Application of 1H HR-MAS NMR-Based Metabolite Fingerprinting of Marine Microalgae.

Natural products from the marine environment as well as microalgae, have been known for the complexity of the metabolites they produce due to their adaptability to different environmental conditions, which has been an inexhaustible source of several bioactive properties, such as antioxidant, anti-tumor, and antimicrobial. This study aims to characterize the main metabolites of three species of microalgae (Nannochloropsis oceanica, Chaetoceros muelleri, and Conticribra weissflogii), which have important applications in the biofuel and nutrition industries, by 1H High-resolution magic angle spinning nuclear magnetic resonance (1H HR-MAS NMR), a method which is non-destructive, is highly reproducible, and requires minimal sample preparation. Even though the three species were found in the same ecosystem and a superior production of lipid compounds was observed, important differences were identified in relation to the production of specialized metabolites. These distinct properties favor the use of these compounds as leaders in the development of new bioactive compounds, especially against environmental, human, and animal pathogens (One Health), and demonstrate their potential in the development of alternatives for aquaculture.

Organocatalytic Synthesis and Antitumor Activity of Novel 1,2,3-triazoles Derived from Fatty ß-ketoesters.

BACKGROUND: Developing methods to synthesize highly functionalized and complex 1,2,3- triazoles from various combinations of substrates remains a significant challenge in organic synthesis. Thus, to the best of our knowledge, an organocatalytic approach to synthesize 1,2,3-triazoles derived from fatty acids has not been explored. OBJECTIVE: In this sense, we describe here the organocatalyzed synthesis and preliminary results of antitumor and cytotoxic activity of a range of 1,2,3-triazoles derived from fatty esters. METHODS: To synthesize 1,2,3-triazoles 3 derived from fatty ß-ketoesters, we performed the reaction of appropriate aryl azides 2a-j with ß -ketoesters 1a-c in the presence of 5 mol% of DBU using DMSO as a solvent at 70 °C for 24 h. The viability of 5637 cells was determined by measuring the reduction of soluble MTT to water-insoluble formazan. The IC50 concentration that inhibits 50% of cell growth and the results were obtained by at least three independent experiments in triplicate for each test. RESULTS: Through enolate-mediated organocatalysis, 1,2,3-triazoles 3 derived from fatty ß-ketoesters were synthesized in moderate to excellent yields by reacting fatty esters 1 with aryl azides 2 in the presence of a catalytic amount of 1,8-diazabicyclo[5.4.0]undec-7-ene (5 mol%). All compounds derived from palmitic acetoacetate 1a were evaluated regarding induced cytotoxicity in vitro in a human bladder cancer cell line, and compounds 3a, 3d, 3e, and 3g were shown to be promising alternatives for bladder cancer treatment and presented the lowest inhibitory concentration of IC50. CONCLUSION: We described a synthetic procedure to prepare 1,2,3-triazoles derived from fatty ß - ketoesters by DBU-catalyzed 1,3-dipolar cycloaddition reactions of fatty esters with different aryl azides. Compounds derived from palmitic acetoacetate were screened for antitumor and cytotoxic activity in vitro in human bladder cancer cell lines, and compounds 3a, 3d, 3e, and 3g showed potential to treat bladder cancer.

Chemical Profile and Antimicrobial Activity of the Marine Diatom Chaetoceros muelleri.

Microalgae, due to its rapid growth, low nutritional requirements, and versatility of adaptation to different environmental conditions, has aroused the biotechnological interest, synthesizing novel molecules with antioxidant, anticoagulant, anti-inflammatory, antitumor, and antimicrobial activities. In this sense, we carried out the bioprospection of Chaetoceros muelleri, a marine diatom employed in aquaculture, as a candidate to the development of new drugs for the treatment of bacterial infections. The chemical profile of extracts in different solvents (hexane, chloroform, methylene chloride, ethyl acetate, methanol, and acetone) were analyzed by 1 H-NMR. The hexane extract was the most active against all bacteria species tested, including Mycobacterium tuberculosis, with a minimum inhibitory concentration of 100 µg/ml. Contrarily, the methanol extract was inactive against all tested microorganisms and, in addition, was the only one with IC50 >800 µg/mL, showing no cytotoxicity in VERO cell lines. All other extracts showed antibacterial potential and IC50 values varying between 267.58 and 142.47 µg/ml. The fact that C. muelleri is a microalga easily grown on bioreactors on a large scale may promote its biotechnological use, especially as scaffolds for the development of new compounds against bacterial species of clinical and public health interest.

Characterization data and kinetic studies of novel lipophilic analogues from 2,4-dichlorophenoxyacetic acid and Propanil herbicides.

This work describes the data collection of new lipophilic esters and amides herbicides, analogues to 2,4-dichlorophenoxyacetic acid (2,4-D) and Propanil. The data include 1H and 13C NMR spectra and UV-VIS spectroscopic experiments, from the work "Novel lipophilic analogues from 2,4-D and Propanil herbicides: Biological activity and kinetic studies". The UV-VIS and 1H NMR spectra were employed to kinetic degradation design, and could be used to access new herbicides derivatives with better environmental properties.

Novel lipophilic analogues from 2,4-D and Propanil herbicides: Biological activity and kinetic studies.

