New syntheses and potential antimalarial activities of new 'retinoid-like chalcones'

Synthesis, spectroscopic (FT-IR, FT-Raman, NMR & UV-Vis), reactive (ELF, LOL, Fukui), drug likeness and molecular docking insights on novel 4-[3-(3-methoxy-phenyl)-3-oxo-propenyl]-benzonitrile by experimental and computational methods

The spectroscopic analysis such as FT-IR, FT-Raman, UV-Vis and NMR are conducted for the synthesized molecule by both experimental and theoretical approach. The theoretical computations were achieved by DFT method with B3LYP functional and 6-311 ++ G (d, P) basis set. Firstly the geometrical parameters obtained by DFT are compared with the related experimental parameters. Experimental FT-IR and FT-Raman spectra of the title molecule have been acquired. The vibrational analysis is conducted and the assignments concerned to the observed bands are mentioned through the potential energy distribution (PED). The GIAO method was employed for theoretical NMR analysis and the results are compared with experimental chemical shifts. In accumulation to these analyses NLO, NBO, FMO and MEP analysis have been conducted to understand the nature of the molecule. ELF and LOL were performed. The drug likeness and molecular docking studies also conducted. The potency of inhibition of molecule against MPRO and PLPRO receptors has been performed using molecular docking studies.

Highlights on Steroidal Arylidene Derivatives as a Source of Pharmacologically Active Compounds: A Review

Steroids constitute a unique class of chemical compounds, playing an important role in physiopathological processes, and have high pharmacological interest. Additionally, steroids have been associated with a relatively low toxicity and high bioavailability. Nowadays, multiple steroidal derivatives are clinically available for the treatment of numerous diseases. Moreover, different structural modifications on their skeleton have been explored, aiming to develop compounds with new and improved pharmacological properties. Thus, steroidal arylidene derivatives emerged as a relevant example of these modifications. This family of compounds has been mainly described as 17β-hydroxysteroid dehydrogenase type 1 and aromatase inhibitors, as well as neuroprotective and anticancer agents. Besides, due to their straightforward preparation and intrinsic chemical reactivity, steroidal arylidene derivatives are important synthetic intermediates for the preparation of other compounds, particularly bearing heterocyclic systems. In fact, starting from arylidenesteroids, it was possible to develop bioactive steroidal pyrazolines, pyrazoles, pyrimidines, pyridines, spiro-pyrrolidines, amongst others. Most of these products have also been studied as anti-inflammatory and anticancer agents, as well as 5α-reductase and aromatase inhibitors. This work aims to provide a comprehensive overview of steroidal arylidene derivatives described in the literature, highlighting their bioactivities and importance as synthetic intermediates for other pharmacologically active compounds.

Ex vivo efficacy of selective chalcone derivatives on reference strains and field isolates of Plasmodium falciparum

The extension of Plasmodium falciparum resistance to existing antimalarial drugs is worrying. Faced with this problem, the search for new and effective molecules is necessary. In this context, six chalcone derivatives (B1, B11, B14, B17, SCA02 and SCA03) were tested on field isolates and then reference strains to evaluate their antiplasmodial activity by using the Rieckmann semi-microtest, recommended by WHO, for in vitro and ex vivo activity tests. Compounds B14 and B17 exhibited promising antiplasmodial activities (IC_50s: 14.41-16.40 μM) regardless of the type of isolate. Compounds B1, B11, SCA02 and SCA03 showed a moderate inhibition of field isolates (IC_50S: 25.63-48.29 μM) and very good activity against reference strains (IC50s: 3.82-10.03 μM). Therefore, more structural modulations should improve their efficiency and make these molecules very good candidates for future effective antimalarial drugs.

