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Publikation

Reisberg, M., Arnold, N., Porzel, A., Neubert, R. H. H. & Dräger, B. Malusides, novel glucosylceramides isolated from apple pomace (Malus domestica). Z NATURFORSCH C 73, 33-39, (2018) DOI: 10.1515/znc-2017-0059

Three new glucosylceramides (GluCers) named malusides I–III (1–3) were isolated from apple (cultivars of Malus domestica) pomace (fruit material remaining after juice extraction). An unusual oxo/hydroxy group pattern within the sphingadienine (d18:2) type sphingoid base was observed. All compounds contained the same α-hydroxylated fatty acid (h16:0) and a β-D-glucose moiety. Their structures were assigned on the basis of one- and two-dimensional (1D and 2D) nuclear magnetic resonance (NMR) spectroscopic analyses and mass spectrometry (MS) measurements.
Publikation

Farag, M. A., Ali, S. E., Hodaya, R. H., El-Seedi, H. R., Sultani, H. N., Laub, A., Eissa, T. F., Abou-Zaid, F. O. F. & Wessjohann, L. A. Phytochemical profiles and antimicrobial activities of Allium cepa red cv. and A. sativum subjected to different drying methods: a comparative MS-based metabolomics.  Molecules 22, 761, (2017) DOI: 10.3390/molecules22050761

Plants of the Allium genus produce sulphur compounds that give them a characteristic (alliaceous) flavour and mediate for their medicinal use. In this study, the chemical composition and antimicrobial properties of Allium cepa red cv. and A. sativum in the context of three different drying processes were assessed using metabolomics. Bulbs were dried using either microwave, air drying, or freeze drying and further subjected to chemical analysis of their composition of volatile and non-volatile metabolites. Volatiles were collected using solid phase micro-extraction (SPME) coupled to gas chromatography–mass spectrometry (GC/MS) with 42 identified volatiles including 30 sulphur compounds, four nitriles, three aromatics, and three esters. Profiling of the polar non-volatile metabolites via ultra-performance liquid chromatography coupled to high resolution MS (UPLC/MS) annotated 51 metabolites including dipeptides, flavonoids, phenolic acids, and fatty acids. Major peaks in GC/MS or UPLC/MS contributing to the discrimination between A. sativum and A. cepa red cv. were assigned to sulphur compounds and flavonoids. Whereas sulphur conjugates amounted to the major forms in A. sativum, flavonoids predominated in the chemical composition of A. cepa red cv. With regard to drying impact on Allium metabolites, notable and clear separations among specimens were revealed using principal component analysis (PCA). The PCA scores plot of the UPLC/MS dataset showed closer metabolite composition of microwave dried specimens to freeze dried ones, and distant from air dried bulbs, observed in both A. cepa and A. sativum. Compared to GC/MS, the UPLC/MS derived PCA model was more consistent and better in assessing the impact of drying on Allium metabolism. A phthalate derivative was found exclusively in a commercial garlic preparation via GC/MS, of yet unknown origin. The freeze dried samples of both Allium species exhibited stronger antimicrobial activities compared to dried specimens with A. sativum being in general more active than A. cepa red cv.
Publikation

Nguyen,T. H. A., Nguyen, V. T., Dao, D. T., Tran, D. Q., Nguyen, T. T., Giang, T. K. L., Franke, K., Trinh, T. T. & Tran, V. S. Chemical Constituents of Chirita drakei. Nat Prod Commun 12 , 563-566, (2017)

Chirita drakei Burtt (now accepted as Primulina drakei (B.L.Burtt)
Mich.Möller & A.Weber) is growing on limestone mountain slopes of Ha Long Bay
islands in Vietnam. The chemical investigation of the aerial parts of C. drakei led to the
isolation and structural elucidation of two new compounds named chiridrakoside A (1)
and chiridrakoside B (2) besides twelve known compounds comprising five
phenylethanoid glycosides (3–7), two lignans (8, 9), a phenyl propanoid (10), an
anthraquinone (11), a furan derivative (12) and two triterpenes (13, 14). All described
compounds, except 4, 5 and 11, were obtained for the first time from the genera Chirita
or Primulina. The cytotoxic activity of the isolated compounds was evaluated against the
four human cancer cell lines KB (mouth epidermal carcinoma), HepG2 (hepatocellular
carcinoma), Lu (lung carcinoma) and MCF7 (breast carcinoma). Epoxyconiferyl alcohol
(10) exhibited cytotoxic activity against the tested cell lines (IC50 from 46 to 128 μM).

