Synthesis, antitubercular activity, and molecular modeling studies of analogues of isoliquiritigenin and liquiritigenin, bioactive components from Glycyrrhiza glabra

Essential oil composition, in vitro antidiabetic, cytotoxicity, antimicrobial, antioxidant activity, and in silico molecular modeling analysis of secondary metabolites from Justicia schimperiana

Justicia schimperiana, known as "Dhumuugaa" in Afan Oromo and "Sensel" or "Smiza" in Amharic, is traditionally used to treat ailments such as scabies, fever, asthma, diarrhea, malaria, and more. This study explored the chemical composition and biological activity of its extracts and isolated compounds. The essential oils were extracted using the hydrodistillation method, and their chemical composition was evaluated using GC-MS. GC-MS analysis identified 54 and 52 chemical components in the essential oils (EOs) from roots and leaves, respectively. The structures of the isolated compounds have been identified using 1D and 2D-NMR techniques. Six compounds - β-sitosterol (1), 5-methoxy durmillone (2), trans-resveratrol (3), tricuspidatol A (4), kaempferol-3-O-α-rhamnopyranoside (5), and kaempferol-3-O-rutinoside (6) - were isolated from the root extracts and reported for the first time in this species. The antimicrobial activity was evaluated using the broth microdilution technique. EOs extracts showed significant antibacterial activity, particularly against Staphylococcus aureus, Streptococcus agalactiae, while compound 6 showed potent activity with an MIC of 0.25 μg/mL. The antioxidant activity revealed strong radical scavenging for compounds 5 and 6, with extracts also demonstrating significant α-amylase inhibitory effects and moderate cytotoxicity against the MCF-7 cell line. Molecular docking and ADMET analysis highlighted compounds 5 and 6 as promising therapeutic agent. These findings highlight the medicinal potential of J. schimperiana roots, warranting further exploration.

Synthesis, molecular modelling studies of artemisinin-chalcone derivatives and their antimalarial activity evaluation

Twenty-two monomers and dimers of artemisinin having chalcone as a linker were synthesised, and their antimalarial activity against Plasmodium falciparum was determined, and a quantitative structure-activity relationship (QSAR) was developed. Artemisinin is a frontline antimalarial drug known worldwide but is threatened because of the rapidly emerging artemisinin-resistant strain Plasmodium falciparum. In vitro, antimalarial IC50 (half-maximal inhibitory concentration) activity of a molecule against malaria parasites provides a good first screen for identifying the antimalarial potential of a particular molecule. The most active compound was artemisinin dimer dimethoxy chalcone as a linker (22) with IC50 of 4.34 nM. The molecular mechanism was explored through in silico docking & ADMET studies for the active compounds.

Improved antioxidant and anti-tubercular potential of liquiritigenin grafted on low molecular weight chitosan from gladius of Sepioteuthis lessoniana

Chitosan (CH) is natural abundant biopolymer present on earth after cellulose. CH can be functionalized by numerous functional groups such as amino and carboxyl groups, potential biologically active compounds. The functionalization of CH with polyphenols had a greater biological than non-grafted CH. In the present study, the polyphenolic compound liquiritigenin (LTG) is chemically functionalized on the low molecular weight chitosan (LMW-CH) (693.09 Da). This was extracted and irradiated with gamma radiation from the gladius of Sepioteuthis lessoniana. The grafted compound was to in vitro anti-oxidant employing physicochemical methods and characterization was made by spectroscopic methods. The degree of deacetylation (DDA) of the LMW-CH was detected in 74 % of the samples, and at higher concentrations (100 g/mL). LMW-CH grafted with LTG had improved water solubility (5 mg/mL), and was thermally stable upto 143.58 °C. Its molecular weight was 855.1 Da. In conclusion the in vitro antioxidant and the anti-tuberculosis (anti-TB) properties of the grafted samples were significantly (P < 0.001) increased compared to the unconjugated LMW-CH and LTG. Overall, functionalization of LTG with LMW-CH improved the anti-tuberculosis activity. Further studies are needed to explore the possibilities of its use in vivo models.

