Intrinsic Antioxidant Potential of the Aminoindole Structure: A Computational Kinetics Study of Tryptamine

Novel C3-Methylene-Bridged Indole Derivatives with and without Substituents at N1: The Influence of Substituents on Their Hemolytic, Cytoprotective, and Antimicrobial Activity

Alkaloids are natural compounds useful as scaffolds for discovering new bioactive molecules. This study utilized alkaloid gramine to synthesize two groups of C3-substituted indole derivatives, which were either functionalized at N1 or not. The compounds were characterized by spectroscopic methods. The protective effects of the new compounds against in vitro oxidative hemolysis induced by standard oxidant 2,2'-azobis(2-amidinopropane dihydro chloride (AAPH) on human erythrocytes as a cell model were investigated. Additionally, the compounds were screened for antimicrobial activity. The results indicated that most of the indole derivatives devoid of the N1 substitution exhibited strong cytoprotective properties. The docking studies supported the affinities of selected indole-based ligands as potential antioxidants. Furthermore, the derivatives obtained exhibited potent fungicidal properties. The structures of the eight derivatives possessing indole moiety bridged to the imidazole-, benzimidazole-, thiazole-, benzothiazole-, and 5-methylbenzothiazoline-2-thiones were determined by X-ray diffraction. The C=S bond lengths in the thioamide fragment pointed to the involvement of zwitterionic structures of varying contribution. The predominance of zwitterionic mesomers may explain the lack of cytoprotective properties, while steric effects, which limit multiple the hydrogen-bond acceptor properties of a thione sulfur, seem to be responsible for the high hemolytic activity.

Varietal Influence on the Formation of Bioactive Amines during the Processing of Fermented Cocoa with Different Pulp Contents

During cocoa processing, there can be the formation of bioactive amines, which are compounds that play relevant roles not only in plant development but also in human health. Thus, we aimed to investigate the presence and levels of bioactive amines during the processing of two important varieties of cocoa (PS 1319 and Parazinho). The seeds were fermented using five different pulp proportions: 100% (E1), 80% (E2), 60% (E3), and 0% (total pulp removal) (E4). The beans were fermented and dried on a farm following traditional procedures. Soon after, they were roasted and processed into chocolates with 60% cocoa in the laboratory. Bioactive amine contents were determined by ion-pair reversed-phase HPLC and fluorometric detection in the samples before, during, and after fermentation, after drying and roasting (nibs), and in the liquor and chocolate. The only amines found before processing in PS 1319 and Parazinho, respectively, in dry weight basis (dwb), were putrescine (pulp, 13.77 and 12.31; seed, 5.88 and 4.58) and serotonin (seed, 2.70 and 2.54). Fermentation was shorter for Parazinho (156 h) compared to PS 1319 (180 h). The changes in amines were affected by the cocoa variety. During drying, the presence of cadaverine stood out, appearing in all treatments of the PS 1319 variety, reaching 17.96 mg/kg dwb, and in two treatments of the Parazinho variety (100 and 60% pulp). During roasting, most of the amines decreased, except for phenylethylamine, which increased up to 2.47 mg/kg dwb for Parazinho and 1.73 mg/kg dwb for PS 1319. Most of the amines formed and built up (e.g., tyramine, putrescine, and cadaverine) during fermentation were not available or were at low levels in the nibs. Most of the amines found during processing did not reach the final product (chocolate), except for cadaverine in PS 1319 without pulp (7.54 mg/kg dwb). Finally, we confirmed how pulp content, processing, and variety influence the content of bioactive amines in cocoa and chocolate. These changes can be better demonstrated through a heatmap and principal component analysis.

Elucidation of reactive oxygen species scavenging pathways of norbergenin utilizing DFT approaches

Bergenin is a polyphenolic compound that contains isocoumarin skeletal derived from C-glycosylated 4-O-methylgallic acid. The biological activities of this compound and its derivatives are quite diverse. Recent studies reveal neuroprotective effects in vitro and in vivo in Alzheimer's. Norbergenin is a demethylated form of bergenin, known for better antioxidant capacity and associated with neuroprotective properties through oxidative stress inhibition. This study focused on investigating the scavenging mechanism of norbergenin with the ^•OH, ^•OOH, and O 2 ∙ - as a radical model under physiological and lipid environments. The thermodynamic and kinetic parameters of the hydrogen transfer (HT), single electron transfer (SET), sequential proton lost-electron transfer (SPLET) and radical adduct formation (RAF) mechanisms were determined theoretically by the density functional theory (DFT) at M06-2X/6-311 + + G(d,p) level of theory. Based on the computational results, this compound has proved as an excellent ^•OOH and ^•OH scavenger under physiological conditions better than Trolox and vitamin C, whereas its radical demonstrated as an efficient O 2 ∙ - scavenger.