Publikation

Ristok, C., Leppert, K. N., Franke, K., Scherer-Lorenzen, M., Niklaus, P. A., Wessjohann, L. A. & Bruelheide, H. Leaf litter diversity positively affects the decomposition of plant polyphenols. Plant Soil 419, 305–317, (2017) DOI: 10.1007/s11104-017-3340-8

Background and Aims
Leaf litter decomposition is closely linked to nutrient cycling and driven by environmental conditions, species-specific leaf chemistry, and here in particular by polyphenols composition. However, not much attention has been paid on the decomposition of polyphenols themselves. We hypothesized that phenolics and tannin decomposition rates are species-specific and positively affected by litter species richness.

Methods
Leaf litter of three Chinese tree species was exposed to field decomposition conditions, aggregated in mixtures of different species richness (1-, 2-, 3-species mixtures). We sampled litter five times over the course of 171 days, calculated species-specific total phenolics and total protein precipitable tannin decomposition rates, assessed changes in polyphenol composition using HPLC, and tentatively identified compounds by LC-ESI-MS/MS.

Results
Leaf litter richness effects on phenolics and tannin decomposition rates were positive, except for Sapindus-specific tannins, and differed between leaf litter species. Decomposition duration changed polyphenol compositions, and significantly interacted with leaf litter species richness with increasing effects of litter richness with time.

Conclusions
Litter diversity effects on polyphenol decomposition are crucial for whole leaf litter decomposition. The contrasting dependencies of phenolics and tannin decomposition rates on leaf litter richness may provide explanations for equivocal results in leaf litter mixture experiments.
Publikation

Ali, N A. A., Chhetri, B. K., Dosoky, N. S., Shari, K., Al-Fahad, A. J. A., Wessjohann, L. & Setzer, W. N. Antimicrobial, antioxidant, and cytotoxic activities of Ocimum forskolei and Teucrium yemense (Lamiaceae) essential oils. Medicines 4(2), 17, (2017) DOI: 10.3390/medicines4020017

Background: Ocimum forskolei and Teucrium yemense (Lamiaceae) are used in traditional medicine in Yemen. Methods: The chemical composition, antimicrobial, antioxidant and cytotoxic activities of the essential oils isolated from the leaves of Ocimum forskolei Benth. (EOOF) and two different populations of Teucrium yemense Deflers., one collected from Dhamar province (EOTY-d), and another collected from Taiz (EOTY-t) were investigated. The antimicrobial activities of the oils were evaluated against several microorganisms with the disc diffusion test or the broth microdilution test. The essential oils were screened for in-vitro cytotoxic activity against human tumor cells. EOOF and EOTY-d were screened for free-radical-inhibitory activity using the DPPH radical scavenging assay. Results: Sixty-four compounds were identified in (EOOF) representing 100% of the oil content with endo-fenchol (31.1%), fenchone (12.2%), τ-cadinol (12.2%), and methyl (E)-cinnamate (5.1%) as the major compounds. In EOTY-d, 67 compounds were identified, which made up 91% of the total oil. The most abundant constituents were (E)-caryophyllene (11.2%), α-humulene (4.0.%), γ-selinene (5.5%), 7-epi-α-selinene (20.1%), and caryophyllene oxide (20.1%), while the major compounds in EOTY-t were α-pinene (6.6%), (E)-caryophyllene (19.1%) α-humulene (6.4%), δ-cadinene (6.5%), caryophyllene oxide (4.3%), α-cadinol (9.5%), and shyobunol (4.6%). The most sensitive microorganisms for EOOF were B. subtilis, S. aureus, and C. albicans with inhibition zones of 34, 16, and 24 mm and MIC values of, 4.3 mg/mL, 4.3 mg/mL, and 8.6 mg/mL, respectively. EOTY-t showed antimicrobial activity against S. aureus, B. cereus, A. niger, and B. cinerea with MIC values of 0.156, 0.156, 0.313 and 0.313 mg/mL, respectively. Neither essential oil showed remarkable radical inhibition (IC50 = 31.55 and 31.41 μL/mL). EOTY-d was active against HT-29 human colorectal adenocarcinoma cell lines with IC50 = 43.7 μg/mL. Consistent with this, EOTY-t was active against both MCF-7 and MDA-MB-231 human breast adenocarcinoma cells. Conclusions: The antimicrobial activity of Ocimum forskolei essential oil against B. subtilis and C. albicans is consistent with its traditional use in Yemeni traditional medicine to treat skin infections. Both O. forskolei and T. yemense show wide variations in their respective essential oil compositions; there remains a need to investigate both species botanically, genetically, and phytochemically more comprehensively.
Publikation