Synthesis and Evaluation of Antiplasmodial Activity of 2,2,2-Trifluoroethoxychalcones and 2-Fluoroethoxy Chalcones against Plasmodium falciparum in Culture

A new class of compounds comprising two series of chalcones with 2,2,2-trifluoroethoxy group and 2-fluoroethoxy groups were synthesized and screened for in vitro antiplasmodial activity against Plasmodium falciparum (3D7) using the [³H] hypoxanthine incorporation inhibition assay. Chalcones with 2,2,2-trifluoroethoxy groups substituted on the p- and m-positions of the 1-phenyl ring showed weak antiplasmodial activity, while compounds substituted on the o-position of the 1-phenyl ring displayed enhanced antiplasmodial activity, thus indicating that 2,2,2-trifluoroethoxy groups on the 1-phenyl ring of chalcones show position-dependent antiplasmodial activity. Of the 34 compounds synthesized, chalcones 3a and 3f exhibited significant inhibitory effects, with IC₅₀ values of 3.0 μg/mL and 2.2 μg/mL, respectively. Moreover, these compounds 3a and 3f showed profound antiplasmodial activity in combination with artemisinin in vitro. The most active molecules, 3a, and 3f, were further assessed for their cytotoxicity towards mammalian Vero cells and the selectivity index (SI) values are 8.6, and 8.2 respectively, being considered non-toxic. We also studied the antiplasmodial activity of 2-fluoroethoxychalcones to discern the effect of the number of fluorine atoms in the fluoroethoxy group. Our results showed that chalcones with 2-fluoroethoxy group on the 1-phenyl ring exhibited more enhanced inhibitory effects on the growth of parasites than their trifluoro analogues, which reveals that monofluoroethoxy group is generally more effective than trifluoroethoxy group in the inhibition of parasite growth. Thus o-2,2,2-trifluoroethoxychalcones (Series 3) and 2-fluoroethoxychalcones may serve as good antiplasmodial candidates for future further development.

Synthesis of novel 4'-acylamino modified 21E-benzylidene steroidal derivatives and their cytotoxic activities

A series of 4'-acylamino modified Δ^1,4-pregnadien-21E-benzylidene-3,20-dione derivatives (6a-v) was synthesized from the commercially available progesterone (1). These title compounds were evaluated for their toxicity against brine shrimp (Artemia salina) and cytotoxic activities against two human cancer cell lines (HeLa and MCF-7). The results revealed that compound 6f exhibited promising in vitro cytotoxic activity to the two cancer cell lines and the nature of acylamino functional group in the benzylidene moiety had a significant influence on cytotoxicity.

Solvent-free synthesis of novel steroidal 2-aminopyridines

The synthesis of novel steroidal 3-cyano-2-aminopyridines using enaminonitrile and various primary amines was established under solvent-free condition. Structures of the new compounds were characterized by MS, ¹H and ¹³C NMR data and the structure of 2-aminopyridine of the product 5b was further confirmed by X-ray analysis. The reaction mechanism was proposed on the basis of the key intermediate obtained. The adjacent amine and nitrile groups existed in the final products have the potential for late stage functionalization, which would provide efficient access to steroidal compound collections with structural diversity and complexity.

Modified quaternary ammonium salts as potential antimalarial agents

A series of new quaternary ammonium salts containing a polyconjugated moiety has been synthesized and characterized; their biological activity as potential antimalarial agents was investigated, as well. All compounds were screened against chloroquine resistant W-2 (CQ-R) and chloroquine sensitive, D-10 (CQ-S) strains of Plasmodium falciparum showing IC50 in the submicromolar range and low toxicity against human endothelial cells.

