Paulo Riceli Vasconcelos Ribeiro

Synthesis, antibacterial and cytotoxic activities of new biflorin-based hydrazones and oximes.

Biflorin 1 is a biologically active quinone, isolated from Capraria biflora. Five new biflorin-based nitrogen derivatives were synthesized, of which two were mixtures of (E)- and (Z)- isomers: (Z)-2a, (Z)-2b, (Z)-3a, (Z)- and (E)-3b, (Z)- and (E)-3c. The antibacterial activity was investigated using the microdilution method for determining the minimum inhibitory concentration (MIC) against six bacterial strains. Tests have shown that these derivatives have potential against all bacterial strains. The cytotoxic activity was also evaluated against three strains of cancer cells, but none of the derivatives showed activity.

Stabilizing effect of montmorillonite on acerola juice anthocyanins

This study was conducted to evaluate color and anthocyanin stability of clarified acerola juice (CAJ) as affected by montmorillonite (Mnt) at different concentrations (0-6 wt%, dry basis). While non-complexed CAJ suffered noticeable color degradation with time and pH variations, the presence of Mnt (especially at 4-6 wt%) not only changed the initial color of CAJ but also made it more stable with time and pH changes. CAJ/Mnt mixtures were ultracentrifuged in order to separate them into supernatants and anthocyanin-complexed Mnt precipitates. The supernatants presented decreasing anthocyanin contents with increasing Mnt concentrations, indicating pigment retention by the precipitates. X-ray diffraction of precipitates showed that Mnt interlayer spacing was increased by increasing anthocyanin/Mnt ratios, corroborating anthocyanin intercalation. FTIR revealed a band at 1530 cm-1 ascribed to formation of anthocyanin-Mnt complexes. Moreover, chromatograms indicated the selective adsorption of two compounds by Mnt, which were identified by LC-MS as cyanidin-3-O-rhamnoside and pelargonidin-3-O-rhamnoside.

Green coffee seed residue: A sustainable source of antioxidant compounds

Oil extraction from green coffee seeds generates residual mass that is discarded by agribusiness and has not been previously studied. Bioactive secondary metabolites in coffee include antioxidant phenolic compounds, such as chlorogenic acids. Coffee seeds also contain caffeine, a pharmaceutically important methylxanthine. Here, we report the chemical profile, antioxidant activity, and cytotoxicity of hydroethanolic extracts of green Coffea arabica L. seed residue. The extracts of the green seeds and the residue have similar chemical profiles, containing the phenolic compounds chlorogenic acid and caffeine. Five monoacyl and three diacyl esters of trans-cinnamic acids and quinic acid were identified by ultra-performance liquid chromatography/electrospray ionization-quadruple time of flight mass spectrometry. The residue extract showed antioxidant potential in DPPH, ABTS, and pyranine assays and low cytotoxicity. Thus, coffee oil residue has great potential for use as a raw material in dietary supplements, cosmetic and pharmaceutical products, or as a source of bioactive compounds.

Chemical profiling of guarana seeds (Paullinia cupana) from different geographical origins using UPLC-QTOF-MS combined with chemometrics

Paullinia cupana, commonly known as guarana, is an Amazonian fruit whose seeds are used to produce the powdered guarana, which is rich in caffeine and consumed for its stimulating activity. The metabolic profile of guarana from the two largest producing regions was investigated using UPLC-MS combined with multivariate statistical analysis. The principal component analysis (PCA) showed significant differences between samples produced in the states of Bahia and Amazonas. The metabolites responsible for the differentiation were identified by orthogonal partial least squares discriminant analysis (OPLS-DA). Fourteen phenolic compounds were characterized in guarana powder samples, and catechin, epicatechin, B-type procyanidin dimer, A-type procyanidin trimer and A-type procyanidin dimer were the main compounds responsible for the geographical variation of the samples.

Impact of bioaccessibility and bioavailability of phenolic compounds in biological systems upon the antioxidant activity of the ethanolic extract of Triplaris gardneriana seeds

The most studied bioactive potential of phenolic compounds corresponds to antioxidant activity, which in turn, is associated with a reduction in the incidence of various human diseases. However, the total quantity of these bioactive substances in foods and medicinal preparations does not reflect the amount absorbed and metabolized by the body. The present study aimed to investigate the bioaccessibility of Triplaris gardneriana seeds ethanolic extract (EETg) by determination of phenolic composition and antioxidant activities before and after in vitro digestion as well as to estimate its bioavailability by chemical analysis of plasma and urine in animal models after oral administration. The bioaccessibility indexes of phenolic compounds in EETg were 48.65 and 69.28% in the presence and absence of enzymes, respectively. Among the identified phenolics classes, flavonoids, represented by galloylated procyanidins type B, proved to be more bioaccessible, 81.48 and 96.29% in the post-intestinal phase with and without enzymes, respectively. The oral administration in Wistar rats resulted in a significant decrease in plasma of the total antioxidant capacity, TAC, by FRAP assay 4h after beginning the experiment. For urine samples, an increase in TAC by DPPH and FRAP was observed from 1 and 4h after administration, respectively. UPLC-QTOF analysis of urine detected 2 metabolites originated from the degradation of phenolic compounds, i.e. hippuric acid and phenylacetil glycine. These results suggest that phenolic compounds in T. gardneriana are unstable under gastrointestinal conditions, being flavonoids the components with higher bioaccessibility; besides that, they showed limited bioavailability due to their rapid biotransformation and urinary elimination.

