Design,synthesis and biological evaluation of several aromatic substituted chalcones as antimalarial agents

Malaria is a communicable disease which is caused by protozoan's mainly Plasmodium species (P. falciparum, P. ovale, P. vivax, P. malariae and P. knowlesi). The increasing resistance of Plasmodium to available malarial drugs poses a great responsibility for the researchers in the field of malaria. To overcome this problem of resistance, this study aimed to design and synthesize a new class of antimalarial agent with chalcone as the main moiety. Chalcones, a member of flavanoid family, consist of two aromatic rings of 1,3-diphenyl-2-propen-1-one linked by a three carbon α,β-unsaturated carbonyl system. Five derivatives were designed and among them one was selected. The CC2 was then synthesized by esterification of Para amino acetophenone followed by treatment with hydrazide to form 2-(4 acetylphenoxy)acetohydrazide. This was then coupled with 2-Bromo substituted Diazotized esterified anilines, which was finally linked with substituted benzaldehyde to yield CC2. These were then structurally verified by Infra Red (IR) and Nuclear Magnetic Resonance (NMR) spectroscopy. The chalcone was then tested for in vitro growth inhibition assays using SYBR GREEN-1 Based assay and IC₅₀ values were identified. The compound CC2 showed quite promising antimalarial activity by inhibiting cysteine protease enzyme. The acute toxicity studies of the compound were carried out as per OECD guideline 425 and the results showed no toxic signs and symptoms indicating CC2 as a safe and less toxic compound.     

Design,synthesis, biological evaluation,and molecular docking of novel flavones as H3R inhibitors

A series of novel flavone derivatives were designed, synthesized, and evaluated for their H₃R inhibitory activity. The results showed that four compounds exhibited significant anti‐H₃R activity. Molecular docking experiments indicated that a salt bridge, hydrogen‐bonding, and hydrophobic interactions all contributed to interactions between inhibitors and H₃R.     

Microwave-assisted synthesis and biological evaluation of novel uracil derivatives inhibiting human thymidine phosphorylase

New 5-chloro-6-substituted-uracil derivatives have been prepared by microwave assisted-synthesis and tested in vitro as thymidine phosphorylase inhibitors. One of these compounds showed potent inhibitory activity, with an IC50 value in the submicromolar range. The biological activity of the new compounds is discussed in terms of structure-activity relationship.     

Design, synthesis, and biological evaluation of new-generation taxoids

Novel second-generation taxoids with systematic modifications at the C2, C10, and C3'N positions were synthesized and their structure-activity relationships studied. A number of these taxoids exhibited exceptionally high potency against multidrug-resistant cell lines, and several taxoids exhibited virtually no difference in potency against the drug-sensitive and drug-resistant cell lines. These exceptionally potent taxoids were termed "third-generation taxoids". 19 (SB-T-1214), 14g (SB-T-121303), and 14i (SB-T-1213031) exhibited excellent activity against paclitaxel-resistant ovarian cancer cell lines with mutations in beta-tubulin as well, wherein the drug resistance is mediated by the beta-tubulin mutation. These taxoids were found to possess exceptional activity in promoting tubulin assembly, forming numerous very short microtubules similar to those formed by discodermolide. Taxoids 19 and 14g also showed excellent cytotoxicity against four pancreatic cancer cell lines, expressing three to four multidrug-resistant genes. Moreover, taxoid 19 exhibited excellent in vivo efficacy against highly drug-resistant CFPAC-1 pancreatic as well as DLD-1 human colon tumor xenografts in mice.     

新型喹诺酮类化合物的设计合成与生物活性研究

目的设计合成具有抗肿瘤和抗HIV活性的新型喹诺酮类化合物。方法邻苯二胺衍生物和苯甲酰乙酸乙酯衍生物经缩合关环反应得到目标产物。结果与结论共合成5个未见文献报道的喹诺酮类化合物（7～11）,目标化合物的结构经1H—NMR、ESI-MS谱确证。并利用谱学方法解析了此类化合物的互变异构现象。其中,化合物11具有明显的抗肿瘤及抗HIV活性。     

咪唑酮类化合物的微波辅助合成与抗肿瘤活性研究

目的设计、合成14个咪唑酮类化合物并进行抗肿瘤活性研究。方法运用微波辅助方法完成咪唑酮类新化合物的合成,采用MTT法测定目标化合物体外抑制多种肿瘤细胞的增殖活性,并初步探究其构效关系。结果与结论化合物15c、15e等在体外抑制SGC-7901等瘤株增殖实验中呈现较好活性,其IC50<10μmol·L-1,为进一步的研究奠定了基础。     

Zinc-naproxen complex: synthesis,physicochemical and biological evaluation

Naproxen has a propensity to cause ulcers whereas zinc ions are known to possess an anti-ulcer and anti-inflammatory activity. Therefore, zinc complex of naproxen was prepared by adding zinc sulfate to an aqueous solution of sodium naproxen and its structure was characterized by IR, ¹H NMR and ¹³C NMR, UV, DSC, atomic absorption spectroscopy, and elemental analysis. Anti-inflammatory studies, using the carrageenan-induced hind paw oedema showed that there was a significant difference (P<0.05, ANOVA plotted by Dunnet’s test) in the anti-inflammatory activity of naproxen, its zinc complex, and the physical mixture of naproxen and zinc sulfate. In addition, zinc complex of naproxen showed a significant reduction in ulcers (lesion index (LI)) as compared to that of naproxen and physical mixture of naproxen and zinc sulfate. Thus, the use of the complex may be preferable to naproxen alone.     