Synthesis and evaluation of chalcone analogues based pyrimidines as angiotensin converting enzyme inhibitors

Hypertension is a widespread and frequently progressive ailment that imparts a foremost threat for cardiovascular and renal disorders. Mammoth efforts are needed for the synthesis of innovative antihypertensive agents to combat this lethal disease. Chalcones have shown antihypertensive activity through inhibition of Angiotensin Converting Enzyme (ACE). Hence, a series of chalcone analogues is synthesized and used as precursor for the synthesis of novel series of pyrimidines. Precursor chalcones were prepared by reacting aldehydes and ketones in presence of sodium hydroxide followed by synthesis of corresponding pyrimidines by reaction with urea in presence of potassium hydroxide. Both groups were then evaluated for their effects on ACE. The results depicted that pyrimidines were more active than chalcones with methoxy (C5 and P5) substitution showing best results to inhibit ACE. Given that chalcone analogues and pyrimidines show a potential as the angiotensin converting enzyme inhibitors.

Synthesis and cytotoxicity of some novel 21E-benzylidene steroidal derivatives

A series of novel derivatives of 21E-benzylidene-pregn-1,4-diene-3,20-dione 7a-g and 21E-benzylidene-4-chloro-pregn-1,4-diene-3,20-dione 8a-g was synthesized from the commercially available progesterone. These title compounds were evaluated for their cytotoxic activity against brine shrimp (Artemia salina) and murine Lewis lung carcinoma cells (LLC). It was found that compounds 7a-g exhibited stronger activities than 8a-g against the brine shrimps, and some of the tested compounds possessed weak inhibition of LLC cells.

Cajachalcone: An Antimalarial Compound from Cajanus cajan Leaf Extract

Cajanus cajan L, a member of the family Fabaceae, was identified from the Nigerian antimalarial ethnobotany as possessing antimalarial properties. The bioassay-guided fractionation of the crude methanol extract of C. cajan leaves was done in vitro using the multiresistant strain of Plasmodium falciparum (K1) in the parasite lactate dehydrogenase assay. Isolation of compound was achieved by a combination of chromatographic techniques, while the structure of the compound was elucidated by spectroscopy. This led to the identification of a cajachalcone, 2′,6′-dihydroxy-4-methoxy chalcone, as the biologically active constituent from the ethyl acetate fraction. Cajachalcone had an IC₅₀ value of 2.0 μg/mL (7.4 μM) and could be a lead for anti-malarial drug discovery.

Synthesis, Characterization, and Biological Activity of 4-(2-Hydroxy-5-(aryl-diazenyl)phenyl)-6-(aryl)pyrimidin-2-ols Derivatives

With the aim of synthesizing new heterocyclic compounds and exploring biological potency, new series of chalcones, that is, 3-(2-hydroxy-5-(aryl-diazenyl)phenyl)-1-(aryl)prop-2-en-1-one and their pyrimidine derivatives, that is, 4-(2-hydroxy-5-(aryl-diazenyl)phenyl)-6-(aryl)pyrimidin-2-ols were synthesized using different aromatic amines and salicylaldehyde as starting moieties. The structures of newly synthesized compounds were confirmed using different spectroscopic techniques such as IR, 1H-NMR, 13C-NMR, and mass spectral analysis, and elemental analysis. The newly synthesized pyrimidines derivatives were screened for their in vitro antibacterial and antifungal activities. It was observed that some of the newly synthesized compounds had shown promising activity against several bacterial and fungal stains. Anti-bacterial activity and anti-fungal activity studies revealed that pyrimidine derivatives consisting of nitro group in their molecular structure possess better activity than their corresponding chalcones.

Anti-inflammatory effects of trans-1,3-diphenyl-2,3-epoxypropane-1-one mediated by suppression of inflammatory mediators in LPS-stimulated RAW 264.7 macrophages

