Polysaccharides from exudate gums of plants and interactions with the intestinal microbiota: A review of vegetal biopolymers and prediction of their prebiotic potential.

Polysaccharides in plant-exuded gums are complex biopolymers consisting of a wide range of structural variability (linkages, monosaccharide composition, substituents, conformation, chain length and branching). The structural features of polysaccharides confer the ability to be exploited in different industrial sectors and applications involving biological systems. Moreover, these characteristics are attributed to a direct relationship in the process of polysaccharide enzymatic degradation by the fermentative action in the gut microbiota, through intrinsic interactions connecting bacterial metabolism and the production of various metabolites that are associated with regulatory effects on the host homeostasis system. Molecular docking analysis between bacterial target proteins and arabinogalactan-type polysaccharide obtained from gum arabic allowed the identification of intermolecular interactions provided bacterial enzymatic mechanism for the degradation of several arabinogalactan monosaccharide chains, as a model for the study and prediction of potential fermentable polysaccharide. This review discusses the main structural characteristics of polysaccharides from exudate gums of plants and their interactions with the intestinal microbiota.

Antinociceptive effect of triterpene acetyl aleuritolic acid isolated from Croton zehntneri in adult zebrafish (Danio rerio).

Croton zehntneri is a plant known as canelinha de cunhã, prevalent in the northeast region of Brazil. Many constituents of the vegetable have already been studied, and their pharmacological properties have been proven, but this is the first study to analyze the antinociceptive effect in adult zebrafish (ZFa) of the triterpene acetyl aleuritolic acid (AAA) isolated from the stem bark. The animals (ZFa; n = 6/group) were treated intraperitoneally (ip; 20 µL) with AAA (0.1 or 0.3 or 1.0 mg/mL) or vehicle (0.9% saline; 20 µL), and submitted to the locomotor activity test, as well as 96 h acute toxicity. Other groups (n = 6/each) received the same treatments and underwent acute nociception tests (formalin, cinnamaldehyde, glutamate, acid saline, capsaicin, and hypertonic saline). Possible neuromodulation mechanisms were evaluated. AAA (0.1 or 0.3 or 1.0 mg/mL) reduced the nociceptive behavior induced by acid saline and capsaicin, as well as inhibited corneal nociception induced by hypertonic saline, both without altering the animals' locomotor system and without toxicity. These analgesic effects of AAA were significantly (p > 0.05) similar to those of morphine, used as a positive control. The antinociceptive effect of AAA was inhibited by methylene blue, ketamine, camphor, ruthenium red, amiloride, and mefenamic acid. The antinociceptive effect of AAA on the cornea of animals was inhibited by capsazepine. Therefore, AAA showed pharmacological potential for the treatment of acute pain, and this effect is modulated by cGMP, NMDA receptors, transient receptor potential channels (TRPs), ASICs and has pharmacological potential for the treatment of corneal pain modulated by the TRPV1 channel.

Anacardic Acid Complexes as Possible Agents Against Alzheimer's Disease Through Their Antioxidant, In vitro, and In silico Anticholinesterase and Ansiolic Actions.

The frequency of Alzheimer's disease (AD) is growing rapidly with longer life expectancy and the consequent increase of people with a high risk of neurodegenerative diseases. Anacardic acid (AA) has several pharmacological actions, such as antioxidants, anticholinesterase, and anti-inflammatory, which are related to the protection against aging disorders. Also, the metals copper and zinc are co-factors of antioxidant enzymes that can be associated with AA to improve brain-protective action. This study aimed to evaluate the potential of AA metal complexes using copper and zinc chelators to produce potential agents against Alzheimer's disease. For this purpose, Cu and Zn were linked to AA in the ratio of 1:1 in a basic medium. The complexes' formation was confirmed by ultraviolet and visible spectroscopy. The toxicity was evaluated in the zebrafish model, and other information related to AD was obtained using the zebrafish model of anxiety. AA-Zn and AA-Cu complexes showed better antioxidant action than free AA. In the anti-AChE activity, AA was like the AA-Cu complex. In models using adult zebrafish, no toxicity for AA complexes was found, and in the locomotor model, AA-Cu demonstrated possible anxiolytic action. In in silico experiments comparing AA and AA-Cu complex, the coupling energy with the enzyme was lower for the AA-Cu complex, showing better interaction, and also the distances of the active site amino acids with this complex were lower, similar to galantamine, the standard anti-AChE inhibitor. Thus, AA-Cu showed interesting results for more detailed study in experiments related to Alzheimer's disease.

