3D QSAR studies on antimalarial alkoxylated and hydroxylated chalcones by CoMFA and CoMSIA

Butein Increases Resistance to Oxidative Stress and Lifespan with Positive Effects on the Risk of Age-Related Diseases in Caenorhabditis elegans

Butein is a flavonoid found in many plants, including dahlia, butea, and coreopsis, and has both antioxidant and sirtuin-activating activities. In light of the postulated role of free radicals in aging, we examined the effects of butein on aging and on genetic or nutritional models of age-related diseases in Caenorhabditis elegans. Butein showed radical scavenging activity and increased resistance to oxidative stress in Caenorhabditis elegans. The mean lifespan of Caenorhabditis elegans was significantly increased by butein, from 22.7 days in the untreated control to 25.0 days in the butein-treated group. However, the lifespan-extending effect of butein was accompanied by reduced production of progeny as a trade-off. Moreover, the age-related decline in motility was delayed by butein supplementation. Genetic analysis showed that the lifespan-extending effect of butein required the autophagic protein BEC-1 and the transcription factor DAF-16 to regulate stress response and aging. At the genetic level, expression of the DAF-16 downstream target genes hsp-16.2 and sod-3 was induced in butein-treated worms. Butein additionally exhibited a preventive effect in models of age-related diseases. In an Alzheimer's disease model, butein treatment significantly delayed the paralysis caused by accumulation of amyloid-beta in muscle, which requires SKN-1, not DAF-16. In a high-glucose-diet model of diabetes mellitus, butein markedly improved survival, requiring both SKN-1 and DAF-16. In a Parkinson's disease model, dopaminergic neurodegeneration was completely inhibited by butein supplementation and the accumulation of α-synuclein was significantly reduced. These findings suggest the use of butein as a novel nutraceutical compound for aging and age-related diseases.

Design of new small molecules derived from indolin-2-one as potent TRKs inhibitors using a computer-aided drug design approach

Tropomyosin receptor kinase (TRKs) enzymes are responsible for cancers associated with the neurotrophic tyrosine kinase receptor gene fusion and are identified as effective targets for anticancer drug discovery. A series of small-molecule indolin-2-one derivatives showed remarkable biological activity against TRKs enzymatic activity. These small molecules could have an excellent profile for pharmaceutical application in the treatment of cancers caused by TRKs activity. The aim of this study is to modify the structure of these molecules to obtain new molecules with improved TRK inhibitory activity and pharmacokinetic properties favorable to the design of new drugs. Based on these series, we carried out a 3D-QSAR study. As a result, robust and reliable CoMFA and CoMSIA models are developed and applied to the design of 11 new molecules. These new molecules have a biological activity superior to the most active molecule in the starting series. The eleven designed molecules are screened using drug-likeness, ADMET proprieties, molecular docking, and MM-GBSA filters. The results of this screening identified the T1, T3, and T4 molecules as the best candidates for strong inhibition of TRKs enzymatic activity. In addition, molecular dynamics simulations are performed for TRK free and complexed with ligands T1, T3, and T4 to evaluate the stability of ligand-protein complexes over the simulation time. On the other hand, we proposed experimental synthesis routes for these newly designed molecules. Finally, the designed molecules T1, T2, and T3 have great potential to become reliable candidates for the conception of new drug inhibitors of TRKs.Communicated by Ramaswamy H. Sarma.

3D-QSAR, ADME-Tox, and molecular docking of semisynthetic triterpene derivatives as antibacterial and insecticide agents

