Voltammetric determination of harmaline in natural food products using boron-doped diamond electrode

UV-light-driven photooxidation of harmaline catalyzed by riboflavin: Product characterization and mechanisms

β-Carboline alkaloid harmaline (HA) is a candidate drug molecule that has been proven to have broad and significant biological activity. Herein, the effects of HA on the riboflavin (RF)-sensitized photooxidation under aerobic conditions were studied for the first time. The photooxidation reaction of HA catalyzed by RF is triggered by UV light at 365 nm and shows a time-dependent stepwise reaction process. Seven transformed products, including five undescribed compounds, oxoharmalines A-E (1-4 and 7), and two known compounds, N-(2-(6-Methoxy-2-oxoindolin-3-yl)ethyl)acetamide (5) and harmine (6), were isolated and identified from the reaction system, following as the gradual oxidation mechanisms. The rare polymerization and dehydrogenation processes in radical-mediated photocatalytic reactions were involved in the process. The transformed products 2-7 exhibited significant neuroprotective activity in a model of H₂O₂-introduced injury in SH-SY5Y cells, which suggested that the products of the interaction between HA and vitamins may be beneficial to health.

Recent advances in ZnO nanostructure-based electrochemical sensors and biosensors

Nanostructured metal oxides, such as zinc oxide (ZnO), are considered as excellent materials for the fabrication of highly sensitive and selective electrochemical sensors and biosensors due to their good properties, including a high specific surface area, high catalytic efficiency, strong adsorption ability, high isoelectric point (IEP, 9.5), wide band gap (3.2 eV), biocompatibility and high electron communication features. Thus, ZnO nanostructures are widely used to fabricate efficient electrochemical sensors and biosensors for the detection of various analytes. In this review, we have discussed the synthesis of ZnO nanostructures and the advances in various ZnO nanostructure-based electrochemical sensors and biosensors for medical diagnosis, pharmaceutical analysis, food safety, and environmental pollution monitoring.

A Review on Recent Advances in the Applications of Boron-Doped Diamond Electrochemical Sensors in Food Analysis

The usage of boron-doped diamond (BDD) material has found to be very attractive in modern electroanalytical methods and received massive consideration as perspective electrochemical sensor due to its outstanding (electro)chemical properties. These generally known facilities include large potential window, low background currents, ability to withstand extreme potentials and strong tendency to resist fouling compared to conventional carbon-based electrodes. As evidence of superiority of this material, couple of reviews describing the overview of various applications of BDD electrodes in the field of analytical and material chemistry has been reported in scientific literature during last decade. However, herein proposed review predominantly focuses on the most recent developments (from 2009 to 2020) dealing with the application of BDD as an advanced and environmental-friendly sensor platform in food analysis. The main method characteristics of analysis of various organic food components with different chemical properties, including additives, flavor and aroma components, phenolic compounds, flavonoids and pesticides in food matrices are described in more details. The importance of BDD surface termination, presence of sp² content and boron doping level on electrochemical sensing is discussed. Apart from this, a special attention is paid to the evaluation of main analytical characteristics of the BDD electrochemical sensor in single- and multi-analyte detection mode in food analysis. The recent achievements in the utilizing of BDD electrodes in amperometric detection coupled to flow injection analysis, batch injection analysis, and high-performance liquid chromatography are also commented. Moreover, actual trends in sample preparation techniques prior to electrochemical sensing in food analysis are referred.

Ayahuasca: Uses, Phytochemical and Biological Activities

Ayahuasca (caapi, yajé), is a psychoactive brew from the Amazon Basin region of South America traditionally considered a "master plant." It is prepared as a decoction from Banisteriopsis caapi and Psychotria viridis, which it is thought that it stimulates creative thinking and visual creativity. Native healers of the Orinoco and Amazon basins have used traditionally ayahuasca as a healing tool for multiple purposes, particularly to treat psychological disorders in the patients, with some beneficial effects experimentally and clinically validated. Recently, several syncretic religions, as the "União de Vegetal" (UDV) group in Brazil, have been spread around the world. The use of ayahuasca has been popularized by internet and smart-shops, bringing the psychoactive substance to new highs, emerging new "ayahuasqueros." Ayahuasca has alkaloids as β-carbolines and dimethyltryptamines, which inhibit the monoamine oxidase and active the 5-HT2A (5-hydroxytryptamine) receptor, respectively, resulting in hallucinations in the users. Ayahuasca induces a psychedelic change in the anteroposterior coupling of the electrophysiological brain oscillations in humans. Traditional ayahuasca beverage is generating pharmacological, commercial and spiritual interest among the scientific community, government people, and different populations worldwide. The goal of this article is to report about the uses, chemistry and biological activities of ayahuasca.