Tag: Japan

Doxepin is an antihistaminic, antidepressant, and sleeping aid that has two geometric isomers—molecules with equal chemical formulas but different 3D arrangements. While its Z-isomer is known to be more effective than its E-isomer, the precise nature of its binding to the histamine H1 receptor remained elusive. Now, in a recent study, researchers from Japan thoroughly addressed this knowledge gap through an innovative experimental protocol, paving the way to next-generation antihistamines with fewer side effects.

Even if two molecules have the exact same chemical formula and the same number and types of bonds, their three-dimensional arrangements can still be different. While some people might mistakenly disregard this as a minor detail, even simple changes in the position or orientation of a functional group can dramatically affect the biological properties of a molecule, sometimes rendering an otherwise benign substance into a highly toxic one. Thus, the study of such possible molecular variants, called ‘geometric isomers,’ is essential in the field of drug development.

Doxepin stands out as a notable example of a drug that is commercialized as a mixture of two geometric isomers, namely the E- and Z-isomers. Both doxepin isomers bind to histamine H1 receptor (H1R), which is expressed throughout the central nervous system, smooth muscle cells, and vascular endothelial cells. Besides its use as an antihistaminic drug, doxepin is also typically used as an antidepressant and sleeping aid. While biological tests in animals have shown that the Z-isomer is more effective than the E-isomer, the differences in affinity to H1R between the E- and Z-isomers are unknown. Moreover, the specifics of how these compounds actually bind to H1R remain elusive.

Against this backdrop, a research team from Tokyo University of Science, Japan, set out to clarify the finer details of the interactions between doxepin isomers and H1R. Their latest paper, which was published on June 25, 2024, in the Journal of Molecular Recognition, was co-authored by Professor Mitsunori Shiroishi, Mr. Hiroto Kaneko, and Associate Professor Tadashi Ando, among others. This study is a follow-up to past work done by Prof. Shiroishi and colleagues. “We previously revealed the crystal structure of the complex formed by H1R and doxepin, but we were unable to determine which isomer was bound,” he explains, “We then came up with a method to determine the binding affinity of the isomers, and thus carried out this study.”

To achieve this challenging goal, the researchers first produced a customized yeast expression vector by strategically inserting the H1R gene into it. This vector was used to modify yeast cultures so that they produce H1R. After retrieving the membranes from these cells, they applied a solution containing commercial doxepin, producing H1R-doxepin complexes. Following extraction and purification of these complexes, they removed any excess (unbound) doxepin. Finally, by denaturing the H1R receptors, they could free the bound doxepin molecules and measure their numbers in a high-performance liquid chromatography setup.

Using this protocol, the researchers could accurately quantify the amount of each isomer that was bound to the extracted receptors, which is directly tied to their relative binding affinity. They found that the affinity to H1R of the Z-isomer was over five times higher than that of the E-isomer.

The team then delved deeper into the nature of how doxepin isomers bind to H1R. Through experiments on a mutant variant of H1R coupled with molecular dynamics simulations, they revealed that the Thr112 side chain in the ligand-binding pocket of H1R creates a chemical environment that enhances selectivity for the Z-isomer.

Taken together, the findings of this study shed light on how a widely used small molecule drug interacts with an important cellular receptor. “Our efforts could serve as the basis for designing next-generation antihistamines that are more effective and have fewer side effects,” highlights Prof. Shiroishi, “Worth noting, this newfound knowledge will be useful for designing compounds that bind not only to H1R, but also other disease-relevant target proteins.”

The rational design of future drugs, aided and validated by computational techniques like molecular dynamics simulations, could usher in a new era in medicine. More specifically, by understanding the binding properties of isomers in detail, many small-molecule drugs could be made more effective, safer, and better suited for targeted therapies.

Let us hope this vision of the future becomes a reality soon!

Solid oxide fuel cells (SOFCs) are a promising avenue to meet global demands for clean energy. They can produce electricity through environmentally friendly electrochemical reactions. However, existing SOFCs operate at high temperatures, which lowers their efficiency. Now, researchers from Japan have developed a novel perovskite-based anode material for SOFCs that exhibits mixed hole–proton conduction at medium-range temperatures. Their findings will help establish more efficient energy technologies, leading the way to more sustainable societies.

Amidst the ongoing energy and climate crises, the stakes have never been higher. We are pressed for time to find better ways of producing clean energy to replace fossil fuels. Thus far, fuel cells appear to be one of the most promising research directions. These electrochemical devices can produce electricity directly from chemical reactions, which can be tailored to be environmentally friendly in terms of their reactants and outputs.

Various types of fuel cells exist, but solid oxide fuel cells (SOFCs) have attracted special attention from researchers. By operating without the need for a liquid electrolyte, they offer higher safety and are often easier to manufacture. Unfortunately, one of their main drawbacks is their high operating temperature. Conventional SOFCs need to be at over 700 °C to work properly, which limits their applicability, reduces their efficiency and power output, and often compromises their durability. Thus, proton-conducting SOFCs (PC-SOFCs), which can operate within a lower temperature range, are being investigated as a promising alternative.

