Indole-pyridine carbonitriles: multicomponent reaction synthesis and bio-evaluation as potential hits against diabetes mellitus

Background: Diabetes mellitus is a significant health disorder; therefore, researchers should focus on discovering new drug candidates. Methods: A series of indole-pyridine carbonitrile derivatives, 1-34, were synthesized through a one-pot multicomponent reaction and evaluated for antidiabetic and antioxidant potential. Results: In this library, 12 derivatives - 1, 2, 4, 5, 7, 8, 10-12, 14, 15 and 31 - exhibited potent inhibitory activities against α-glucosidase and α-amylase enzymes, in comparison to acarbose (IC50 = 14.50 ± 0.11 μM). Furthermore, kinetics, absorption, distribution, metabolism, excretion and toxicity and molecular docking studies were used to interpret the type of inhibition, binding energies and interactions of ligands with target enzymes. Conclusion: These results indicate that the compounds may be promising hits for controlling diabetes mellitus and its related complications.

Multicomponent diastereoselective synthesis of tetrahydropyridines as α-amylase and α-glucosidase enzymes inhibitors

Background: Researchers seeking new drug candidates to treat diabetes mellitus have been exploring bioactive molecules found in nature, particularly tetrahydropyridines (THPs). Methods: A library of THPs (1-31) were synthesized via a one-pot multicomponent reaction and investigated for their inhibition potential against α-glucosidase and α-amylase enzymes. Results: A nitrophenyl-substituted compound 5 with IC50 values of 0.15 ± 0.01 and 1.10 ± 0.04 μM, and a Km value of 1.30 mg/ml was identified as the most significant α-glucosidase and α-amylase inhibitor, respectively. Kinetic studies revealed the competitive mode of inhibition, and docking studies revealed that compound 5 binds to the enzyme by establishing hydrophobic and hydrophilic interactions and a salt bridge interaction with His279. Conclusion: These molecules may be a potential drug candidate for diabetes in the future.

Indole-Containing Natural Products 2019-2022: Isolations, Reappraisals, Syntheses, and Biological Activities

Indole alkaloids represent a large subset of natural products, with more than 4100 known compounds. The majority of these alkaloids are biologically active, with some exhibiting excellent antitumor, antibacterial, antiviral, antifungal, and antiplasmodial activities. Consequently, the natural products of this class have attracted considerable attention as potential leads for novel therapeutics and are routinely isolated, characterized, and profiled to gauge their biological potential. However, data on indole alkaloids, their various structures, and bioactivities are complex due to their diverse sources, such as plants, fungi, bacteria, sponges, tunicates, and bryozoans; thus, isolation methods produce an incredible trove of information. The situation is exacerbated when synthetic derivatives, as well as their structures, bioactivities, and synthetic schemes, are considered. Thus, to make such data comprehensive and inform researchers about the current field's state, this review summarizes recent reports on novel indole alkaloids. It deals with the isolation and characterization of 250 novel indole alkaloids, a reappraisal of previously reported compounds, and total syntheses of indole alkaloids. In addition, several syntheses and semi-syntheses of indole-containing derivatives and their bioactivities are reported between January 2019 and July 2022.

Evaluation of synthetic 2-aryl quinoxaline derivatives as α-amylase, α-glucosidase, acetylcholinesterase, and butyrylcholinesterase inhibitors

Variety of 2-aryl quinoxaline derivatives 1-23 were synthesized in good yields, by reacting 1,2-phenylenediamine with varyingly substituted phenacyl bromides in the presence of pyridine catalyst. All molecules 1-23 were characterized by spectroscopic techniques and evaluated for their diverse biological potential against α-amylase (α-AMY), α-glucosidase (α-GLU), acetylcholinesterase (AChE), and butyrylcholinesterase (BChE) enzymes. Synthetic derivatives possess enhanced inhibitory potential against all enzymes at nanomolar concentrations. In particular, compound 14 was found much superior with IC₅₀ = 294.35, 198.21, 17.04, and 21.46 nM against α-AMY, α-GLU, AChE, and BChE, respectively, as compared to standard inhibitors. Furthermore, selected potent compounds, including 3, 4, 8, 14, 15, 17, and 18, were subjected to molecular docking studies to decipher the binding energies and interactions of ligands (synthetic molecules) with all four target enzymes.

Isatin thiazoles as antidiabetic: Synthesis, in vitro enzyme inhibitory activities, kinetics, and in silico studies

Diabetes mellitus is one of the most prevalent diseases nowadays. Several marketed drugs are available for the cure and treatment of diabetes, but there is still a dire need of introducing compatible drug molecules with lesser side effects. The current study is based on the synthesis of isatin thiazole derivatives 4-30 via the Hantzsch reaction. The synthetic compounds were characterized using different spectroscopic techniques and evaluated for their α-amylase and α-glucosidase inhibition potential. Of 27 isatin thiazoles, five (4, 5, 10, 12, and 16) displayed good activities against the α-amylase enzyme with IC₅₀ values in the range of 22.22 ± 0.02-27.01 ± 0.06 µM, and for α-glucosidase, the IC₅₀ values of these compounds were in the range of 20.76 ± 0.17-27.76 ± 0.17 µM, respectively. The binding interactions of the active molecules within the active site of enzymes were studied with the help of molecular docking studies. In addition, kinetic studies were carried out to examine the mechanism of action of the synthetic molecules as well. Compounds 3a, 4, 5, 10, 12, and 16 were also examined for their cytotoxic effect and were found to be noncytotoxic. Thus, several molecules were identified as good antihyperglycemic agents, which can be further modified to enhance inhibition ability and to find the lead molecule that can act as a potential antidiabetic agent.