In the present work, 27 triterpene derivatives have been subjected to 3D-QSAR, ADME-Tox, and molecular docking for their insecticidal activity. The selected derivatives are previously semi-synthesized based on compounds obtained from Euphorbia resinifera and Euphorbia officinarum latex. The in silico studies were used to predict and to evaluate the antibacterial and insecticidal properties of the 3D structure of triterpene derivatives. The 3D-QSAR models are developed using CoMFA and CoMSIA techniques, and they have showed excellent statistical results (R² = 0.99; Q² = 0.672; R²_pred = 0.91 for CoMFA and R² = 0.97; Q² = 0.61; R²_pred = 0.94 for CoMSIA). The results indicate that the built models are able to describe the relationship between the structure of triterpene derivatives and the pLD₅₀ bioactivity. Based on contour maps obtained from CoMFA and CoMSIA models, 38 new molecules are designed and their pLD₅₀ activities are predicted. The drug-like and ADME-Tox properties of the molecule designed are examined and led to the selection of four molecules (55, 56, 59, 64) as promising antibacterial and insecticidal agents. Compounds 55, 56, 59, and 64 are able to inhibit the MurE (PDB code: 1E8C) and EcR (PDB code: 1R20) proteins involved in the process of antibacterial and insecticidal activities. This hypothesis is confirmed by the implementation of a molecular docking test. This test predicted the most important referential interactions that occur between the structure of triterpene derivatives and the targeted receptors. Among the four docked molecules, three molecules (55, 56, and 59) showed greater stability than the reference molecule 16 inside the MurE and EcR receptors pocket. Therefore, the structure of the three new triterpene derivatives can be adopted as reference for the synthesis of antibacterial drugs and also in the development of insecticides.

Efficient Synthesis of Novel N-[4-Methyl-3-(4-(5-phenyl-1,3,4-oxadiazol-2-yl)phenyl)thiazol-2(3H)-ylidene]benzamide Hybrid Ring System as Potential Antibacterial Agents

BACKGROUND

Heterocyclic compounds display versatile biological applications, so the aim of this paper was to prepare biologically important heterocycles with enhanced bacterial resistance and to evaluate for their various structural features that are responsible for their biological properties.

OBJECTIVE

The objective was to synthesize bacterial resistance compounds with enhanced antibacterial properties.

METHOD

Ester moiety containing thiazole ring was converted into its hydrazide derivatives. These heterocyclic derivatives were cyclized into another ring oxadiazole; hence a hybrid ring system of two biologically active rings was prepared.

RESULT

All the synthesized compounds were characterized by spectroscopic techniques and were screened for their antibacterial potential; they possess significant antibacterial activities.

CONCLUSION

New hybrid heterocyclic ring systems were synthesized by cyclization of hydrazide derivatives by adopting two step strategy in good yields. All the synthesized compounds were evaluated for their antioxidant activities; they showed moderate to significant activities. QSAR and Molecular docking studies were performed to determine the mode of interaction. Experimental and computational data is in accordance with the determined antibacterial activities.

Chalcone hybrids and their antimalarial activity

Malaria, one of the most striking, re-emerging infectious diseases caused by the genus Plasmodium, places a huge burden on global healthcare systems. A major challenge in the control and eradication of malaria is the continuous emergence of increasingly widespread drug-resistant malaria, creating an urgent need to develop novel antimalarial agents. Chalcone derivatives are ubiquitous in nature and have become indispensable units in medicinal chemistry applications due to their diverse biological profiles. Many chalcone derivatives demonstrate potential in vitro and in vivo antimalarial activity, so chalcone could be a useful template for the development of novel antimalarial agents. This review covers the recent development of chalcone hybrids as antimalarial agents. The critical aspects of the design and structure-activity relationship of these compounds are also discussed.

In silico Guided Drug Repurposing: Discovery of New Competitive and Non-competitive Inhibitors of Falcipain-2

Malaria is among the leading causes of death worldwide. The emergence of Plasmodium falciparum resistant strains with reduced sensitivity to the first line combination therapy and suboptimal responses to insecticides used for Anopheles vector management have led to renewed interest in novel therapeutic options. Here, we report the development and validation of an ensemble of ligand-based computational models capable of identifying falcipain-2 inhibitors, and their subsequent application in the virtual screening of DrugBank and Sweetlead libraries. Among four hits submitted to enzymatic assays, two (odanacatib, an abandoned investigational treatment for osteoporosis and bone metastasis, and the antibiotic methacycline) confirmed inhibitory effects on falcipain-2, with Ki of 98.2 nM and 84.4 μM. Interestingly, Methacycline proved to be a non-competitive inhibitor (α = 1.42) of falcipain-2. The effects of both hits on falcipain-2 hemoglobinase activity and on the development of P. falciparum were also studied.