Against this backdrop, a research team including Professor Tohru Higuchi from Tokyo University of Science has achieved a breakthrough in PC-SOFCs by developing a novel hole–proton mixed-conductor material. Their findings, which have been published in the Journal of the Physical Society of Japan on June 18, 2024, could pave the way for important technological advancements in energy technologies.

The material in question is a perovskite-type oxide ceramic with the formula BaCe0.4Pr0.4Y0.2O3−δ (BCPY). These particular dopants, namely Pr and Y ions, were selected based on previous works by members of the research team. They observed that BaCe0.9Y0.1O3−δ and BaPrO3−δ exhibited proton and hole (a type of positive charge carrier) conduction, respectively. Thus, they theorized that co-doping with both Pr and Y might lead to high proton–hole mixed conductivity.

Such a material could be used in the anode electrode of PC-SOFCs, as Prof. Higuchi explains: “The Pt metal electrode used in other fuel cells has issues, such as a large drop in power output because electrochemical reactions occur only at the three-phase interface where the fuel gas/electrode/electrolyte intersect. To solve this issue, a dense membrane with mixed conduction could be useful for improving the performance of PC-SOFC by expanding the electrochemical reaction area.”

Using a sputtering technique, the researchers produced thin films of BCPY and carefully analyzed its conduction properties, seeking to find evidence of mixed proton–hole conduction. To this end, they established a quantitative evaluation method to determine oxygen vacancies using X-ray absorption spectroscopy and defect chemistry analysis. Through these and several additional experiments, including synchrotron radiation photoelectron spectroscopy for electronic band structure analysis, they found substantial evidence that mixed hole–proton conductivity can occur on the surface of the proposed electrode material.

Notably, BCPY electrodes exhibited a high conductivity of over 10−2 S.K/cm at 300 °C, which outlines a bright future not only for PC-SOFCs, but for other technologies as well. “If we can further confirm that BCPY thin films do enable hole–proton mixed conductivity, BCPY may become a novel oxide material for not only PC-SOFC anode electrode membranes but also electric-double-layer-transistors,” highlights Prof. Higuchi. To clarify, this transistor technology can address the scalability and miniaturization problems of conventional transistors, which will be crucial to developing artificial intelligence systems and increasing the computational capacity of personal electronic devices.

In any case, this study sheds some much-needed light on new electrode materials for PC-SOFCs. With further advances in this exciting field, electrochemical energy generation could eventually enable us to power up our homes and cars with cleaner electricity, paving the way to more sustainable societies.

Nanoscale electron transfer (ET) in solids is fundamental to the development of multifunctional materials. However, ET in solids is not yet clearly understood. Now, researchers from Japan achieved a direct observation of solid-state ET through X-ray crystal analysis by fabricating a novel double-walled non-covalent crystalline nanotube, which can absorb electron donor molecules and maintain its crystalline structure during ET. This innovative approach can lead to the design of novel functional materials soon.

Electron transfer (ET) is a process in which an electron is transferred from one atom or molecule to another. ET is fundamental to electrochemical reactions with applications in many fields. Nanoscale ET, which involves the transfer of electrons in the range of 1–100 nanometers in solids is fundamental to the design of multifunctional materials. However, this process is not yet clearly understood.

Nanotubes, nanomaterials with unique cylindrical nanostructures, offer a variety of ET properties that can be realized through electron and hole (vacant spaces left by electrons) injections into the nanotubes, making them a suitable candidate for studying nanoscale ET. Although carbon-based nanotubes have fascinating ET properties, they are particularly difficult to control in terms of their shape and size due to extreme conditions, such as high temperatures, required for their synthesis. A viable approach for fabricating well-defined tunable nanotubes is bottom-up fabrication of non-covalent nanotubes, which sometimes result in crystalline-form nanotubes. Non-covalent nanotubes are formed through the inherent attractive interactions or non-covalent interactions between atoms, instead of the strong covalent interactions seen in carbon nanotubes. However, they are not strong enough to endure electron and hole injections, which can break their non-covalent interactions and destroy their crystalline structure.

In a recent study, a team of researchers from the Department of Applied Chemistry at Tokyo University of Science, led by Professor Junpei Yuasa and including Dr. Daiji Ogata, Mr. Shota Koide, and Mr. Hiroyuki Kishi, used a novel approach to directly observe solid-state ET. Prof. Yuasa explains, “We have developed crystalline nanotubes with a special double-walled structure. By incorporating electron donor molecules into the pores of these crystalline nanotubes through a solid-state oxidation reaction, we succeeded in directly observing the electron transfer reaction in the solid using X-ray crystal structure analysis.” Their findings were published in the journal Nature Communications on May 23, 2024.

The researchers used a novel supramolecular crystallization method, which involves oxidation-based crystallization, to fabricate zinc-based double-walled crystalline nanotubes. This double-walled structure with large windows in the nano-tube walls makes the crystal robust and flexible enough to maintain its crystalline state when subjected to ET oxidation processes. Moreover, this structure allows the crystal to absorb electron donor molecules. The researchers used ferrocene and tetrathiafulvalene as electron donor molecules, which were absorbed through the windows of the nanotube crystals. This allows electrons to be removed from the absorbed electron donors through solid-state ET oxidation reactions, resulting in the accumulation of holes in the donors inside the nanotube. Due to the robustness of the crystals, the researchers were able to observe this ET oxidation process using X-ray crystal structure analysis directly, uncovering key insights.

