Computation-guided scaffold exploration of 2E,6E-1,10-trans/cis-eunicellanes.

Eunicellane diterpenoids are a unique family of natural products containing a foundational 6/10-bicyclic framework and can be divided into two main classes, cis and trans, based on the configurations of their ring fusion at C1 and C10. Previous studies on two bacterial diterpene synthases, Bnd4 and AlbS, revealed that these enzymes form cis- and trans-eunicellane skeletons, respectively. Although the structures of these diterpenes only differed in their configuration at a single position, C1, they displayed distinct chemical and thermal reactivities. Here, we used a combination of quantum chemical calculations and chemical transformations to probe their intrinsic properties, which result in protonation-initiated cyclization, Cope rearrangement, and atropisomerism. Finally, we exploited the reactivity of the trans-eunicellane skeleton to generate a series of 6/6/6 gersemiane-type diterpenes via electrophilic cyclization.

Cryptic Isomerization in Diterpene Biosynthesis and the Restoration of an Evolutionarily Defunct P450.

Biosynthetic modifications of the 6/10-bicyclic hydrocarbon skeletons of the eunicellane family of diterpenoids are unknown. We explored the biosynthesis of a bacterial trans-eunicellane natural product, albireticulone A (3), and identified a novel isomerase that catalyzes cryptic isomerization in the biosynthetic pathway. We also assigned functions of two cytochromes P450 that oxidize the eunicellane skeleton, one of which was a naturally evolved non-functional P450 that, when genetically repaired, catalyzes allylic oxidation. Finally, we described the chemical susceptibility of the trans-eunicellane skeleton to undergo Cope rearrangement to yield inseparable atropisomers.

Biosynthesis, enzymology, and future of eunicellane diterpenoids.

Eunicellane diterpenoids are a remarkable family of terpene natural products and have been of high interest for over five decades. Widely distributed in soft corals and rare in plants, eunicellanes were also recently identified in actinobacteria. These terpenoids have foundational 6/10-bicyclic frameworks that are frequently oxidized into structures containing transannular ether bridges. Interest in their unique structures and promising biological activities, such as the paclitaxel-like activities of eleutherobin and the sarcodictyins, has led to advancements in natural product isolation, total synthesis, medicinal chemistry, and drug lead development. Until recently, however, there was little known about the biosynthesis and enzymology of these natural products, but several recent studies in both bacteria and coral have opened up the field. This review summarizes recent advancements in the biosynthesis and enzymology of eunicellane diterpenoids and highlights future research prospects in the field. ONE-SENTENCE SUMMARY: A summary of recent advancements in the biosynthesis and enzymology of eunicellane diterpenoids, a structurally unique and biologically active family of natural products found in coral, plants, and bacteria.

Cytochrome P450 Mediated Cyclization in Eunicellane Derived Diterpenoid Biosynthesis.

Terpene cyclization, one of the most complex chemical reactions in nature, is generally catalyzed by two classes of terpene cyclases (TCs). Cytochrome P450s that act as unexpected TC-like enzymes are known but are very rare. In this study, we genome-mined a cryptic bacterial terpenoid gene cluster, named ari, from the thermophilic actinomycete strain Amycolatopsis arida. By employing a heterologous production system, we isolated and characterized three highly oxidized eunicellane derived diterpenoids, aridacins A-C (1-3), that possess a 6/7/5-fused tricyclic scaffold. In vivo and in vitro experiments systematically established a noncanonical two-step biosynthetic pathway for diterpene skeleton formation. First, a class I TC (AriE) cyclizes geranylgeranyl diphosphate (GGPP) into a 6/10-fused bicyclic cis-eunicellane skeleton. Next, a cytochrome P450 (AriF) catalyzes cyclization of the eunicellane skeleton into the 6/7/5-fused tricyclic scaffold through C2-C6 bond formation. Based on the results of quantum chemical computations, hydrogen abstraction followed by electron transfer coupled to barrierless carbocation ring closure is shown to be a viable mechanism for AriF-mediated cyclization. The biosynthetic logic of skeleton construction in the aridacins is unprecedented, expanding the catalytic capacity and diversity of P450s and setting the stage to investigate the inherent principles of carbocation generation by P450s in the biosynthesis of terpenoids.

Bacterial terpenome.

