Omanische Heilpflanze im Fokus der Phytochemie IPB-Wissenschaftler und Partner aus Dhofar haben jüngst die omanische Heilpflanze Terminalia dhofarica unter die phytochemische Lupe genommen. Die Pflanze ist reich an…
Geschmack ist vorhersagbar: Mit FlavorMiner. FlavorMiner heißt das Tool, das IPB-Chemiker und Partner aus Kolumbien jüngst entwickelt haben. Das Programm kann, basierend auf maschinellem Lernen (KI), anhand der…
de Moura, P. H. B.; de Sousa, A. A.; Porzel, A.; Wessjohann, L. A.; Leal, I. C. R.; Martins, R. C. C.;Characterization of antibacterial proanthocyanidins of Dalbergia monetaria, an amazonian medicinal plant, by UHPLC-HRMS/MSPlanta Med.86858– 866(2020)DOI: 10.1055/a-1170-8016
Dalbergia monetaria is an Amazonian plant whose bark is widely used to treat urinary tract infections. This paper describes a bio-guided study of ethanolic extracts from the bark and leaves of D. monetaria, in a search for metabolites active against human pathogenic bacteria. In vitro assays were performed against 10 bacterial strains, highlighting methicillin-sensitive Staphylococcus aureus and methicillin-resistant Staphylococcus aureus and Pseudomonas aeruginosa. Fractioning of the extracts was performed using instrumental and classical techniques, and samples were characterized by UHPLC-HRMS/MS. Ethyl acetate fractions from bark and leaves showed similar antibacterial activities. EAFB is enriched in isoflavone C-glucosides and EAFL enriched in proanthocyanidins. Subfractions from EAFL presented higher activity and showed a complex profile of proanthocyanidins constructed by (epi)-cassiaflavan and (epi)-catechin units, including dimers, trimers and tetramers. The fragmentation pattern emphasized the neutral loss of cassiaflavan units by quinone-methide fission. Fraction SL7-6, constituted by (ent)-cassiaflavan-(ent)-cassiaflavan-(epi)-catechin isomers, showed the lowest MIC against the S. aureus and P. aeruginosa with values corresponding to 64 and 32 µg/mL, respectively. Cassiaflavan-proanthocyanidins have not been found previously in another botanical genus, except in Cassia, and the traditional medicinal use of D. monetaria might be related to the antibacterial activity of proanthocyanidins characterized in the species.
Publikation
Jouda, J.-B.; Njoya, E. M.; Fobofou, S. A. T.; Zhou, Z. Y.; Qiang, Z.; Mbazoa, C. D.; Brandt, W.; Zhang, G.-l.; Wandji, J.; Wang, F.;Natural Polyketides Isolated from the Endophytic Fungus
Phomopsis sp. CAM212 with a Semisynthetic Derivative Downregulating
the ERK/IκBα Signaling PathwaysPlanta Med.861032-1042(2020)DOI: 10.1055/a-1212-2930
AbstractThree previously undescribed natural products, phomopsinin A – C
(1 – 3), together with three known compounds, namely,
cis-hydroxymellein (4), phomoxanthone A (5) and
cytochalasin L-696,474 (6), were isolated from the solid culture of
Phomopsis sp. CAM212, an endophytic fungus obtained from Garcinia
xanthochymus. Their structures were determined on the basis of
spectroscopic data, including IR, NMR, and MS. The absolute configurations of
1 and 2 were assigned by comparing their experimental and
calculated ECD spectra. Acetylation of compound 1 yielded 1a, a
new natural product derivative that was tested together with other isolated
compounds on lipopolysaccharide-stimulated RAW 264.7 cells. Cytochalasin
L-696,474 (6) was found to significantly inhibit nitric oxide production,
but was highly cytotoxic to the treated cells, whereas compound 1
slightly inhibited nitric oxide production, which was not significantly
different compared to lipopolysaccharide-treated cells. Remarkably, the
acetylated derivative of 1, compound 1a, significantly inhibited
nitric oxide production with an IC50 value of 14.8 µM and no
cytotoxic effect on treated cells, thereby showing the importance of the acetyl
group in the anti-inflammatory activity of 1a. The study of the mechanism
of action revealed that 1a decreases the expression of inducible nitric
oxide synthase, cyclooxygenase 2, and proinflammatory cytokine IL-6 without an
effect on IL-1β expression. Moreover, it was found that 1a exerts
its anti-inflammatory activity in lipopolysaccharide-stimulated RAW 264.7
macrophage cells by downregulating the activation of ERK1/2 and by preventing
the translocation of nuclear factor κB. Thus, derivatives of phomopsinin
A (1), such as compound 1a, could provide new anti-inflammatory
leads.
Publikation
Puentes, A. R.; Neves Filho, R. A. W.; Rivera, D. G.; Wessjohann, L. A.;Total Synthesis of Cordyheptapeptide ASynlett281971-1974(2017)DOI: 10.1055/s-0036-1588433
The first total synthesis of cordyheptapeptide A is described. The synthesis is accomplished by a convergent approach featuring a combination of peptide coupling and the Ugi reaction for the preparation of the main building blocks and the acyclic precursor. The assembly of an N-methylated fragment by the Ugi reaction comprised the utilization of a convertible isonitrile followed by activation of the C-terminal amide. Two different macrocyclization sites were evaluated, proving greater efficacy the macrolactamization at the site Ile-Tyr, likely due of a more suitable conformational bias of the acyclic precursor having an internal β-turn centered at the N-Me-d-Phe-Pro moiety.
Publikation
Farag, M. A.; Wessjohann, L. A.;Metabolome Classification of Commercial Hypericum perforatum (St. John's Wort) Preparations via UPLC-qTOF-MS and ChemometricsPlanta Med.78488-496(2012)DOI: 10.1055/s-0031-1298170
The growing interest in the efficacy of phytomedicines and herbal supplements but also the increase in legal requirements for safety and reliable contents of active principles drive the development of analytical methods for the quality control of complex, multicomponent mixtures as found in plant extracts of value for the pharmaceutical industry. Here, we describe an ultra-performance liquid chromatography method (UPLC) coupled with quadrupole time of flight mass spectrometry (qTOF-MS) measurements for the large scale analysis of H. perforatum plant material and its commercial preparations. Under optimized conditions, we were able to simultaneously quantify and identify 21 metabolites including 4 hyperforins, 3 catechins, 3 naphthodianthrones, 5 flavonoids, 3 fatty acids, and a phenolic acid. Principal component analysis (PCA) was used to ensure good analytical rigorousness and define both similarities and differences among Hypericum samples. A selection of batches from 9 commercially available H. perforatum products available on the German and Egyptian markets showed variable quality, particularly in hyperforins and fatty acid content. PCA analysis was able to discriminate between various preparations according to their global composition, including differentiation between various batches from the same supplier. To the best of our knowledge, this study provides the first approach utilizing UPLC-MS-based metabolic fingerprinting to reveal secondary metabolite compositional differences in Hypericum extract.