This novel approach is highly valuable for direct observation of ET in solid nanomaterials. Highlighting the potential applications of this study, Prof. Yuasa says, “Understanding ET can lead to the development of novel functional materials, which in turn can lead to the design of more efficient semiconductors, transistors, and other electronic devices. Optoelectronic devices, such as solar cells, rely heavily on ET. Hence, direct observation of ET can help improve these devices’ performance. Additionally, this approach can lead to advancements in energy storage, nanotechnology, and materials science research.”

Overall, this study is a striking example of direct observation of solid-state ET, which can be expanded to observe ET and related phenomena in other nanomaterials.

 

Obesity and inflammatory diseases are increasing in prevalence and contribute to the growing burden of lifestyle disorders such as diabetes and hypertension. There is a lack of naturally derived alternatives to tackle these issues. Researchers from Tokyo University of Science have synthesized novel amino acid derivatives of menthol and studied its properties. The menthyl esters showed exceptional anti-inflammatory and anti-obesity activities during preclinical studies and can be developed as therapeutic compounds with further research.

Modified derivatives of natural products have led to significant therapeutic advances and commercial success in recent times. Menthol is a naturally occurring cyclic monoterpene alcohol found in various plants, particularly in members of the mint family such as peppermint and spearmint. It is a common ingredient found in a wide range of confectionaries, chewing gums and oral care products. Interestingly, menthol also has high medicinal value due to its analgesic, anti-inflammatory, and anti-cancer effects.

In a recent study, a team of researchers led by Professor Gen-ichiro Arimura from the Department of Biological Science and Technology, Tokyo University of Science, Japan, developed and investigated menthyl esters of valine (MV) and isoleucine (MI), which are derived from menthol by replacing its hydroxyl group with valine and isoleucine, respectively.

Their research findings were published in the Immunology journal on May 08, 2024. Sharing the motivation behind the present work, Prof. Arimura says, “The functional components of plants that contribute to human health have always intrigued me. Discovering new molecules from natural materials inspired our research team to develop these amino acid derivatives of menthol.”

The researchers began by synthesizing menthyl esters of six amino acids characterized by less-reactive side chains. Subsequently, they assessed the properties of these esters using in vitro cell line studies. Finally, they conducted experiments in mice to explore the effects of these compounds under induced disease conditions. The exceptional anti-inflammatory profiles of MV and MI was determined by assessing the transcript levels of tumor necrosis factor-α (Tnf) in stimulated macrophage cells. Remarkably, both MV and MI outperformed menthol in the anti-inflammatory assay. RNA sequencing analysis revealed that 18 genes involved in inflammatory and immune responses were effectively suppressed.

Elated with their findings, the researchers went a step further and investigated the mechanism of action of the menthyl esters. They discovered that liver X receptor (LXR) – an intracellular nuclear receptor, had an important role in the anti-inflammatory effects and this was independent of the cold-sensitive transient receptor TRPM8, which primarily detects menthol. Delving deeper into the LXR-dependant activation of MV and MI, they found that Scd1 gene – central to lipid metabolism was upregulated by LXR. Moreover, in mice with induced intestinal colitis, the anti-inflammatory effects were further validated with suppressed transcript levels of Tnf and Il6 genes by MV or MI, in an LXR-dependent manner.

Driven by the discovery of LXR-SCD1 intracellular machinery, Prof. Arimura and his team hypothesized the menthyl esters to possess anti-obesity properties. They found that these esters inhibited adipogenesis-fat accumulation, specifically at the mitotic clonal expansion stage in 3T3-L1 adipocyte cells. During animal studies, the diet-induced obesity in mice was ameliorated and adipogenesis was suppressed.

Menthyl esters possess unique advantages compared to other anti-inflammatory or anti-obesity compounds currently being researched or used. Their specific mechanisms of action, that contribute to their dual anti-inflammatory and anti-obesity effects sets them apart from other compounds and may make them particularly effective in addressing both inflammatory conditions and metabolic disorders. They could benefit specific populations like individuals with chronic inflammatory conditions, metabolic syndrome, or obesity-related complications.

“Although this study focused on their functions and mechanisms of action in diseases modeled after inflammation and obesity, we expect that these compounds will also be effective against a wide range of lifestyle-related diseases caused by metabolic syndrome, such as diabetes and hypertension, as well as allergic symptoms,” says Prof. Arimura optimistically.

In conclusion, this study underscores the importance and value of multi-faceted molecules derived from naturally occurring substances. Future research involving these novel and superior menthyl esters may result in therapeutic compounds to tackle the ever-growing health concerns of obesity and inflammatory conditions.

Gut bacteria convert dietary fatty acids into useful metabolites with benefits in metabolic and inflammatory disorders. However, their immunomodulatory effects and underlying molecular mechanisms remain unclear. Now, researchers from Tokyo University of Science have uncovered a novel gut bacteria-generated, fatty acid metabolite — ‘gKetoC’ which exerts protective effects against inflammatory bowel disease. Their study sheds light on molecular targets which mediate their immunosuppressive effects against intestinal bowel inflammation and highlights their therapeutic potential.