Covering: up to mid-2020 Terpenoids, also called isoprenoids, are the largest and most structurally diverse family of natural products. Found in all domains of life, there are over 80 000 known compounds. The majority of characterized terpenoids, which include some of the most well known, pharmaceutically relevant, and commercially valuable natural products, are produced by plants and fungi. Comparatively, terpenoids of bacterial origin are rare. This is counter-intuitive to the fact that recent microbial genomics revealed that almost all bacteria have the biosynthetic potential to create the C5 building blocks necessary for terpenoid biosynthesis. In this review, we catalogue terpenoids produced by bacteria. We collected 1062 natural products, consisting of both primary and secondary metabolites, and classified them into two major families and 55 distinct subfamilies. To highlight the structural and chemical space of bacterial terpenoids, we discuss their structures, biosynthesis, and biological activities. Although the bacterial terpenome is relatively small, it presents a fascinating dichotomy for future research. Similarities between bacterial and non-bacterial terpenoids and their biosynthetic pathways provides alternative model systems for detailed characterization while the abundance of novel skeletons, biosynthetic pathways, and bioactivies presents new opportunities for drug discovery, genome mining, and enzymology.

TfOH- and HBF4-Mediated Formal Cycloisomerizations and [4+3] Cycloadditions of Allene-alkynylbenzenes.

A metal-free, TfOH (1.1 equiv)-mediated formal cycloisomerization of easily prepared allene-alkynylbenzenes to give pyrrolidines and cyclopentanes derivatives was developed. This reaction is initiated by the generation of allylic cation from allene, followed by alkyne's reaction with the allylic cation, to give a vinyl cation, which is finally intercepted by the triflate (TfO) anion. This cycloisomerization can be further tuned to become an acid-mediated intramolecular formal [4+3] cycloaddition by using 10 equiv of TfOH (The excess acid was used to promote the Friedel-Crafts reaction of the acid-mediated cycloisomerization products). The present system can also be applied to synthesized F-incorporated products by using HBF4 or Me3OBF4 as the fluoro source.

Hydrogen sulfide ameliorates rat myocardial fibrosis induced by thyroxine through PI3K/AKT signaling pathway.

This study aims to investigate the role and regulatory mechanism of the Hydrogen sulfide (H2S) in amelioration of rat myocardial fibrosis induced by thyroxine through interfering the autophagy via regulating the activity of PI3K/AKT1 signaling pathway and the expression of relative miRNA. 40 adult male SD rats were randomly divided into 4 groups (n = 10): the control group, the thyroxine model group (TH group), the model group with H2S intervention (TH + H2S group) and the normal group with H2S intervention (H2S group). Pathological changes were observed via H&E staining and Masson staining, Expressions of MMPs/TIMPs, PI3K/AKT, autophagy-related proteins in myocardial tissues were detected via Western blotting, and the expressions of miR-21, miR-34a, miR-214 and miR-221 were detected via RT-qPCR. Compared with the control group, in the TH group, myocardial fibrosis was more significant, the expressions of proteins in PI3K/AKT and autophagy-related proteins were significantly decreased, as well as the expression of miR-221; while the expressions of miR-21, miR-34a and miR-214 were significantly elevated. By contrast, all above-mentioned changes were obviously reversed with H2S treatment, which demonstrated the positive function of H2S in amelioration of rat myocardial fibrosis induced by thyroxine. The mechanism of such amelioration may be correlated with autophagy activated by the upregulation of expression of PI3K/AKT signaling pathway and downregulation of expressions of miR-21, miR-34a and miR-214.

Two sex pheromone receptors for sexual communication in the American cockroach.

Volatile sex pheromones are vital for sexual communication between males and females. Females of the American cockroach, Periplaneta americana, produce and emit two sex pheromone components, periplanone-A (PA) and periplanone-B (PB). Although PB is the major sex attractant and can attract males, how it interacts with PA in regulating sexual behaviors is still unknown. In this study, we found that in male cockroaches, PA counteracted PB attraction. We identified two odorant receptors (ORs), OR53 and OR100, as PB/PA and PA receptors, respectively. OR53 and OR100 were predominantly expressed in the antennae of sexually mature males, and their expression levels were regulated by the sex differentiation pathway and nutrition-responsive signals. Cellular localization of OR53 and OR100 in male antennae further revealed that two types of sensilla coordinate a complex two-pheromone-two-receptor pathway in regulating cockroach sexual behaviors. These findings indicate distinct functions of the two sex pheromone components, identify their receptors and possible regulatory mechanisms underlying the male-specific and age-dependent sexual behaviors, and can guide novel strategies for pest management.

Has pilot zones policy for green finance reform and innovations improved the level of green financial development and environmental quality?

