Fleurdeliz Maglangit

Bio: Fleurdeliz Maglangit is an academic researcher from University of the Philippines Cebu College. The author has contributed to research in topics: Streptomyces & Water quality. The author has an hindex of 5, co-authored 18 publications receiving 93 citations. Previous affiliations of Fleurdeliz Maglangit include University of the Philippines & University of Aberdeen.

Accramycin A, A New Aromatic Polyketide, from the Soil Bacterium, Streptomyces sp. MA37

Abstract: 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.

A Co-Culturing Approach Enables Discovery and Biosynthesis of a Bioactive Indole Alkaloid Metabolite.

Abstract: 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.

Signalling and Bioactive Metabolites from Streptomyces sp. RK44

Abstract: 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.

Heavy metal monitoring, analysis and prediction in lakes and rivers: state of the art

Abstract: Several research efforts have been conducted to monitor and analyze the impact of environmental factors on the heavy metal concentrations and physicochemical properties of water bodies (lakes and rivers) in different countries worldwide. This article provides a general overview of the previous works that have been completed in monitoring and analyzing heavy metals. The intention of this review is to introduce the historical studies to distinguish and understand the previous challenges faced by researchers in analyzing heavy metal accumulation. In addition, this review introduces a survey on the importance of time increment sampling (monthly and/or seasonally) to comprehend and determine the rate of change of different parameters on a monthly and seasonal basis. Furthermore, suggestions are made for future research to achieve more understandable figures on heavy metal accumulation by considering climate conditions. Thus, the intent of the current study is the provision of reliable models for predicting future heavy metal accumulation in water bodies in different climates and pollution conditions so that water management can be achieved using intelligent proactive strategies and artificial neural network (ANN) techniques.