Gut microbiota or the population of microbial inhabitants in the intestine, plays a key role in digestion and maintenance of overall health. Any disturbance in the gut microbiota can, therefore, have a systemic impact. Intestinal microbes metabolize dietary components into beneficial fatty acids (FAs), supporting metabolism and maintaining host body homeostasis. Metabolites originating from polyunsaturated fatty acids (PUFAs), influenced by gut microbes such as Lactobacillus plantarum, exhibit potent effects on inflammation and immune responses. Manipulating gut bacteria and their metabolites shows promise in treating metabolic and inflammatory disorders. However, despite advances in gut health and wellness trends, the precise mechanisms governing the immunomodulatory properties of microbe-derived metabolites remain elusive.

To bridge this gap, a team of researchers led by Professor Chiharu Nishiyama from the Tokyo University of Science conducted a series of experiments using both in vitro and in vivo mouse models to understand how bacteria-generated FAs regulate immune responses. Explaining the rationale behind their work published in Frontiers in Immunology on 30 April, 2024, Prof. Nishiyama says, “PUFAs undergo metabolic transformations such as hydroxylation and saturation by enzymes possessed by intestinal bacteria. In recent years, a variety of beneficial physiological effects have been discovered for these intestinal bacterial metabolites. In this study, we have investigated the activity of multiple FA metabolites using mouse-derived immune cells.”

To this end, the researchers used antigen-stimulated spleen cells to elicit an enhanced immune response. Subsequently, they investigated the impacts of different polyunsaturated fatty acid (PUFA) derivatives, focusing on metabolites of linoleic acid, a prevalent dietary fatty acid. Their findings revealed that KetoC, αKetoC, gKetoA, and gKetoC (enon derivatives of LA) markedly reduced the levels of interleukin 2 — a key protein that triggers the expansion of immune cells and inflammation. However, the original PUFAs in their unconverted form did not demonstrate the same immunosuppressive effects, emphasizing the critical role of bacterial conversion in activating their immunomodulatory properties. Furthermore, they observed that the enon (a functional group) FAs also suppressed prolonged T-cell proliferation and dendritic cell activation, which can lead to inflammation and autoimmune diseases. This anti-inflammatory effect was most pronounced with gKetoC. Hence, the researchers aimed to unravel the molecular mechanisms through which gKetoC exerted its immunosuppressive effects.

In addition, previous studies have shown the involvement of G protein-coupled receptors (GPCRs) and the transcription factor, NRF2, in anti-oxidant responses, which are mediated by several FA metabolites, whereas the involvement of GPCRs and NRF2 in the effects of gKetoC in dendritic cells was largely unknown. To clarify the role of these proteins in gKetoC-mediated immune responses, the researchers assessed the levels of inflammatory cytokines released from antigen-stimulated and gKetoC-treated dendritic cells. Their results suggested that gKetoC stimulated the NRF2 signaling pathway, which suppressed the production of inflammatory cytokines. Additionally, GPCR-signaling also inhibited inflammatory cytokine production in dendritic cells in an NRF2-dependent manner. This unveils a potential molecular axis governing the immunomodulatory effects of gKetoC.

To further validate their findings in vivo, the researchers used a mouse model of inflammatory bowel disease and examined immune and inflammatory responses by involving gKetoC treatment. They found that gKetoC treatment significantly reduced fibrosis-induced tissue damage in the colon, reduced colitis-induced weight loss, and improved stool scores. Furthermore, the treated mice showed decreased epithelial cell disruption and ulcers, along with reduced infiltration of immune cells and lower serum levels of inflammatory factors. Notably, the models that were deficient in NRF2 showed significant restoration of colitis-induced tissue damage following gKetoC treatment.

Overall, the present study sheds light on the potential mechanism by which gKetoC alleviates antigen-induced intestinal inflammation. Further studies are needed to understand the complex interplay between gKetoC, GPCR-signaling, and the NRF2 pathway, and uncover other potential targets of gKetoC which mediate its anti-inflammatory effects. Nevertheless, anti-inflammatory FA metabolites hold therapeutic promise in the treatment of intestinal inflammatory diseases and maintenance of gut health, as prebiotic or probiotic formulations. Sharing her concluding thoughts, Dr. Nishiyama states, “Our findings demonstrate that the compounds of dietary oils are converted into useful metabolites with anti-inflammatory effects by gut bacteria. By conducting detailed analyses at the individual, cellular, and genetic levels, we hope to understand how the food we eat daily influences the function of immune cells, and how these effects can be targeted for the prevention and mitigation of inflammatory diseases.”

In summary, while the beneficial effects of bacterial PUFA metabolites were known, this study identified gKetoC as a metabolite playing a protective role in a colitis mice model. In the long run, these findings can help improve the quality of life for patients suffering from inflammatory diseases, and augment the possibility of developing functional foods, supplements, and nutraceuticals based on these microbial metabolites. Moreover, the researchers also speculate that these developments could help in the identification and development of compounds that are capable of preventing or alleviating immune-related diseases.

Here’s wishing the team luck in their future research endeavors!