This study uses the green finance reform and innovation pilot zone policy approved by the State Council in 2017 as a quasi-natural experiment to explore whether the implementation of the policy has improved the level of green finance development and environmental quality in Chinese cities at the prefecture level and above. The results show that the green financial reform and innovation pilot zone policy can significantly improve the level of regional green financial development and environmental quality, and the results are robust. Further heterogeneity analysis finds that the green financial reform and innovation pilot zone policy have heterogeneous effects on the level of green financial development and environmental quality in different regions, sizes, environmental regulation intensity, financial development levels, and cities of different administrative levels. Based on this conclusion, suggestions are made that the scope should be further expanded and green finance policies should be formulated differently.

Phenyl-Terminated Coupling Interface Enabled Highly Efficient and Stable Multiwavelength Perovskite Single Crystal/Silicon Integrated Photodetector.

The use of amino-terminated siloxanes as coupling interface for perovskite single crystals (PSCs)/silicon integrated devices has been demonstrated to be an effective method toward CMOS compatible optoelectronics; however, it suffers from the coupling stability against the hydrophilicity of the exposed terminal amino groups. In this work, a phenyl-terminated interfacial molecule, anilino-methyl-triethoxysilane (AMTES), is proposed to achieve the effectively galvanic coupling between PSCs and silicon, which can not only improve the device environmental reliability but also lower the surface energy of the silicon substrate so as to facilitate the epitaxial growth of PSCs. Benefiting from the interfacial coupling of AMTES, the obtained MAPbI3 SC/silicon integrated device possesses highly efficient multiwavelength photodetection properties across the X-ray and NIR range, which exhibits a specific detectivity D* of 3.84 × 1013 cm Hz1/2 W-1 in the visible-NIR region and an X-ray sensitivity of 1.18 × 104 µC Gyair-1 cm-2 with the lowest detection limit of 49.6 nGyair s-1. The ultra wide -3 dB bandwidth of 67,300 Hz and the linear dynamic range (LDR) of 112 dB also prove its impressive dynamic response capabilities. Moreover, the AMTES modified integrated device almost maintains 96% of the initial photodetection performance even after keeping in the atmosphere environment for 28 days. This work opens a new avenue for interfacial engineering toward the development of on-chip PSC integrated silicon optoelectronic devices.

Safety and effects of a home-based Tai Chi exercise rehabilitation program in patients with chronic heart failure: study protocol for a randomized controlled trial.

Introduction: Chronic heart failure (CHF), as the final stage of the progression of many cardiovascular disorders, is one of the main causes of hospitalization and death in the elderly and has a substantial impact on patients' quality of life (QOL). Exercise-based cardiac rehabilitation (CR) has been shown to considerably enhance QOL and prognosis. Given the barriers to center-based CR faced by most developing countries in the form of expensive instruments, the development of home-based CR is necessary. Tai Chi, as an instrument-free exercise, has been shown to be successful in treating elderly CHF individuals. Fu Yang, as one of the academic concept of Traditional Chinese Medicine (TCM), believes that the fundamental pathogenesis of CHF is the gradual decline of Yang, and emphasizes the restoration of Yang physiological function in the treatment process. Therefore, we develope a home-based Tai Chi exercise rehabilitation program called Fu Yang Tai Chi (FYTC) for elderly CHF patients by combining the Fu Yang Theory of TCM with the CR theory. The objective of this study is to evaluate the effectiveness, acceptability, and safety of the program. Methods and analysis: We suggest conducting a parallel randomized controlled clinical trial with open label. Eighty CHF elderly participants will be randomly assigned in a 1:1 ratio to the FYTC rehabilitation program group or the moderate-intensity aerobic walking control group. Eligible participants will engage in either three sessions weekly of FYTC or walking exercise for 12 weeks. The primary outcome is the relative change in 6 min walk distance (6MWD). The secondary outcomes are the plasma levels of N-terminal pro-B-type natriuretic peptide (NT-proBNP), QOL, left ventricular ejection fraction (LVEF), left ventricular end-diastolic diameter (LVEDd), self-rating anxiety scale (SAS) and depression scale (SDS), exercise skills, and noninvasive hemodynamic monitoring. Throughout the trial, adverse events will be recorded for safety evaluation. Researchers who are blinded to the treatment allocation will analyze the data. Ethics and dissemination: This research was authorized by the Guang'anmen Hospital Ethics Committee of the Chinese Academy of Medical Sciences (2022-141-KY). Our findings will be shared online and in academic conferences as well as in peer-reviewed journals. Trial registration number: ChiCTR2200063511.

