Covering: 2017-2019Guanidine natural products isolated from microorganisms, marine invertebrates and terrestrial plants, amphibians and spiders, represented by non-ribosomal peptides, ...guanidine-bearing polyketides, alkaloids, terpenoids and shikimic acid derived, are the subject of this review. The topics include the discovery of new metabolites, total synthesis of natural guanidine compounds, biological activity and mechanism-of-action, biosynthesis and ecological functions.
Covering period: up to 2019
Water-soluble natural products constitute a relevant group of secondary metabolites notably known for presenting potent biological activities. Examples are ...aminoglycosides, β-lactam antibiotics, saponins of both terrestrial and marine origin, and marine toxins. Although extensively investigated in the past, particularly during the golden age of antibiotics, hydrophilic fractions have been less scrutinized during the last few decades. This review addresses the possible reasons on why water-soluble metabolites are now under investigated and describes approaches and strategies for the isolation of these natural compounds. It presents examples of several classes of hydrosoluble natural products and how they have been isolated. Novel stationary phases and chromatography techniques are also reviewed, providing a perspective towards a renaissance in the investigation of water-soluble natural products.
The isolation of water-soluble metabolites significantly diminished during the last decades. A comprehensive analysis on the isolation of hydrophilic natural products is discussed with a perspective for the future of natural product sciences.
Objectives
The physicochemical properties and the tissue reaction promoted by microparticulated or nanoparticulated niobium pentoxide (Nb
2
O
5
) added to calcium silicate-based cement (CS), compared ...to MTA-Angelus
™
, were evaluated.
Materials and methods
Materials were submitted to the tests of radiopacity, setting time, pH, and calcium ion release. Polyethylene tubes filled with the materials were implanted into rats subcutaneously. After 7, 15, 30, and 60 days, the specimens were fixed and embedded in paraffin. Hematoxylin & eosin (H&E)-stained sections were used to compute the number of inflammatory cells (IC). Interleukin-6 (IL-6) detection was performed, and the number of immunolabeled cells was obtained; von Kossa method was also carried out. Data were subjected to ANOVA and Tukey test (
p
≤ 0.05).
Results
Nb
2
O
5
micro and Nb
2
O
5
nano provided to the CS radiopacity values (3.52 and 3.75 mm Al, respectively) superior to the minimum recommended. Groups containing Nb
2
O
5
presented initial setting time significantly superior than mineral trioxide aggregate (MTA). All materials presented an alkaline pH and released calcium ions. The number of IC and IL-6 immunolabeled cells in the CS + Nb
2
O
5
groups was significantly reduced in comparison to MTA in all periods. von Kossa-positive structures were observed adjacent to implanted materials in all periods.
Conclusions
The addition of Nb
2
O
5
to the CS resulted in a material biocompatible and with adequate characteristics regarding radiopacity and final setting time and provides an alkaline pH to the environment. Furthermore, the particle size did not significantly affect the physicochemical and biological properties of the calcium silicate-based cement.
Clinical relevance
Niobium pentoxide can be used as radiopacifier for the development of calcium silicate-based materials.
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CMK, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Aim
To evaluate the influence of the addition of microparticulate (micro) and nanoparticulate (nano) zirconium oxide (ZrO2) and niobium pentoxide (Nb2O5) to a calcium silicate‐based cement (CS) on ...the subcutaneous healing process in rats compared with MTA Angelus™.
Methodology
In each rat, two polyethylene tubes filled with the following materials: (i) MTA; (ii) CS + ZrO2micro; (iii) CS + ZrO2nano; (iv) CS + Nb2O5micro or (v) CS + Nb2O5nano were implanted subcutaneously; empty polyethylene tubes were used in the Control group. After 7, 15, 30 and 60 days, the specimens (n = 5 per group in each period) were fixed and embedded in paraffin. Masson's trichrome sections were used to obtain the volume density of the inflammatory cells (VvIC) and fibroblasts (VvFb). The sections were also stained with Picrosirius‐red to calculate the birefringent collagen content. Fibroblast growth factor‐1 (FGF‐1) was detected by immunohistochemistry, and the number of immunolabelled cells was obtained. The data were subjected to two‐way anova followed by Tukey's test (P ≤ 0.05).
Results
At all periods, the VvIC was significantly lower (P < 0.001) in all the CS and Control groups than in the MTA group. At all periods, the VvFb was reduced significantly (P = 0.023) in the MTA group in comparison with the other groups. In addition, the number of immunolabelled cells in the capsules of the CS groups was significantly higher (P < 0.001) than in the MTA group at all time‐points.
Conclusions
The experimental materials (CS + ZrO2 and CS + Nb2O5) induced fibroblast proliferation and accelerated the regression of the inflammatory reaction. However, the addition of nanoparticulate radiopacifiers did not improve the biological properties of a calcium silicate‐based cement when compared to microparticulate agents.
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Available for:
BFBNIB, CMK, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
Covering: up to 2019
The discovery of new bioactive natural products gained momentum during the last few decades, resulting from instrumentation advances, from the expansion of genome mining and ...regulation, as well as by exploration of untapped biological sources. However, water-soluble, volatile, minor and photosensitive natural products are yet poorly known. This review discusses the literature reporting the isolation strategies for some of these metabolites. Analysis of minor metabolites at sub-milligram level are also presented, since analytical instrumentation enabling structure assignment in minute quantities is now routine. Major trends related to natural products discovery are discussed, under the light of further developments in biodiscovery.