On The Radical Scavenging and DNA Repairing Activities by Natural Oxygenated Diterpenoids: Theoretical Insights

Diterpenoids are abundant and important compounds in Euphorbia species owing to their structural diversity; therefore, in this study, we investigate the modern-concept antioxidant activities, including free-radical scavenging and oxidative DNA damage repairing, of highly oxygenated diterpenoids originating from the aerial part of Euphorbia helioscopia. Four compounds with structural types of ent-abietane, containing a fused furan ring in their structures, including euphelionolide A (1), euphelionolide D (2), euphelionolide I (3), and euphelionolide L (4) are selected. First, the radical-scavenging activity of these compounds was evaluated with two typical radicals HOO^• and HO^• in water and pentyl ethanoate (PEA, to mimic lipid environment) via three main mechanisms, namely, hydrogen atom transfer (HAT), radical adduct formation (RAF), and single electron transfer. It is found that the studied compounds are able to scavenge free radicals at multiple reactive sites favorably via HAT and RAF mechanisms, in which the former dominates in the case with HOO^• while both mechanisms are competitive in the reaction with HO^•. Second, chemical repairing of DNA damage is modeled with the H-atom and single electron being transferred from the studied molecules to damaged 2'-deoxyguanosine (2dG) (i.e., 2dG^• radicals and 2dG^•+ radical cation). Among the four compounds, euphelionolide A is shown as the most effective radical scavenger and also the highest potential species for chemical repairing of radical-damaged DNA in both water and PEA.

Current Trends in Computational Quantum Chemistry Studies on Antioxidant Radical Scavenging Activity

The antioxidative nature of chemicals is now routinely studied using computational quantum chemistry. Scientists are constantly proposing new approaches to investigate those methods, and the subject is evolving at a rapid pace. The goal of this review is to collect, consolidate, and present current trends in a clear, methodical, and reference-rich manner. This paper is divided into several sections, each of which corresponds to a different stage of elaborations: preliminary concerns, electronic structure analysis, and general reactivity (thermochemistry and kinetics). The sections are further subdivided based on methodologies used. Concluding remarks and future perspectives are presented based on the remaining elements.

New insights into the competition between antioxidant activities and pro-oxidant risks of rosmarinic acid

Direct and indirect antioxidant activities of rosmarinic acid (RA) based on HOO˙/CH₃OO˙ radical scavenging and Fe(iii)/Fe(ii) ion chelation were theoretically studied using density functional theory at the M05-2X/6-311++G(2df,2p) level of theory. First, four antioxidant mechanisms including hydrogen atom transfer (HAT), radical adduct formation (RAF), proton loss (PL) and single electron transfer (SET) were investigated in water and pentyl ethanoate (PEA) phases. Regarding the free radical scavenging mechanism, HAT plays a decisive role with overall rate coefficients of 1.84 × 10³ M⁻¹ s⁻¹ (HOO˙) and 4.49 × 10³ M⁻¹ s⁻¹ (CH₃OO˙) in water. In contrast to PL, RAF and especially SET processes, the HAT reaction in PEA is slightly more favorable than that in water. Second, the [Fe(iii)(H₂O)₆]³⁺ and [Fe(ii)(H₂O)₆]²⁺ ion chelating processes in an aqueous phase are both favorable and spontaneous especially at the O5, site-1, and site-2 positions with large negative Δ_rG⁰ values and great formation constant K_f. Finally, the pro-oxidant risk of RA⁻ was also considered via the Fe(iii)-to-Fe(ii) complex reduction process, which may initiate Fenton-like reactions forming reactive HO˙ radicals. As a result, RA⁻ does not enhance the reduction process when ascorbate anions are present as reducing agents, whereas the pro-oxidant risk becomes remarkable when superoxide anions are found. The results encourage further attempts to verify the speculation using more powerful research implementations of the antioxidant activities of rosmarinic acid in relationship with its possible pro-oxidant risks.