Synthesis of azachalcones, their α-amylase, α-glucosidase inhibitory activities, kinetics, and molecular docking studies

Diabetes being a chronic metabolic disorder have attracted the attention of medicinal chemists and biologists. The introduction of new and potential drug candidates for the cure and treatment of diabetes has become a major concern due to its increased prevelance worldwide. In the current study, twenty-seven azachalcone derivatives 3-29 were synthesized and evaluated for their antihyperglycemic activities by inhibiting α-amylase and α-glucosidase enzymes. Five compounds 3 (IC₅₀ = 23.08 ± 0.03 µM), (IC₅₀ = 26.08 ± 0.43 µM), 5 (IC₅₀ = 24.57 ± 0.07 µM), (IC₅₀ = 27.57 ± 0.07 µM), 6 (IC₅₀ = 24.94 ± 0.12 µM), (IC₅₀ = 27.13 ± 0.08 µM), 16 (IC₅₀ = 27.57 ± 0.07 µM), (IC₅₀ = 29.13 ± 0.18 µM), and 28 (IC₅₀ = 26.94 ± 0.12 µM) (IC₅₀ = 27.99 ± 0.09 µM) demonstrated good inhibitory activities against α-amylase and α-glucosidase enzymes, respectively. Acarbose was used as the standard in this study. Structure-activity relationship was established by considering the parent skeleton and different substitutions on aryl ring. The compounds were also subjected for kinetic studies to study their mechanism of action and they showed competitive mode of inhibition against both enzymes. The molecular docking studies have supported the results and showed that these compounds have been involved in various binding interactions within the active site of enzyme.

Analysis of the fecal microbiome in Kemp’s ridley sea turtles Lepidochelys kempii undergoing rehabilitation

The impact of the intestinal and fecal microbiome on animal health has received considerable attention in recent years and has direct implications for the veterinary and wildlife rehabilitation fields. To examine the effects of rehabilitation on the microbiome in Kemp’s ridley sea turtlesLepidochelys kempii, fecal samples from 30 incidentally captured juveniles were collected during rehabilitation. Samples were analyzed to determine alpha- (α) and beta- (β) diversity as well as the taxonomic abundance of the fecal microbiota during rehabilitation and in response to treatment with antibiotics. The fecal microbial communities of animals housed in rehabilitation for a ‘short-term’ stay (samples collected 0-9 d post-capture) were compared with ‘long-term’ (samples collected 10+ d post-capture) and ‘treated’ groups (samples collected from turtles that had received antibiotic medication). Results of this study indicate that the most dominant phylum in fecal samples wasBacteroidetes(relative abundance, 45.44 ± 5.92% [SD]), followed byFirmicutes(26.62 ± 1.58%),Fusobacteria(19.49 ± 9.07%), andProteobacteria(7.39 ± 1.84%). Similarly, at the family level,Fusobacteriaceae(28.36 ± 17.75%),Tannerellaceae(15.41 ± 10.50%),Bacteroidaceae(14.58 ± 8.48%), andRuminococcaceae(11.49 ± 3.47%) were the most abundant. Our results indicated that both antibiotic-treated and long-term rehabilitated turtles demonstrated a significant decrease in β-diversity when compared to short-term rehabilitated turtles. Our results likewise showed that the length of time turtles spent in rehabilitation was negatively correlated with α- and β-diversity. This study demonstrates the importance of a judicious use of antibiotics during the rehabilitation process and emphasizes the importance of limiting the length of hospital stays for sick and injured sea turtles as much as possible.

Indole acrylonitriles as potential anti-hyperglycemic agents: Synthesis, α-glucosidase inhibitory activity and molecular docking studies

One of the most prevailing metabolic disorder diabetes mellitus has become the global health issue that has to be addressed and cured. Different marketed drugs have been made available for the treatment of diabetes but there is still a need of introducing new therapeutic agents that are economical and have lesser or no side effects. The current study deals with the synthesis of indole acrylonitriles (3-23) and the evaluation of these compounds for their potential for α-glucosidase inhibition. The structures of these synthetic molecules were deduced by using different spectroscopic techniques. Acarbose (IC₅₀ = 2.91 ± 0.02 μM) was used as standard in this study and the synthetic molecules (3-23) have shown promising α-glucosidase inhibitory activity. Compounds 4, 8, 10, 11, 14, 18, and 21 displayed superior inhibition of α-glucosidase enzyme in the range of (IC₅₀ = 0.53 ± 0.01-1.36 ± 0.04 μM) as compared to the standard acarbose. Compound 10 (IC₅₀ = 0.53 ± 0.01 μM) was the most effective inhibitor of this library and displayed many folds enhanced activity in contrast to the standard. Molecular docking of synthetic compounds was performed to verify the binding interactions of ligand with the active site of enzyme. This study had identified a number of potential α-glucosidase inhibitors that can be used for further research to identify a potent therapeutic agent against diabetes.