Plant-derived nanoparticles have demonstrated significant anticancer effects. Researchers from Japan recently developed rice bran-derived nanoparticles (rbNPs) that efficiently suppressed cell proliferation and induced programmed cell death of only cancer cells. Furthermore, rbNPs successfully suppressed the growth of tumors in mice having aggressive adenocarcinoma in their peritoneal cavity, without any adverse effects. Given their low production costs and high efficacy, rbNPs hold great promise for developing affordable and safe anticancer agents.

Several types of conventional cancer therapies, such as radiotherapy or chemotherapy, destroy healthy cells along with cancer cells. In advanced stages of cancer, tissue loss from treatments can be substantial and even fatal. Cutting-edge cancer therapies that employ nanoparticles can specifically target cancer cells, sparing healthy tissue. Recent studies have demonstrated that plant-derived nanoparticles (pdNPs) that have therapeutic effects can be an effective alternative to traditional cancer treatments. However, no pdNPs have been approved as anticancer therapeutic agents till date.

Rice bran is a byproduct generated during rice refining process that has limited utility and low commercial value. However, it contains several compounds with anticancer properties, such as γ-oryzanol and γ-tocotrienol. To explore these therapeutic properties of rice bran, a team of researchers led by Professor Makiya Nishikawa from Tokyo University of Science (TUS) in Japan developed nanoparticles from rice bran and tested their effectiveness in mice models. Their study, published in Volume 22 of Journal of Nanobiotechnology on 16 March 2024, was co-authored by Dr. Daisuke Sasaki, Ms. Hinako Suzuki, Associate Professor Kosuke Kusamori, and Assistant Professor Shoko Itakura from TUS.

“In recent years, an increasing number of new drug modalities are being developed. At the same time, development costs associated with novel therapies have increased dramatically, contributing to the burden of medical expenses. To address this issue, we used rice bran, an industrial waste with anticancer properties, to develop nanoparticles,” explains Prof. Nishikawa.

The study evaluated the anticancer effects of rice bran-derived nanoparticles (rbNPs), which were obtained by processing and purifying a suspension of Koshihikari rice bran in water. When a cancer cell line named colon26 was treated with rbNPs, cell division was arrested and programmed cell death was induced, indicating strong anticancer effects of the nanoparticles. The observed anticancer activity of rbNPs can be attributed to γ-tocotrienol and γ-oryzanol, that are easily taken up by cancer cells resulting in cell cycle arrest and programmed cell death. Additionally, rbNPs reduced the expression of proteins, such as β-catenin (a protein associated with Wnt signaling pathway involved in cell proliferation) and cyclin D1, which are known to promote cancer recurrence and metastases. Moreover, the rbNPs reduced the expression of β-catenin only in colon26 cells without affecting the non-cancerous cells.

“A key concern in the context of pdNPs is their low pharmacological activity compared to pharmaceutical drugs. However, rbNPs exhibited higher anticancer activity than DOXIL®, a liposomal pharmaceutical formulation of doxorubicin. Additionally, doxorubicin is cytotoxic to both cancer cells and non-cancerous cells, whereas rbNPs are specifically cytotoxic to cancer cells, suggesting that rbNPs are safer than doxorubicin,” highlights Prof. Nishikawa.

To confirm the anticancer properties of rbNPs in the living body, the researchers injected rbNPs into mice having aggressive adenocarcinoma in their peritoneal cavity (enclosed by the diaphragm, abdominal muscles, and pelvis and houses organs like intestines, liver, and kidneys). They observed significant suppression of tumor growth with no adverse effects on the mice. Additionally, the rbNPs significantly inhibited metastatic growth of murine melanoma B16-BL6 cells in a lung metastasis mouse model.

Rice bran has several attributes that make it an excellent source of therapeutic pdNPs. Firstly, it is economic as compared to many other sources of pdNPs. Nearly 40% of the rice bran is discarded in Japan, providing a readily available source of raw material. Secondly, the preparation efficiency of rbNPs is higher than that of previously reported pdNPs. Besides being practical and safe as an anticancer therapeutic, the physicochemical properties of rbNPs are very stable. However, a few parameters, such as establishment of separation technologies at the pharmaceutical level, assessing production process control parameters, and evaluation of efficacy and safety in human cancer cell lines and xenograft animal models, must be investigated prior to clinical trials in humans.

In conclusion, rice bran, an agricultural waste product, is a source of therapeutic pdNPs that are affordable, effective, and safe, and has the potential to revolutionize cancer treatment in the future.

“By establishing a manufacturing method for rice bran nanoparticles with stable quality and confirming their safety and effectiveness, we can develop drugs for cancer treatment that are sustainable, eco-friendly, and affordable. Consequently, we may be able to help more cancer patients maintain good physical and mental health after treatment,” concludes Prof. Nishikawa.

Euglena gracilis, often regarded as a “superfood,” is a promising microalga with many health and nutritional benefits. In a recent study, researchers from Japan found an efficient and low-resource approach to trigger a reddening reaction in E. gracilis using red light and a bonito fish-based culture medium. This reaction is a sign of higher and diverse carotenoid content ratio, meaning the proposed method could help turn E. gracilis into an even more nutritious food source.