Pharmacokinetics, drug-likeness, antibacterial and antioxidant activity of secondary metabolites from the roots extracts of Crinum abyssinicum and Calotropis procera and in silico molecular docking study

Crinum abyssinicum and Calotropis procera were traditionally used for the treatment of different diseases such as hypertension, diabetes, hepatitis B, skin infection, anticancer, asthma, fever, and diarrhea. The structures of the compounds were characterized by 1H NMR, 13C NMR, and DEPT-135 spectra. Compounds 1-3 were reported herein for the first time from the species of C. abyssinicum. The DCM/MeOH (1:1) and MeOH roots extracts of C. abyssinicum showed significant inhibitory activity against S. aureus and P. aeruginosa with a mean inhibition zone of 16.67 ± 1.20 and 16.33 ± 0.33 mm, respectively. Compounds 4 and 5 showed promising activity against E. coli with a mean inhibition zone of 17.7  0.8 and 17.7  1.2 mm, respectively. The results of DPPH activity showed the DCM: MeOH (1:1) and MeOH roots extracts of C. abyssinicum inhibited the DPPH radical by 52.86  0.24 % and 45.6  0.11 %, respectively, whereas compound 5 displayed 85.7 % of inhibition. The drug-likeness analysis showed that compounds 2-4 satisfy Lipinski’s rule of five with zero violations. Compounds 2, and 6 showed binding affinities of −6.0, and −6.7 kcal/mol against E. coli DNA gyrase B, respectively, while 3 and 5 showed −5.0 and −5.0 kcal/mol, respectively against human peroxiredoxin 5. Therefore, the in vitro antibacterial, radical scavenging activity along with the molecular docking analysis suggest the potential use of the extracts of C. abyssinicum and compounds 2, 5, 6, and 3, 5 can be considered as promising antibacterial agents and free radical scavengers, respectively.

Virtual screening and molecular dynamic simulations of the antimalarial derivatives of 2-anilino 4-amino substituted quinazolines docked against a Pf-DHODH protein target

Background

The processes of drug development and validation are too expensive to be subjected to experimental trial and errors. Hence, the use of the insilico approach becomes imperative. To this effect, the drug-likeness and pharmacokinetic properties of the ten (10) previously designed derivatives of 2-anilino 4-amino substituted quinazolines were carried out. Their predicted ligand binding interactions were also carried out by docking them against the Plasmodium falciparum dihydroorotate dehydrogenase (Pf-DHODH) protein target, and the stability of the complex was determined through dynamic simulations. The drug-likeness and pharmacokinetic characteristics were estimated using the online SwissADME software, while the Molegro Virtual Docker (MVD) software was used for molecular docking. And the dynamic simulation was performed for the duration of 100 ns to verify the stability of the docked complex, with the aid of a Schrödinger program, Desmond.

Results

The designed derivatives were all found to pass the Lipinski test of drug likeness, while the pharmacokinetic studies result that the skin permeability and molar refractivity values of the derivatives are both within the limits. In addition, except for derivative C-01, most of the derivatives have strong gastrointestinal absorptions and lack Pgp substrate. Furthermore, no derivative inhibited CYP1A2, CYP2C9, or CYP2C19. The docking studies show the better binding affinities between the ligands and Pf-DHODH than those between the atovaquone or chloroquine standards. The derivative C-02, {5-((6,7-dimethoxy-4-((3-nitrobenzyl)amino)quinazolin-2-yl)amino)-2-fluorobenzaldehyde} was found to be the most stable derivative, with a re-rank docking score of - 173.528 kcal/mol and interaction energy of - 225.112 kcal/mol. The dynamic simulation analysis shows that the derivative C-02 forms a stable complex with the protein target over the simulation time.

Conclusions

The ability of these ligands to form hydrogen bonds, as well as various other interactions, was cited as a factor responsible for their better binding affinity. These findings could aid further the development of enhanced antimalarial drugs.

Pharmacokinetic predictions and docking studies of substituted aryl amine-based triazolopyrimidine designed inhibitors of Plasmodium falciparum dihydroorotate dehydrogenase (PfDHODH)

Background

The sixteen (16) designed data set of substituted aryl amine-based triazolopyrimidine were docked against Plasmodium falciparum dihydroorotate dehydrogenase (PfDHODH) employing Molegro Virtual Docker (MVD) software and their pharmacokinetic property determined through SwissADME predictor.

