Synthesis and biological evaluation of novel hydrogen sulfide releasing nicotinic acid derivatives

A meta-analysis of animal studies evaluating the effect of hydrogen sulfide on ischemic stroke: is the preclinical evidence sufficient to move forward?

Hydrogen sulfide (H2S) is a gasotransmitter that has been studied for its potential therapeutic effects, including its role in the pathophysiology and treatment of stroke. This systematic review and meta-analysis aimed to determine the sufficiency of overall preclinical evidence to guide the initiation of clinical stroke trials with H2S and provide tailored recommendations for their design. PubMed, Web of Science, Scopus, EMBASE, and MEDLINE were searched for studies evaluating the effect of any H2S donor on in vivo animal models of regional ischemic stroke, and 34 publications were identified. Pooling of the effect sizes using the random-effect model revealed that H2S decreased the infarct area by 34.5% (95% confidence interval (CI) 28.2-40.8%, p < 0.0001), with substantial variability among the studies (I2 = 89.8%). H2S also caused a 37.9% reduction in the neurological deficit score (95% CI 29.0-46.8%, p < 0.0001, I2 = 63.8%) and in the brain water content (3.2%, 95% CI 1.4-4.9%, p = 0.0014, I2 = 94.6%). Overall, the studies had a high risk of bias and low quality of evidence (median quality score 5/15, interquartile range 4-9). The majority of the included studies had a "high" or "unclear" risk of bias, and none of the studies overall had a "low" risk. In conclusion, H2S significantly improves structural and functional outcomes in in vivo animal models of ischemic stroke. However, the level of evidence from preclinical studies is not sufficient to proceed to clinical trials due to the low external validity, high risk of bias, and variable design of existing animal studies.

5-(4-Hydroxyphenyl)-3H-1,2-dithiole-3-thione derivatives of brefeldin A: Design, synthesis and cytotoxicity in MDA-MB-231 human breast cancer cells

27 novel 5-(4-hydroxyphenyl)-3H-1,2-dithiole-3-thione derivatives of brefeldin A were designed and synthesized to make them more conducive to the cancer treatment. The antiproliferative activity of all the target compounds was tested against six human cancer cell lines and one human normal cell line. Compound 10d exhibited nearly the most potent cytotoxicity with IC₅₀ values of 0.58, 0.69, 1.82, 0.85, 0.75, 0.33 and 1.75 μM against A549, DU-145, A375, HeLa, HepG2, MDA-MB-231 and L-02 cell lines. Moreover, 10d inhibited metastasis and induced apoptosis of MDA-MB-231 cells in a dose-dependent manner. The potent anticancer effects of 10d were prompted based on the aforementioned results, the therapeutic potential of 10d for breast cancer was worth further exploration.

Hydrogen sulfide and its donors for the treatment of cerebral ischaemia-reperfusion injury: A comprehensive review

As an endogenous gas signalling molecule, hydrogen sulfide (H₂S) is frequently present in a variety of mammals and plays a significant role in the cardiovascular and nervous systems. Reactive oxygen species (ROS) are produced in large quantities as a result of cerebral ischaemia-reperfusion, which is a very serious class of cerebrovascular diseases. ROS cause oxidative stress and induce specific gene expression that results in apoptosis. H₂S reduces cerebral ischaemia-reperfusion-induced secondary injury via anti-oxidative stress injury, suppression of the inflammatory response, inhibition of apoptosis, attenuation of cerebrovascular endothelial cell injury, modulation of autophagy, and antagonism of P2X7 receptors, and it plays an important biological role in other cerebral ischaemic injury events. Despite the many limitations of the hydrogen sulfide therapy delivery strategy and the difficulty in controlling the ideal concentration, relevant experimental evidence demonstrating that H₂S plays an excellent neuroprotective role in cerebral ischaemia-reperfusion injury (CIRI). This paper examines the synthesis and metabolism of the gas molecule H₂S in the brain as well as the molecular mechanisms of H₂S donors in cerebral ischaemia-reperfusion injury and possibly other unknown biological functions. With the active development in this field, it is expected that this review will assist researchers in their search for the potential value of hydrogen sulfide and provide new ideas for preclinical trials of exogenous H₂S.

Research Progress of H2S Donors Conjugate Drugs Based on ADTOH

H₂S is an endogenous gas signaling molecule and its multiple biological effects have been demonstrated. The abnormal level of H₂S is closely related to the occurrence and development of many diseases, and H₂S donors has important pharmacological implications. In recent years, H₂S donors represented by ADTOH (5-(4-hydroxyphenyl)-3H-1,2-dithiole-3-thione) are often used to synthesize new 'conjugate' compounds that can release H₂S and parent drugs. These hybrids retain the pharmacological activity of the parent drugs and H₂S and have a synergistic effect. ADTOH and parent drug hybrids have become one of the important strategies for the development of H₂S donor conjugate drugs. This review summarizes molecular hybrids between ADTOH and clinical drugs to provide new ideas for the study of H₂S donor drug design.

