Antiviral Activity and Underlying Action Mechanism of Euglena Extract against Influenza Virus.

It is difficult to match annual vaccines against the exact influenza strain that is spreading in any given flu season. Owing to the emergence of drug-resistant viral strains, new approaches for treating influenza are needed. Euglena gracilis (hereinafter Euglena), microalga, used as functional foods and supplements, have been shown to alleviate symptoms of influenza virus infection in mice. However, the mechanism underlying the inhibitory action of microalgae against the influenza virus is unknown. Here, we aimed to study the antiviral activity of Euglena extract against the influenza virus and the underlying action mechanism using Madin-Darby canine kidney (MDCK) cells. Euglena extract strongly inhibited infection by all influenza virus strains examined, including those resistant to the anti-influenza drugs oseltamivir and amantadine. A time-of-addition assay revealed that Euglena extract did not affect the cycle of virus replication, and cell pretreatment or prolonged treatment of infected cells reduced the virus titer. Thus, Euglena extract may activate the host cell defense mechanisms, rather than directly acting on the influenza virus. Moreover, various minerals, mainly zinc, in Euglena extract were found to be involved in the antiviral activity of the extract. In conclusion, Euglena extract could be a potent agent for preventing and treating influenza.

Euglena Species: Bioactive Compounds and their Varied Applications.

Euglena, a microalga, has gained a great attention as it contains several bioactive compounds including food supplements, drugs and biofuels. The genus Euglena includes >300 species of unicellular, fresh water flagellates. The objective of this review article concerns the presentation of updated information on pharmacological and therapeutic properties and industrial implications of molecules isolated from Euglena species. A bibliographic search of scientific literature published till March, 2020 was made from scientific databases using different search engines. Euglena produces several antioxidant molecules, such as ß-carotene, L-ascorbic acid, polymers of unsaturated fatty acids and phytotoxins useful in manufacturing many pharmaceutical, cosmetics, and nutraceutical compounds. It is a rich source of antimicrobial, anticancer, immunomodulatory compounds. Though, several studies have indicated its therapeutic applications, extensive research is needed to explore its efficacy against many pathophysiological conditions including toxicity assessment of compound(s). Nevertheless, the biotechnological influence on industrial production of Euglena has been less exploited.

Exploring the Microalga Euglena cantabrica by Pressurized Liquid Extraction to Obtain Bioactive Compounds.

In the present study, the chemical composition of the microalga Euglena cantabrica was investigated. The extraction of bioactive compounds was done using pressurized liquid extraction (PLE) at different temperatures (40-180 °C) and using green solvents (ethanol-water mixtures). A statistical design of experiments was used to optimize the maximum antioxidant capacity of the extracts by response surface methodology. The antioxidant capacity was determined through the inhibition of 2,2'-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid (ABTS) and 1,1-diphenyl-2-picrylhydrazyl (DPPH) radicals, while the chemical analyses of the extracts were carried out using different chromatographic techniques. Chlorophylls and carotenoids were analyzed by high-performance liquid chromatography coupled to a diode array detector and mass spectrometry (HPLC-DAD-MS/MS) and carbohydrates by gas chromatography with flame ionization detection (GC-FID) and high-pressure size-exclusion chromatography coupled to an evaporative light-scattering detector (HPSEC-ELSD). The results showed different possibilities for the extraction conditions, depending on the desired bioactivity or chemical composition. Briefly, (i) mixtures of ethanol-water containing around 40% ethanol at 180 °C gave the best antioxidant capacity, (ii) mixtures containing around 50% ethanol at 110 °C gave the best yield of ß-glucan paramylon, and (iii) the use of pure ethanol at a low temperature (40 °C) is the best choice for the recovery of carotenoids such as diatoxanthin. Summing up, E. cantabrica seems to be a good candidate to be used in biorefinery to obtain different bioactive compounds.

Dietary supplement product composed of natural ingredients as a suspected cause of erythema multiforme: A case report and identification for the confident false positivity of lymphocyte transformation test.

Growing and sustainable consumption of health-care products raises a controversial issue underlying the reliability of an in vitro diagnostic approach for adverse skin reaction. This report aimed to: (i) discuss the causative nature of a commercial dietary supplement composed of natural ingredients, particularly an Euglena-containing product, suspicious for erythema multiforme in our exemplified case; and (ii) to address the assay suitability of the lymphocyte transformation test (LTT) for identifying allergic reaction to any ingredient(s) of the product. A Japanese elderly man developed erythema multiforme after intake of a commercially available natural dietary product, whose LTT was positive. His clinical course and positive LTT suggested a provisional diagnosis of natural dietary product-induced eruption. We conducted an inquiry survey for the standard LTT with any commercial products containing Euglena in three major Japanese laboratory services and identified 22 subjects, almost all of whom (21/22, 95.6%) showed a positive LTT for any Euglena-containing products as a suspected causative. Seven normal healthy volunteers who had no intake history of Euglena-containing products showed an equivalent LTT positivity rate with the same product taken by our case; culprit components of the product included Euglena, Angelica keiskei, Barley grass and Chlorella. A cell-free culture system and enzyme-linked immunoassay suggest that the high LTT positivity relies on the non-specific lymphoproliferative activity, and not contamination of uncharacterized microorganisms and endotoxins. Because of the constitutive false positivity of LTT, this assay is unreliable for in vitro supportive diagnosis of adverse skin events caused by dietary products containing particular natural ingredients, as well as herbal materials.

Protein translocation within chloroplast is similar in Euglena and higher plants.

It is currently thought that chloroplasts of higher plants were derived from endosymbiont oxygenic photosynthetic bacteria (primary endosymbiosis), while Euglena, a photosynthetic protista, gained chloroplasts by secondary endosymbiosis (i.e., incorporation of a photosynthetic eukaryote into heterotrophic eukaryotic host). To examine if the protein transport inside chloroplasts is similar between these organisms, we carried out heterologous protein import experiments with Euglena precursor proteins and spinach chloroplasts. The precursor of a 30-kDa subunit of the oxygen-evolving complex (OEC30) from the thylakoid lumen of Euglena chloroplasts contained the N-terminal signal, stroma targeting, and thylakoid transfer domains. Truncated preOEC30s lacking the N-terminal domain were post-translationally imported into spinach chloroplasts, transported into the thylakoid lumen, and processed to a mature protein. These results showed that protein translocations within chloroplasts in Euglena and higher plants are similar and supported the hypothesis that Euglena chloroplasts are derived from the ancestral Chlorophyta.