Results

The docking studies shows compound D16, 5-((6-methoxy-5-methyl-[1,2,4]triazolo[1,5-a]pyrimidin-7-yl)amino)benzo[b]thiophen-4-ol to be the most interactive and stable derivative (re-rank score = − 114.205 kcal/mol) resulting from the hydrophobic as well as hydrogen interactions. The hydrogen interaction produced one hydrogen bond with the active residues LEU359 (H∙∙H∙∙O) at a bond distances of 2.2874 Å. All the designed derivatives were found to pass the Lipinski rule of five tests, supporting the drug-likeliness of the designed compounds.

Conclusion

The ADME analysis revealed a perfect concurrence with the Lipinski Ro5, where the derivatives were found to possess good pharmacokinetic properties such as molar refractivity (MR), number of rotatable bonds (nRotb), log of skin permeability (log Kp), blood-brain barrier (BBB). These results could a deciding factor for the optimization of novel antimalarial compounds.

Synthesis, docking study, and in vitro anticancer evaluation of new flufenamic acid derivatives

Novel compounds (6–10) were synthesized and confirmed by spectroscopic analysis, including AT-IR, 1HNMR and CHNS. Their cytotoxic effect was evaluated by MTT assay against two cancer cell lines and two normal cell types. Compound 7 exhibited anticancer activity against MCF-7 breast cancer cell line (GI50 = 63.9 µg/ml, 148 µM), without any effect against A549 lung cancer cells, or the normal cells. Compound 7 caused cytotoxicity in MCF-7 breast cancer cells by apoptotic cell death, as suggested by fragmented nuclei after DAPI staining and agarose gel electrophoresis. In addition, treating MCF-7 cells with compound 7 resulted in an increase in the level of caspase 9 mRNA level, and its activation. Moreover, compound 7-treated MCF-7 cells showed enhanced cytochrome c release from the mitochondria to the cytosol, signifying an induction of the intrinsic apoptotic pathway. Finally, compound 7 exhibited epidermal growth factor receptor (EGFR) kinase inhibitory activity at (EC50 = 0.13 µM), which was matched by molecular docking studies that showed compound 7 might be an important EGFR kinase inhibitor.

Phenolic Compounds as Promising Drug Candidates in Tuberculosis Therapy

Tuberculosis (TB), caused by Mycobacterium tuberculosis (MTB) remains one of the deadliest, infectious diseases worldwide. The detrimental effects caused by the existing anti-TB drugs to TB patients and the emergence of resistance strains of M. tuberculosis has driven efforts from natural products researchers around the globe in discovering novel anti-TB drugs that are more efficacious and with less side effects. There were eleven main review publications that focused on natural products with anti-TB potentials. However, none of them specifically emphasized antimycobacterial phenolic compounds. Thus, the current review’s main objective is to highlight and summarize phenolic compounds found active against mycobacteria from 2000 to 2017. Based on the past studies in the electronic databases, the present review also focuses on several test organisms used in TB researches and their different distinct properties, a few types of in vitro TB bioassay and comparison between their strengths and drawbacks, different methods of extraction, fractionation and isolation, ways of characterizing and identifying isolated compounds and the mechanism of actions of anti-TB phenolic compounds as reported in the literature.

Investigation of the anti-TB potential of selected propolis constituents using a molecular docking approach

Human tuberculosis (TB), caused by Mycobacterium tuberculosis, is the leading bacterial killer disease worldwide and new anti-TB drugs are urgently needed. Natural remedies have long played an important role in medicine and continue to provide some inspiring templates for drug design. Propolis, a substance naturally-produced by bees upon collection of plant resins, is used in folk medicine for its beneficial anti-TB activity. In this study, we used a molecular docking approach to investigate the interactions between selected propolis constituents and four ‘druggable’ proteins involved in vital physiological functions in M. tuberculosis, namely MtPanK, MtDprE1, MtPknB and MtKasA. The docking score for ligands towards each protein was calculated to estimate the binding free energy, with the best docking score (lowest energy value) indicating the highest predicted ligand/protein affinity. Specific interactions were also explored to understand the nature of intermolecular bonds between the most active ligands and the protein binding site residues. The lignan (+)-sesamin displayed the best docking score towards MtDprE1 (−10.7 kcal/mol) while the prenylated flavonoid isonymphaeol D docked strongly with MtKasA (−9.7 kcal/mol). Both compounds showed docking scores superior to the control inhibitors and represent potentially interesting scaffolds for further in vitro biological evaluation and anti-TB drug design.