Direct and indirect antioxidant activities of rosmarinic acid (RA) based on HOO˙/CH₃OO˙ radical scavenging and Fe(iii)/Fe(ii) ion chelation were theoretically studied using density functional theory at the M05-2X/6-311++G(2df,2p) level of theory.

The therapeutic potential of diet on immune-related diseases: based on the regulation on tryptophan metabolism

Tryptophan (TRP), as an essential amino acid, plays crucial roles in maintaining immune homeostasis due to its complex metabolism pathway, including the microbial metabolism, 5-hydroxytryptamine and kynurenine pathways (KP). Metabolites from these pathways can act antioxidant and endogenous ligand of aryl hydrocarbon receptor (including microbiota metabolites: indole, indole aldehyde, indole acetic acid, indole acrylic acid, indole lactate, indole pyruvate acid, indole propionic acid, skatole, tryptamine, and indoxyl sulfate; and KP metabolites: kynurenine, kynurenic acid, 3-hydroxyanthranilic acid, xanthurenic acid, and cinnabarinic acid) for regulating immune response. In immune-related diseases, the production of pro-inflammatory cytokine activates indoleamine-2,3-dioxygenase, a rate-limiting enzyme of KP, leading to abnormal TRP metabolism in vivo. Many recent studies found that TRP metabolism could be regulated by diet, and the diet regulation on TRP metabolism could therapy related diseases. Accordingly, this review provides a critical overview of the relationships among diet, TRP metabolism and immunity with the aim to seek a treatment opportunity for immune-related diseases.

FTIR and PLS-regression in the evaluation of bioactive amines, total phenolic compounds and antioxidant potential of dark chocolates

Cloning techniques are used to improve agronomical traits and answer to the demand for fine chocolate. The objective of this study was to predict the concentrations of bioactive amines, phenolic compounds, and the antioxidant potential of dark monoclonal chocolate from nine fine cocoa varieties by FTIR analysis and conventional techniques. Total phenolic compounds, bioactive amines and antioxidant activity varied significantly among chocolates. The antioxidant activity was also affected by the analytical method (DPPH vs. Rancimat). Chemometric models based on FTIR data provided satisfactory predictions of the concentrations of the amines: spermidine (R2 = 0.92; RMSEP = 0.39; RMSEC = 0.21), tryptamine (R2 = 0.92; RMSEP = 0.41; RMSEC = 0.20), cadaverine (R2 = 0.82; RMSEP = 1.58; RMSEC = 0.75) and tyramine (R2 = 0.87; RMSEP = 1.87; RMSEC = 0.68); as well as phenolic compounds and antioxidant activity by Rancimat® (R2 = 0.98; RMSEP = 0.32; RMSEC = 0.21) and DPPH (R2 = 0.97; RMSEP = 4.05; RMSEC = 1.66). The wavenumbers of amines vibrations are among those that most affected antioxidant prediction models, confirming the contribution of amines to the antioxidant activity of chocolates.

In vitro bioaccessibility of amino acids and bioactive amines in 70% cocoa dark chocolate: What you eat and what you get

Chocolate is an important source of free bioactive amines and amino acids which play important roles in human health. Considering the limited information on the bioaccessibility of these compounds from chocolate, the objective of this study was to characterize their profiles and bioaccessibility in 70% cocoa dark chocolate through in vitro simulation of oral, gastric and intestinal digestions. Seven amines were detected; polyamines were predominant before in vitro digestion, whereas tyramine, cadaverine and spermidine after digestion. All amines showed high bioaccessibility with slight influence of digestive enzymes. Amines increased after gastrointestinal digestion: tyramine (13-fold), tryptamine (9-fold), others (2.4-4.2-fold) and histamine appeared. All amino acids, GABA and ammonia were detected in chocolate, and their contents increased after in vitro digestion due to digestive enzymes (4.6, 2.8 and 2.1, respectively). Dark chocolate protein is a good source of tryptophan, phenylalanine + tyrosine, isoleucine, histidine, but limiting for lysine, leucine, and threonine.