Antinociceptive activity of 3ß-6ß-16ß-trihydroxylup-20 (29)-ene triterpene isolated from Combretum leprosum leaves in adult zebrafish (Danio rerio).

Drugs used to treat pain are associated with adverse effects, increasing the search for new drugs as an alternative treatment for pain. Therefore, we evaluated the antinociceptive behavior and possible neuromodulation mechanisms of triterpene 3ß, 6ß, 16ß-trihydroxylup-20(29)-ene (CLF-1) isolated from Combretum leprosum leaves in zebrafish. Zebrafish (n = 6/group) were pretreated with CLF-1 (0.1 or 0.3 or 1.0 mg/mL; i.p.) and underwent nociception behavior tests. The antinociceptive effect of CFL-1 was tested for modulation by opioid (naloxone), nitrergic (L-NAME), nitric oxide and guanylate cyclase synthesis inhibitor (methylene blue), NMDA (Ketamine), TRPV1 (ruthenium red), TRPA1 (camphor), or ASIC (amiloride) antagonists. The corneal antinociceptive effect of CFL-1 was tested for modulation by TRPV1 (capsazepine). The effect of CFL-1 on zebrafish locomotor behavior was evaluated with the open field test. The acute toxicity study was conducted. CLF-1 reduced nociceptive behavior and corneal in zebrafish without mortalities and without altering the animals' locomotion. Thus, CFL-1 presenting pharmacological potential for the treatment of acute pain and corneal pain, and this effect is modulated by the opioids, nitrergic system, NMDA receptors and TRP and ASIC channels.

Anxiolytic-like effect of chalcone N-{4'[(2E)-3-(3-nitrophenyl)-1-(phenyl)prop-2-en-1-one]} acetamide on adult zebrafish (Danio rerio): Involvement of the 5-HT system.

The action of anxiolytic compounds that act on selective serotonin receptors (SSRIs) have been scarcely evaluated. Serotonergic drugs have been shown to be effective in treating anxiety without presenting adverse effects as benzodiazepines. However, the anxiolytic effects take days to occur. This study aimed to evaluate the anxiolytic effect of the synthetic chalcone, 4'-[(2E) -3- (3-nitrophenyl) -1- (phenyl) prop-2-en-1-one] acetamide (PAAMNBA), and its possible mechanism of action in adult zebrafish (Danio rerio). PAAMNBA was synthesized with a yield of 51.3% and its chemical structure was determined by 1H and 13C NMR. Initially, PAAPMNBA was intraperitoneally administered to zebrafish (n = 6/group) at doses of 4, 12, or 40 mg/kg, and the animals were subsequently subjected to acute and open field toxicity tests. PAAMNBA was administered to the other groups (n = 6/group) for analyzing its effect in the light and dark test. The involvement of the serotonergic (5HT) system was also evaluated using 5-HTR 1, 5-HTR 2A/2C, and 5-HTR 3A/3B receptor antagonists, namely, pizotifeo, granizetron, and ciproeptadina, respectively. Molecular coupling was performed using the 5-HT1 receptor. PAAMNBA was found to be non-toxic, reduced the locomotor activity, and had an anxiolytic effect in adult zebrafish. The effect was reduced by pretreatment with pizotifene and was not reversed by treatment with granizetron and cyproeptadine. A previous in vivo molecular coupling study indicated that chalcones interact with the 5-HT1 receptor. The results suggested that the chalcone, PAAPMNBA, has anxiolytic activity, that is mediated by the serotonergic system via the 5-HT1 receptor. The interaction of PAAPMNBA with the 5-HT1 receptor was confirmed by molecular docking studies.