First trans-eunicellane terpene synthase in bacteria.

Terpenoids are the largest family of natural products, but prokaryotes are vastly underrepresented in this chemical space. However, genomics supports vast untapped biosynthetic potential for terpenoids in bacteria. We discovered the first trans-eunicellane terpene synthase (TS), AlbS from Streptomyces albireticuli NRRL B-1670, in nature. Mutagenesis, deuterium labeling studies, and quantum chemical calculations provided extensive support for its cyclization mechanism. In addition, parallel stereospecific labeling studies with Bnd4, a cis-eunicellane TS, revealed a key mechanistic distinction between these two enzymes. AlbS highlights bacteria as a valuable source of novel terpenoids, expands our understanding of the eunicellane family of natural products and the enzymes that biosynthesize them, and provides a model system to address fundamental questions about the chemistry of 6,10-bicyclic ring systems.

How industrial upgrading can improve China's air quality: empirical analysis based on multilevel growth model.

With the rapid development of industrialization and urbanization in China, the ecological environment has been damaged, especially the air quality, which has negatively impacted the productivity and lives of residents. China has taken various measures to improve air quality, and industrial upgrading is one of these measures. This article uses urban and provincial data from 2015 to 2018 and a multilevel growth model to study how industrial upgrading can improve air quality. The following conclusions are drawn through empirical analysis. If industrial upgrading is not considered, with time, air quality will gradually deteriorate. However, once the country adopts strategic measures for industrial upgrading, the combined effect of industrial upgrading and time will improve air quality. Industrial upgrading and industrial restructuring jointly reduce air pollution and have a significant impact on the improvement of air quality. Company goals for economic profit and survival will eventually lead to overall industrial upgrades that have little effect on air improvement. According to the empirical results, this paper puts forward some suggestions to improve the air quality.

LncRNA MEG3: Potential stock for precision treatment of cardiovascular diseases.

The prevalence and mortality rates of cardiovascular diseases are increasing, and new treatment strategies are urgently needed. From the perspective of basic pathogenesis, the occurrence and development of cardiovascular diseases are related to inflammation, apoptosis, fibrosis and autophagy of cardiomyocytes, endothelial cells and other related cells. The involvement of maternally expressed gene 3 (MEG3) in human disease processes has been increasingly reported. P53 and PI3K/Akt are important pathways by which MEG3 participates in regulating cell apoptosis. MEG3 directly or competitively binds with miRNA to participate in apoptosis, inflammation, oxidative stress, endoplasmic reticulum stress, EMT and other processes. LncRNA MEG3 is mainly involved in malignant tumors, metabolic diseases, immune system diseases, cardiovascular and cerebrovascular diseases, etc., LncRNA MEG3 has a variety of pathological effects in cardiomyocytes, fibroblasts and endothelial cells and has great clinical application potential in the prevention and treatment of AS, MIRI, hypertension and HF. This paper will review the research progress of MEG3 in the aspects of mechanism of action, other systemic diseases and cardiovascular diseases, and point out its great potential in the prevention and treatment of cardiovascular diseases. lncRNAs also play a role in endothelial cells. In addition, lncRNA MEG3 has shown biomarker value, prognostic value and therapeutic response measurement in tumor diseases. We boldly speculate that MEG3 will play a role in the emerging discipline of tumor heart disease.

Vapor-Deposited Amino Coupling of Hybrid Perovskite Single Crystals and Silicon Wafers toward Highly Efficient Multiwavelength Photodetection.

The complementary integration of perovskite single crystals (PSCs) and silicon-based circuitry provides a feasible way to combine their superiority toward efficient multiwavelength photodetection and imaging readout; however, it suffers from distinct lattice mismatch as well as the ambiguous coupling interface effect. Herein, we develop a vacuum-assisted vapor deposition strategy to realize an ultrauniform aminosiloxane interface-modified silicon wafer, which enables the monolithic epitaxial growth of PSCs with the highest mechanical coupling strength up to 340,000 N m-2 achieved so far. According to the molecular coupling engineering development with different aminosiloxanes, we achieve a highly efficient multiwavelength-responsive integrated photodetector, possessing specific photodetectivity values of 4.36 × 1012 jones and 4.55 × 1011 jones within the visible and NIR regions, respectively, as well as the lowest X-ray detection limit of 42.6 nGyair s-1. Moreover, a particularly wide -3dB cut-off frequency of 6350 Hz as well as a 120 dB linear dynamic range (LDR) also endows the integrated device with excellent dynamic photodetection capability. This work provides an efficacious approach in the integration technology for PSC-based optoelectronic applications.