Ionic Liquid-Mediated One-Pot 3-Acylimino-3H-1,2-dithiole Synthesis from Thiocarboxylic Acids and Alkynylnitriles via In Situ Generation of Disulfide Intermediates

A practical and straightforward strategy for the synthesis of 3-acylimino-3H-1,2-dithiol derivatives via a metal-free annulation reaction of alkynylnitriles with thiocarboxylic acids mediated by ionic liquids [BMIM]Br has been reported. This operationally simple protocol offers an easy and rapid access to a library of dithiol derivatives in moderate to good yields. The mechanistic studies show a benzoyldithio anion addition to alkynylnitriles followed by an annulation reaction through the involvement of a disulfide moiety as the key intermediate.

Optimization of clofibrate with O-desmethyl anetholtrithione lead to a novel hypolipidemia compound with hepatoprotective effect

Oxidative stress and inflammation were considered to be the major mechanisms in liver damage caused by clofibrate (CF). In order to obtain lipid-lowering drugs with less liver damage, the structure of clofibrate was optimized by O-desmethyl anetholtrithione and got the target compound clofibrate-O-desmethyl anetholtrithione (CF-ATT). CF-ATT significantly reduced the levels of plasma triglycerides (TG), total cholesterol (TC) in hyperlipidemia mice induced by Triton WR-1339. In addition, CF-ATT has a significantly protective effect on the liver compared with CF. The liver weight and liver coefficient were reduced. The hepatic function indexes were also decreased, such as aspartate aminotransferase (AST), alanine aminotransferase (ALT), and alkaline phosphatase (ALP). Histopathological examination of the liver revealed that inflammatory cell infiltration, nuclear degeneration, cytoplasmic loosening and hepatocyte necrosis were ameliorated by administration with CF-ATT. The hepatoprotective mechanism showed that CF-ATT significantly up-regulated Nrf2 and HO-1 protein expression and down-regulated p-NF-κB P65 expression in the liver. CF-ATT has obviously antioxidant and anti-inflammatory activity. These findings suggested that CF-ATT has significant hypolipidemia activity and exact hepatoprotective effect possibly through the Nrf2/NF-κB-mediated signal pathway.

Novel Derivatives of Nicotinic Acid as Promising Anticancer Agents

BACKGROUND

Cancer has become the second leading cause of death worldwide. Despite of the availability of significant number of anticancer agents, cancer is still incurable especially at the last stages. Remarkable targets for anticancer research and drug discovery are heterocyclic compounds, and among them, superior effect has been shown by the nitrogen containing compounds than non-nitrogen containing compounds. Nicotinic acid, a nitrogen containing moiety and its derivatives have gained an immense importance in the development of anticancer drugs owing to the wide variety of biological properties displayed by them.

OBJECTIVE

The objective of this review is to provide researchers the information about various synthetic approaches used for the synthesis of anticancer drugs of nicotinic acid from 2001 onwards and to reveal their application and importance in the treatment of this dreadful disease.

CONCLUSION

As indicated by this review, considerable work has been done in terms of synthesis and investigation of anticancer potential of nicotinamide derivatives. The information provided in this article may be of great value for the researchers seeking to develop efficient anticancer drugs.

Synthesis and Reactivity of 3H-1,2-dithiole-3-thiones

3H-1,2-Dithiole-3-thiones are among the best studied classes of polysulfur-containing heterocycles due to the almost explosive recent interest in these compounds as sources of hydrogen sulfide as an endogenously produced gaseous signaling molecule. This review covers the recent developments in the synthesis of these heterocycles, including both well-known procedures and important novel transformations for building the 1,2-dithiole-3-thione ring. Diverse ring transformations of 3H-1,2-dithiole-3-thiones into various heterocyclic systems through 1,3-dipolar cycloaddition, replacement of one or two sulfur atoms to form carbon- and carbon-nitrogen containing moieties, and other unexpected reactions are considered.