Over the past few years, people have generally become more conscious about the food they consume. Thanks to easier access to information as well as public health campaigns and media coverage, people are more aware of how nutrition ties in with both health benefits and chronic diseases. As a result, there is an ongoing cultural shift in most countries, with people prioritizing eating healthily. In turn, the demand for healthier food options and nutritional supplements is steadily growing.

In line with these changes, Assistant Professor Kyohei Yamashita from Tokyo University of Science (TUS), Japan, has been studying a promising “superfood” called Euglena gracilis for over half a decade. A species of edible microalgae, E. gracilis has a rich nutritional profile, with a unique combination of vitamins, fibers, lipids, and proteins. Like most other photosynthetic plants, E. gracilis also contains carotenoids—natural substances with a wide variety of health benefits.

In a study published in 2023, a research team from TUS found a simple method to efficiently grow E. gracilis in an inexpensive medium (solid or liquid that contains nutrients and is used to grow bacteria) based on tomato juice. Now, in a new study, the researchers have explored a promising technique to make cultured E. gracilis produce carotenoids at a higher rate, rendering it even more nutritious. This study, which was co-authored by Dr. Kengo Suzuki from Euglena Co., Ltd., as well as Professor Tatsuya Tomo and Professor Eiji Tokunaga from TUS, was published in Volume 13, Issue 4 of the journal Plants in February 12, 2024.

The proposed approach is quite straightforward, and so is its rationale. When a plant is exposed to high-intensity light for extended periods of time, it undergoes a light-stress response. This, in turn, can cause the organism to produce molecules that protect it from further light exposure, including carotenoids. Based on these facts, the researchers investigated whether they could induce such a reaction in E. gracilis to enhance its carotenoid content ratio.

To this end, the team ran a series of experiments on multiple batches of cultured E. gracilis. They exposed cultures to light of different wavelengths (or colors) and at different intensities looking for a “reddening reaction,” which is a tell-tale sign of higher carotenoid production in many plant species. Moreover, they also tested a new culture medium based on bonito stock, a soup stock extracted from Katsuobushi, a traditional Japanese dish made from smoked bonito fish.

Interestingly, the researchers found that strong red-light irradiation at 605–660 nm triggered a reddening reaction in E. gracilis when cultured in bonito stock. They also looked at the chemical profiles of the cultures using high-performance liquid chromatography, both at the culture and single-cell level. These analyses revealed that reddened cells not only had a high concentration of diadinoxanthin, the most abundant carotenoid in E. gracilis, but also produced an unidentified xanthophyll-type carotenoid. On top of these, the team also noted that bonito stock cultures grew quicker and reached higher densities than cultures grown on conventional media, and likely produced more types or amounts of carotenoids.

Together, the results of this study could pave the way for an innovative and easily scalable technique for growing nutritious E. gracilis. The method’s simplicity is certainly one of its strengths, as Dr. Yamashita remarks, “Our approach does not involve genetic modifications and could thus be readily adopted by the food industry to expand the use of E. gracilis, both in food and as a nutritional supplement.” Notably, bonito stock is a nutritious food and using it in the culture medium would, therefore, provide additional health benefits.

Aside from its benefits to us humans, growing E. gracilis can also help the environment. “E. gracilis cultivation, which requires relatively few resources, can be a sustainable food resource,” explains Dr. Yamashita. “Our research marks an important step toward the development of new food technologies that contribute to people’s lives from both health and environmental perspectives.”

With the carotenoid market poised to become a multi-billion-dollar industry by 2030, this study will help deepen our understanding of carotenoid biosynthetic pathways, hopefully leading to the development of sustainable practices in the production of nutritional supplements and emerging foods.

Researchers find that rose essential oil activates tomato defense genes and attracts herbivore predators that protect the plants.

Following injury, plants release terpenoids to enhance their defenses. Researchers at the Tokyo University of Science studying terpenoid-enriched essential oils (EOs) have found that rose EO (REO) can stimulate defense genes in tomato leaves. Furthermore, REO attracts herbivores that protect the plant from the moth species, Spodoptera litura, and Tetranychus urticae, a mite pest. This suggests that applying REO could be a sustainable approach to pest management in organic farming.

Plants-derived essential oils (EOs) find applications in various industries, such as detergents, cosmetics, pharmacology, and food additives. Moreover, EOs have an exceptional safety profile, and their numerous bioactivities greatly benefit human health. Beyond these benefits, EOs have also been found to illicit insect-repellent responses by inducing neurotoxic effects.

Terpenoids are abundant in plant EOs and have garnered widespread attention as they can regulate plant defense responses by regulating the expression of defense genes. For example, soybean and komatsuna plants, when grown near mint, experience a significant improvement in defense properties and become resistant to herbivores. This phenomenon occurs through a process known as “eavesdropping,” wherein volatile compounds are released from the mint plant. These volatile compounds trigger the activation of defense genes, protecting against potential herbivore threats.

Today, applying chemical pesticides is the method of choice for crop protection, but the damage they cause to the environment and ecosystems, along with the need to increase food productivity, stresses the need for safer alternatives. Thus, there is an urgent need for investigation of plant defense potentiators. In this regard, the availability of EOs makes them attractive candidates as environmentally friendly plant defense activators. However, there is a lack of sufficient proven examples to meet the demand.