Rahn, J., Lennicke, C., , Kipp, A. P., Müller, A. S., Wessjohann, L. A., Lichtenfels, R. & Seliger, B.  Altered protein expression pattern in colon tissue of mice upon supplementation with distinct selenium compounds.  Proteomics 17, 1600486, (2017) DOI: 10.1002/pmic.201600486

The essential trace element selenium (Se) is controversially discussed concerning its role in health and disease. Its various physiological functions are largely mediated by Se incorporation in the catalytic center of selenoproteins. In order to gain insights into the impact of Se deficiency and of supplementation with different Se compounds (selenite, selenate, selenomethionine) at defined concentrations (recommended, 150 μg/kg diet; excessive, 750 μg/kg diet) in murine colon tissues, a 20-week feeding experiment was performed followed by analysis of the protein expression pattern of colon tissue specimens by 2D-DIGE and MALDI-TOF MS. Using this approach, 24 protein spots were identified to be significantly regulated by the different Se compounds. These included the antioxidant enzyme peroxiredoxin-5 (PRDX5), proteins with binding capabilities, such as cofilin-1 (COF1), calmodulin, and annexin A2 (ANXA2), and proteins involved in catalytic processes, such as 6-phosphogluconate dehydrogenase (6PGD). Furthermore, the Se compounds demonstrated a differential impact on the expression of the identified proteins. Selected target structures were validated by qPCR and Western blot which mainly confirmed the proteomic profiling data. Thus, novel Se-regulated proteins in colon tissues have been identified, which expand our understanding of the physiologic role of Se in colon tissue.
Publikation

Lennicke, C., Rahn, J., Kipp, A. P., Dojčinović, B. P., Müller, A. S., Wessjohann, L. A., Lichtenfels, R. & Seliger, B. . In: Individual effects of different selenocompounds on the hepatic proteome and energy metabolism of mice.  BBA - General Subjects 1861(1, Part A), 3323-3334, (2017) DOI: 10.1016/j.bbagen.2016.08.015

Background
Selenium (Se) exerts its biological activity largely via selenoproteins, which are key enzymes for maintaining the cellular redox homeostasis. However, besides these beneficial effects there is also evidence that an oversupply of Se might increase the risk towards developing metabolic disorders. To address this in more detail, we directly compared effects of feeding distinct Se compounds and concentrations on hepatic metabolism and expression profiles of mice.

Methods
Male C57BL6/J mice received either a selenium-deficient diet or diets enriched with adequate or high doses of selenite, selenate or selenomethionine for 20 weeks. Subsequently, metabolic parameters, enzymatic activities and expression levels of hepatic selenoproteins, Nrf2 targets, and additional redox-sensitive proteins were analyzed. Furthermore, 2D-DIGE-based proteomic profiling revealed Se compound-specific differentially expressed proteins.

Results
Whereas heterogeneous effects between high concentrations of the Se compounds were observed with regard to body weight and metabolic activities, selenoproteins were only marginally increased by high Se concentrations in comparison to the respective adequate feeding. In particular the high-SeMet group showed a unique response compromising higher hepatic Se levels in comparison to all other groups. Accordingly, hepatic glutathione (GSH) levels, glutathione S-transferase (GST) activity, and GSTpi1 expression were comparably high in the high-SeMet and Se-deficient group, indicating that compound-specific effects of high doses appear to be independent of selenoproteins.