To assess the potential therapeutic properties of trans-1,3-diphenyl-2,3-epoxypropane-1-one (DPEP), its anti-inflammatory effects were investigated in lipopolysaccharide (LPS)-stimulated mouse macrophage (RAW 264.7) cells. DPEP induced dose-dependent reduction of the protein levels of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) and concomitant reduction in the production of NO and prostaglandin E(2) (PGE(2)). Additionally, DPEP suppressed the production of inflammatory cytokines, including tumor necrosis factor-α (TNF-α), interleukin (IL)-1β, and IL-6. We investigated the mechanism by which DPEP inhibits NO and PGE(2) by examining the level of nuclear factor-κB (NF-κB) activation within the mitogen-activated protein kinase (MAPK) pathway, which is an inflammation-induced signaling pathway in RAW 264.7 cells. DPEP inhibited LPS-induced phosphorylation of ERK, JNK, and p38. Furthermore, DPEP inhibited the LPS-induced phosphorylation of inhibitor κB (IκB)-α and NF-κB p50. Taken together, the results of this study demonstrate that DPEP inhibits LPS-stimulated inflammation by blocking the NF-κB and MAPK pathways in macrophages.

Synthesis and antimicrobial studies of chalconyl pregnenolones

An efficient and facile synthesis of 17-chalconyl derivatives of pregnenolone and their evaluation as antimicrobial agents against various microbial strains is reported. The scheme involves the transformation of the starting pregnenolone acetate into pregnenolone, conversion of pregnenolone to the corresponding chalcone derivatives. The compounds 3a-3j showed significant antimicrobial activity against all microbial strains used for testing.

(E)-1-(2,5-Dimethyl-3-thien-yl)-3-(2,4,5-trimeth-oxy-phen-yl)prop-2-en-1-one

In the title compound, C₁₈H₂₀O₄S, the thio­phene and benzene rings are oriented at a dihedral angle of 10.83 (11)°. The central chain makes dihedral angles of 1.86 (13) and 9.25 (12)° with the benzene and thio­phene rings, respectively. In the crystal, mol­ecules are linked through weak inter­molecular C—H⋯O inter­actions. π–π inter­actions are also observed between the benzene rings with a centroid–centroid distance of 3.6832 (12) Å. The slippage between the benzene rings is 0.956 Å.

Evaluation of anti-pigmentary effect of synthetic sulfonylamino chalcone

The 4'-(p-toluenesulfonylamino)-4-hydroxychalcone (TSAHC), which bears inhibitory chemotypes for both alpha-glucosidase and tyrosinase, was evaluated for tyrosinase activity and depigmenting ability relative to compounds designed to only target tyrosianse activity. TSAHC emerged to be a competitive reversible inhibitor of mushroom tyrosinase. More importantly, it was also able to return the melanin content of alpha-melanocyte stimulated by alpha-MSH to base levels unlike other inhibitors that only targeted tyrosinase. The Western blot for expression levels of proteins involved in melanogenesis showed that TSAHC significantly decreased three main tyrosinase related protein in melanin biosynthesis, tyrosinase, TRP-1 and TRP-2.

Synthesis of new chalcone derivatives containing acridinyl moiety with potential antimalarial activity

A series of novel chalcones bearing acridine moiety attached to the amino group in their ring A have been synthesized through noncatalyzed nucleophilic aromatic substitution reaction between various 3'-aminochalcone or 4'-aminochalcones and 9-chloroacridine. The synthesized chalcone derivatives have been characterized and screened for in vitro antimalarial activity against Plasmodium falciparum NF-54. All the chalcones showed complete inhibition at concentration of 10 microg/mL and above while three compounds showed significant inhibition at concentration of 2 microg/mL. The three most active chalcone derivatives were screened for in vivo activity as well, but no significant inhibition in parasitaemia was observed when given intraperitoneally to Plasmodium yoelii infected mice model.

Structural characterization and differentiation of isomeric omega-bromoalkoxy derivatives of (E)-chalcone by means of mass spectrometry

Mass spectrometry with electron ionization and electrospray ionization have been applied to characterize and differentiate the isomeric ortho-, meta- or para-(E)-bromoalkyloxychalcones 1-15. The difference in the values of micro1-micro5 (i.e. the ratio of abundances of the selected fragment ions to those of the molecular ions) in the series of isomeric chalcones studied and the so-called "in-source" fragmentation induced by increasing cone voltage have been found to be important and reliable indicators differentiating the isomers studied.