Three-Dimensional Quantitative Structure-Activity Relationships (3D-QSAR) on a Series of Piperazine-Carboxamides Fatty Acid Amide Hydrolase (FAAH) Inhibitors as a Useful Tool for the Design of New Cannabinoid Ligands

Fatty Acid Amide Hydrolase (FAAH) is one of the main enzymes responsible for endocannabinoid metabolism. Inhibition of FAAH increases endogenous levels of fatty acid ethanolamides such as anandamide (AEA) and thus consitutes an indirect strategy that can be used to modulate endocannabinoid tone. In the present work, we present a three-dimensional quantitative structure-activity relationships/comparative molecular similarity indices analysis (3D-QSAR/CoMSIA) study on a series of 90 reported irreversible inhibitors of FAAH sharing a piperazine-carboxamide scaffold. The model obtained was extensively validated (q² = 0.734; r² = 0.966; r²_m = 0.723). Finally, based on the information derived from the contour maps we designed a series of 10 new compounds with high predicted FAAH inhibition (predicted pIC₅₀ of the best-proposed compounds = 12.196; 12.416).

(E)-1-(Anthracen-9-yl)-3-(2-chloro-6-fluoro-phen-yl)prop-2-en-1-one: crystal structure and Hirshfeld surface analysis

In the title compound, C23H14ClFO, the enone moiety adopts an E conformation. The dihedral angle between the benzene and anthracene ring is 63.42 (8)° and an intra-molecular C-H⋯F hydrogen bond generates an S(6) ring motif. In the crystal, mol-ecules are arranged into centrosymmetric dimers via pairs of C-H⋯F hydrogen bonds. The crystal structure also features C-H⋯π and π-π inter-actions. Hirshfeld surface analysis was used to confirm the existence of inter-molecular inter-actions.

Anti-HIV cytotoxicity enzyme inhibition and molecular docking studies of quinoline based chalcones as potential non-nucleoside reverse transcriptase inhibitors (NNRT)

A series of fourteen (A1 - A14) qunioline based chalcones were screened for reverse transcriptase inhibitors (RT) and found potentially active against RT. Bioassay, theoretical and dockings studies with RT (the enzyme required for reverse transcription of viral RNA) results showed that the type and positions of the substituents seemed to be critical for their inhibition against RT. The bromo and chloro substituted chalcone displayed high degree of inhibition against RT. The A4 andA6 showed high interaction with RT, contributing high free binding energy (ΔG -9.30 and -9.13kcal) and RT inhibition value (IC50 0.10μg/ml and 0.11μg/ml).

Synthesis, biological evaluation and QSAR studies of diarylpentanoid analogues as potential nitric oxideinhibitors

A series of forty-five diarylpentadienone analogues were synthesized and were screened for their anti-inflammatory properties. Compound 7d had potent nitric oxide (NO) activity with an IC₅₀ value of 10.24 μM.

Understanding electrostatic and steric requirements related to hypertensive action of AT(1) antagonists using molecular modeling techniques

AT1 receptor is an interesting biological target involved in several important diseases, such as blood hypertension and cardiovascular pathologies. In this study we investigated the main electrostatic and steric features of a series of AT1 antagonists related to hypertensive activity using structure and ligand-based strategies (docking and CoMFA). The generated 3D model had good internal and external consistency and was used to predict the potency of an external test set. The predicted values of pIC50 are in good agreement with the experimental results of biological activity, indicating that the 3D model can be used to predict the biological property of untested compounds. The electrostatic and steric CoMFA maps showed molecular recognition patterns, which were analyzed with structure-based molecular modeling studies (docking). The most and the least potent compounds docked into the AT1 binding site were subjected to molecular dynamics simulations with the aim to verify the stability and the flexibility of the ligand-receptor interactions. These results provided valuable insights on the electronic/structural requirements to design novel AT1 antagonists.

(3E)-11,16-Dioxatricyclo-[15.4.0.0(5,10)]henicosa-1(21),3,5,7,9,17,19-heptaen-2-one

The title compound, C₁₉H₁₈O₃, crystallizes with three mol­ecules (A, B and C) in the asymmetric unit. The carbonyl O atom shows positional disorder over two sites in mol­ecules A and B; the site-occupancy ratios are 0.76 (3):0.24 (3) and 0.86 (3):0.14 (3), respectively. The ethyl­ene fragments in each mol­ecule have an E conformation, while the C—O—C—C torsion angles indicate near planarity. The dihedral angles formed by the aromatic rings are 20.0 (1), 23.7 (1) and 16.1 (1)° for mol­ecules A, B and C, respectively. Intra­molecular C—H⋯O hydrogen bonds occur in each mol­ecule.

