The significance of hydrogen sulfide (H2S) as a crucial gasotransmitter has been shown extensively in plants, and endogenous H2S is often modulated to activate H2S signaling when plants respond to numerous developmental and environmental cues. Consequently, elucidating the H2S physiological concentrations and the H2S generation intensity of plants is key to understanding the activation mechanism of H2S signaling, which has attracted increasing attention. Currently, a variety of reaction-based methods have been reported for monitoring H2S concentration in vivo and in vitro. In this review, we summarize and describe in detail several methods for quantifying and bioimaging endogenous H2S in plants systems, mainly the spectrophotometer-dependent methylene blue (MB) method and fluorescence probes, including the reaction mechanisms, design strategies, response principles, and application details. Moreover, we also summarize the advantages and disadvantages of these methods as well as the research scenarios in which they are applicable. We expect that this review will provide some guidelines on the selection of methods for H2S sensing and the comprehensive investigations into H2S signaling in plants.

Gases are essential for various applications relevant to human health, including in medicine, biomedical imaging, and pharmaceutical synthesis. However, gases are significantly more challenging to safely handle than liquids and solids. Herein, we review the use of porous materials, such as metal-organic frameworks (MOFs), zeolites, and silicas, to adsorb medicinally relevant gases and facilitate their handling as solids. Specific topics include the use of MOFs and zeolites to deliver H2S for therapeutic applications, 129Xe for magnetic resonance imaging, O2 for the treatment of cancer and hypoxia, and various gases for use in organic synthesis. This Perspective aims to bring together the organic, inorganic, medicinal, and materials chemistry communities to inspire the design of next-generation porous materials for the storage and delivery of medicinally relevant gases.

Irisin is a myokine secreted under the influence of physical activity and exposure to low temperatures and through different exogenous stimuli by the cleavage of its precursor, fibronectin type III domain-containing protein 5 (FNDC5). It is mainly known for maintaining of metabolic homeostasis, promoting the browning of white adipose tissue, the thermogenesis process, and glucose homeostasis. Growing experimental evidence suggests the possible central role of irisin in the regulation of cardiometabolic pathophysiological processes. On the other side, hydrogen sulfide (H2S) is well recognized as a pleiotropic gasotransmitter that regulates several homeostatic balances and physiological functions and takes part in the pathogenesis of cardiometabolic diseases. Through the S-persulfidation of cysteine protein residues, H2S is capable of interacting with crucial signaling pathways, exerting beneficial effects in regulating glucose and lipid homeostasis as well. H2S and irisin seem to be intertwined; indeed, recently, H2S was found to regulate irisin secretion by activating the peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α)/FNDC5/irisin signaling pathway, and they share several mechanisms of action. Their involvement in metabolic diseases is confirmed by the detection of their lower circulating levels in obese and diabetic subjects. Along with the importance of metabolic disorders, these modulators exert favorable effects against cardiovascular diseases, preventing incidents of hypertension, atherosclerosis, heart failure, myocardial infarction, and ischemia-reperfusion injury. This review, for the first time, aims to explore the role of H2S and irisin and their possible crosstalk in cardiovascular diseases, pointing out the main effects exerted through the common molecular pathways involved.

Sulfide-releasing compounds reduce reperfusion injury by decreasing mitochondria-derived reactive oxygen species production. We previously characterised ammonium tetrathiomolybdate (ATTM), a clinically used copper chelator, as a sulfide donor in rodents. Here we assessed translation to large mammals prior to clinical testing. In healthy pigs an intravenous ATTM dose escalation revealed a reproducible pharmacokinetic/pharmacodynamic (PK/PD) relationship with minimal adverse clinical or biochemical events. In a myocardial infarction (1-h occlusion of the left anterior descending coronary artery)-reperfusion model, intravenous ATTM or saline was commenced just prior to reperfusion. ATTM protected the heart (24-h histological examination) in a drug-exposure-dependent manner (r2 = 0.58, p < 0.05). Blood troponin T levels were significantly (p < 0.05) lower in ATTM-treated animals while myocardial glutathione peroxidase activity, an antioxidant selenoprotein, was elevated (p < 0.05). Overall, our study represents a significant advance in the development of sulfides as therapeutics and underlines the potential of ATTM as a novel adjunct therapy for reperfusion injury. Mechanistically, our study suggests that modulating selenoprotein activity could represent an additional mode of action of sulfide-releasing drugs.