Water-soluble, volatile, minor and photosensitive natural products are yet poorly known, and this review discusses the literature reporting the isolation strategies for some of these metabolites.
ZnO-based materials are one of the most studied systems. Their applicability spans over several research areas and industries, like optoelectronics, catalysis and spintronics. Here we demonstrate the ...feasibility to prepare Co-doped ZnO thin films (Zn
1−
x
Co
x
O, with
x
= 0; 0.01; 0.03 and 0.05) deposited by the dip-coating technique, a very simple and a low-cost process. We focus the structural and the optical characterization in the context of dilute magnetic materials. Detailed analyses were carried out to investigate alternative sources of ferromagnetism, such as secondary phases and nanocrystals embedded in the nanostructured thin films. Conjugating different techniques, we confirmed the Zn replacement by Co ions in the ZnO wurtzite structure with no secondary phases up to
x
= 0.05. It was further observed that the major structural defects in the films are oxygen vacancies (V
O
) and zinc interstices (Zn
i
), and that the relative densities of these defects increase with the increase in Co concentration, which promotes the studied thin films to candidates to present room temperature ferromagnetism.
We demonstrate the feasibility to prepare Co-doped ZnO thin films (Zn
1−
x
Co
x
O,
x
= 0; 0.01; 0.03 and 0.05)
via
the dip-coating technique, a very simple and a low-cost process. We focus the structural and the optical analyses in the context of the DMOs.
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IJS, KILJ, NUK, UL, UM, UPUK
While tetrodotoxin (TTX) is commonly found in pufferfish tissues, it is unclear if bacterial symbionts isolated from pufferfish tissues can produce TTX. In this investigation, UPLC qTOF-MS/MS ...analysis of tissue extracts obtained from Sphoeroides spengleri and Canthigaster figuereidoi identified TTX in their composition, indicating their consumption is unsafe. UPLC qTOF-MS/MS analysis coupled with Molecular Networking indicated new TTX analogs (methyl-TTX, TTX-acetate, hydroxypropyl-TTX and glycerol-TTX). Bacterial extracts from sixteen strains revealed a compound with a M+H+ ion at m/z 320.1088, identical to TTX. However, TTX itself was not detected in these cultures by UPLC-MS/MS. Neurotoxicity of Vibrio A665 purified fraction 2 (with precursor M+H+ ion at m/z 320.1088) was significant in human neural stem cells (hNSCs), but the Nav blockage activity was not confirmed by the veratridine/ouabain essays, indicating a possible difference in the mechanism of action between the bacterium A665 purified fraction 2 and TTX. Vibrios symbionts of pufferfish point out involving in the production of TTX precursors.
Display omitted
•TTX was detected in all organs from Brazilian pufferfish C. figueiredoi and S. spengleri and their consumption is unsafe.•First report on the TTX and analogs in pufferfish C. figueiredoi.•Molecular Networking indicated new TTX analogs.•TTX and analogs contents in pufferfish were determined by using the UPLC qTOF-MS/MS.•Vibrios symbionts of pufferfish point out involving in the production of TTX precursors.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Herein reported are results of the chemical and biological investigation of red propolis collected at the Brazilian Northeast coastline. New propolones A–D (1–4), with a ...3-{3-(2-phenylbenzofuran-3-yl)methylphenyl}chromane skeleton; propolonones A–C (5–7), with a 3-3-(3-benzylbenzofuran-2-yl)phenylchromane skeleton; and propolol A (8), with a 6-(3-benzylbenzofuran-2-yl)-3-phenylchromane skeleton, were isolated as constituents of Brazilian red propolis by cytotoxicity-guided assays and structurally identified by analysis of their spectroscopic data. Propolone B (2) and propolonone A (5) display significant cytotoxic activities against an ovarian cancer cell line expressing a multiple drug resistance phenotype when compared with doxorubicin.
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IJS, KILJ, NUK, PNG, UL, UM
In addition to the systemic inflammation present in rheumatoid arthritis (RA), decreased estradiol levels in postmenopausal RA patients further accelerate bone loss in these patients. The ...tissue-selective estrogen complex (TSEC), an estrogen combined with a selective estrogen receptor modulator, is a new hormone replacement therapy option. The first approved TSEC, containing conjugated estrogens and bazedoxifene (BZA), reduces menopausal symptoms and prevents osteoporosis with an improved safety profile compared with conventional hormone replacement therapy. Previous studies have shown that estrogens strongly inhibit experimental arthritis whereas BZA is mildly suppressive. In this study the antiarthritic potential of combined BZA and estradiol is explored for the first time. Female ovariectomized DBA/1 mice were subjected to collagen-induced arthritis, an experimental postmenopausal RA model, and treated with BZA, 17β-estradiol (E2), combined BZA and E2 (BZA/E2), or vehicle. BZA/E2 suppressed arthritis severity and frequency, synovitis, and joint destruction, equally efficient as E2 alone. Unwanted estrogenic proliferative effects on the endometrium were blocked by the addition of BZA, determined by collecting uterine weights. Bone mineral density was measured by peripheral quantitative computed tomography, and all treatments protected collagen-induced arthritis mice from both trabecular and cortical bone loss. Moreover, BZA/E2, but not E2 alone, inhibited preosteoclast formation and reduced serum anticollagen type II antibodies. In conclusion, a TSEC, herein combined BZA/E2, suppresses experimental arthritis and prevents associated bone loss as efficiently as E2 alone but with minimal uterine effects, highlighting the need for clinical trials that evaluate the addition of a TSEC to conventional postmenopausal RA treatment.
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