This work describes the synthesis of new lipophilic amides and esters analogues of classical organochlorides herbicides by incorporation of long-chains from fatty acids and derivatives. The new fatty esters and amides were synthesized in 96-99% and 80-89% yields, respectively. In general, all compounds tested showed superior in vitro activity than commercial herbicides against growth L. sativa and A. cepa, in ranges 86-100% of germinative inhibition. The target compounds showed, significantly more susceptible towards acid hydrolysis than 2,4-dichlorophenoxyacetic acid (2,4-D). The kinetic and NMR studies showed that the incorporation of lipophilic chains resulted in a decrease in half-life time of new herbicides compounds (1.5 h) than 2,4-D (3 h). These findings suggest the synthesis of new lipophilic herbicides as potential alternative to traditional formulations, by incorporation of long fatty alkyl chains in the molecular structure of 2,4-D, resulting in superior in vitro herbicidal activity, best degradation behavior and more hydrophobic derivatives.

Extraction and characterization of lipids from Sarcocornia ambigua meal: a halophyte biomass produced with shrimp farm effluent irrigation.

Sarcocornia ambigua is a perennial glasswort, native of South America and a potential new seed-oil crop and forage for direct irrigation with salt water. Small seeds develop inside fertile segments of its cylindrical leafless shoots and, at the harvest, seeds are typically mixed with remnant cellulose material difficult to separate. This work evaluated different extraction methods and the composition of total esterified fatty acids in a meal of ground fertile shoots of S. ambigua, seeking for an alternative primary matter and larger yield of total lipids. The highest lipid yield was obtained with a chloroform:methanol mixture (2:1)(v/v) (5.2% of dry weight). The most abundant polyunsaturated fatty acids in the meal were linoleic acid (C18:2; 21.4%) and oleic acid (C18:1; 18.3%). Fifty six percent of the lipids in S. ambigua meal were saturated and palmitic acid (C16:0) was the main fraction (19.8%). Long-chain fatty acids (≥ C20) represented 29.5% of the lipids. Most abundant long-chain fatty acids were behenic acid (C22:0; 7.1%), lignoceric acid (C24:0; 5.3%) and montanic acid (C28:0; 4.0%). The percentage of saturated lipids in S. ambigua meal was higher than that of vegetable oils with a MUFA nutritional profile and some of these lipids have known bioactive properties.

Fatty acids composition in seeds of the South American glasswort Sarcocornia ambigua.

Sarcocornia ambigua (Michx.) M.A. Alonso & M.B. Crespo is the most widely distributed species of the perennial genus of glasswort in South America, and it shows great biotechnological potential as a salt-water irrigated crop. Qualitative and quantitative compositions of fatty acids were determined in the seeds of S. ambigua that were cultivated in southern Brazil. Hexane extraction of the seed oil from S. ambigua yielded 13% of total lipids. The GC-FID (Gas Chromatography Flame Ionization Detector) analysis of the hexane extracts showed five prominent peaks for the seed oil: 42.9 wt.% linoleic-ω6 acid (18:2), 20.4 wt.% palmitic acid (16:0), 18.5 wt.% oleic acid (18:1), 4.5 wt.% stearic acid (18:0) and 4.0 wt.% linolenic-ω3 acid (18:3). The sum of the saturated palmitic and stearic acids (24.8%) in S. ambigua seed oil exceeded values cited for commercial oils use, as well as the seed oil from the cultivated annual glasswort Salicornia bigelovii. No undesirable fatty acid components were found in S. ambigua seed oil, and it could be recommended for animal consumption or biofuel production.

Synthesis and differential antiproliferative activity of Biginelli compounds against cancer cell lines: Monastrol, oxo-monastrol and oxygenated analogues.

The synthesis and differential antiproliferative activity of monastrol (1a), oxo-monastrol (1b) and eight oxygenated derivatives 3a,b-6a,b on seven human cancer cell lines are described. For all evaluated cell lines, monastrol (1a) was shown to be more active than its oxo-analogue, except for HT-29 cell line, suggesting the importance of the sulfur atom for the antiproliferative activity. Monastrol (1a) and the thio-derivatives 3a, 4a and 6a displayed relevant antiproliferative properties with 3,4-methylenedioxy derivative 6a being approximately more than 30 times more potent than monastrol (1a) against colon cancer (HT-29) cell line.

Mannich-type reactions in the gas-phase: the addition of enol silanes to cyclic N-acyliminium ions.

The intrinsic gas-phase reactivity of cyclic N-acyliminium ions in Mannich-type reactions with the parent enol silane, vinyloxytrimethylsilane, has been investigated by double- and triple-stage pentaquadrupole mass spectrometric experiments. Remarkably distinct reactivities are observed for cyclic N-acyliminium ions bearing either endocyclic or exocyclic carbonyl groups. NH-Acyliminium ions with endocyclic carbonyl groups locked in s-trans forms participate in a novel tandem N-acyliminium ion reaction: the nascent adduct formed by simple addition is unstable and rearranges by intramolecular trimethylsilyl cation shift to the ring nitrogen, and an acetaldehyde enol molecule is eliminated. An NSi(CH(3))(3)-acyliminium ion is formed, and this intermediate ion reacts with a second molecule of vinyloxytrimethylsilane by simple addition to form a stable acyclic adduct. N-Acyl and N,N-diacyliminium ions with endocyclic carbonyl groups, for which the s-cis conformation is favored, react distinctively by mono polar [4(+) + 2] cycloaddition yielding stable, ressonance-stabilized cycloadducts. Product ions were isolated via mass-selection and structurally characterized by triple-stage mass spectrometric experiments. B3LYP/6-311G(d,p) calculations corroborate the proposed reaction mechanisms.