Synthesis of Quercetin-Metal Complexes, In Vitro and In Silico Anticholinesterase and Antioxidant Evaluation, and In Vivo Toxicological and Anxiolitic Activities.

The level of acetylcholine, a neurotransmitter essential for processing memory and learning, is lower in the brains of patients with Alzheimer's disease due to the higher concentration of the enzyme acetylcholinesterase. The main compounds used for Alzheimer's treatment are acetylcholinesterase inhibitors. Quercetin coordination complexes with the metal ions Cu+2, Zn+2, Ni+2, Co+2, and Fe+2 were synthesized to investigate their potential use against Alzheimer's disease, by evaluating the inhibition of acetylcholinesterase in vitro and in silico, as well as the antioxidant activity, toxicity, and anxiolytic action in the zebrafish (Danio rerio) model. The organic complexes were characterized by UV-Vis and FT-IR. The spectral information suggested that coordination of metals occurs with the carbonyl group and OH linked to the C-3 carbon of quercetin. The quercetin-Fe (QFe) complex presented the best antioxidant and antiacetylcholinesterase actions, and these results were confirmed by molecular docking. In the toxicity and locomotor evaluation, the quercetin molecules and the synthesized complexes, mainly QCu and QZn derivatives, showed the highest degree of inhibition of the fish's locomotor activity, suggesting a possible anxiolytic action. Then, quercetin complexes with metals, mainly with Fe+2, represent valuable compounds and deserve more investigation as promising agents against Alzheimer's disease.

Trypanocidal activity of polysaccharide extract from Genipa americana leaves.

ETHNOPHARMACOLOGICAL RELEVANCE: The parts of the Genipa americana (Rubiaceae) tree, also known as "jenipapo" or "jenipapeiro", has been used in traditional Medicine in parasitic and bacterial infections. Thus, the experimental evolution of the antiparasitic activity of polysaccharide extracts from Genipa americana leaves, and correlation with antiparasitic and popular use is important. AIM OF THE STUDY: To evaluate the effect of polysaccharide extract obtained from Genipa americana leaves on all Trypanosoma cruzi (Y strain: benznidazole-resistant) developmental forms, a protozoan that causes Chagas' disease. MATERIALS AND METHODS: An extract rich in polysaccharides was obtained from the leaves of Genipa americana (GaEPL) by associating depigmentation in methanol followed by extraction of polysaccharides in NaOH and precipitation with ethanol. Cytotoxicity to mammalian cells (LLC-MK2) was determined using an MTT assay. Antiparasitic activity was evaluated against epimastigote, trypomastigote and amastigote forms of T. cruzi. Cell-death mechanism was determined in epimastigote forms by flow cytometry analysis after FITC-annexin V (Ax), 7-AAD, and H2DCFDA staining. Striking morphological changes were observed by scanning electron microscope. RESULTS: GaEPL (6.5% yield; 54.6% total carbohydrate; 21.1% uronic acid and 12% protein), inhibited all T. cruzi developmental forms, epimastigotes after periods of 24h (IC50 = 740 ± 0.075µg/mL), 48h (IC50 = 710 ± 0.053µg/mL) and 72h (IC50 = 870 ± 0.052µg/mL) of incubation; trypomastigotes (IC50 = 470 ± 0.082µg/mL) after periods of 24h and intracellular amastigotes (IC50/2 = 235 or IC50 = 470µg/mL) after periods of 24 and 48h of incubation, with no toxicity on LLC-MK2 cells at the used concentrations. Analysis of the possible action mechanism in the parasites suggested cell death by necrosis with the involvement of reactive oxygen species (ROS). The scanning electron microscopy (SEM) confirmed T. cruzi death by necrosis. CONCLUSIONS: GaEPL showed significant activity against the epimastigote, trypomastigote and amastigote forms of T. cruzi, strain Y, suggesting cell death by necrosis with involvement of reactive oxygen species.