Preparation of Hard Palm Seeds for Matrix-Assisted Laser Desorption/Ionization-Imaging Mass Spectrometry Analysis.

Matrix-assisted laser desorption/ionization-imaging mass spectrometry (MALDI-IMS) is applied to identify compounds in their native environments. Currently, MALDI-IMS is frequently used in clinical analysis. Still, an excellent perspective exists for better applying this technique to understand chemical compounds' physiological information in plant tissues. However, preparation may be challenging for specific samples from botanical materials, as MALDI-IMS requires thin slices (12-20 µm) for appropriate data acquisition and successful analysis. In this sense, previously, we developed a sample preparation protocol to obtain thin sections of Euterpe oleracea (açaí palm) hard seeds, enabling their molecular mapping by MALDI-IMS. Here, we show that the developed protocol is suitable for preparing other seeds from the same genus. Briefly, the protocol was based on submerging the seeds in deionized water for 24 h, embedding samples with gelatin, and sectioning them in an acclimatized cryostat. Then, for matrix deposition, an xy motion platform was coupled to an electrospray ionization (ESI) needle spray using a 1:1 (v/v) 2,5-dihydroxybenzoic acid (DHB) and methanol solution with 0.1% trifluoroacetic acid at 30 mg/mL. E. precatoria and E. edulis seed data were processed using software to map their metabolite patterns. Hexose oligomers were mapped within sample slices to prove the adequacy of the protocol for those samples, as it is known that those seeds contain large amounts of mannan, a polymer of the hexose mannose. As a result, peaks of hexose oligomers, represented by [M + K]+ adducts of (Δ = 162 Da), were identified. Thus, the sample preparation protocol, previously developed tailor-made for E. oleracea seeds, also enabled MALDI-IMS analysis of two other hard palm seeds. In short, the method could constitute a valuable tool for research in the morpho-anatomy and physiology of botanical materials, especially from cut-resistant samples.

The acquisition of thin sections of açaí (Euterpe oleracea Mart.) seed with elevated potassium content for molecular mapping by mass spectrometry imaging.

RATIONALE: Matrix-assisted laser desorption/ionization imaging mass spectrometry (MALDI-IMS) of tissues became popular in the last decade. Consequently, adapting sample preparation methods for different materials turned out to be a pivotal step for successful analysis due to the requirement of sample slices of 12-20 µm thickness. However, acquiring thin sections compatible with MALDI-IMS for unusual samples is challenging, as existing histological protocols may not be suitable, thus requiring new methods. Açaí (Euterpe oleracea Mart.) seed is an example of a challenging material due to its toughness and resistance to crack, therefore our goal was to develop a methodology to obtain thin (12-20 µm) and entire sections of açaí seeds for MALDI-IMS analysis. METHODS: Different strategies were evaluated for obtaining thin sections of seeds, and the combination of the following steps was found to be the most suitable option: (i) softening of seeds by water immersion for 24 h; (ii) transversal cut of seeds to obtain half-seeds using a razor blade and a hammer; (iii) half-seeds imbibition in gelatin; (iv) samples sectioning using a cryostat at -20°C to obtain samples with 12-20 µm thickness; (v) collection of samples in an indium tin oxide-coated glass slide covered by double-sided copper tape to avoid sample wrapping and ensure adhesion after unfreezing; and (vi) storage of samples in a -80°C freezer, if necessary. RESULTS: This adapted sample preparation method enabled the analysis of açaí seeds by MALDI-IMS, providing spatial distribution of carbohydrates in the endosperm. CONCLUSIONS: The adaptations developed for sample preparation will help investigate the metabolic and physiological properties of açaí seeds in future studies.

Proteomic changes associated with the development of açaí (Euterpe oleracea Mart.) seeds.