BACKGROUND: Manic depressive psychosis (MDP) or bipolar disorder, a prevalent psychiatric condition globally and in the Indian population, has been attributed to various pathological mechanisms. Hydrogen sulphide (H2S), a member of the gasotransmitter family, may be linked to the development of bipolar disorder because it plays a crucial role in maintaining proper neuronal function in terms of excitability, plasticity, and homeostatic functions. There is very little data regarding the role of the gasotransmitter H2S in MDP in terms of its association, diagnostic ability, and severity prediction, which led us to conduct this study among MDP patients in the Sub-Himalayan region of West Bengal.
METHODS: This was an observational case-control study performed in the Department of Biochemistry, North Bengal Medical College and Hospital, Siliguri, West Bengal, India, from January 2022 to December 2022. Fifty diagnosed MDP patients and 50 healthy age- and sex-matched control subjects satisfying the inclusion and exclusion criteria were studied. The H2S level in the blood was assayed using the standardised spectrophotometric methylene blue method. The severity of depression was assessed by Hamilton Depression Rating Scale (HAM-D) scoring.
RESULTS: Of the 50 MDP patients, 45 (90%) were in the depressive phase, and five (10%) were in the manic phase. Of the 45 depressive patients, eight (17.8%) had mild depression, 12 (26.7%) had moderate depression, 19 (42.2%) had severe depression, and six (13.3%) had very severe depression. The mean H2S level in MDP patients (41.98±18.88 μmol/l) was significantly (P<0.05) lower than that in control subjects (99.20± 15.20 μmol/l). It was also observed that the mean H2S level in MDP patients decreased with the duration of the disease but was not statistically significant. The mean H2S levels in the different depression severity groups were found to be significantly different (P<0.001). Receiver operating characteristic (ROC) curve analysis revealed that a cut-off value of H2S <78.5 μmol/l was associated with MDP, with a sensitivity of 96% and a specificity of 88%, and a cut-off value of H2S < 53 μmol/l predicted the severity of depression with a sensitivity of 89.3% and a specificity of 76.5%.
CONCLUSIONS: The significant association of the gasotransmitter H2S in MDP patients and its role as a diagnostic and severity predictive marker can help us to employ proper measures for better management of MDP and improving quality of life.

Nitric oxide (NO) is a gasotransmitter required in a broad range of mechanisms controlling plant development and stress conditions. However, little is known about the specific role of this signaling molecule during lipid storage in the seeds. Here, we show that NO is accumulated in developing embryos and regulates the fatty acid profile through the stabilization of the basic/leucine zipper transcription factor bZIP67. NO and nitro-linolenic acid target and accumulate bZIP67 to induce the downstream expression of FAD3 desaturase, which is misregulated in a non-nitrosylable version of the protein. Moreover, the post-translational modification of bZIP67 is reversible by the trans-denitrosylation activity of peroxiredoxin IIE and defines a feedback mechanism for bZIP67 redox regulation. These findings provide a molecular framework to control the seed fatty acid profile caused by NO, and evidence of the in vivo functionality of nitro-fatty acids during plant developmental signaling.