To address this, a research team led by Professor Gen-ichiro Arimura from the Department of Biological Science and Technology at the Tokyo University of Science (TUS) assessed the efficacy of 11 EOs in activating tomato defense responses. “EOs used as fragrances for various purposes contain odor components, which may have the ability to work like volatile compounds in conferring pest resistance. We aimed to investigate the effects of these EOs on plants’ insect pest resistance,” says Prof. Arimura. The team’s findings were published in the Journal of Agricultural and Food Chemistry on March 18, 2024.

The team profiled the effects of terpenoid-enriched EOs on tomato plants. They applied ethanol-diluted solutions of 11 different EOs to the soil of potted tomato plants, performed molecular analyses to study the gene expression inside leaf tissue, and observed that rose EO (REO) increased the transcript levels of PIR1 and PIN2, the genes involved in plant defense. Additionally, tomato plants treated with REO exhibited reduced leaf damage caused by the Spodoptera litura (a moth species) larvae and Tetranychus urticae (a mite pest). Furthermore, to explore the possibility of broader application, the researchers conducted a field experiment to measure REO activity in field conditions. They observed a 45.5% reduction in tomato pest damage compared to the control solution. The researchers believe that REO could serve as a viable alternative to pesticides during the winter and spring seasons when pest infestation is less severe and could potentially reduce pesticide usage by almost 50% during summers.

Explaining the research findings, Prof. Arimura says, “REO is rich in β-citronellol, a recognized insect repellent, which enhances REO’s efficacy. Owing to this, damage caused by the moth larvae and mites was significantly minimized, confirming REO as an effective biostimulant. The findings also showed that a low concentration of REO did not repel T. urticae but attracted Phytoseiulus persimilis, a predator of these spider mites, thus exhibiting a dual function of REO.”

Overall, the study highlights the role of β-citronellol-enriched EO in activating defense genes in tomato leaves. Additionally, it provides evidence that REO is an effective biostimulant for enhancing plant defense against pests, which is also safe as it does not lead to phytotoxicity or leave any toxic residues behind. “Our study suggests a practical approach to promoting organic tomato production that encourages environmentally friendly and sustainable practices. This research may open doors for new organic farming systems. The dawn of potent environmentally friendly and natural pesticides is upon us,” concludes Prof. Arimura.

Artificial intelligence (AI) is known for its high energy consumption, especially in data-intensive tasks like health monitoring. To address this, researchers at Tokyo University of Science (TUS) have developed a flexible paper-based sensor composed of nanocellulose and zinc oxide (ZnO) nanoparticles that operates like the human eyes and brain. The sensor is energy-efficient, responds to optical input in real-time, and is both flexible and easy to dispose of, making it ideal for health monitoring applications.

A paper-based sensor based on the operation of the human brain paves the way for standalone energy-efficient AI-based health monitoring devices

From creating images, generating text, and enabling self-driving cars, the potential uses of artificial intelligence (AI) are vast and transformative. However, all this capability comes at a very high energy cost. For instance, estimates indicate that training OPEN AI’s popular GPT-3 model consumed over 1,287 MWh, enough to supply an average U.S. household for 120 years. This energy cost poses a substantial roadblock, particularly for using AI in large-scale applications like health monitoring where large amounts of critical health information are sent to centralized data centers for processing. This not only consumes a lot of energy but also raises concerns about sustainability, bandwidth overload, and communication delays.

Achieving AI-based health monitoring and biological diagnosis requires a standalone sensor that operates independently without the need for constant connection to a central server. At the same time, the sensor must have a low power consumption for prolonged use, should be capable of handling the rapidly changing biological signals for real-time monitoring, be flexible enough to attach comfortably to the human body, and be easy to make and dispose of due to the need for frequent replacements for hygiene reasons.

Considering these criteria, researchers from Tokyo University of Science (TUS) led by Associate Professor Takashi Ikuno have developed a flexible paper-based sensor that operates like the human brain. Their findings were published online in the journal Advanced Electronic Materials on 22 February 2024.

“A paper-based optoelectronic synaptic device composed of nanocellulose and ZnO was developed for realizing physical reservoir computing. This device exhibits synaptic behavior and cognitive tasks at a suitable timescale for health monitoring,” says Dr. Ikuno.

In the human brain, information travels between networks of neurons through synapses. Each neuron can process information on its own, enabling the brain to handle multiple tasks at the same time. This ability for parallel processing makes the brain much more efficient compared to traditional computing systems. To mimic this capability, the researchers fabricated a photo-electronic artificial synapse device composed of gold electrodes on top of a 10 µm transparent film consisting of zinc oxide (ZnO) nanoparticles and cellulose nanofibers (CNFs).

The transparent film serves three main purposes. Firstly, it allows light to pass through, enabling it to handle optical input signals representing various biological information. Secondly, the cellulose nanofibers impart flexibility and can be easily disposed of by incineration. Thirdly, the ZnO nanoparticles are photoresponsive and generate a photocurrent when exposed to pulsed UV light and a constant voltage. This photocurrent mimics the responses transmitted by synapsis in the human brain, enabling the device to interpret and process biological information received from optical sensors.