Bacterial diterpene synthases prenylate small molecules.

The biosynthesis of terpenoid natural products begins with a carbocation-based cyclization or prenylation reaction. While these reactions are mechanistically similar, there are several families of enzymes, namely terpene synthases and prenyltransferases, that have evolved to specifically catalyze terpene cyclization or prenylation reactions. Here, we report that bacterial diterpene synthases, enzymes that are traditionally considered to be specific for cyclization, are capable of efficiently catalyzing both diterpene cyclization and the prenylation of small molecules. We investigated this unique dual reactivity of terpene synthases through a series of kinetic, biocatalytic, structural, and bioinformatics studies. Overall, this study unveils the ability of terpene synthases to catalyze C-, N-, O-, and S-prenylation on small molecules, proposes a substrate decoy mechanism for prenylation by terpene synthases, supports the physiological relevance of terpene synthase-catalyzed prenylation in vivo, and addresses questions regarding the evolution of prenylation function and its potential role in natural products biosynthesis.

Traditional Chinese medicine as a therapeutic option for cardiac fibrosis: Pharmacology and mechanisms.

Cardiovascular diseases are one of the leading causes of death worldwide and cardiac fibrosis is a common pathological process for cardiac remodeling in cardiovascular diseases. Cardiac fibrosis not only accelerates the deterioration progress of diseases but also becomes a pivotal contributor for futile treatment in clinical cardiovascular trials. Although cardiac fibrosis is common and prevalent, effective medicines to provide sufficient clinical intervention for cardiac fibrosis are still unavailable. Traditional Chinese medicine (TCM) is the natural essence experienced boiling, fry, and other processing methods, including active ingredients, extracts, and herbal formulas, which have been applied to treat human diseases for a long history. Recently, research has increasingly focused on the great potential of TCM for the prevention and treatment of cardiac fibrosis. Here, we aim to clarify the identified pro-fibrotic mechanisms and intensively summarize the application of TCM in improving cardiac fibrosis by working on these mechanisms. Through comprehensively analyzing, TCM mainly regulates the following pathways during ameliorating cardiac fibrosis: attenuation of inflammation and oxidative stress, inhibition of cardiac fibroblasts activation, reduction of extracellular matrix accumulation, modulation of the renin-angiotensin-aldosterone system, modulation of autophagy, regulation of metabolic-dependent mechanisms, and targeting microRNAs. We also discussed the deficiencies and the development direction of anti-fibrotic therapies on cardiac fibrosis. The data reviewed here demonstrates that TCM shows a robust effect on alleviating cardiac fibrosis, which provides us a rich source of new drugs or drug candidates. Besides, we also hope this review may give some enlightenment for treating cardiac fibrosis in clinical practice.

Rapid Construction of the Common [5-5-6] Tricyclic Ring Skeleton in Polycyclic Cembranoids and Norcembranoids via Intramolecular 1,3-Dipolar Cycloaddition.

A synthetically challenging bowl-shaped [5-5-6] tricyclic framework commonly seen in many polycyclic cembranoids and norcembranoids was strategically established in a convenient six-step sequence featuring an intramolecular 1, 3-dipolar cycloaddition reaction. Synthetic manipulations of such a valuable intermediate were explored for future applications.

Hydrogen sulfide attenuates myocardial fibrosis in diabetic rats through the JAK/STAT signaling pathway.