Discovery of novel antimalarial compounds enabled by QSAR-based virtual screening

Quantitative structure-activity relationship (QSAR) models have been developed for a data set of 3133 compounds defined as either active or inactive against P. falciparum. Because the data set was strongly biased toward inactive compounds, different sampling approaches were employed to balance the ratio of actives versus inactives, and models were rigorously validated using both internal and external validation approaches. The balanced accuracy for assessing the antimalarial activities of 70 external compounds was between 87% and 100% depending on the approach used to balance the data set. Virtual screening of the ChemBridge database using QSAR models identified 176 putative antimalarial compounds that were submitted for experimental validation, along with 42 putative inactives as negative controls. Twenty five (14.2%) computational hits were found to have antimalarial activities with minimal cytotoxicity to mammalian cells, while all 42 putative inactives were confirmed experimentally. Structural inspection of confirmed active hits revealed novel chemical scaffolds, which could be employed as starting points to discover novel antimalarial agents.

(E)-1-(4-Decyl-oxyphen-yl)-3-(2-hy-droxy-phen-yl)prop-2-en-1-one

In the title compound, C₂₅H₃₂O₃, the enone group adopts an s-cis conformation. The alk­oxy chain is in an all-trans conformation. The dihedral angle between the benzene rings is 7.86 (5)°. In the crystal, mol­ecules are connected by pairs of O—H⋯O hydrogen bonds, forming inversion dimers and giving R₂²(10) rings. Within these dimers, weak C—H⋯O hydrogen bonds form two R₂²(7) rings. In the crystal, the approximately planar mol­ecules [largest deviation for an atom being 0.4737 (12) Å for the terminal C atom of the alk­oxy chain] are arranged in sheets parallel to (20-1). Weak C—H⋯π inter­actions are also observed.

(E)-1-(3-Hy-droxy-phen-yl)-3-[4-(tetra-dec-yl-oxy)phen-yl]prop-2-en-1-one

In the title compound, C(29)H(40)O(3), the enone moiety adopts an s-cis conformation. The dihedral angle between the benzene rings is 4.33 (5)° The least-squares mean line through the tetra-decyl side chain forms a dihedral angle of 83.99 (7)° with the normal to the attached benzene ring. In the crystal, O-H⋯O and C-H⋯O hydrogen bonds involving the keto and the hy-droxy O atoms form ribbons along [-41-1]. The crystal structure also features C-H⋯π inter-actions.

Investigation of antigen-antibody interactions of sulfonamides with a monoclonal antibody in a fluorescence polarization immunoassay using 3D-QSAR models

A three-dimensional quantitative structure-activity relationship (3D-QSAR) model of sulfonamide analogs binding a monoclonal antibody (MAb_SMR) produced against sulfamerazine was carried out by Distance Comparison (DISCOtech), comparative molecular field analysis (CoMFA), and comparative molecular similarity indices analysis (CoMSIA). The affinities of the MAb_SMR, expressed as Log₁₀IC₅₀, for 17 sulfonamide analogs were determined by competitive fluorescence polarization immunoassay (FPIA). The results demonstrated that the proposed pharmacophore model containing two hydrogen-bond acceptors, two hydrogen-bond donors and two hydrophobic centers characterized the structural features of the sulfonamides necessary for MAb_SMR binding. Removal of two outliers from the initial set of 17 sulfonamide analogs improved the predictability of the models. The 3D-QSAR models of 15 sulfonamides based on CoMFA and CoMSIA resulted in q²_cv values of 0.600 and 0.523, and r² values of 0.995 and 0.994, respectively, which indicates that both methods have significant predictive capability. Connolly surface analysis, which mainly focused on steric force fields, was performed to complement the results from CoMFA and CoMSIA. This novel study combining FPIA with pharmacophore modeling demonstrates that multidisciplinary research is useful for investigating antigen-antibody interactions and also may provide information required for the design of new haptens.

(E)-3-(Furan-2-yl)-1-(4-meth-oxy-phen-yl)prop-2-en-1-one

In the title mol­ecule, C₁₄H₁₂O₃, the prop-2-en-1-one unit forms dihedral angles of 12.96 (5) and 7.89 (7)° with the 4-meth­oxy­phenyl group and the furan ring, respectively. The furan and benzene rings form a dihedral angle of 8.56 (5)°. In the crystal, C—H⋯π and π–π inter­actions are observed between the benzene and heterocyclic rings [centroid–centroid distance = 3.760 (1) Å].