Açaí palm (Euterpe oleracea Mart.) seeds are a rich source of mannans, which can be used to generate bioethanol or be converted to high-value D-mannose, in addition to being a source of polyphenols with beneficial health properties. Here, we present a quantitative proteome dataset of açaí seeds at four stages of development (S1, S2, S3, and S4 stages), in which 2465 high confidence proteins were identified and 524 of them show statistically different abundance profiles during development. Several enzymes involved in the biosynthesis of nucleotide-sugars were quantified, especially those dedicated to the formation of GDP-mannose, which showed an increase in abundance between stages S1 and S3. Our data suggest that linear mannans found abundantly in endosperm cell walls are initially deposited as galactomannans, and during development lose the galactosyl groups. Two isoforms of alpha-galactosidase enzymes showed significantly increased abundances in the S3 and S4 stages. Additionally, we quantified the enzymes participating in the central pathway of flavonoid biosynthesis responsible for the formation of catechin and epicatechin, which are subunits of procyanidins, the main class of polyphenols in the açaí seeds. These proteins showed the same pattern of deposition, in which higher abundances were seen in the S1 and S2 stages.

Phenolic Profile and Antioxidant Properties in Extracts of Developing Açaí (Euterpe oleracea Mart.) Seeds.

We investigated changes in the phenolic profile and antioxidant properties in the extracts of developing seeds of açaí (Euterpe oleracea). Four developmental stages were evaluated, with earlier stages displaying higher antioxidant activity and polyphenols content, while mass spectrometry analysis identified procyanidins (PCs) as the major components of the extracts in all stages. B-type PCs varied from dimers to decamers, with A-type linkages in a smaller number. Extracted PCs decreased in average length from 20.5 to 10.1 along seed development. PC composition indicated that (-)-epicatechin corresponded to over 95% of extension units in all stages, while (+)-catechin presence as the starter unit increased from 42 to 78.8% during seed development. This variation was correlated to the abundance of key enzymes for PC biosynthesis during seed development. This study is the first to report PC content and composition variations during açaí seed development, which can contribute to studies on the plant's physiology and biotechnological applications.

Proanthocyanidins with Corrosion Inhibition Activity for AISI 1020 Carbon Steel under Neutral pH Conditions of Coconut (Cocos nucifera L.) Husk Fibers.

Cocos nucifera L. is a palm tree (Arecaceae) with a high economic value. The coconut husk fibers are nonedible, thick, and abrasion-resistant and correspond up to 85% of biomass discarded as solid waste residue. Therefore, the husk fibers are an underexploited byproduct with a high content of extractives of unreported nature. Two varieties of C. nucifera L. husk extracts were investigated to uncover bioactive metabolites and their possible application as a green corrosion inhibitor for carbon steel AISI 1020 under neutral pH conditions. The chemical analysis indicated 3% (w/w) of proanthocyanidins in the husk fibers with a high B-type procyanidin content. The husk fibers' crude extract showed promising results as an eco-friendly corrosion inhibitor for carbon steel AISI 1020 under neutral pH conditions. Although it formed a film on the metal surface in all tested concentrations (0.4, 0.8, 1.2, and 1.6 g L-1), the highest protective efficiency was shown at a concentration of 1.2 g L-1, determined by electrochemical techniques and mass loss. This was the first comprehensive report on coconut husk fibers' chemical composition, which was similar between the two varieties with potential for industrial application.

Antifungal Phenylpropanoid Glycosides from Lippia rubella.

Lippia species share various pharmacological activities and are used in traditional cooking and medicine worldwide. Combined chromatographic techniques such as column chromatography, high-performance liquid chromatography, and countercurrent chromatography led to the purification of two new antifungal phenylpropanoid glycosides, lippiarubelloside A (1) and lippiarubelloside B (2), by bioactivity-directed fractionation of an ethanol-soluble extract from Lippia rubella, in addition to the known active related compounds forsythoside A (3), verbascoside (4), isoverbascoside (5), and poliumoside (6). The structures of compounds 1 and 2 were determined by comparison of their NMR spectroscopic data with the prototype active compound 4. Cryptococcus neoformans, which causes opportunistic lung infections, was sensitive to compounds 1-6 in the concentration range of 15-125 µg/mL. A synergistic effect (FICindex = 0.5) between 3 and amphotericin B was demonstrated. The glycosylated flavonoids pectolinarin (7), linarin (8), and siparunoside (9) were also isolated.