Conclusions
Not only the nature, but also the concentration of Se compounds differentially affect biological processes.
Publikation

Reisberg, M., Arnold, N., Bisrat, D., Asres, K., Neubert, R. H. H. & Dräger, B. Quantification of glycosylceramides in plants by automated multiple development–high-performance thin-layer chromatography. J Planar Chromatog - Modern TLC 30(6), 460-466, (2017) DOI: 10.1556/1006.2017.30.6.1

Glycosylceramides (GlyCers) are precursors of ceramides (Cers) that are major components of the outer layer of human skin, the stratum corneum. A Cer deficiency is associated with skin diseases such as psoriasis and atopic dermatitis and can be treated with Cer-containing semisolid formulations. Plants may serve as alternative sources for expensive semisynthetic Cer production. Since the GlyCer contents of plants vary widely, there is a need to develop a rapid, simple, selective, and precise method for GlyCer quantification in plants. In the present study, an effective and validated automated multiple development‒high-performance thin-layer chromatography (AMD‒HPTLC) method has been developed for GlyCer quantification in 9 different plant materials. An 18-step gradient elution program (n-hexane, chloroform, ethyl acetate, methanol) led to a clear separation of bands from complex matrices and allowed densitometric analysis for quantification purposes. Apple pomace and wheat germs yielded 26.8 and 39.5 mg of GlyCer per 100 g plant material, respectively, while the yields of coffee grounds were below the limit of quantification. The GlyCer contents of the seeds of six Fabaceae species, namely, Albizia grandibracteata, Albizia gummifera, Albizia lebbeck, Albizia schimperiana, Acacia etbaica, and Robinia pseudoacacia, ranged from 9.4 to 23.1 mg per 100 g plant material. GlyCers were separated by preparative thin-layer chromatography (TLC) and identified by offline high-performance liquid chromatography–mass spectrometry (HPLC–MS). Intact GlyCers were detected in the Fabaceae species for the first time. A simple AMD–HPTLC screening and quantification technique for GlyCers was developed, which may serve as a tool in searching plant GlyCers for a possible “phyto”-Cer production.
Publikation

Farag, M. A., Westphal, H., Eissa, T. F., Wessjohann, L. A. & Meyer, A. Effect of Oxylipins, Terpenoid Precursors and Wounding on Soft Corals’ Secondary Metabolism as Analyzed via UPLC/MS and Chemometrics Molecules 22, 2195, (2017) DOI: 10.3390/molecules22122195

The effect of three oxylipin analogues, a terpenoid intermediate and wounding on the secondary metabolism of the soft corals Sarcophyton glaucum and Lobophyton pauciflorum was assessed. Examined oxylipins included prostaglandin (PG-E1), methyl jasmonate (MeJA), and arachidonic acid (AA) in addition to the diterpene precursor geranylgeranylpyrophosphate (GGP). Post-elicitation, metabolites were extracted from coral heads and analyzed via UPLC-MS followed by multivariate data analyses. Both supervised and unsupervised data analyses were used for sample classification. Multivariate data analysis revealed clear segregation of PG-E1 and MeJA elicited S. glaucum at 24 and 48 h post elicitation from other elicitor samples and unelicited control group. PG-E1 was found more effective in upregulating S. glaucum terpene/sterol levels compared to MeJA. Metabolites showing upregulation in S. glaucum include campestene-triol and a cembranoid, detected at ca. 30- and 2-fold higher levels compared to unelicited corals. Such an elicitation effect was less notable in the other coral species L. pauciflorum, suggesting a differential oxylipin response in soft corals. Compared to MeJA and PG, no elicitation effect was observed for GGP, AA or wounding on the metabolism of either coral species.
Publikation

Janković-Tomanikć, M., Todorović, D., Stanivuković, Z., Perić Mataruga, V., Wessjohann, L. A. & Kaluđerović, G. N. Mesoporous silica nanoparticles SBA-15 loaded with emodin upregulate the antioxidative defense of Euproctis chrysorrhoea  (L.) larvae. Turk J Biol 41, 935-942, (2017) DOI: 10.3906/biy-1705-76

The study presented here aims to elucidate the effects of emodin (EO = 1,3,8-trihydroxy-6-methylanthraquinone) in its free form and when loaded into a mesoporous silica nanocarrier SBA-15 (→ SBA-15¦EO) on the activities of the main antioxidative enzymes, superoxide dismutase, catalase, glutathione S-transferase, and glutathione reductase, in larvae of a polyphagous insect pest, the browntail moth Euproctis chrysorrhoea (L.). The results show that only SBA-15¦EO upregulates the activities of the tested antioxidative enzymes. These results point to significant differences in the effectiveness of the compound in the free versus the loaded form.
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