(E)-1-[4-(Hex-yloxy)phen-yl]-3-(4-hy-droxy-phen-yl)prop-2-en-1-one

In the title compound, C₂₁H₂₄O₃, inter­molecular O—H⋯O and C—H⋯O inter­actions form bifurcated acceptor bonds, generating R₂¹(6) ring motifs. These ring motifs link the mol­ecules into extended chains along [010]. The crystal structure is further stabilized by C—H⋯π inter­actions.

(E)-1-[4-(Hex-yloxy)phen-yl]-3-(3-hy-droxy-phen-yl)prop-2-en-1-one

There are two mol­ecules in the asymmetric unit of the title compound, C₂₁H₂₄O₃, in which the dihedral angles between the aromatic rings are 6.4 (1) and 7.0 (1)°. The enone moiety of both mol­ecules adopts an s–cis configuration. In the crystal, inter­molecular O—H⋯O and C—H⋯O inter­actions to the same acceptor O atom generate R₂¹(6) ring motifs and further C—H⋯O inter­actions generate R₂²(8) ring motifs. Topologically, the R₂¹(6) and R₂²(8) ring motifs are arranged alternately, forming [001] chains of mol­ecules. The crystal structure is further stabilized by C—H⋯π inter­actions.

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.

(E)-3-[4-(Hex-yloxy)phen-yl]-1-(4-hydroxy-phen-yl)prop-2-en-1-one

In the title compound, C₂₁H₂₄O₃, the enone group adopts an s–cis conformation. The planes of the aromatic rings are inclined at an angle of 6.1 (1)°. The alk­oxy tail is not linear, with the maximum deviation from the least-squares plane being 0.375 (2) Å. Mol­ecules are connected into extended chains along the a axis through O—H⋯O_carbon­yl hydrogen bonds and are inter­linked via C—H⋯O inter­actions to form a two-dimensional array parallel to the ab plane.

(E)-3-[4-(Hex-yloxy)phen-yl]-1-(2-hydroxy-phen-yl)prop-2-en-1-one

In the title compound, C(21)H(24)O(3), the conformation of the enone group is s-cis. The benzene rings are inclined at an angle of 7.9 (1)°. The alk-oxy tail is planar, with a maximum deviation from the least-squares plane of 0.009 (2) Å, and adopts a trans conformation throughout. An intra-molecular O-H⋯O inter-action between the keto and hydr-oxy groups forms S(6) ring motifs. In the crystal, mol-ecules are arranged in a head-to-tail manner down the a axis and are subsequently stacked along the b axis, forming mol-ecular sheets parallel to the ab plane. The crystal structure is further stabilized by weak C-H⋯π inter-actions and short C⋯O [3.376 (2) Å] contacts.

(E)-3-[4-(Dodec-yloxy)phen-yl]-1-(2-hydroxy-phen-yl)prop-2-en-1-one

In the title compound, C₂₇H₃₆O₃, the asymmetric unit consists of two crystallographically independent mol­ecules. The aromatic rings form dihedral angles of 17.1 (2) and 17.6 (2)° in the two molecules. In both mol­ecules, the enone groups adopt an s–cis conformation and the alkoxyl chains are in trans conformations curving out of the zigzag plane. Intra­molecular O—H⋯O hydrogen bonds involving the keto and hydr­oxy groups generate S(6) ring motifs. The mol­ecules are stacked alternately in a head-to-tail fashion along the a axis and the crystal structure is stabilized by weak C—H⋯π inter­actions. The crystal studied was a non-merohedral twin, the ratio of components being 0.788 (2):0.212 (2).

(E)-3-[4-(Dec-yloxy)phen-yl]-1-(4-hydroxy-phen-yl)prop-2-en-1-one

In the title compound, C₂₅H₃₂O₃, the enone group adopts an s–cis conformation. The alk­oxy unit is nearly planar and is in a trans conformation. The two benzene rings make a dihedral angle of 18.87 (9)°. In the crystal structure, mol­ecules are linked into chains running along the a axis by inter­molecular O—H⋯O hydrogen bonds involving the hydr­oxy and keto groups. The chains are crosslinked along the b axis via C—H⋯O hydrogen bonds, forming a two-dimensional network parallel to the ab plane.