Drying kinetics and effect of air-drying temperature on chemical composition of Phyllanthus amarus and Phyllanthus niruri

ABSTRACT In this study, the drying kinetics of Phyllanthus amarus and Phyllanthus niruri were investigated experimentally in an air-drying oven as a function of drying temperature (50, 60, and 70°C). The effects of the air-drying temperature on the phenolic content and the LC–MS profile were also studied. Increases in air-drying temperature reduced the drying time and increased the effective moisture diffusivity. An Arrhenius relationship with activation energy values of 22.828 and 43.129 kJ/mol for P. niruri and P.amarus, respectively, expressed the effect of temperature on the diffusivity. Air drying at 70°C increased the availability of some phenolic compounds. However, the higher temperature negatively affected some sensitive components.

UPLC–qTOF-MS/MS-based phenolic profile and their biosynthetic enzyme activity used to discriminate between cashew apple (Anacardium occidentale L.) maturation stages

Cashew immature and ripe peduncles (Anacardium occidentale L.) from orange- and red-colored clones CCP 76 and BRS 189, respectively, were prepared as juice or fibrous fraction and submitted to UPLC-MS analyses, while the soluble fraction was also submitted to enzymatic evaluation. Cinnamoyl glucoside was present in ripe juice samples from both cashew clones, while monogalloyl diglucoside and digalloyl glucoside were present in immature juice samples from both cashew clones. Four compounds were found at immature fiber of both clones, anacardic acids (1, 2, 3) and GA19. The phenolic biosynthetic pathway was evaluated in juice samples and phenylalanine ammonia-lyase activity decreased significantly during the development, although it was much higher in ripe CCP 76. UDP-glycosyltransferases activity differed between clones, however its product cinnamoyl glucoside was a possible chemical marker of ripe juice samples from both clones. Flavonol synthase showed the highest specific activity in both cashew clones and its product, flavonols were identified in cashew apple at immature and ripe stages.

Spirostanol glucosides from the leaves of Cestrum laevigatum L.

Two new steroidal saponins, (25R)-spirost-5-ene-3β,26β-diol 3-O-α-L-rhamnopyranosyl-(1 → 4)-α-L-rhamnopyranosyl-(1 → 4)-[(1 → 2)-α-L-rhamnopyranosyl]-β-D-glucopyranoside (1) and (25R)-spirost-6-ene-3β,5β-diol 3-O-α-L-rhamnopyranosyl-(1 → 4)-α-L-rhamnopyranosyl-(1 → 4)-[(1 → 2)-α-L-rhamnopyranosyl]-β-D-glucopyranoside (2), along with the known diosgenin 3-O-α-L-rhamnopyranosyl-(1 → 4)-α-L-rhamnopyranosyl-(1 → 4)-β-D-glucopyranoside (3), chonglouoside SL-5 (4) and Paris saponin Pb (5) were isolated from the leaves of Cestrum laevigatum. The structures of the compounds were determined using spectroscopic analyses including HRESI-MS, 1D and 2D NMR data, followed by comparison with data from the literature. Among them, two are particularly unique, compound 1 is the first (6)Δ-spirostanol saponin and compound 2 has an unusual C-26 hydroxyl in the (5)Δ-spirostanol skeleton. Antifungal testing showed a potent activity to formosanin C against Candida albicans and Candida parapsilosis. Evaluation of the cytotoxic activity indicated that compound 1 has a moderate activity against HL-60 and SF-295 cell lines, while compound 2 were active only against HL-60.

New Cytotoxic Bibenzyl and Other Constituents from Bauhinia ungulata L. (Fabaceae)

A new bibenzyl, 2′‐hydroxy‐3,5‐dimethoxy‐4‐methylbibenzyl (1) and four known compounds identified as 2′‐hydroxy‐3,5‐dimethoxybibenzyl (2), liquiritigenin (3), guibourtinidol (4) and fisetinidol (5) were isolated from the roots of Bauhinia ungulata L. Phytochemical investigations of the stems of B. ungulata led to the isolation of the known compounds identified as liquiritigenin (3), guibourtinidol (4), fisetinidol (5), taraxerol (6), betulinic acid (7), taraxerone (8), glutinol (9), a mixture of sitosterol (10) and stigmasterol (11), pacharin (12), naringenin (13) and eriodictyol (14). The structures of these compounds were elucidated on the basis of their spectral data (IR, MS, 1D‐ and 2D‐NMR). The cytotoxicity of the bibenzyl 1 has been evaluated against four human cancer cell lines, showing the IC50 values of 4.3 and 6.5 μg ml−1 against pro‐myelocytic leukemia (HL‐60) and cervical adenocarcinoma (HEP‐2) cell lines, respectively. This article also registers for the first time the 13C‐NMR data of the known bibenzyl 2.

Analysis by UPLC-MS-QTOF and antifungal activity of guava (Psidium guajava L.)

Psidium guajava L. is a plant widely used for food and in folk medicine all over the world. Studies have shown that guava leaves have antifungal properties. In this study, Flavonoid and Tannic fractions were tested to investigate their chemical composition and antifungal potential in vitro.21 compounds in the two fractions, presenting a higher content of phenolic compounds. The antifungal assays were performed against Candida albicans, Candida tropicalis and Candida krusei by microdilution to determine the IC50 and the cell viability curve. Minimal Fungicidal Concentration(MFC) and the inhibitory effects of the association of the fractions with Fluconazole, as well as the assays used to verify any morphological changes were performed in microculture chambers based on the concentrations from the microdilution. The IC50 of the isolated fractions and the fractions associated with each other were calculated, varying from 69.29 to 3444.62 μg/mL and the fractions associated with fluconazole varied from 925.56 to 1.57 μg/mL, it was clear that the association of the natural product with the antifungal presented a synergism. The fractions affected pleomorphism capacity and have a potential antifungal activity as they caused fungal inhibition in isolated use, potentiated the action of Fluconazole, reducing its concentration and impeding morphological transition, one of the virulence factors of the genus.