Many living beings use exogenous and/or endogenous gases to attain evolutionary benefits. We make a comprehensive assessment of one of the major gaseous reservoirs in the human body, i.e., the bowel, providing extensive data that may serve as reference for future studies. We assess the intestinal gases in healthy humans, including their volume, composition, source and local distribution in proximal as well as distal gut. We analyse each one of the most abundant intestinal gases including nitrogen, oxygen, nitric oxide, carbon dioxide, methane, hydrogen, hydrogen sulfide, sulfur dioxide and cyanide. For every gas, we describe diffusive patterns, active trans-barrier transport dynamics, chemical properties, intra-/extra-intestinal metabolic effects mediated by intracellular, extracellular, paracrine and distant actions. Further, we highlight the local and systemic roles of gasotransmitters, i.e., signalling gaseous molecules that can freely diffuse through the intestinal cellular membranes. Yet, we provide testable hypotheses concerning the still unknown effects of some intestinal gases on the myenteric and submucosal neurons.

Nitric Oxide (NO), a significant gasotransmitter in biological systems, plays a crucial role in neurological diseases and cancer. Currently, there is a lack of effective methods for rapidly and sensitively identifying NO and elucidating its relationship with neurological diseases. Novel diamino-cyclic-metalloiridium phosphorescence probes, Ir-CDA and Ir-BDA, have been designed to visualize the gasotransmitter NO in Alzheimer\'s disease (AD) and glioblastoma (GBM). Ir-CDA and Ir-BDA utilize iridium (III) as the central ion and incorporate a diamino group as a ligand. The interaction between the diamino structure and NO leads to the formation of a three-nitrogen five-membered ring structure, which opens up phosphorescence. The two probes can selectively bind to NO and offer low detection limits. Additionally, Ir-BDA/Ir-CDA can image NO in brain cancer cell models, neuroinflammatory models, and AD cell models. Furthermore, the NO content in fresh brain sections from AD mice was considerably higher than that in wild-type (WT) mice. Consequently, it is plausible that NO is generated in significant quantities around cells hosting larger Aβ deposits, gradually diffusing throughout the entire brain region. Furthermore, we posit that this phenomenon is a key factor contributing to the higher brain NO content in AD mice compared to that in WT mice. This discovery offers novel insights into the diagnosis and treatment of AD.

Hydrogen sulfide (H2S) was recognized as a gaseous signaling molecule, similar to nitric oxide (-NO) and carbon monoxide (CO). The aim of this review is to provide an overview of the formation of hydrogen sulfide (H2S) in the human body. H2S is synthesized by enzymatic processes involving cysteine and several enzymes, including cystathionine-β-synthase (CBS), cystathionine-γ-lyase (CSE), cysteine aminotransferase (CAT), 3-mercaptopyruvate sulfurtransferase (3MST) and D-amino acid oxidase (DAO). The physiological and pathological effects of hydrogen sulfide (H2S) on various systems in the human body have led to extensive research efforts to develop appropriate methods to deliver H2S under conditions that mimic physiological settings and respond to various stimuli. These functions span a wide spectrum, ranging from effects on the endocrine system and cellular lifespan to protection of liver and kidney function. The exact physiological and hazardous thresholds of hydrogen sulfide (H2S) in the human body are currently not well understood and need to be researched in depth. This article provides an overview of the physiological significance of H2S in the human body. It highlights the various sources of H2S production in different situations and examines existing techniques for detecting this gas.

Background: Hydrogen sulfide (H2S), an endogenous gasotransmitter, has potential applications in several conditions. However, its quantification in simulated physiological solutions is a major challenge due to its gaseous nature and other physicochemical properties. Aim: This study was designed to compare four commonly used H2S detection and quantification methods in aqueous solutions. Methods: The four techniques compared were one colorimetric, one chromatographic and two electrochemical methods. Results: Colorimetric and chromatographic methods quantified H2S in millimolar and micromole ranges, respectively. The electrochemical methods quantified H2S in the nanomole and picomole ranges and were less time-consuming. Conclusion: The H2S quantification method should be selected based on the specific requirements of a research project in terms of sensitivity, response time and cost-effectiveness.