The aim of the present study was to determine the role of hydrogen sulfide (H2S) in improving myocardial fibrosis and its effects on oxidative stress, endoplasmic reticulum (ER) stress and cell apoptosis in diabetic rats, by regulating the Janus kinase̸signal transducer and activator of transcription (JAK̸STAT) signaling pathway. A total of 40 male Sprague­Dawley rats were randomly divided into four groups (n=10) as follows: normal (control group), diabetes mellitus [streptozotocin (STZ) group], diabetes mellitus treated with H2S (STZ + H2S group), and normal rats treated with H2S (H2S group). Diabetes in rats was induced by intraperitoneal (i.p.) injection of STZ at a dose of 40 mg̸kg. NaHS (100 µmol̸kg, i.p.), which was used as an exogenous donor of H2S, was administered to rats in the STZ + H2S and H2S groups. After 8 weeks, the pathological morphological changes in myocardial fibers were observed following hematoxylin and eosin and Masson's trichrome staining. Apoptosis of myocardial tissue was analyzed by the terminal deoxynucleotidyl transferase dUTP nick end labeling assay. Oxidative stress was evaluated through detecting the content of malondialdehyde (MDA), 4-hydroxynonenal (4-HNE), glutathione (GSH) and superoxide dismutase (SOD) in the myocardial cells by ELISA. The expression of collagen III, matrix metalloproteinase (MMP)8, MMP14, tissue inhibitor of metalloproteinase (TIMP)2, transforming growth factor (TGF)-ß, cystathionine­Î³­lyase (CSE), eukaryotic initiation factor 2α (eIF2α), GRP94, Bcl-2, caspase-3, tumor necrosis factor (TNF)-α, nuclear factor­κB (NF­κB) and proteins related to the JAK̸STAT pathway, was detected by western blot analysis. The results indicated that the array of myocardial cells was markedly disordered in STZ group rats; compared with the control group, both myocardial interstitial fibrosis and the deposition of collagen III were increased. Furthermore, the expression ratio of MMPs̸TIMPs was dysregulated, while the expression levels of TGF-ß, eIF2α, GRP94, caspase-3, TNF-α, NF-κB, MDA and 4-HNE were significantly increased. Furthermore, the expressions of JAK-1̸2 and STAT1̸3̸5̸6 were also markedly upregulated, while those of CSE, SOD, GSH and Bcl-2 were downregulated. Compared with the STZ group, these changes were reversed in the STZ + H2S group. The results of the present study demonstrated that H2S can improve myocardial fibrosis in diabetic rats, and the underlying mechanism may be associated with the downregulation of the JAK̸STAT signaling pathway, thereby suppressing oxidative stress and ER stress, inflammatory reaction and cell apoptosis.

Gaseous signalling molecule SO2 via Hippo­MST pathway to improve myocardial fibrosis of diabetic rats.

Recent studies have indicated the existence of an endogenous sulfur dioxide (SO2)­generating system in the cardiovascular system. The present study aimed to discuss the function and regulatory mechanism of gaseous signal molecule SO2 in inhibiting apoptosis and endoplasmic reticulum stress (ERS) via the Hippo­MST signaling pathway to improve myocardial fibrosis of diabetic rats. A total of 40 male Sprague­Dawley rats were randomly divided into four groups (10 rats per group): Normal control group (control group), diabetic rats group [streptozotocin (STZ) group], SO2 intervention group (STZ+SO2 group) and diabetes mellitus rats treated with L­Aspartic acid ß­hydroxamate (HDX) group (HDX group). Diabetic rats models were established by intra­peritoneal injection of STZ (40 mg/kg) Following model establishment, intra­peritoneal injection of Na2SO3/NaHSO3 solution (0.54 mmol/kg) was administered in the STZ+SO2 group, and HDX solution (25 mg/kg/week) was administered in the HDX group. A total of 4 weeks later, echocardiography was performed to evaluate rats' cardiac function; Masson staining, terminal deoxynucleotidyl transferase dUTP nick end labeling staining and transmission electron microscopy examinations were performed to observe myocardial morphological changes. ELISA was employed to determine the SO2 content. Western blot analysis was performed to detect the expression of proteins associated with apoptosis, ERS and the Hippo­MST signalling pathway. Compared with the control group, the STZ group and HDX group had a disordered arrangement of myocardial cells with apparent myocardial fibrosis, and echocardiography indicated that the cardiac function was lowered, there was an obvious increase of apoptosis in myocardial tissue, the expression levels of apoptosis­associated protein B­cell lymphoma associated protein X, caspase­3 and caspase­9 were upregulated, and Bcl­2 expression was downregulated. The expression of ERS and Hippo­MST pathway­associated proteins, including CHOP, GRP94, MST1 and MST2, were significantly upregulated. By contrast, these above­mentioned changes were reversed by SO2 treatment. Compared with STZ group, the HDX group had a further increase of myocardial fibrosis and apoptosis, while there were no statistically significant differences in the expression of Bax/Bcl­2, caspase­3, caspase­9 and ERS and Hippo­MST pathway­associated proteins. The results of the present study demonstrated that the gaseous signal molecule SO2 can effectively improve the myocardial fibrosis of diabetic rats, and its mechanism may be associated with reduced apoptosis and ERS by downregulated Hippo­MST pathway.