Diterpenes and a new benzaldehyde from the mangrove plant Rhizophora mangle

ABSTRACT This work describes the isolation, by high-speed counter-current chromatography, of the diterpenes manool, jhanol and steviol and the benzaldehyde p-oxy-2-ethylhexyl benzaldehyde from the stilt roots hexane extract of the mangrove plant Rhizophora mangle L., Rhizophoraceae. For this, a non-aqueous biphasic solvent system composed of hexane–acetonitrile–methanol 1:1:0.5 (v/v/v) was applied. As far as we know, only steviol was previously isolated in Rhizophoraceae and this is the first time that p-oxy-2-ethylhexyl benzaldehyde is reported.

Characterization of anti-inflammatory effect and possible mechanism of action of Tibouchina granulosa.

OBJECTIVES: Tibouchina granulosa, popularly known as 'quaresmeira', belong to a genus widely used in the traditional medicine as infusions from their leaves. Other species of Tibouchina are used as antibacterial, antioxidant or antileishmanial. In this work, our objectives were to investigate the biological effects of T. granulosa in models of acute inflammation. METHODS: Chemical analysis showed the presence of proanthocyanidins and flavonoids. Infusions from leaves of T. granulosa (1, 3, 10, 30 or 100 mg/kg) were orally administered to mice, and the anti-inflammatory effects were evaluated by the formalin-induced licking response, inhibition of carrageenan-induced cell migration into subcutaneous air pouch (SAP) and inhibition of inflammatory mediator production in inflammatory exudate collected from SAP. KEY FINDINGS: Our data indicate that tested doses of T. granulosa infusion reduced cell migration, protein extravasated to SAP and cytokine production (i.e. TNF-α and IL-10). All doses also inhibited the first and second phase of formalin-induced licking response. CONCLUSIONS: Taken together, our results indicate that leaves of T. granulosa present anti-inflammatory effect and can be useful in the preparation of new phytomedicines.

Euterpe oleracea Mart.-Derived Polyphenols Protect Mice from Diet-Induced Obesity and Fatty Liver by Regulating Hepatic Lipogenesis and Cholesterol Excretion.

The aim of this study was to investigate the effect of a polyphenol-rich Açaí seed extract (ASE, 300 mg/kg-1d-1) on adiposity and hepatic steatosis in mice that were fed a high-fat (HF) diet and its underlying mechanisms based on hepatic lipid metabolism and oxidative stress. Four groups were studied: C57BL/6 mice that were fed with standard diet (10% fat, Control), 10% fat + ASE (ASE), 60% fat (HF), and 60% fat + ASE (HF + ASE) for 12 weeks. We evaluated the food intake, body weight gain, serum glucose and lipid profile, hepatic cholesterol and triacyglycerol (TG), hepatic expression of pAMPK, lipogenic proteins (SREBP-1c, pACC, ACC, HMG-CoA reductase) and cholesterol excretion transporters, ABCG5 and ABCG8. We also evaluated the steatosis in liver sections and oxidative stress. ASE reduced body weight gain, food intake, glucose levels, accumulation of cholesterol and TG in the liver, which was associated with a reduction of hepatic steatosis. The increased expressions of SREBP-1c and HMG-CoA reductase and reduced expressions of pAMPK and pACC/ACC in HF group were antagonized by ASE. The ABCG5 and ABCG8 transporters expressions were increased by the extract. The antioxidant effect of ASE was demonstrated in liver of HF mice by restoration of SOD, CAT and GPx activities and reduction of the increased levels of malondialdehyde and protein carbonylation. In conclusion, ASE substantially reduced the obesity and hepatic steatosis induced by HF diet by reducing lipogenesis, increasing cholesterol excretion and improving oxidative stress in the liver, providing a nutritional resource for prevention of obesity-related adiposity and hepatic steatosis.