(18)2019 Sep 17.
Artigo em Inglês | MEDLINE | ID: mdl-31533358

RESUMO

Drug-like molecules are known to contain many different building blocks with great potential as pharmacophores for drug discovery. The continued search for unique scaffolds in our laboratory led to the isolation of a novel Ghanaian soil bacterium, Streptomyces sp. MA37. This strain produces many bioactive molecules, most of which belong to carbazoles, pyrrolizidines, and fluorinated metabolites. Further probing of the metabolites of MA37 has led to the discovery of a new naphthacene-type aromatic natural product, which we have named accramycin A 1. This molecule was isolated using an HPLC-photodiode array (PDA) guided isolation process and MS/MS molecular networking. The structure of 1 was characterized by detailed analysis of LC-MS, UV, 1D, and 2D NMR data. Preliminary studies on the antibacterial properties of 1 using Group B Streptococcus (GBS) produced a minimum inhibitory concentration (MIC) of 27 µg/mL. This represents the first report of such bioactivity amongst the naphthacene-type aromatic polyketides, and also suggests the possibility for the further development of potent molecules against GBS based on the accramycin scaffold. A putative acc biosynthetic pathway for accramycin, featuring a tridecaketide-specific type II polyketide synthase, was proposed.


Assuntos
Policetídeos/química , Policetídeos/isolamento & purificação , Microbiologia do Solo , Streptomyces/química , Antibacterianos/química , Antibacterianos/isolamento & purificação , Antibacterianos/farmacologia , Produtos Biológicos/química , Produtos Biológicos/isolamento & purificação , Produtos Biológicos/farmacologia , Vias Biossintéticas , Genes Bacterianos , Espectroscopia de Ressonância Magnética , Testes de Sensibilidade Microbiana , Estrutura Molecular , Família Multigênica , Policetídeos/metabolismo , Policetídeos/farmacologia , Streptomyces/genética , Streptomyces/metabolismo
18.
Artigo em Inglês | MEDLINE | ID: mdl-31354849

RESUMO

African trypanosomiasis is a disease caused by the parasitic protozoa of the Trypanosoma genus. Despite several efforts at chemotherapeutic interventions, the disease poses serious health and economic concerns to humans and livestock of many sub-Saharan African countries. Zanthoxylum zanthoxyloides (Lam.) Zepern. & Timler (Z. zanthoxyloides LZT) is a plant species of important phytochemical and pharmacological relevance in the subtropical zones of the African continent. However, the mechanisms of its antitrypanosomal effects in African trypanosomes remain to be elucidated. The aim of the study was to determine the in vitro effects and mechanisms of action of Z. zanthoxyloides LZT (root) fractions against Trypanosoma brucei. T. brucei (GUTat 3.1 strain), L. donovani (D10 strain), P. falciparum (3D 7 strain), Jurkat cells, and Chang liver cells were cultivated in vitro to the log phase in their respective media at 37°C. Crude extracts and fractions were prepared from air-dried pulverized plant material of Z. zanthoxyloides LZT (root) using the modified Kupchan method of solvent partitioning. Half-maximal inhibitory concentrations (IC50) were determined through the alamar blue cell viability assay. Effects of fractions on cell death and cell cycle of T. brucei were determined using flow cytometry. Fluorescence microscopy was used to investigate the effects of fractions on the morphology and distribution of T. brucei. Antitrypanosomal compounds of fractions were characterized using high-performance liquid chromatography (HPLC) and attenuated total reflectance infrared (ATR-IR) spectroscopy. Methanol, butanol, and dichloromethane fractions were selectively active against T. brucei with respective IC50 values of 3.89, 4.02, and 5.70 µg/ml. Moreover, methanol, butanol, and dichloromethane fractions significantly induced apoptosis-like cell death with remarkable alteration in the cell cycle of T. brucei. Furthermore, dichloromethane and methanol fractions altered the morphology, induced aggregation, and altered the ratio of nuclei to kinetoplasts in the parasite. The HPLC chromatograms and ATR-IR spectra of the active fractions suggested the presence of aromatic hydrocarbons with hydroxyl, carbonyl, amine, or amide functional groups. The results suggest that Z. zanthoxyloides LZT have potential chemotherapeutic effects on African trypanosomes with implications for novel therapeutic interventions in African trypanosomiasis.

19.
Mar Drugs ; 17(1)2018 Dec 24.
Artigo em Inglês | MEDLINE | ID: mdl-30586918

RESUMO

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.


Assuntos
Alcaloides/farmacologia , Antiparasitários/farmacologia , Paenibacillus/química , Pterocarpus/microbiologia , Alcaloides/química , Alcaloides/isolamento & purificação , Alcaloides/uso terapêutico , Anfotericina B/farmacologia , Animais , Antiparasitários/química , Antiparasitários/isolamento & purificação , Antiparasitários/uso terapêutico , Artesunato/farmacologia , Cercárias/efeitos dos fármacos , Avaliação Pré-Clínica de Medicamentos , Gana , Imidazóis/química , Concentração Inibidora 50 , Leishmania donovani/efeitos dos fármacos , Doenças Parasitárias/tratamento farmacológico , Plasmodium falciparum/efeitos dos fármacos , Rizosfera , Microbiologia do Solo , Trypanosoma brucei brucei/efeitos dos fármacos , Áreas Alagadas
20.
Indian J Microbiol ; 58(2): 214-221, 2018 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-29651181

RESUMO

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.

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