(E)-3-(4-Decyl-oxyphen-yl)-1-(2-hydroxy-phen-yl)prop-2-en-1-one

In the title compound, C₂₅H₃₂O₃, the enone group is in an s–cis configuration. The dihedral angle between the benzene rings is 8.84 (7)°. An intra­molecular O—H⋯O inter­action between the keto and hydr­oxy groups forms an S(6) ring motif. Inter­molecular C—H⋯O inter­actions link the mol­ecules into supra­molecular chains along the c axis which are subsequently stacked down the b axis; the crystal structure is further consolidated by C—H⋯π inter­actions.

(E)-3-(4-Hexyl-oxyphen-yl)-1-(3-hydroxy-phen-yl)prop-2-en-one

In the title compound, C(21)H(24)O(3), the enone unit is in the s-cis configuration. The dihedral angle between the benzene rings is 2.18 (4)°. In the crystal, mol-ecules are linked by pairs of O-H⋯O inter-molecular hydrogen bonds, forming inversion dimers. The crystal structure is also consolidated by C-H⋯π inter-actions.

(E)-1-(4-Decyl-oxyphen-yl)-3-(4-hydroxy-phen-yl)prop-2-en-1-one

In the title compound, C(25)H(32)O(3), the asymmetric unit contains two crystallographically independent mol-ecules: both enone groups adopt an s-cis configuration. In the crystal, O-H⋯O and C-H⋯O inter-molecular inter-actions form bifurcated hydrogen bonds, which generate R(1) (2)(6) ring motifs. These inter-molecular inter-actions link the mol-ecules into one-dimensional chains along the [10] direction. The crystal structure is further stabilized by C-H⋯π inter-actions.

Synthesis and spectral characterization of 2'-hydroxy chalconate complexes of ruthenium(II) and their catalytic and biological applications

The reactions of [RuHCl(CO)(B)(EPh3)2] (B=EPh3 or pyridine; E=P or As) and 2'-hydroxychalcones in 1:2 ratio led to the formation of [Ru(CO)(B)(L)2] (B=PPh3, AsPh3 or Py; L=2'-hydroxychalcones). The new complexes have been characterized by analytical and spectral (IR, electronic and 1H NMR) data. They have been assigned an octahedral structure. The new complexes were found to catalyze the oxidation of alcohols to aldehydes using N-methylmorpholine-N-oxide as co-oxidant. All the new complexes were found to be active against bacteria such as E. coli, Salmonella typhi and fungi Aspergillus niger. The activity was compared with standard Streptomycin or Bavistin.

Quantitative structure–selectivity relationship for M2 selectivity between M1 and M2 of piperidinyl piperidine derivatives as muscarinic antagonists

Muscarinic M2 receptor antagonists with high subtype selectivity (M2/M1) will decrease the toxicity in central nervous system in treatment of AD. The exploration of quantitative structure-selectivity relationship (QSSR) to muscarinic M2 receptor antagonists will provide design information for drug with fewer side effects. In this paper, CoMFA models of pK(i)(M1), pK(i)(M2) and p[K(i)(M2)/K(i)(M1)] (pK(i)(M2)-pK(i)(M1)) were used to study the subtype selectivity (M2/M1) of piperidinyl piperidine derivatives as muscarinic M2 subtype receptor antagonists. The parameters of the three models are: 0.633, 0.636 and 0.726 for cross-validated r(2) (r(cv)(2)), 0.109, 0.204 and 0.09 for the Standard error of estimate (SD), respectively. The results show the model of p[K(i)(M2)/K(i)(M1)] is the best one for design of piperidinyl piperidine derivatives as muscarinic antagonists with high subtype selectivity (M2/M1).

Recent advances in antimalarial drug development

Malaria caused by protozoa of the genus Plasmodium, because of its prevalence, virulence, and drug resistance, is the most serious and widespread parasitic disease encountered by mankind. The inadequate armory of drugs in widespread use for the treatment of malaria, development of strains resistant to commonly used drugs such as chloroquine, and the lack of affordable new drugs are the limiting factors in the fight against malaria. These factors underscore the continuing need of research for new classes of antimalarial agents, and a re-examination of the existing antimalarial drugs that may be effective against resistant strains. This review provides an in-depth look at the most significant progress made during the past 10 years in antimalarial drug development.