Design, synthesis, and biological evaluation of potent c-Met inhibitors

c-Met is a receptor tyrosine kinase that plays a key role in several cellular processes but has also been found to be overexpressed and mutated in different human cancers. Consequently, targeting this enzyme has become an area of intense research in drug discovery. Our studies began with the design and synthesis of novel pyrimidone 7, which was found to be a potent c-Met inhibitor. Subsequent SAR studies identified 22 as a more potent analog, whereas an X-ray crystal structure of 7 bound to c-Met revealed an unexpected binding conformation. This latter finding led to the development of a new series that featured compounds that were more potent both in vitro and in vivo than 22 and also exhibited different binding conformations to c-Met. Novel c-Met inhibitors have been designed, developed, and found to be potent in vitro and in vivo.     

Microwave-assisted synthesis and evaluation of naphthalimides derivatives as free radical scavengers

A facile and efficient microwave-assisted reaction of 1,8-naphthalic anhydride derivatives with primary amines, leading to the synthesis of 1,8-naphthalimides, has been developed. Subsequently, the free radical scavenging properties of the 1,8-naphthalimide derivatives were evaluated against 2,2-diphenyl-1-picrylhydrazyl (DPPH^•). The results showed that the scavenging activities of compounds 2a, NBNA, 3b, and 3c were more efficient than that of the common synthetic antioxidant 2,6-diter-butyl-4-methylphenol (BHT), with IC₅₀ values of 61.9, 54.0, 42.2, and 43.1 μM, respectively. The imide groups introduced at position 4 as well as the nitro functionality at position 3 of the naphthalene moiety were the major contributors to the free radical scavenging activities.     

Design,synthesis, and biological evaluation of multiple targeting antimalarials

Malaria still threatens global health seriously today. While the current discoveries of antimalarials are almost totally focused on single mode-of-action inhibitors, multi-targeting inhibitors are highly desired to overcome the increasingly serious drug resistance. Here, we performed a structure-based drug design on mitochondrial respiratory chain of Plasmodium falciparum and identified an extremely potent molecule, RYL-581, which binds to multiple protein binding sites of P. falciparum simultaneously (allosteric site of type II NADH dehydrogenase, Q_o and Q_i sites of cytochrome bc₁). Antimalarials with such multiple targeting mechanism of action have never been reported before. RYL-581 kills various drug-resistant strains in vitro and shows good solubility as well as in vivo activity. This structure-based strategy for designing RYL-581 from starting compound may be helpful for other medicinal chemistry projects in the future, especially for drug discovery on membrane-associated targets.     

Design, synthesis, and biological evaluation of conformationally restricted rivastigmine analogues

Rivastigmine (1), an acetylcholinesterase (AChE) inhibitor approved in 2000 for the treatment of Alzheimer disease, bears a carbamate moiety in its structure, which is able to react covalently with the active site of the enzyme. Kinetic and structural studies on the interaction of 1 with different cholinesterases have been published, giving deeper, but not definitive, insights on the catalysis mechanism. On the basis of these findings and in connection with our previous studies on a series of benzopyrano[4,3-b]pyrrole carbamates as AChE inhibitors, we designed a series of conformationally restricted analogues of 1 by including the dimethylamino-alpha-methylbenzyl moiety in different tricyclic systems. A superimposition between the conformation of 1 and the carbon derivative 4, as obtained from Monte Carlo simulations, supported the idea that the tricyclic derivatives might act as rigid analogues of 1. The biological profile of 4-9, assessed in vitro against human AChE and BChE, validated our rational design. Compound 5, bearing a sulfur-containing system, showed the highest inhibitory activity, being 192-fold more potent than 1. In the present study, the most potent inhibitors were always methyl derivatives 3-5, endowed with a nanomolar range potency, whereas the ethyl ones were 40 times less potent. A reasonable explanation for this finding might be a steric hindrance effect between the ethyl group of 1 and His440 in the active site, as already suggested by the crystal structure of the complex AChE/1. The unfavorable influence of the carbamic N-alkyl chain on AChE inhibition is less striking when considering BChE inhibition, since BChE is characterized by a bigger acyl binding pocket than AChE. In fact, methyl carbamates 3-5 did not show AChE/BChE selectivity, whereas compounds 6-9 were significantly more potent in inhibiting BChE than AChE activity. At 100 microM, 5 was found to inhibit the AChE-induced aggregation only by 19% likely because it is not able to strongly interact with the peripheral anionic site of AChE, which plays an essential role in the Abeta aggregation mediated by the enzyme but is lacking in BChE structure.     