Notably, the film was able to distinguish 4-bit input optical pulses and generate distinct currents in response to time-series optical input, with a rapid response time on the order of subseconds. This quick response is crucial for detecting sudden changes or abnormalities in health-related signals. Furthermore, when exposed to two successive light pulses, the electrical current response was stronger for the second pulse. This behavior termed post-potentiation facilitation contributes to short-term memory processes in the brain and enhances the ability of synapses to detect and respond to familiar patterns.

To test this, the researchers converted MNIST images, a dataset of handwritten digits, into 4-bit optical pulses. They then irradiated the film with these pulses and measured the current response. Using this data as input, a neural network was able to recognize handwritten numbers with an accuracy of 88%.

Remarkably, this handwritten-digit recognition capability remained unaffected even when the device was repeatedly bent and stretched up to 1,000 times, demonstrating its ruggedness and feasibility for repeated use. “This study highlights the potential of embedding semiconductor nanoparticles in flexible CNF films for use as flexible synaptic devices for PRC,” concludes Dr. Ikuno.

Let us hope that these advancements pave the way for wearable sensors in health monitoring applications!

Quick-acting targeted therapies with minimal side effects are an urgent need for the treatment of anxiety-related disorders. While delta opioid receptor (DOP) agonists have shown ‘anxiolytic’ or anxiety-reducing effects, their mechanism of action is not well-understood. A new study by researchers from Tokyo University of Science highlights the role of specific neuronal circuits in the brain involved in the development of anxiety, and distinct mechanisms of action of the therapeutic DOP agonist – KNT-127.

Anxiety-related disorders can have a profound impact on the mental health and quality of life of affected individuals. Understanding the neural circuits and molecular mechanisms that trigger anxiety can aid in the development of effective targeted pharmacological treatments. Delta opioid receptors (DOP), which localize in the regions of the brain associated with emotional regulation, play a key role in the development of anxiety. Several studies have demonstrated the therapeutic effects of DOP agonists (synthetic compounds which selectively bind to DOPs and mimic the effect of the natural binding compound) in a wide range of behavioral disorders. One such selective DOP agonist—KNT-127—has been shown to exert ‘anxiolytic’ or anxiety-reducing effects in animal models, with minimal side effects. However, its mechanism of action is not clearly understood, thereby limiting its widespread clinical application.

To bridge this gap, Professor Akiyoshi Saitoh, along with Ms. Ayako Kawaminami and team from the Tokyo University of Science, Japan, conducted a series of experiments and behavioral studies in mice. Explaining the rationale behind their work, Prof. Saitoh says, “There are currently no therapeutic drugs mediated by delta opioid receptors (DOPs). DOPs likely exert anti-depressant and anti-anxiety effects through a mechanism of action different from that of existing psychotropic drugs. DOP agonists may, therefore, be useful for treatment-resistant and intractable mental illnesses which do not respond to existing treatments.” Their study was published on 29 December 2024, in Neuropsychopharmacology Reports,

The neuronal network projecting from the ‘prelimbic cortex’ (PL) of the brain to the ‘basolateral nucleus of the amygdala’ (BLA) region, has been implicated in the development of depression and anxiety-like symptoms. The research team has previously shown that KNT-127 inhibits the release of glutamate (a key neurotransmitter) in the PL region. Based on this, they hypothesized that DOP activation by KNT-127 suppresses glutamatergic transmission and attenuates PL-BLA-mediated anxiety-like behavior. To test this hypothesis, they developed an ‘optogenetic’ mouse model wherein they implanted a light-responsive chip in the PL-BLA region of mice and activated the neural circuit using light stimulation. Further, they went on to assess the role of PL-BLA activation on innate and conditioned anxiety-like behavior.

They used the elevated-plus maze (EPM) test, which consists of two open arms and two closed arms on opposite sides of a central open field, to assess behavioral anxiety in the mice. Notably, mice with PL-BLA activation spent lesser time in the central region and open arms of the maze, compared to controls, which was consistent with innate anxiety-like behavior. Next, the researchers assessed conditioned fear response of the animals by exposing them to foot shocks and placing them in the same shock chamber the following day without re-exposing them to current. They recorded the freezing response of the animals which reflects fear. Notably, animals with PL-BLA activation and controls exhibited similar behavior, suggesting that distinct neural pathways control innate anxiety-like behavior and conditioned fear response.

Finally, they examined the effects or KNT-127 treatment on anxiety-like behavior of mice using the EPM test. Remarkably, animals treated with KNT-127 exhibited an increase in the percentage time spent in the open arms and central field of the maze, compared to controls. These findings suggest that KNT-27 reduces anxiety-like behavior induced by the specific activation of the PL-BLA pathway.

Overall, the study reveals the role of the PL-BLA neuronal axis in the regulation of innate anxiety, and its potential function in DOP-mediated anxiolytic effects. Further studies are needed to understand the precise underlying molecular and neuronal mechanisms, for the development of novel therapies targeting DOP in the PL-BLA pathway.

Highlighting the long-term clinical applications of their work, Prof. Saitoh remarks, “The brain neural circuits focused on in this study are conserved in humans, and research on human brain imaging has revealed that the PL-BLA region is overactive in patients with depression and anxiety disorders. We are optimistic that suppressing overactivity in this brain region using DOP-targeted therapies can exert significant anxiolytic effects in humans.”