A facile method for vancomycin C-terminus functionalization and derivatization through hydrazide

Over 60-year clinical use of vancomycin led to the emergence of vancomycin-resistant bacteria and threatened our health. To combat vancomycin-resistant strains, numerous vancomycin analogues were developed, such as Telavancin, Oritavancin and Dalbavancin. Extra structures embedded on C-terminus has been proved to be an effective strategy to promote antibacterial activity of vancomycin against vancomycin-resistant strains. Here, we reported a facile strategy, inspired by native chemical ligation, for vancomycin C-terminus functionalization and derivatization. The introduction of C-terminal hydrazide on vancomycin not only provided us an accessible method for C-terminus functionalization through carbonyl azide and thioester, also acted as an efficient site for vancomycin structure modifications. Based on hydrazide-vancomycin, we effectively conjugated cysteine and cysteine containing peptides onto vancomycin C-terminus, and two fluorescent FITC-vancomycin were prepared through Cys-Maleimide conjugation. Meanwhile, we introduced lipophilic structures onto vancomycin C-terminus via the hydrazide moiety. The obtained vancomycin derivatives were evaluated against both Gram-positive and negative bacteria strains.

Development and Characterization of Inkjet Printed Edible Films for Buccal Delivery of B-Complex Vitamins

Buccal films containing two vitamins, i.e., thiamine hydrochloride (THCl) and nicotinic acid (NA), were fabricated via two-dimensional (2D) inkjet printing. For the preparation of buccal films, solubility studies and rheological evaluations were conducted in distilled water and propylene-glycol (PG) as main solvent and viscosity/surface tension modifier, respectively. The increased solubility in the solvents' mixture indicated that manufacturing of several doses of the THCl and NA is achievable. Various doses were deposited onto sugar-sheet substrates, by increasing the number of printing passes. The physiochemical characterization (SEM, DSC, FTIR) revealed that inkjet printing does not affect the solid state of the matrix. Water uptake studies were conducted, to compare the different vitamin-loaded formulations. The in vitro release studies indicated the burst release of both vitamins within 10 min, a preferable feature for buccal administration. The in vitro permeation studies indicated that higher concentrations of the vitamins onto the sugar sheet improved the in vitro permeation performance of printed formulations.

Copper-Catalyzed Tandem Sulfuration/Annulation of Propargylamines with Sulfur via C-N Bond Cleavage

Copper-catalyzed aerobic oxidative sulfuration and annulation of propargylamines with elemental sulfur is described. The tandem reaction involves C-N bond cleavage and the formation of multiple C-S bonds, affording 1,2-dithiole-3-thiones in good to excellent yields with good functional group tolerance.

International Union of Basic and Clinical Pharmacology. CII: Pharmacological Modulation of H2S Levels: H2S Donors and H2S Biosynthesis Inhibitors

Over the last decade, hydrogen sulfide (H2S) has emerged as an important endogenous gasotransmitter in mammalian cells and tissues. Similar to the previously characterized gasotransmitters nitric oxide and carbon monoxide, H2S is produced by various enzymatic reactions and regulates a host of physiologic and pathophysiological processes in various cells and tissues. H2S levels are decreased in a number of conditions (e.g., diabetes mellitus, ischemia, and aging) and are increased in other states (e.g., inflammation, critical illness, and cancer). Over the last decades, multiple approaches have been identified for the therapeutic exploitation of H2S, either based on H2S donation or inhibition of H2S biosynthesis. H2S donation can be achieved through the inhalation of H2S gas and/or the parenteral or enteral administration of so-called fast-releasing H2S donors (salts of H2S such as NaHS and Na2S) or slow-releasing H2S donors (GYY4137 being the prototypical compound used in hundreds of studies in vitro and in vivo). Recent work also identifies various donors with regulated H2S release profiles, including oxidant-triggered donors, pH-dependent donors, esterase-activated donors, and organelle-targeted (e.g., mitochondrial) compounds. There are also approaches where existing, clinically approved drugs of various classes (e.g., nonsteroidal anti-inflammatories) are coupled with H2S-donating groups (the most advanced compound in clinical trials is ATB-346, an H2S-donating derivative of the non-steroidal anti-inflammatory compound naproxen). For pharmacological inhibition of H2S synthesis, there are now several small molecule compounds targeting each of the three H2S-producing enzymes cystathionine-β-synthase (CBS), cystathionine-γ-lyase, and 3-mercaptopyruvate sulfurtransferase. Although many of these compounds have their limitations (potency, selectivity), these molecules, especially in combination with genetic approaches, can be instrumental for the delineation of the biologic processes involving endogenous H2S production. Moreover, some of these compounds (e.g., cell-permeable prodrugs of the CBS inhibitor aminooxyacetate, or benserazide, a potentially repurposable CBS inhibitor) may serve as starting points for future clinical translation. The present article overviews the currently known H2S donors and H2S biosynthesis inhibitors, delineates their mode of action, and offers examples for their biologic effects and potential therapeutic utility.