Microwave-assisted synthesis of some novel and potent antibacterial and antifungal compounds with biological screening

Hydantoins have widely been used as antiarrythmic, anticonvulsant and antitumor agents but recent research has shown a different and novel cytotoxic activity of hydantoins and its derivatives, i.e. anti HIV, antibacterial and antifungal. The following research article deals with the synthesis of hydantoins and their derivatives by Mannich reaction viz., 3-(substituted)-5,5-diphenylimidazolidine-2,4-dione and 1-(substituted)-3,5,5-triphenylimidazolidine-2,4-dione. The synthesised compounds are novel and some of the compounds showed good antibacterial and antifungal activity equivalent to the standards used. All synthetic procedures were carried out in a microwave and not by conventional methods, which led to speedy process and high yield for the same.     

联苯类PD-L1抑制剂的设计合成及生物活性评价

目的设计并合成新型联苯类PD-L1小分子抑制剂。方法以BMS-1018为先导化合物,通过变换苯环上取代基的相对位置,按照生物电子等排原理,结合分子对接技术,设计了3个系列联苯类目标化合物。采用均相时间分辨荧光法评价目标化合物对PD-1/PD-L1结合的抑制活性。结果与结论合成了10个未见文献报道的联苯类目标化合物,结构经~1H-NMR、ESI-MS谱确证。生物活性评价结果表明,大多数目标化合物对PD-L1显示不同程度的抑制活性。其中4个化合物A-1、A-3、A-4和C-2的活性较为突出,值得进一步研究。     

Design, synthesis, and biological evaluation of Plasmodium falciparum lactate dehydrogenase inhibitors

Plasmodium falciparum lactate dehydrogenase (pfLDH) is a key enzyme for energy generation of malarial parasites and is a potential antimalarial chemotherapeutic target. It is known that the oxamate moiety, a pyruvate analog, alone shows higher inhibition against pfLDH than human LDHs, suggesting that it can be used for the development of selective inhibitors. Oxamic acid derivatives were designed and synthesized. Derivatives 5 and 7 demonstrated activities against pfLDH with IC50 values of 3.13 and 1.75 muM, respectively, and have 59- and 7-fold selectivity over mammalian LDH, respectively. They also have micromolar range activities against Plasmodium falciparum malate dehydrogenase (pfMDH), which may fill the role of pfLDH when the activity of pfLDH is reduced. Thus, certain members of these oxamic acid derivatives may have dual inhibitory activities against both pfLDH and pfMDH. It is presumed that dual LDH/MDH inhibitors would have enhanced potential as antimalarial drugs.     

Design,synthesis, and biological evaluation of monopyrrolinone-based HIV-1 protease inhibitors

The design, synthesis, and biological evaluation of a series of HIV-1 protease inhibitors [(-)-6, (-)-7, (-)-23, (+)-24] based upon the 3,5,5-trisubstituted pyrrolin-4-one scaffold is described. Use of a monopyrrolinone scaffold leads to inhibitors with improved cellular transport properties relative to the earlier inhibitors based on bispyrrolinones and their peptide counterparts. The most potent inhibitor (-)-7 displayed 13% oral bioavailability in dogs. X-ray structure analysis of the monopyrrolinone compounds cocrystallized with the wild-type HIV-1 protease provided valuable information on the interactions between the inhibitors and the HIV-1 enzyme. In each case, the inhibitors assumed similar orientations for the P2'-P1 substituents, along with an unexpected hydrogen bond of the pyrrolinone NH with Asp225. Interactions with the S2 pocket, however, were not optimal, as illustrated by the inclusion of a water molecule in two of the three inhibitor-enzyme complexes. Efforts to increase affinity by displacing the water molecule with second and third generation inhibitors did not prove successful. Lack of success with this venture is a testament to the difficulty of accurately predicting the many variables that influence and build binding affinity. Comparison of the inhibitor positions in three complexes with that of Indinavir revealed displacements of the protease backbones in the enzyme flap region, accompanied by variations in hydrogen bonding to accommodate the monopyrrolinone ring. The binding orientation of the pyrrolinone-based inhibitors may explain their sustained efficacy against mutant strains of the HIV-1 protease enzyme as compared to Indinavir.     

Design,synthesis, and biological evaluation of lipophilically modified bisphenol Z derivatives

In the present study, a small library of bisphenol Z (BPZ) derivatives was synthesized and investigated for anti‐proliferative effects in cultured breast and glioblastoma cell lines. Synthesized BPZ derivatives varied in molecular size, polarity, and lipophilicity. Of the 8 derivatives tested, compounds 4 and 6 , both of which displayed the highest degree of lipophilicity, were most active at inducing cell death as determined by the XTT assay. Cell membranes were interrogated using trypan blue staining and were shown to remain intact during treatments with 4 and 6 . Activation of caspase enzymes (3 and/or 7) was noted to occur following treatment with compound 4 . Polar BPZ derivatives, those with a substituted amine or alcohol, were devoid of any inhibitory or proliferative effects. The remaining derivatives seem to lack sufficient lipophilicity to execute an overt toxic effect. Our results suggest that increasing the lipophilic character of BPZ enhances the cytotoxic effects.